ZCD
GATE
LM3450/50A
GND
COMP
FB
HOLD
CS
DIM
FLT2
FLT1
PWM
BIAS
RETURN
SECONDARY
LED DRIVER
OPTICAL
ISOLATION
RETURN
EMI FILTER
PWM
AC
INPUT
LED
LOAD
VCC
VAC
ISEN
VREF
VADJ
HOLD
LM3450
www.ti.com
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
LED Drivers with Active Power Factor Correction and Phase Dimming Decoder
Check for Samples: LM3450
1FEATURES DESCRIPTION
The LM3450/50A is a power factor controller (PFC)
2• Critical Conduction Mode PFC with separate phase dimming decoder. The PFC
• Over-Voltage Protection regulates the output voltage while maintaining
• Feedback Short Circuit Protection excellent power factor. The phase dimming decoder
interprets the phase angle and remaps it to a 500Hz
• 70:1 PWM Decoded From Phase Dimmer PWM output. This device is ideal for implementing a
• Analog Dimming dimmable off-line LED driver for 10-100W loads.
• Programmable Dimming Range The phase dimming decoder has several unique
• Digital Angle and Dimmer Detection features. The input-output mapping is programmable
• Dynamic Holding Current for design flexibility, while a dynamic filter and
variable sampling rate provide smooth uniform
• Smooth Dimming Transitions dimming. A dynamic hold circuit ensures that the
• Low Power Operation phase dimmer angle is decoded properly while
• Start-Up Pre-Regulator Bias minimizing extra power loss.
• Precision Voltage Reference The LM3450A is identical to the LM3450 with the
exception of one circuit operation. The dynamic hold
APPLICATIONS current is sampled in the LM3450 while it
continuously operates in the LM3450A. This
• Dimmable Downlights, Troffers, and Lowbays difference between the two devices defines the
• Large Form Factor Bulbs suitable applications for each. The following is a
• Indoor and Outdoor Area SSL general guideline for choosing the correct device:
• Power Supply PFC • Any 120V designs with POUT > 15W - LM3450A
• Any 230V designs with POUT > 25W - LM3450A
• 120V 2-Stage designs with POUT < 15W - LM3450
• 230V 2-Stage designs with POUT < 25W - LM3450
Typical Application
1Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
2All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date. Copyright © 2010–2013, Texas Instruments Incorporated
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
VCC
VREF
ZCDFLT2
DIM GATE
VAC CS
COMP GND
FB ISEN
HOLDVADJ
FLT1
BIAS
9
10
11
12
13
14
15
16
8
7
6
5
4
3
2
1
LM3450
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
www.ti.com
Connection Diagram
Top View
Figure 1. 16-Lead TSSOP
Package Number PW
PIN DESCRIPTIONS
Pin Name Description Application Information
Reference Output: Connect directly to VADJ or to resistor divider feeding VADJ
1 VREF 3V Reference and to necessary external circuits.
Analog Dim and Phase Dimming Range Input: Connect directly to VREF to force
standard 70% phase dimming range. Connect to resistor divider from VREF to
2 VADJ Analog Adjust extend usable range of some phase dimmers or for analog dimming. Connect to
GND for low power mode.
Ramp Comparator Input: Connect a series resistor from FLT1 capacitor and a
3 FLT2 Filter 2 capacitor to GND to establish second filter pole.
Angle Decoder Output: Connect a series resistor to a capacitor to GND to
4 FLT1 Filter 1 establish first filter pole.
Open Drain PWM Dim Output: Connect to dimming input of output stage LED
5 DIM 500 Hz PWM Output driver (directly or with isolation) to provide decoded dimming command.
Multiplier and Angle Decoder Input: Connect to resistor divider from rectified AC
6 VAC Sampled Rectified Line line.
Error Amplifier Output and PWM Comparator Input: Connect a capacitor to GND
7 COMP Compensation to set the compensation.
Error Amplifier Inverting Input: Connect to output voltage via resistor divider to
control PFC voltage loop for non-isolated designs. Connect a 5.11kΩresistor to
8 FB Feedback GND for isolated designs (bypasses error amplifier). Also includes over-voltage
protection and shutdown modes.
Input Current Sense Non-Inverting Input: Connect to diode bridge return and
9 ISEN Input Current Sense resistor to GND to sense input current for dynamic hold. Connect a 0.1µF
capacitor and Schottky diode to GND, and a 0.22µF capacitor to HOLD.
10 GND Power Ground System Ground
MosFET Current Sense Input: Connect to positive terminal of sense resistor in
11 CS Current Sense PFC MosFET source.
12 GATE Gate Drive Gate Drive Output: Connect to gate of main power MosFET for PFC.
Power Supply Input: Connect to primary bias supply. Connect a 0.1µF bypass
13 VCC Input Supply capacitor to ground.
Demagnetization Sense Input: Connect a 100kΩresistor to transformer/inductor
14 ZCD Zero Crossing Detector winding to detect when all energy has been transferred.
Open Drain Dynamic Hold Input: Connect to holding resistor which is connected
15 HOLD Dynamic Hold to source of passFET.
Pre-regulator Gate Bias Output: Connect to gate of passFET and through
16 BIAS Pre-regulator Gate Bias resistor to rectified AC (drain of passFET) to aid with startup.
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SNVS681D –NOVEMBER 2010–REVISED MAY 2013
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
ABSOLUTE MAXIMUM RATINGS (1)(2)
VCC, HOLD, DIM, BIAS -0.3V to 25.0V
HOLD Power 250 mW Continuous
BIAS Current 5.0mA Continuous
ZCD Current +/- 10mA
COMP, FB, VAC, FLT1, FLT2, VREF, CS, VADJ -0.3V to 7.0V
ISEN -7.0V to 7.0V
GATE -0.3V to 18V Continuous
-2.5V for 100ns
20.5V for 100ns
-1mA to +1mA Continuous
Continuous Power Dissipation Internally Limited
Maximum Junction Temperature Internally Limited
Storage Temperature Range -65°C to +150°C
Maximum Lead Temperature (Solder and Reflow) (3) 260°C
ESD Susceptibility (4) HBM 2kV
MM 200V
FICDM 750V
(1) Absolute Maximum Ratings indicate limits beyond which damage to the component may occur. Operating Ratings are conditions under
which operation of the device is specified and do not imply ensured performance limits. For specified performance limits and associated
test conditions, see the Electrical Characteristics table. All voltages are with respect to the potential at the GND pin, unless otherwise
specified.
(2) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/Distributors for availability and
specifications.
(3) Refer to http://www.ti.com/packaging for more detailed information and mounting techniques.
(4) Human Body Model, applicable std. JESD22-A114-C. Machine Model, applicable std. JESD22-A115-A. Field Induced Charge Device
Model, applicable std. JESD22-C101-C.
OPERATING CONDITIONS (1)
VCC Range 8.5V to 20V
Junction Temperature Range -40°C to +125°C
(1) Absolute Maximum Ratings indicate limits beyond which damage to the component may occur. Operating Ratings are conditions under
which operation of the device is specified and do not imply ensured performance limits. For specified performance limits and associated
test conditions, see the Electrical Characteristics table. All voltages are with respect to the potential at the GND pin, unless otherwise
specified.
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LM3450
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
www.ti.com
ELECTRICAL CHARACTERISTICS(1)
Unless otherwise specified VCC = 14V. Specifications in standard type face are for TJ= 25°C and those with boldface type
apply over the full Operating Temperature Range ( TJ=−40°C to +125°C). Typical values represent the most likely
parametric norm at TA= TJ= +25°C, and are provided for reference purposes only.
Symbol Parameter Conditions Min(2) Typ(3) Max(2) Units
SUPPLY VOLTAGE INPUT (VCC)
VCC-RISE Controller Enable Threshold VCC Rising 12.2 13.0 13.6 V
VCC-FALL Controller Disable Threshold VCC falling 7.4 7.9 8.5
Glitch Filter Delay 9 µs
Turn-on Delay 40
IQVCC Quiescent Current No Switching 1.6 mA
IQ-SD VCC Shutdown Current VFB = 0V 515 625 µA
ERROR AMPLIFIER & COMPENSATION (FB, COMP)
VFB FB Reference (Normal Operation) 2.43 2.50 2.57 V
Input Bias Current VFB = 2.5V 100 nA
GMTransconductance VFB =2.5V 69 115 161 µS
Output Source / Sink Capability 60 85 110 µA
FB Pull-up Current Source VFB < 1.8V 43 51 59
COMP Pull-up Resistor 5 kΩ
VCMP-B COMP Low Threshold (Burst) VCMP Falling VTHM -0.08 V
COMP Low Hysteresis 20
VFB-SD Low Threshold (Shutdown) VFB Falling 150 168 186
FB Low Hysteresis 20 mV
VFB-EAD FB Mid Threshold (EA Disabled) VFB Falling 328 346 368
FB Mid Hysteresis 20
VFB-OV FB High Threshold (Over-voltage) 1.20 x VFB 1.22 x VFB V
COMP Pre-bias Source Current VCMP= 0.5V 415 µA
VTHM Minimum COMP Voltage (Normal) 1.47 V
ANGLE DEMODULATION & MULTIPLIER (COMP, VAC)
VAC-DET VAC Angle Detection Threshold 334 356 378 mV
Angle Demodulation Delay Time Both edges 8 µs
VAC Dynamic Input Voltage Range 0 to 5.5 V
COMP Dynamic Input Voltage Range VTHM to
VTHM+2
VAC Input Impedance 500 kΩ
KMMultiplier Gain (Includes Internal VAC = 3V, VCMP =0.5 1/V
Resistor Divider) VTHM+1.5V
ZERO CURRENT DETECTOR (ZCD)
VZCD-RIS ZCD Input Threshold VZCORising 1.45 1.5 1.55 V
Hysteresis 150 200 250 mV
Delay to Output 135 ns
VZCD-H Positive Clamp Voltage IZCO = 1mA 6.0 V
VZCD-L Negative Clamp Voltage IZCO = –50µA 0.61
PWM COMPARATOR (CS)
VOS PWM Comparator Input Offset Voltage 30 mV
(1) Absolute Maximum Ratings indicate limits beyond which damage to the component may occur. Operating Ratings are conditions under
which operation of the device is specified and do not imply ensured performance limits. For specified performance limits and associated
test conditions, see the Electrical Characteristics table. All voltages are with respect to the potential at the GND pin, unless otherwise
specified.
(2) All limits specified at room temperature (standard typeface) and at temperature extremes (bold typeface). All room temperature limits are
100% production tested. All limits at temperature extremes are specified via correlation using standard Statistical Quality Control (SQC)
methods. All limits are used to calculate Average Outgoing Quality Level (AOQL).
(3) Typical numbers are at 25°C and represent the most likely norm.
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SNVS681D –NOVEMBER 2010–REVISED MAY 2013
ELECTRICAL CHARACTERISTICS(1) (continued)
Unless otherwise specified VCC = 14V. Specifications in standard type face are for TJ= 25°C and those with boldface type
apply over the full Operating Temperature Range ( TJ=−40°C to +125°C). Typical values represent the most likely
parametric norm at TA= TJ= +25°C, and are provided for reference purposes only.
Symbol Parameter Conditions Min(2) Typ(3) Max(2) Units
PWM Comparator Input Bias Current 20 nA
VLIM CS Current Limit Threshold 1.40 1.50 1.60 V
CS Delay to Output 100 ns
CS Blanking Sinking Impedance 1 kΩ
tLEB Leading Edge Blanking (LEB) Time 140 ns
ANALOG ADJUST INPUT (VADJ)
VADJ-LP VADJ Low Threshold (Low Power Mode) VADJ Falling 56 75 mV
VADJ Low Hysteresis 50
VADJ Pull-up Current Source 1 µA
VADJ Open Voltage VADJ Open 3 V
DYNAMIC HOLD CIRCUIT (HOLD, ISEN)
RDSON-HD HOLD MosFET On-Resistance ISEN Short to GND 22 30 42 Ω
VSEN-REF ISEN Reference Voltage 162 200 232 mV
ISEN Bias Current 5 µA
PRE-REGULATOR GATE DRIVE OUTPUT (BIAS)
VBIAS BIAS High Voltage @ 100µA VCC < VCC-FALL 18.8 21 22.6 V
BIAS Low Voltage @ 100µA VCC > VCC-RISE 13.5 14 14.5
GATE DRIVER OUTPUT (GATE)
VGATE-H GATE Voltage High IGATE = 20mA 11.5 V
IGATE = 200mA 10.5
GATE Pull Down Resistance 2 8Ω
GATE Peak Current (4)±1.5 A
REFERENCE VOLTAGE OUTPUT (VREF)
VREF Reference Voltage No Load 2.85 33.15 V
Current Limit 1.5 2.0 3.0 mA
DIMMING OUTPUT (DIM, FLT1, FLT2)
FLT1 Output Impedance Standby Mode 500 kΩ
Transition mode 1.6
Triangle Waveform Compared to FLT2 High 1.49 V
Low 15 mV
fDIM DIM Frequency 180 460 700 Hz
OFF-TIMERS
tOFF-MAX Maximum Off-Time (Normal Operation) 340 µs
tOFF-LP Off-Time (Low Power Mode) 42
THERMAL SHUTDOWN
Thermal Limit Threshold (4) 160 °C
Thermal Limit Hysteresis 20
THERMAL RESISTANCE
θJA Junction to Ambient TSSOP-16(4)(5) 38.0 °C/W
θJC Junction to Case 10.0
(4) These electrical parameters are specified by design, and are not verified by test.
(5) Junction-to-ambient thermal resistance is highly board-layout dependent. In applications where high maximum power dissipation exists,
namely driving a large MOSFET at high switching frequency from a high input voltage, special care must be paid to thermal dissipation
issues during board design. In high-power dissipation applications, the maximum ambient temperature may have to be derated.
Maximum ambient temperature (TA-MAX) is dependent on the maximum operating junction temperature (TJ-MAX-OP = 125°C for Q1, or
150°C for Q0), the maximum power dissipation of the device in the application (PD-MAX), and the junction-to ambient thermal resistance
of the package in the application (θJA), as given by the following equation: TA-MAX = TJ-MAX-OP – (θJA × PD-MAX).
Copyright © 2010–2013, Texas Instruments Incorporated Submit Documentation Feedback 5
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TEMPERATURE (°C)
GM (S)
140
130
120
110
100
90
-50 -14 22 58 94 130
TEMPERATURE (°C)
VBIAS (V)
25
22
19
16
13
10
-50 -14 22 58 94 130
BIAS High
BIAS Low
TEMPERATURE (°C)
VLIM (V)
1.505
1.503
1.501
1.499
1.497
1.495
-50 -14 22 58 94 130
TEMPERATURE (°C)
KM
0.510
0.504
0.498
0.492
0.486
0.480
-50 -14 22 58 94 130
TEMPERATURE (°C)
RDS-ON ()
40
36
32
28
24
20
-50 -14 22 58 94 130
TEMPERATURE (°C)
tLEB (ns)
150
146
142
138
134
130
-50 -14 22 58 94 130
LM3450
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
www.ti.com
TYPICAL PERFORMANCE CHARACTERISTICS
TA=+25°C and VCC = 14V unless otherwise specified
HOLD RDSON vs. Junction Temperature Leading Edge Blanking vs. Junction Temperature
Figure 2. Figure 3.
Current Limit Threshold vs. Junction Temperature Multiplier Gain vs. Junction Temperature
VAC = 3V; VCMP = VTHM + 1.5V VAC = 3V; VCMP = VTHM + 1.5V
Figure 4. Figure 5.
Transconductance BIAS Voltage vs. Junction Temperature
VFB = 2.5V; ΔVFB = 50mV High @ VCC < VCCFALL; Low @ VCC > VCCRISE
Figure 6. Figure 7.
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TEMPERATURE (°C)
VSEN-REF (mv)
205
203
201
199
197
195
-50 -14 22 58 94 130
TEMPERATURE (°C)
VVAC-REF (mv)
357.0
356.6
356.2
355.8
355.4
355.0
-50 -14 22 58 94 130
TEMPERATURE (°C)
VREF (V)
3.03
3.02
3.01
3.00
2.99
2.98
-50 -14 22 58 94 130
TEMPERATURE (°C)
VFB (V)
2.510
2.506
2.502
2.498
2.494
2.490
-50 -14 22 58 94 130
TEMPERATURE (°C)
VCC (V)
14
13
11
10
8
7
-50 -14 22 58 94 130
UVLO Rising
UVLO Falling
TEMPERATURE (°C)
IQ (#A)
580
560
540
520
500
480
-50 -14 22 58 94 130
LM3450
www.ti.com
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
TA=+25°C and VCC = 14V unless otherwise specified
VCC UVLO Threshold vs. Junction Temperature Shutdown Current vs. Junction Temperature
Figure 8. Figure 9.
VREF Reference vs. Junction Temperature FB Reference vs. Junction Temperature
Figure 10. Figure 11.
ISEN Reference vs. Junction Temperature VAC Detection Threshold vs. Junction Temperature
Figure 12. Figure 13.
Copyright © 2010–2013, Texas Instruments Incorporated Submit Documentation Feedback 7
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0.0 0.2 0.4 0.6 0.8 1.0
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
DIM PIN DUTY CYCLE
DEMODULATED VAC PIN DUTY CYCLE
VADJ=3V
2V
1.5V
1V
0.5V
2.5V
VFB (V)
GM (Ps)
250
200
150
100
50
0
1.5 2.0 2.5 3.0 3.5
VCMP (V)
VCS (V)
4.90
3.92
2.94
1.96
0.98
0.00
1.0 1.8 2.6 3.4 4.2 5.0
VAC = 3V
VAC = 4V
VAC = 2V
VAC = 1V
VAC = 0.1V
VAC = 0.5V
LM3450
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
www.ti.com
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
TA=+25°C and VCC = 14V unless otherwise specified
Transconductance vs. VFB Current Sense Threshold vs. VCOMP and VAC
Figure 14. Figure 15.
Decoder Mapping from VAC to DIM
Figure 16.
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+
-
+
-
+
-
ANGLE
DEMOD
DIM
R
2R
COMP
FB
2.7V
2.5V
346mV
50 PA
1 PA
168mV
3V
75 mV
FLT1
FLT2
500 k:
+
-
Low Power
VCCUV
CS
GND
ZCD
HOLD
GATE
+
-
5 PA
5 k:
40 k:
+
-
LEB
1.5V
LOGIC
&
CONTROL
Over Voltage
Shutdown
Error Amp
Disable
5V
+
-
PWM
Current Limit
Multiplier
1.5V
Zero Crossing
6V
BIAS
VCCUV
6V
14V
INTERNAL
REGULATORS
VCC UVLO
+
-
3V
Q
Q
R
S
THERMAL
SHUTDOWN
10V
LEB
VCCUV
Sampled Hold
Transition
140 ns
Low Power
MAXIMUM
OFF-TIME
(340 Ps, 42 Ps)
1 k:
VCCUV
COMP
PRE-BIAS
Amplitude Adjust
Low Power Reset Off-Timer
Timer Expired
+
-
+
-
+
-
+
-
+
-Burst
1.4V
Burst
1.5V
SAMPLE and
LOG REMAP
DIN
DOUT
500 Hz Triangle
DIN
DOUT
VCC
ISEN
VREF
VAC
VADJ
LM3450A has
Continuous Hold
*LM3450 and LM3450A are identical except where indicated in blue
LM3450
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SNVS681D –NOVEMBER 2010–REVISED MAY 2013
BLOCK DIAGRAM
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ZCD
GATE
LM3450/50A
GND
COMP
FB
HOLD
CS
DIM
FLT2
FLT1
PWM
TO OPTO
BIAS
+
-
RETURN
RETURN
AC
INPUT 24V
RZCD
RHLD
RBS
CVCC
QPS
COUT
VCC
ISEN
VREF
VADJ
VAC
CHLD CSEN
CCMP
CF1
CF2
CREF
CPFC
RAD2
RAD1
RF2
RF1
RAC2
RAC1
RFB1
RCS
RSEN
QSW
DSW
FLYBACK
OUTPUT
FEEDBACK
FROM OPTO
LM3450
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
www.ti.com
Figure 17. Typical Flyback Application
THEORY OF OPERATION
The LM3450/50A is a single device with both power factor control (PFC) and phase dimming decoder functions.
This device is designed to control isolated flyback converters and provide active power factor correction. In
addition to being a PFC, the LM3450/50A can interpret a phase dimming (frequently called triac dimming) input
and provide a corresponding PWM output to properly dim an LED load. This combination of features provides an
excellent method to convert a standard AC mains input to a dimmable LED output of 10-100W. It should be
noted that the LM3450/50A can control a boost converter in a similar manner. However, this datasheet will focus
mostly on the flyback topology due to the high demand for isolated LED driver applications. Discussion of the
LM3450/50A functionality will refer to Figure 17 component designators.
The PFC control operates in critical conduction mode (CRM) using zero crossing detection (ZCD) to terminate
the off-time. The PFC portion of this device includes an error amplifier, multiplier, current sense circuit, zero
crossing detector, and gate driver. The internal error amplifier is used for feedback of the output voltage in non-
isolated designs. However, it can be disabled for isolated designs where the error amplifier needs to be on the
secondary side.
The phase dimmer decoder detects the dimming angle of the rectified AC line, decodes, filters and remaps it to a
500Hz PWM output. The PWM output can then be sent directly, or through optical isolation, to the dimming input
of a second stage LED driver. To ensure the decoder properly interprets the dimming angle, dynamic hold is
provided which prevents the phase dimmer from misfiring. The input current is sensed and when the current
drops below a preset minimum, the system adds more current.
Both the dynamic hold and the decoder are sampled synchronously in the LM3450 to reduce the overall
efficiency drop due to the additional hold current. When a decoding sample period occurs, the dynamic hold is
activated to ensure a proper angle is decoded. Because of this sampling method, non-sampled cycles will
potentially cause the phase dimmer to misfire but should not affect the output LED current regulation.
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DISPDIST KKPF x
=
PF=AVG
P
RMSRMS IV x
VREF +
-
Switching Regulator
+
VREF +
-
EMI Bridge Rectifier Energy
Storage
LM3450
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SNVS681D –NOVEMBER 2010–REVISED MAY 2013
For higher power applications, where the dynamic hold provides much less current on average, the LM3450A
can be used. The LM3450A has continuous dynamic hold which prevents the dimmer from ever misfiring. This is
extremely helpful when designing for single stage solutions, where there is no second stage to provide good line
rejection. The continuous dynamic hold is also helpful for the higher power two stage applications where the
input capacitance is larger.
One last feature of the phase decoder is a dynamic filter that, combined with the variable sampling rate, provides
fast, smooth dimming transitions.
Figure 18. PFC System Architecture
PFC BACKGROUND
Power factor (PF) is a number between 0 and 1 that indicates how well energy is transmitted from input to output
of a system. It can be described by average power (PAVG), RMS voltage (VRMS), and RMS current (IRMS):
(1)
Or by distortion factor (KDIST) and displacement factor (KDISP):
(2)
With a purely resistive system, PF = 1. The addition of reactive elements necessary in any converter, such as
EMI filters and energy storage, will induce some amount of displacement (phase shift between the input voltage
and input current). The addition of switching devices will also create distortion (energy present in the harmonics
relative to the switching frequencies). These non-idealities decrease the PF towards zero.
Active power factor correction attempts to make the input impedance look as resistive as possible to the power
source. Since the output of the converter is usually a regulated voltage or current, there is a need for large
energy storage elements to remove the twice line frequency (100Hz or 120Hz) ripple. A power factor control
architecture, as shown in Figure 18, has very little capacitance at the input. Instead, the twice line frequency
content is removed with large energy storage capacitance at the output.
Using this control architecture, the converter is able to provide two important functions at the same time:
• Shape the input current
• Regulate the output voltage
The PFC control approach requires two separate control loops to achieve both functions: a fast loop which
shapes the input current, and a slow loop that regulates the output voltage.
The fast control loop shapes the input current to have the same sinusoidal shape as the AC input voltage.
Assuming both are perfect sinusoids with zero distortion or phase shift, the power factor will be perfect (unity).
Unfortunately, distortion is always present in switching converters. An input filter, which is required to comply with
EMI standards, helps to attenuate the switching content, thereby reducing distortion. However, the added filter
capacitance will increase the phase shift at the same time. Though perfect PF is not achievable within real
applications, extremely high PF (>.99) is possible using most active PFCs.
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)2()
tDI PKP x
-
(tIin =
t
iL (t)
IL-MAX
IL
0
TS
tON = DTStOFF = (1-D)TS
LM3450
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
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The output voltage has to be regulated slowly to ensure the converter ignores the twice line frequency ripple
present on the output. Therefore, the voltage loop containing the error amplifier should have a bandwidth at least
an order of magnitude slower (<20Hz is common). Sometimes the bandwidth is increased to improve transient
response, which is the case with off-line dimmable LED drivers. Though PF decreases with the increase in
bandwidth, high PF (>.95) is still possible.
Figure 19. Basic CRM Inductor Current Waveform
CRM BACKGROUND
During critical conduction mode (CRM), a converter operates at the boundary of continuous conduction mode
(CCM) and discontinuous conduction mode (DCM). This is usually implemented as follows. The main switching
MosFET (QSW) is turned on and the inductor current rises to a peak threshold. QSW is then turned off and the
current falls until it reaches zero. At this point, QSW is turned on and the cycle repeats. Near zero voltage
switching, enabled by the inductor current return to zero, gives CRM topologies an efficiency improvement
compared to CCM topologies. Figure 19 shows the resulting inductor current waveform, where the average
inductor current (IL) is half of the peak current (IL-MAX).
In a CRM flyback PFC application, the rectified AC input is fed forward to the control loop, creating a sinusoidal
primary peak current envelope (IP-pk) as shown in Figure 20. The secondary peak current envelope (IS-pk) will
simply be a scaled version of the primary according to the turns ratio of the transformer. Assuming good
attenuation of the switching ripple via the EMI filter, the average input current (IIN), represented by the red line in
Figure 20, can also be approximated as a sinusoid proportional to the duty cycle (D(t)):
(3)
Since CRM operation is hysteretic and the input voltage is fed-forward, the input current shaping loop is as fast
as possible. Only the output voltage needs to be regulated with a narrow bandwidth error amplifier, which greatly
simplifies the system dynamics.
12 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated
Product Folder Links: LM3450
LOGIC
Rectified AC
ZCD
GATE
LM3450/50A
GND
COMP
FB
VAC
CS
2.7V
2.5V
346mV
50 P$
+
-
5 k:
1.5V
Error Amp
Disable
5V
+
-
+
-
Multiplier
+
-
VOUT
(Non-
isolated)
1/3
OPTO
(Isolated)
RAC2
RAC1
RZCD
QSW
RCS
CCMP
RFB1
RFB2
L
168mV Shutdown
+
-
3V OVP
+
-
IIN-PK
IP-PK
IS-PK
t
i
tON TSW
LM3450
www.ti.com
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
Figure 20. CRM Flyback Current Waveforms
Figure 21. PFC Control Circuit
Copyright © 2010–2013, Texas Instruments Incorporated Submit Documentation Feedback 13
Product Folder Links: LM3450
( ) OSTHMCOMPACMMLT VVVVKV +-
x
x=
ON
t=PKP
IL -
x
PKIN
V-
LM3450
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
www.ti.com
POWER FACTOR CONTROLLER
The LM3450/50A uses CRM control to regulate the output voltage and provide power factor correction. In a non-
isolated boost topology, an external voltage divider (RFB1, RFB2) is used to sense the output voltage, as shown in
Figure 21. The divider is connected to the inverting input (FB) of the internal error amplifier. The LM3450/50A
regulates the feedback voltage (VFB) to 2.5V in a closed loop fashion.
The FB pin has a shutdown mode to protect against a feedback short and an OVP mode which terminates
switching when output over-voltage is sensed.
With the FB shutdown mode, it is necessary to have a preliminary biasing method for the output of the error
amplifier (COMP). Otherwise, the converter would never start. COMP is pre-biased with a 415µA current until the
voltage at COMP (VCMP) exceeds the minimum operational voltage (VTHM).
For an isolated flyback topology, where the error amplifier is on the secondary, the LM3450/50A internal error
amplifier can be bypassed using a single 5.11kΩresistor (RFB1) from FB to GND. This engages an internal 5kΩ
pull-up resistor at COMP. COMP can then be connected directly to the optical isolation as shown in Figure 21.
COMP and the sensed rectified AC input voltage (VAC), provided via a resistor divider (RAC1, RAC2), are inputs to
the multiplier. The current through the sense resistor (RCS) produces a voltage (VCS) that is compared to the
multiplier output. When VCS exceeds the multiplier output, QSW is turned off. The peak detect threshold and the
current slope during an on-time are proportionally changing which yields a nearly constant on-time, shown in
Figure 20:
(4)
Once QSW is turned off, the LM3450/50A waits until the inductor (boost) or transformer (flyback) is demagnetized
to turn QSW on again. Demagnetization, sensed at ZCD, occurs when the current through the magnetic
component falls to zero. Since the output voltage is regulated, the slope of the current remains relatively constant
and, coupled with the variable peak detect, creates a variable off-time.
The sinusoidal peak detection envelope creates an input current that is sinusoidal and in phase with the input
voltage providing excellent PF. The PWM comparator 30mV input offset voltage ensures current is drawn at the
zero-crossings of the AC line, reducing distortion and further improving PF.
CURRENT SENSE
The LM3450/50A senses current through QSW via a sense resistor (RCS) between the source of QSW and GND.
When VCS exceeds the output of the multiplier (VMLT), QSW is turned off. VMLT is variable over the line cycle and is
a function of the scaled rectified AC voltage (VAC), the COMP voltage referenced from its operational minimum
(VCOMP-VTHM), the multiplier gain (KM) and the PWM comparator offset (VOS):
(5)
The LM3450/50A has a leading edge blanking (LEB) circuit that pulls the current sense input to the PWM
comparator low for 140µs at the beginning of each on-time. The LEB blanks the current spike and associated
ringing due to the turn-on transient of QSW, limiting the minimum achievable duty cycle.
OVER CURRENT PROTECTION
The LM3450/50A has a current limit threshold (VLIM = 1.5V) at CS to protect the system from over-current
conditions. If VCS exceeds VLIM, QSW is immediately turned off until ZCD triggers a new on-time.
14 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated
Product Folder Links: LM3450
¸
¸
¹
·
¨
¨
©
§
()x=
SW tDf xPK-P
IL PKIN-
V
t
VSW
VRING
t
VZCD
VR
1.3V
VIN
LM3450
www.ti.com
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
Figure 22. ZCD Waveforms for Flyback Design
ZERO CURRENT DETECTION
ZCD is implemented with a 100kΩresistor from the ZCD pin to a coupled winding on the transformer or inductor
as shown in Figure 21. This winding is also used to bootstrap VCC after start-up. When QSW turns off, the voltage
at the ZCD pin (VZCD) increases as energy is transferred through the auxiliary winding. The circuit arms when
VZCD exceeds 1.5V. Then, when the energy is fully transferred, VZCD decreases towards zero. When VZCD falls
below 1.3V, the transformer is assumed to be demagnetized, the circuit disarms, and QSW is turned back on as
shown in Figure 22. The ZCD pin voltage will remain low until QSW is turned off via peak detection and the cycle
repeats.
SWITCHING FREQUENCY
With a constant on-time and variable off-time, there is a variable switching frequency:
(6)
Figure 20 shows that the minimum switching frequency occurs at the peak of the rectified AC waveform, while
the maximum switching frequency occurs at the valley.
ERROR AMPLIFIER
The LM3450/50A internal error amplifier is used for non-isolated designs (boost) where the output voltage can be
directly sensed, via a resistor divider, at the FB pin. The FB pin is the inverting input of the trans-conductance
amplifier which is regulated to 2.5V. The COMP pin is the output of the amplifier and external compensation is
placed from COMP to GND in the form of a single capacitor (CCMP) as shown in Figure 21, a series resistor and
capacitor, or both. The output of the amplifier sources or sinks current as necessary to force the inputs of the
amplifier to be equal. The compensation method depends upon the transient performance desired and requires a
loop gain analysis. This analysis can be somewhat complex and cumbersome. A detailed analysis can be found
Application Notes AN-2098 (literature number SNVA463) and/or AN-2150 (literature number SNVA485).
Copyright © 2010–2013, Texas Instruments Incorporated Submit Documentation Feedback 15
Product Folder Links: LM3450
VOUT
VSB
LMV431
COMP
OPTO
5V
LM3450/50A
5k
RFB2
RFB1
RSC
CSC
RSBS
CCMP
SOFT
START
FB
RFB
LM3450
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
www.ti.com
If the COMP pin voltage (VCMP) falls below 1.4V at any time, the device enters burst mode where the GATE is off
for 340µs then is turned on. If VCMP is still below 1.4V at the end of the on-time then another 340µs off-time
occurs. However, if VCMP has risen above 1.4V, the converter continues switching until it falls below the threshold
again. This feature is necessary to prevent the output of the converter from rising arbitrarily high because the
minimum on-time of the device prevents less energy transfer.
The LM3450/50A also implements both feedback short circuit protection and output over-voltage protection
(OVP) functions at the FB pin. If VFB exceeds 3V, then OVP is engaged and the part stops switching until VFB
falls below 3V. In the same manner, if VFB falls below 168mV, then shutdown is engaged and switching stops
until VFB exceeds 188mV.
The flyback topology is frequently used to provide isolation from input to output. Since, the current transfer ratio
(CTR) of standard optical isolation varies over temperature, proper regulation using primary error amplifiers is
difficult. An error amplifier is usually placed in the secondary to regulate the output voltage accurately. To
accommodate isolated designs, the LM3450/50A internal error amplifier can be bypassed by placing a 5.11kΩ
resistor from FB to GND. This engages a 5kΩpull-up resistor from COMP to an internal 5V rail.
SECONDARY ERROR AMPLIFIER
For isolated designs, the error amplifier on the secondary should take the form of a proportional integral (PI)
compensator. The amplifier is frequently implemented with an LMV431. The output voltage resistor divider (RFB1,
RFB2) provides the sensed output voltage to the LMV431 inverting input. The PI compensation is achieved by
connecting RSC and CSC in between the LMV431 input and output, shown in Figure 23. In addition, CCMP is
placed from COMP to GND on the primary for higher frequency noise attenuation.
In addition to the basic error amplifier, a soft-start circuit can be implemented using a capacitor, two diodes and a
Zener diode as shown in Figure 23. This secondary softstart circuit has no restart mechanism, therefore a
primary side softstart is recommended as described in the SOFTSTART section of this document.
Figure 23. Secondary Error Amplifier
PRECISION VOLTAGE REFERENCE
The LM3450/50A provides a 3V voltage reference (VREF) for biasing the VADJ pin as well as any external circuitry.
VREF is regulated once VCC exceeds 3V. There is a 2mA current limit for the reference. A 10nF ceramic bypass
capacitor should be placed from VREF to GND.
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DELAY
DELAY
(a)
(b)
(c)
LM3450
www.ti.com
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
LOW POWER SHUTDOWN
The LM3450/50A can be placed into a low power shutdown by grounding the VADJ pin (any voltage below 75mV).
During low power shutdown, the device will turn on the GATE for one cycle followed by a fixed off-time of 42µs
and the cycle repeats. During shutdown, the DIM output will be high (zero light output) since the buffer rail at
FLT1 will be at or near zero. This feature is designed to hold up the PFC output voltage while removing the load
(turning the LEDs off).
THERMAL SHUTDOWN
Internal thermal shutdown circuitry is provided to protect the IC in the event that the maximum junction
temperature is exceeded. The threshold for thermal shutdown is 160°C with a 20°C hysteresis. During thermal
shutdown GATE is disabled.
Figure 24. Phase Dimming Waveforms
Copyright © 2010–2013, Texas Instruments Incorporated Submit Documentation Feedback 17
Product Folder Links: LM3450
BRIGHT
DIM
R1MAX 250 k:
DIAC
R2 3.3 k:
C1 100 nF
LOAD
AC
MAINS
TRIAC
FORWARD PHASE DIMMER
LM3450
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
www.ti.com
PHASE DIMMER OPERATION
A simplified schematic of a phase dimmer is shown in Figure 25. An RC network consisting of R1, R2, and C1
delay the turn-on of the triac until the voltage on C1 reaches the trigger voltage of the diac. Increasing the
resistance of the potentiometer (wiper moving downward) increases the turn-on delay which decreases the on-
time or “conduction angle” of the triac (θ). This reduces the average power delivered to the load.
Figure 25. Basic Forward Phase Dimmer
Phase dimmer voltage waveforms are shown in Figure 24.
Figure 24a shows the full sinusoid of the input voltage. Even when set to full brightness; few dimmers will provide
100% conduction angle.
Figure 24b shows a waveform from a forward phase dimmer. The off-time can be referred to as the firing angle
and is simply 180° – θ.
Figure 24c shows the waveform of a reverse phase dimmer (also called an electronic dimmer in the lighting
industry). These typically or more expensive, microcontroller based dimmers that use switching devices other
than triacs. Note that the conduction angle starts from the zero-crossing, and terminates some time later. This
method of control reduces the noise spike at the transition.
Any form of phase dimming modulates the incoming AC waveform by chopping part of the sinusoid, reducing the
average power to the load. These dimmers work very well with standard incandescent bulbs, but not with power
converters. A converter attempts to regulate the load in with presence of any input, effectively ignoring the phase
angle. To implement a dimmable converter, the angle must be sensed at the input, decoded and used to properly
control the LED current regulator.
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Product Folder Links: LM3450
356 mV
VAC
DIN
OPTO
0-3V
Analog
Input
VCC
VSB
PWM OUT
Rectified AC
RF1 RF2
CF1 CF2
RPB
RSB
RAC2
RAC1
+
-DIM
VAC
500k
Transition
LM3450/50A
ANGLE
DEMOD
SAMPLE / REMAP
DIN
DOUT
DIN DOUT
FLT2
FLT1
VADJ
VREF
3V
REF
500 Hz
LM3450
www.ti.com
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
Figure 26. Dimming Decoder Circuit
PHASE DIMMING DECODER
The LM3450/50A uses the rectified AC line voltage to interpret the conduction angle. Figure 26 shows the
LM3450/50A decoder circuit with associated external circuitry. The rectified AC line voltage is scaled via a
resistor divider (RAC1, RAC2) and connected to the VAC pin. VAC is compared to a 356mV reference to generate a
twice line frequency PWM signal with corresponding duty cycle as shown in Figure 27.
Figure 27. Phase Angle Demodulation
For best results, RAC1 and RAC2 are suggested to be sized so that the VAC voltage crosses the 356mV threshold
when the rectified AC line is as follows:
• 120V systems: 25V to 45V
• 230V systems: 40V to 70V
The demodulated duty cycle is sampled and logarithmically remapped to a 300Hz PWM signal improving the
resolution of low dimming levels to the human eye. A minimum duty cycle limits the maximum achievable
contrast ratio to approximately 70:1. The remapped PWM signal is buffered and output at FLT1 with amplitude
equal to VADJ as shown in Figure 28.
Copyright © 2010–2013, Texas Instruments Incorporated Submit Documentation Feedback 19
Product Folder Links: LM3450
VFLT2
VDIM
VADJ
VFLT2
VFLT1
LM3450
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
www.ti.com
Figure 28. FLT1 to FLT2 Mapping
The FLT1 signal is routed through a 2 pole low pass filter (RF1, CF1, RF2, CF2), as shown in Figure 26, to remove
the twice line frequency ripple. The resulting analog signal at FLT2 is compared to a 500Hz Triangle wave to
create the inverted PWM signal at the DIM pin as shown in Figure 29:
Figure 29. FLT2 to DIM Mapping
This PWM signal at the DIM pin can be used as the dim input to a secondary LED driver. DIM is an open drain
output designed for isolated solutions. Optical isolation is used to transmit signals across the isolation boundary.
With most opto-isolators, the edge rate is dependent on the amount of drive current through the photodiode. The
open-drain configuration allows the primary bias supply (VCC) to provide the current as shown in Figure 26. The
choice of resistor (RPB) between VCC and the photodiode anode will set the drive current. This enables the user
to trade-off PWM accuracy with system efficiency.
The open drain configuration also ensures that the secondary has a resistor from the phototransistor’s emitter to
secondary ground (not from collector to secondary bias). During system turn-off, this prevents an undesired LED
blink because the secondary stage LED driver is forced off.
A variable sample rate and dynamic filter ensure fast, smooth dimming transitions (movement of the dimmer)
while maintaining robust flicker-free behavior when the dimmer is static. The sample rate depends on past and
present angle information. The dynamic filter is a dual mode filter. During standby mode, when a transition has
not been made and the dimmer is static, a 500kΩseries resistor is connected between the buffered output and
FLT1 as shown in Figure 26.
The 500kΩresistor is shorted when the LM3450/50A senses a large transition of the dimmer. This increases the
filter speed while the dimmer is transitioning between levels to improve response time.
The FLT1 and FLT2 poles created by each RC pair (RF1 and CF1, RF2 and CF2) should be set as follows:
• CF1 and CF2 can be 1µF ceramic capacitors for all designs.
• RF1 and RF2 should be set between 15kΩ(~10Hz) and 75kΩ(~2Hz).
2 Hz poles provide a “smooth fade” while 10Hz poles create a “snappy” response.
These component values ensure that the static filter condition in standby mode has 1 pole approximately a
decade lower than the nominal in order to provide good noise immunity to the system.
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GND
+
-
5 P$
40 k:
Rectified AC
BIAS
AC AC
LM3450/50A
Sample
CHLD
CSEN
RSEN
RHLD
QPS
RBS
+
-
VSEN
ISEN
HOLD
10k
NTC
15k
3904
Connect if thermal
protection circuit is
not desired
QPS
thermal
protection
circuit
0.0 0.2 0.4 0.6 0.8 1.0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
DIM PIN DUTY CYCLE (INVERTED)
LM3450/A DEMODULATED VAC PIN DUTY CYCLE
1V
0.5V
2V
2.5V
1.5V
VADJ=3V
LM3450
www.ti.com
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
Figure 30. Complete Decoder Mapping
Since the buffered decoder output has amplitude equal to VADJ and the resulting PWM signal is filtered into an
analog voltage at FLT2, the VADJ pin can be used to change the mapping as shown in Figure 30. The maximum
LED current (DIM = 0) when VADJ = 3V corresponds to decoded angles of 70% or greater. Some dimmers have a
maximum angle greater than this. If VADJ is reduced to 2.5V, the maximum LED current will correspond to an
angle of 80% and at VADJ = 2V the maximum will occur at a decoded angle of 95%.
The VADJ pin can also be used to implement a standard analog adjust function. If the demodulated phase angle
at VAC is above 85%, then the fast filter is always enabled (500kΩshorted) and the VADJ pin can solely be used
to scale the DIM pin duty cycle. When VADJ is pulled below 75mV the part enters low power shutdown so the
maximum attainable contrast ratio using VADJ only is approximately 40:1.
Both FLT1 and FLT2 have pull-down MosFETs that are turned on when VCC UVLO falling threshold is triggered.
This provides a quick discharge path for the capacitors and eliminates the possibility of an undesired light level at
the next startup.
Figure 31. Dynamic Hold Circuit
Copyright © 2010–2013, Texas Instruments Incorporated Submit Documentation Feedback 21
Product Folder Links: LM3450
1
IIN-MIN-REG Added
Hold
Current
~VCC
23
1
VHOLD
IIN
2
Misfire
1
356 mV
Misfire
2
Original
Angle
VAC
DIN
LM3450
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
www.ti.com
DYNAMIC HOLD
A forward phase “triac” dimmer requires a minimum amount of current to be flowing through it during the entire
conduction angle. This is referred to as hold current. If the minimum hold current requirement is not met, the triac
will shut off (misfire). During normal operation, the converter will demand some amount of input current.
However, at any point during the cycle, the input current can be low enough to cause a misfire.
During an LM3450/50A sampling period, the triac should not misfire or the decoded angle will be inaccurate as
shown in Figure 32. Since the triac is asymmetrical phase-to-phase, misfires can occur at different points in the
waveform. After the triac misfires, the voltage returns to zero exponentially. This can create a large difference
between decoded angles which can be observed as a “fluttering” of the light.
Figure 32. Forward Phase Waveform
To ensure the triac does not misfire during a sampling period and the angle is correctly decoded, a dynamic hold
function is enabled. The input current is sensed with a resistor (RSEN) from GND to ISEN (the return of the full
bridge rectifier). If the voltage across this resistor is less than 200mV, the device adds holding current via the
HOLD circuitry to maintain 200mV across RSEN.
The hold current is added by linearly adjusting the gate voltage of QHLD as shown in Figure 31. As the gate
voltage of QHLD is increased, the HOLD pin voltage decreases, forcing a voltage across the resistance (RHLD)
from the source of QPS to HOLD. This extra current is drawn from the input through the triac, but is not
processed by the converter. Figure 33 shows a typical dynamic hold waveform of the LM3450 where interval 1 is
a non-sampled conduction angle, 2 is the firing angle, and 3 is a sampled conduction angle. It should be noted
that using the LM3450A will ensure every conduction angle looks like interval 3 in Figure 33.
Figure 33. Dynamic Hold Waveform
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Product Folder Links: LM3450
=I MAX-HOLD VCC
:
+30
RHLD
REGMIN-IN-
I=mV200
SEN
R
1
356 mV
Turn-off
no bleeder
2
Turn-off
with bleeder
VAC
DIN
LM3450
www.ti.com
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
The dynamic hold function is also necessary for reverse phase dimmers, but for a different reason. Reverse
phase dimmers do not use triacs, therefore they do not require a minimum “holding” current. Instead, they need
what is commonly called bleeder current. When a reverse phase dimmer turns off, the AC voltage is at a high
value. There is an RC time constant associated with discharging the total effective input capacitance (EMI
capacitors, PFC capacitor, damper capacitance). The decoder does not record the angle until the voltage
reaches the 356mV threshold. This can cause the decoded angle to be much larger than it actually is and
dependent on the RC time constant as shown in Figure 34.
Figure 34. Reverse Phase Waveforms
The dynamic hold will quickly bleed off the excess charge in an attempt to regulate the voltage across RSEN. This
will preserve the accuracy of the decoded phase angle.
During the conduction angle (θ), dynamic hold is enabled only during a sample period for the LM3450. However,
during the firing angle (delay time), dynamic hold is always enabled with the LM3450. This will ensure the
rectified line voltage does not begin to rise due to leakage currents through the phase dimmer. Again, with the
LM3450A the dynamic hold is continuously active during all conduction and firing angles.
The minimum regulated input current can be calculated:
(7)
The maximum possible additional holding current (which can occur when HOLD is still transitioning usually at the
rising edge of the triac firing) can be approximated:
(8)
It is recommended that the maximum hold current is set 10-15% higher than the minimum regulated input
current.
A minimum of 0.1µF capacitance should be placed between ISEN and HOLD to limit the bandwidth of the dynamic
hold circuit to well below the switching frequency. However, if too large a capacitor is used, the bandwidth will be
too low to respond to line transients. A maximum of 0.47µF should ensure good performance.
Finally, a small Schottky diode should be placed from GND to ISEN to absorb the large current spikes associated
with the triac firing edge. This diode should have a forward voltage above 200mV at the worst-case operating
temperature so that it won’t interfere with dynamic hold regulation.
Copyright © 2010–2013, Texas Instruments Incorporated Submit Documentation Feedback 23
Product Folder Links: LM3450
Rectified AC
BIAS
AC
LM3450/50A
VCCUV
6V
14V
VCC
AC
RETURN
VCC UVLO
24V
CVCC
QPS
RBS
QSW
LM3450
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
www.ti.com
THERMAL PROTECTION
With the LM3450A, QPS has to dissipate more power than with the LM3450. During worst case conditions such
as open LED load, the converter will be demanding very little current regardless of the triac position. If the phase
dimmer conduction angle is large and the load is not present, QPS has to dissipate many watts since the dynamic
hold is attempting to regulate the current to ten's of mA. Using the LM3450, this is nominally not a problem since
it is sampling the dynamic hold infrequently. However, the LM3450A is drawing the hold current every cycle
which becomes a problem very quickly. It should be noted that If the input AC line is very noisy, the VAC input to
the decoder could have enough variation in steady state to cause the decoder to think the dimmer is transitioning
all of the time. This would increase the sampling rate dramatically, putting much more thermal strain on the
passFET in LM3450 applications as well.
To mitigate these problems, a thermal protection circuit should be implemented on the LM3450A designs (and
can be on the LM3450 designs as well) as shown in red in Figure 31. The NTC thermistor should be placed on
the opposite side of the PCB directly under the drain of QPS. This will provide the best thermal coupling while
maintaining the necessary high voltage spacing constraints. At startup the NTC is at a high resistance value,
turning the PNP fully on which provides the dynamic hold path. As the NTC heats up the resistance decreases
and the base voltage increases. Eventually, the PNP will transition into linear mode and the effective resistance
from collector to emitter will increase. This will decrease the maximum holding current, thereby decreasing the
thermal stress on QPS. Given enough headroom, the circuit should reach thermal equilibrium in a safe controlled
manner.
Since this method of thermal protection linearly reduces the maximum hold current with increasing temperature,
the foldback will not be perceptible to the consumer. Instead, the result of the foldback will simply be a reduction
of contrast ratio, meaning the minimum achievable LED current will increase as the temperature increases
beyond the foldback level.
Figure 35. Primary Bias Circuitry
PRIMARY BIAS SUPPLY
The LM3450/50A requires a supply voltage at VCC, not to exceed 25V. The device has VCC under-voltage lockout
(UVLO) with rising and falling thresholds of 12.9V and 7.9V respectively. A 24V Zener diode should be placed
from the VCC pin to GND to protect the device from substantial spikes that could cause damage.
24 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated
Product Folder Links: LM3450
18V
3.9V
500k
47uF
20k
COMP
LM3450/50A
BIAS VADJ VCC
LM3450
www.ti.com
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
Figure 35 shows how the LM3450/50A provides a quick way to generate the necessary primary bias supply at
start-up. Since the AC line peak voltage is always higher than the rating of the controller, all designs require an
N-channel MosFET (passFET). The passFET (QPS) is connected with its drain attached to the rectified AC. The
gate of QPS is connected to the BIAS pin which has a stack of 2 Zener diodes internal to the device. These
diodes are then biased from the rectified AC line through series resistance (RBS). The source of QPS is held at a
VGS below the Zener voltage and current flows through QPS to charge up whatever capacitance is present. If the
capacitance is large enough, the source voltage will remain relatively constant over the line cycle and this
becomes the input bias supply at VCC.
This bias circuit enables instant turn-on. However, once the circuit is operational it is desirable to bootstrap VCC
to an auxiliary winding of the inductor or transformer (also used for ZCD). The two bias paths are each
connected to VCC through a diode to ensure the higher of the two is providing VCC current. This bootstrapping
greatly improves efficiency when quick start-up is necessary.
To ensure that the auxiliary winding is powering VCC at all times except start-up, the LM3450/50A has a dual
BIAS mode. The BIAS voltage at startup is 20V through two Zener diodes. When the VCC UVLO rising threshold
is exceeded and the device turns on, the BIAS pin voltage is reduced to 14V (bottom 6V Zener is shorted). Once
the VCC UVLO falling threshold is reached again, the BIAS pin will return to 20V to attempt to restart the device.
It should be noted that the large hysteresis of VCC UVLO and the dual BIAS mode allow for a large variation of
the auxiliary bias circuitry easing the design of the magnetics.
SOFTSTART
As in any off-line system, softstart is an important part of the design. Since the LM3450/50A are used with phase
dimming applications, the typical startup problems are magnified since a phase dimmer is frequently turned on
and off rapidly. This requires a softstart mechanism that quickly resets when the LM3450/50A turns off. Since the
LM3450/50A has two distinct functional parts (PFC and phase decoder), ideally both should be softstarted
simultaneously. This will ensure the most controlled start-up possible.
The circuit in Figure 36 provides this exact functionality. Both VADJ and COMP are diode or'ed into an RC
charging circuit fed from VCC. The reset mechanism is accomplished using an 18V Zener from BIAS, a current
limiting resistor and an NPN transistor. The reset is activated when VCC uvlo falling is triggered and BIAS
transitions to 20V. This discharges the RC to zero and as soon as VCC uvlo rising is passed BIAS transitions to
14V again, releasing the clamp on the RC softstart circuit. The RC will charge up to the 3.9V Zener clamp (which
is above the dynamic range of COMP and VADJ and become effectively out of the circuit until the next turn-off.
Figure 36. Dual Softstart Circuit
Copyright © 2010–2013, Texas Instruments Incorporated Submit Documentation Feedback 25
Product Folder Links: LM3450
LM3450
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
www.ti.com
DESIGN INFORMATION
HOW TO SELECT THE CORRECT DEVICE (LM3450 or LM3450A)
What application(s) are suitable for the LM3450, and when is the LM3450A appropriate? The difference centers
on the power dissipation in the passFET. The passFET stands off the high AC voltage from the LM3450/50A,
and provides a path for the hold current. The passFET operates in the linear region and dissipates power equal
to the product of the voltage across it and the current through it.
The LM3450 was designed to minimize the power dissipation in the passFET by applying holding current in a
sampled form. The standby sampling rate (when the dimmer is not moving) is infrequent, allowing minimal impact
on the thermal considerations of the passFET. Sampling of the dynamic hold is not desired for some applications
although. An example where the sampled hold current may cause undesirable effects is the single stage flyback
topology where the output of the flyback is directly connected to the LEDs. If the phase dimmer is allowed to
misfire or create erratic differences in the input voltage and current waveforms, this behavior will appear as a
"fluttering" of the LED light output at the sampling rate when the single stage topology is used. The light flutter is
most observable at low input currents (dimming). A small perturbation in the input voltage due to phase dimmer
misfire can create a visible difference in the output light. Using a secondary LED driver stage eliminates this
problem.
Cost sensitive applications may drive the design to a single stage solution, and the LM3450A was developed to
address this market. The LM3450A provides continuous dynamic hold current on every AC cycle preventing the
phase dimmer from misfire, and the sampling frequency from appearing at the output. Another design
consideration where continuous dynamic hold may be advantageous is the reduced stresses on input EMI R/C
snubber networks.
The designer must pay close attention to the power loss of the passFET when using the LM3450A. Designers
must consider worst case possibilities with any power conversion designs. Worst case operating conditions with
the LM3450A are usually found with the largest triac holding current requirements. Many phase dimmers require
25mA-40mA of holding current, and frequently designers are choosing 50mA as their minimum holding current
requirement. The passFET package for common LM3450/50A designs should be capable of dissipating between
1W and 1.5W. The pass-FET can always be increased in size and/or the hold current can be reduced. Power
calculations for the dynamic hold circuit as well as effective thermal protection are both described in the
DYNAMIC HOLD section.
The LM3450 and LM3450A is best differentiated in terms of the appropriate applications for each device. The
Table 1 can be used as a general guide for when to use each part.
Table 1. Device Selection Guide
Product AC Input Output Power Device Topology
POUT < 15W LM3450
120V POUT > 15W LM3450A
High End Downlight Two Stage Design
POUT < 25W LM3450
230V POUT > 25W LM3450A
Low Cost Downlight 120V POUT > 15W
or LM3450A Single Stage Design
230V POUT > 25W
Large High End Bulb
26 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated
Product Folder Links: LM3450
ZCD
GATE
LM3450
VCC
GND
COMP
FB
HOLD
VAC
VADJ
CS
DIM
FLT2
FLT1
ISEN
PWM
VREF BIAS
IADJ
EN
CSN
LM3409HV
UVLO
VCC
COFF
GND
CSP
PGATE
DAP
VIN
VOUT
PWM
VOP1
VOP2
RETURN
RETURN
VLED
LMV431
OPTO1
OPTO2
VOP2
VOP1
VCC
VOUT
EMI
FILTER
CONTROL
FEEDBACK
SECONDARY
LED DRIVER
DIMMING
VREF +
-
AC
MAINS
LED
LOAD
Q1
Q2
D1
D2
D3 D5
C1
C2
C4
C5
C6
C7
C8
D7
D6
C9 D8
C10
C12
C13
C14 C15
D9
C16
L1
L2
T1
R1 R2
R3
R5
R6
R8
R9
R11
R12
R13
R14
R15
R16
R17 R18
R19
R20
R21
R22
R23
R24
R25
C17
C18
C19 C21
C22
C20
D16
D13
D14
D15
D11D12
Q5 L4
Q3
Q4
R28
HOLD
VLED
R27
D10
C11
L3
VCC
VADJ
COMPBIAS
D18
D17
R7
Q6
R10
SOFTSTART
C3
D4
R4
AUX
AUX
LM3450
www.ti.com
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
Applications Information
See AN-2098 (literature number SNVA463) and/or AN-2150 (literature number SNVA485) for detailed design and
application information.
TWO STAGE LED DRIVER – LM3450 PRIMARY AND LM3409HV SECONDARY
Copyright © 2010–2013, Texas Instruments Incorporated Submit Documentation Feedback 27
Product Folder Links: LM3450
LM3450
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
www.ti.com
15W TWO STAGE DESIGN SPECIFICATIONS
AC Input Voltage: 120VAC nominal (90VAC - 135VAC) or 230VAC nominal (180VAC - 265VAC)
Regulated Flyback Output Voltage: 50V
Regulated LED Current: 350mA
LED Stack Voltage Maximum: 45V
Table 2. Bill of Materials(1)
Reference Designator Description Manufacturer Part Number
LM3450 IC PFC CONT 16-TSSOP TI LM3450MT
LM3409HV IC LED DRIVR 10-eMSOP TI LM3409HVMY
LMV431 IC SHUNT REG SOT-23 TI LMV431AIM5
C1a, C1b, C5a, 120V CAP CER 0.22µF 250V 1210 MURATA GRM32DR72E224KW01L
C5b 230V CAP CER 68nF 250V 1210 MURATA GRM32QR72E683KW01L
C2 CAP MPY 33nF 250VAC X1 RAD EPCOS B32912A3333M
C3 CAP CER 47µF 6.3V 0805 TAIYO YUDEN JMK212BJ476MG-T
C4 120V CAP MPY 0.1µF 400V RAD EPCOS B32612A4104J008
230V CAP MPY 33nF 1000V RAD WIMA MKP10 - .033/1000/10
C6 CAP CER 4.7nF 500VAC Y1 RAD EPCOS VY1472M63Y5UQ63V0
C7a CAP ELEC 470µF 63V RAD NICHICON UPW1J471MHD3
C7b, C8b, C9b, C11, C15 CAP CER 0.1µF 50V 1206 MURATA GRM188R71H104KA93D
C8a, C9a CAP ELEC 100µF 50V RAD NICHICON UHE1H101MPD
C10 CAP CER 10nF 25V 0603 MURATA GRM188R71E103KA01D
C12, C13 C14, C21 CAP CER 1µF 16V 0603 MURATA GRM188R71C105KA12D
C16 CAP CER 0.22µF 16V 0603 TDK C1608X7R1C224K
C17 CAP CER 10µF 16V 1206 MURATA GRM31CR71C106KAC7L
C18, C20 CAP CER 1µF 100V 1206 TDK C3216X7R2A105M
C19 CAP CER 2.2µF 6.3V 0603 TDK C1608X5R0J225M
C22 CAP CER 470pF 100V 0603 TDK C1608C0G2A471J
D1 120V DIODE ULTRAFAST 200V 1A SMA FAIRCHILD ES1D
230V DIODE FAST 400V 1A DO-214AC FAIRCHILD ES1G
D2 DIODE ULTRAFAST 200V 1A SMA FAIRCHILD ES1D
D3, D5 DIODE ULTRAFAST 100V 0.2A SOT-23 FAIRCHILD MMBD914
D4 DIODE DUAL SCHOTTKY 20V 0.5A SOT-23 NXP SEMI PMEG3005CT,215
D6 120V DIODE TVS 150V 600W UNI SMB LITTLEFUSE SMBJ150A
230V DIODE TVS 220V 600W UNI SMB LITTLEFUSE SMBJ220A
D7 DIODE ULTRAFAST 600V 1A SMA FAIRCHILD ES1J
D8 DIODE ZENER 24V 1.5W SMA MICRO-SEMI SMAJ5934B-TP
D9 DIODE SCHOTTKY 20V 3A SMA FAIRCHILD ES2AA-13-F
D10 DIODE RECT 600V 0.5A Minidip COMCHIP HD06
D11, D12 DIODE ZENER 10V 500mW SOD-123 FAIRCHILD MMSZ5240B
D13 DIODE ULTRAFAST 70V 0.2A SOT-23 FAIRCHILD BAV99
D14 DIODE ZENER 3.3V 500mW SOD-123 ON-SEMI MMSZ3V3T1G
D15 DIODE ZENER 1.8V 500MW SOD-123 ON-SEMI MMSZ4678T1G
D16 DIODE SCHOTTKY 60V 2A SMB ON-SEMI SS26T3G
D17 DIODE ZENER 3.9V 500MW SOD-123 ON-SEMI MMSZ4686T1G
D18 DIODE ZENER 18V 500MW SOD-123 ON-SEMI MMSZ5248T1G
L1, L2, L3 IND SHIELD 1mH 0.46A SMT COILCRAFT MSS1038-105KL
(1) Components are used in both versions unless otherwise noted
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SNVS681D –NOVEMBER 2010–REVISED MAY 2013
Table 2. Bill of Materials(1) (continued)
Reference Designator Description Manufacturer Part Number
L4 IND SHIELD 470µH 1.06A SMT COILCRAFT MSS1278-474KLB
Q1 MOSFET N-CH 800V 3A DPAK ST MICRO STD4NK80ZT4
Q2 120V MOSFET N-CH 600V 4.4A DPAK INFINEON IPD60R950C6
230V MOSFET N-CH 800V 3A DPAK ST MICRO STD4NK80ZT4
Q3, Q4 TRANS NPN 40V 0.6A SOT-23 FAIRCHILD MMBT4401
Q5 MOSFET P-CH 70V 5.7A DPAK ZETEX ZXMP7A17K
Q6 TRANS PNP 40V 0.2A SOT-23 FAIRCHILD MMBT3904
R1 120V RES 330Ω5% 1W 2512 VISHAY CRCW2512330RJNEG
230V RES 510Ω5% 1W 2512 VISHAY CRCW2512510RJNEG
R2 120V RES 430Ω5% 1W 2512 VISHAY CRCW2512430RJNEG
230V RES 1.6kΩ5% 1W 2512 VISHAY CRCW25121K60JNEG
R3 120V RES 402kΩ1% 0.25W 1206 VISHAY CRCW1206402KFKEA
230V RES 953kΩ1% 0.25W 1206 VISHAY CRCW1206953KFKEA
R4 RES 100Ω1% 1W 2512 VISHAY WSL2512100RFKEA
R5 RES 100kΩ1% 0.1W 0603 VISHAY CRCW0603100KFKEA
R6 RES 6.04kΩ1% 0.1W 0603 VISHAY CRCW06036K04FKEA
R7 RES 499kΩ1% 0.1W 0603 VISHAY CRCW0603499KFKEA
R8, R9 RES 75.0kΩ1% 0.1W 0603 VISHAY CRCW060375K0FKEA
R10 RES 20.0kΩ1% 0.1W 0603 VISHAY CRCW060320K0FKEA
R11 120V RES 1.00MΩ1% 0.25W 1206 VISHAY CRCW12061M00FKEA
230V RES 2.00MΩ1% 0.25W 1206 VISHAY CRCW12062M00FKEA
R12 RES 15.0kΩ1% 0.1W 0603 VISHAY CRCW060315K0FKEA
R13 RES 5.11kΩ1% 0.1W 0603 VISHAY CRCW06035K11FKEA
R14a RES 10Ω1% 0.25W 1206 VISHAY CRCW120610R0FKEA
R14b RES 1.00Ω1% 0.33W 1210 VISHAY CRCW12101R00FNEA
R15a, R15b RES 5.62Ω1% 0.25W 1206 VISHAY CRCW12065R62FNEA
R16 RES 2.00kΩ1% 0.125W 0805 VISHAY CRCW08052K00FKEA
R17 120V RES 20.0kΩ1% 0.1W 0603 VISHAY CRCW060320K0FKEA
230V RES 10.0kΩ1% 0.1W 0603 VISHAY CRCW060310K0FKEA
R18 RES 105kΩ1% 0.125W 0805 VISHAY CRCW0805105KFKEA
R19 RES 2.67kΩ1% 0.1W 0603 VISHAY CRCW06032K67FKEA
R20 RES 6.04kΩ1% 0.125W 0805 VISHAY CRCW08056K04FKEA
R21 RES 10.0kΩ1% 0.125W 0805 VISHAY CRCW080510K0FKEA
R22 RES 80.6kΩ1% 0.1W 0603 VISHAY CRCW060380K6FKEA
R23 RES .62Ω1% 0.5 2010 SMD ROHM MCR50JZHFLR620
R24, R25 RES 10kΩ1% 0.1W 0603 VISHAY CRCW060310K0FKEA
R27, R28 120V RES 10Ω10% 2W FILM WELWYN EMC2-10R0
230V RES 22Ω10% 2W FILM WELWYN EMC2-22R0
OPTO1, OPTO2 OPTO-ISOLATOR SMD LITE ON CNY17F-3S
T1 120V XFORMER 120V 15W OUTPUT 50V WURTH 750813550
230V XFORMER 230V 15W OUTPUT 50V WURTH 750817550
Copyright © 2010–2013, Texas Instruments Incorporated Submit Documentation Feedback 29
Product Folder Links: LM3450
ZCD
GATE
LM3450A
VCC
GND
COMP
FB
HOLD
VAC
VADJ
CS
DIM
FLT2
FLT1
ISEN
PWM
VREF BIAS
VOP1
VOP2
RETURN
RETURN
VOP1
VOUT
EMI
FILTER
VREF +
-
AC
MAINS
Q1
Q2
D1
D2
D3 D5
C1
C2
C4
C5
C6
C7
C8
D7
D6
C9 D8
C10
C12
C13
C14 C15
D9
C16
L1
L2
T1
R1 R2
R3
R5
R6
R8
R9
R11
R12
R13
R14
R15
R24
R25
D11D12
Q3
Q4
R28
HOLD
R27
D10
C11
L3
VCC
VADJ
COMPBIAS
D18
D17
R7
Q6
R10
SOFTSTART
C3
D4
R4
AUX
AUX
R18
R19
R20
R21 C18
D13
+
-
+
-
PWM
VOUT
OPTO1 OPTO2
VOP2
VOP1 VCC
CONTROL
FEEDBACK DIMMING
LED
LOAD
U1
VSDIM
R17
C17
R16
VSDIM C19
R23
R22
R30 R29
R32
1.24V
Thermal
Protect
R26
1.24V
LMV431
D19
LM3450
SNVS681D –NOVEMBER 2010–REVISED MAY 2013
www.ti.com
SINGLE STAGE LED DRIVER – LM3450A FLYBACK
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LM3450
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SNVS681D –NOVEMBER 2010–REVISED MAY 2013
30W SINGLE STAGE DESIGN SPECIFICATIONS
AC Input Voltage: 120VAC nominal (90VAC - 135VAC) or 230VAC nominal (180VAC - 265VAC)
Flyback Output Voltage Maximum: 60V
Regulated LED Current: 700mA
Table 3. Bill of Materials(1)
Reference Designator Description Manufacturer Part Number
LM3450A IC PFC CONT 16-TSSOP TI LM3450AMT
LMV431 IC SHUNT REG SOT-23 TI LMV431AIM5
U1 IC DUAL OP-AMP TI LM2904
C1a, C1b, C1c, 120V CAP CER 0.22µF 250V 1210 MURATA GRM32DR72E224KW01L
C5a, C5b, C5c 230V CAP CER 68nF 250V 1210 MURATA GRM32QR72E683KW01L
C2 CAP MPY 33nF 250VAC X1 RAD EPCOS B32912A3333M
C3 CAP CER 47µF 6.3V 0805 TAIYO YUDEN JMK212BJ476MG-T
C4 120V CAP MPY 0.22µF 400V RAD WIMA MKP10-.22/400/20
230V CAP MPY 62nF 1000V RAD VISHAY BFC238330623
C6 CAP CER 4.7nF 500VAC Y1 RAD EPCOS VY1472M63Y5UQ63V0
C7a CAP ELEC 1mF 63V RAD NICHICON UPW1J102MHD
C7b, C8b, C9b, C11, C15 CAP CER 0.1µF 50V 1206 MURATA GRM188R71H104KA93D
C8a, C9a CAP ELEC 220µF 50V RAD NICHICON UHE1H221MPD
C10 CAP CER 10nF 25V 0603 MURATA GRM188R71E103KA01D
C12, C13, C14, C18, C19 CAP CER 1µF 16V 0603 MURATA GRM188R71C105KA12D
C16 CAP CER 0.22µF 16V 0603 TDK C1608X7R1C224K
C17 CAP CER 10µF 16V 1206 MURATA GRM31CR71C106KAC7L
D1a, D1b 120V DIODE ULTRAFAST 200V 1A SMA FAIRCHILD ES1D
230V DIODE FAST 400V 1A DO-214AC FAIRCHILD ES1G
D2 DIODE ULTRAFAST 200V 1A SMA FAIRCHILD ES1D
D3, D5 DIODE ULTRAFAST 100V 0.2A SOT-23 FAIRCHILD MMBD914
D4 DIODE DUAL SCHOTTKY 20V 0.5A SOT-23 NXP SEMI PMEG3005CT,215
D6 120V DIODE TVS 150V 600W UNI SMB LITTLEFUSE SMBJ150A
230V DIODE TVS 220V 600W UNI SMB LITTLEFUSE SMBJ220A
D7 DIODE ULTRAFAST 600V 1A SMA FAIRCHILD ES1J
D8 DIODE ZENER 24V 1.5W SMA MICRO-SEMI SMAJ5934B-TP
D9 DIODE SCHOTTKY 20V 3A SMA FAIRCHILD ES2AA-13-F
D10 DIODE RECT 600V 0.5A Minidip COMCHIP HD06
D11, D12 DIODE ZENER 10V 500mW SOD-123 FAIRCHILD MMSZ5240B
D13 DIODE ZENER 1.8V 500MW SOD-123 ON-SEMI MMSZ4678T1G
D17 DIODE ZENER 3.9V 500MW SOD-123 ON-SEMI MMSZ4686T1G
D18 DIODE ZENER 18V 500MW SOD-123 ON-SEMI MMSZ5248T1G
D19 DIODE SCHOTTKY 30V 200mA SOT-23 FAIRCHILD BAT54
L1 IND LINE FILTER 6mH 0.3A 11M PANASONIC ELF-11M030E
L1, L2, L3 IND SHIELD 1mH 1.18A SMT COILCRAFT MSS1278-105KL
L4 IND SHIELD 270µH 2.34A SMT COILCRAFT MSS1278-274KLB
Q1 MOSFET N-CH 800V 3A DPAK ST MICRO STD4NK80ZT4
Q2 120V MOSFET N-CH 500V 9A DPAK ST MICRO STD11NM50N
230V MOSFET N-CH 800V 6A DPAK INFINEON SPD06N80C3
Q3, Q4 TRANS NPN 40V 0.6A SOT-23 FAIRCHILD MMBT4401
Q6 TRANS NPN 40V 0.2A SOT-23 FAIRCHILD MMBT3904
(1) Components are used in both versions unless otherwise noted
Copyright © 2010–2013, Texas Instruments Incorporated Submit Documentation Feedback 31
Product Folder Links: LM3450
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SNVS681D –NOVEMBER 2010–REVISED MAY 2013
www.ti.com
Table 3. Bill of Materials(1) (continued)
Reference Designator Description Manufacturer Part Number
R1 120V RES 330Ω5% 1W 2512 VISHAY CRCW2512330RJNEG
230V RES 510Ω5% 1W 2512 VISHAY CRCW2512510RJNEG
R2 120V RES 430Ω5% 1W 2512 VISHAY CRCW2512430RJNEG
230V RES 1.6kΩ5% 1W 2512 VISHAY CRCW25121K60JNEG
R3 120V RES 402kΩ1% 0.25W 1206 VISHAY CRCW1206402KFKEA
230V RES 953kΩ1% 0.25W 1206 VISHAY CRCW1206953KFKEA
R4 RES 100Ω1% 1W 2512 VISHAY WSL2512100RFKEA
R5 RES 100kΩ1% 0.1W 0603 VISHAY CRCW0603100KFKEA
R6 RES 6.04kΩ1% 0.1W 0603 VISHAY CRCW06036K04FKEA
R7 RES 499kΩ1% 0.1W 0603 VISHAY CRCW0603499KFKEA
R8, R9 RES 49.9kΩ1% 0.1W 0603 VISHAY CRCW060349K9FKEA
R10 RES 20kΩ1% 0.1W 0603 VISHAY CRCW060320K0FKEA
R11 120V RES 1.00MΩ1% 0.25W 1206 VISHAY CRCW12061M00FKEA
230V RES 2.00MΩ1% 0.25W 1206 VISHAY CRCW12062M00FKEA
R12 RES 15.0kΩ1% 0.1W 0603 VISHAY CRCW060315K0FKEA
R13 RES 5.11kΩ1% 0.1W 0603 VISHAY CRCW06035K11FKEA
R14a, R14b, R23a, R23b, RES 1.00Ω1% 0.33W 1206 VISHAY CRCW12061R00FKEA
R23c
R15a, R15b RES 5.62Ω1% 0.25W 1206 VISHAY CRCW12065R62FKEA
R16 RES 1.00kΩ1% 0.125W 0805 VISHAY CRCW08051K00FKEA
R17 120V RES 30.1kΩ1% 0.1W 0603 VISHAY CRCW060330K1FKEA
230V RES 15.0kΩ1% 0.1W 0603 VISHAY CRCW060315K0FKEA
R18 RES 105kΩ1% 0.125W 0805 VISHAY CRCW0805105KFKEA
R19 RES 2.49kΩ1% 0.1W 0603 VISHAY CRCW06035K49FKEA
R20 RES 6.04kΩ1% 0.125W 0805 VISHAY CRCW08056K04FKEA
R21 RES 10.0kΩ1% 0.125W 0805 VISHAY CRCW080510K0FKEA
R22 RES 1.4kΩ1% 0.125W 0805 VISHAY CRCW08051K40FKEA
R24, R25 RES 10kΩ1% 0.1W 0603 VISHAY CRCW060310K0FKEA
R26 120V RES 2.49kΩ1% 0.125W 0805 VISHAY CRCW08052K49FKEA
230V RES 4.99kΩ1% 0.125W 0805 VISHAY CRCW08054K99FKEA
R27, R28 120V RES 5Ω10% 3W WIREWOUND VISHAY PAC300005008FAC000
230V RES 10Ω10% 3W WIREWOUND VISHAY PAC300001009FAC000
R29, R30 RES 4.99kΩ1% 0.1W 0603 VISHAY CRCW06034K99FKEA
R32 RES 909Ω1% 0.1W 0603 VISHAY CRCW0603909RFKEA
OPTO1, OPTO2 OPTO-ISOLATOR SMD LITE ON CNY17F-3S
T1 120V XFORMER 120V 30W OUTPUT 50V WURTH 750813651
230V XFORMER 230V 30W OUTPUT 50V WURTH 750817651
Thermal Protect see DYNAMIC HOLD section
32 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated
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SNVS681D –NOVEMBER 2010–REVISED MAY 2013
REVISION HISTORY
Changes from Revision C (May 2013) to Revision D Page
• Changed layout of National Data Sheet to TI format .......................................................................................................... 32
Copyright © 2010–2013, Texas Instruments Incorporated Submit Documentation Feedback 33
Product Folder Links: LM3450
PACKAGE OPTION ADDENDUM
www.ti.com 10-Dec-2020
Addendum-Page 1
PACKAGING INFORMATION
Orderable Device Status
(1)
Package Type Package
Drawing Pins Package
Qty Eco Plan
(2)
Lead finish/
Ball material
(6)
MSL Peak Temp
(3)
Op Temp (°C) Device Marking
(4/5)
Samples
LM3450AMT/NOPB ACTIVE TSSOP PW 16 92 RoHS & Green NIPDAU | SN Level-1-260C-UNLIM LM3450
AMT
LM3450AMTX/NOPB ACTIVE TSSOP PW 16 2500 RoHS & Green NIPDAU | SN Level-1-260C-UNLIM LM3450
AMT
LM3450MT/NOPB ACTIVE TSSOP PW 16 92 RoHS & Green NIPDAU | SN Level-1-260C-UNLIM -40 to 125 LM3450
MT
LM3450MTX/NOPB ACTIVE TSSOP PW 16 2500 RoHS & Green NIPDAU | SN Level-1-260C-UNLIM -40 to 125 LM3450
MT
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based
flame retardants must also meet the <=1000ppm threshold requirement.
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6) Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two
lines if the finish value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
PACKAGE OPTION ADDENDUM
www.ti.com 10-Dec-2020
Addendum-Page 2
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device Package
Type Package
Drawing Pins SPQ Reel
Diameter
(mm)
Reel
Width
W1 (mm)
A0
(mm) B0
(mm) K0
(mm) P1
(mm) W
(mm) Pin1
Quadrant
LM3450AMTX/NOPB TSSOP PW 16 2500 330.0 12.4 6.95 5.6 1.6 8.0 12.0 Q1
LM3450MTX/NOPB TSSOP PW 16 2500 330.0 12.4 6.95 5.6 1.6 8.0 12.0 Q1
PACKAGE MATERIALS INFORMATION
www.ti.com 9-Aug-2020
Pack Materials-Page 1
*All dimensions are nominal
Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)
LM3450AMTX/NOPB TSSOP PW 16 2500 367.0 367.0 35.0
LM3450MTX/NOPB TSSOP PW 16 2500 367.0 367.0 35.0
PACKAGE MATERIALS INFORMATION
www.ti.com 9-Aug-2020
Pack Materials-Page 2
www.ti.com
PACKAGE OUTLINE
C
14X 0.65
2X
4.55
16X 0.30
0.19
TYP
6.6
6.2
1.2 MAX
0.15
0.05
0.25
GAGE PLANE
-80
BNOTE 4
4.5
4.3
A
NOTE 3
5.1
4.9
0.75
0.50
(0.15) TYP
TSSOP - 1.2 mm max heightPW0016A
SMALL OUTLINE PACKAGE
4220204/A 02/2017
1
89
16
0.1 C A B
PIN 1 INDEX AREA
SEE DETAIL A
0.1 C
NOTES:
1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing
per ASME Y14.5M.
2. This drawing is subject to change without notice.
3. This dimension does not include mold flash, protrusions, or gate burrs. Mold flash, protrusions, or gate burrs shall not
exceed 0.15 mm per side.
4. This dimension does not include interlead flash. Interlead flash shall not exceed 0.25 mm per side.
5. Reference JEDEC registration MO-153.
SEATING
PLANE
A 20
DETAIL A
TYPICAL
SCALE 2.500
www.ti.com
EXAMPLE BOARD LAYOUT
0.05 MAX
ALL AROUND 0.05 MIN
ALL AROUND
16X (1.5)
16X (0.45)
14X (0.65)
(5.8)
(R0.05) TYP
TSSOP - 1.2 mm max heightPW0016A
SMALL OUTLINE PACKAGE
4220204/A 02/2017
NOTES: (continued)
6. Publication IPC-7351 may have alternate designs.
7. Solder mask tolerances between and around signal pads can vary based on board fabrication site.
LAND PATTERN EXAMPLE
EXPOSED METAL SHOWN
SCALE: 10X
SYMM
SYMM
1
89
16
15.000
METAL
SOLDER MASK
OPENING METAL UNDER
SOLDER MASK SOLDER MASK
OPENING
EXPOSED METAL
EXPOSED METAL
SOLDER MASK DETAILS
NON-SOLDER MASK
DEFINED
(PREFERRED)
SOLDER MASK
DEFINED
www.ti.com
EXAMPLE STENCIL DESIGN
16X (1.5)
16X (0.45)
14X (0.65)
(5.8)
(R0.05) TYP
TSSOP - 1.2 mm max heightPW0016A
SMALL OUTLINE PACKAGE
4220204/A 02/2017
NOTES: (continued)
8. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate
design recommendations.
9. Board assembly site may have different recommendations for stencil design.
SOLDER PASTE EXAMPLE
BASED ON 0.125 mm THICK STENCIL
SCALE: 10X
SYMM
SYMM
1
89
16
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