(R) RT8297A/B 1.5A, 17V, 340/800kHz Synchronous Step-Down Converter General Description Features The RT8297A/B is a high efficiency, monolithic synchronous step-down DC-DC converter that can operate at 340kHz/800kHz, while delivering up to 1.5A output current from a 4V to 17V input supply. The RT8297A/B's current mode architecture allows the transient response to be optimized. Cycle-by-cycle current limit provides protection against shorted outputs and soft-start eliminates input current surge during start-up. Fault conditions also include output under voltage protection, output over voltage protection, and thermal shutdown. The low current (<5A) shutdown mode provides output disconnect, enabling easy power management in battery-powered systems. The RT8297A/B is available in a WDFN-8L 2x2 package. 4V to 17V Input Voltage Range 1.5A Output Current Internal N-MOSFETs Current Mode Control Fixed Frequency Operation : 340kHz/800kHz Output Adjustable from 0.8V to 12V Up to 95% Efficiency Internal Compensation Stable with Low ESR Ceramic Output Capacitors Cycle-by-Cycle Over Current Protection Input Under Voltage Lockout Output Under Voltage Protection Output Over Voltage Protection Power Good Indicator Thermal Shutdown Protection RoHS Compliant and Halogen Free Ordering Information RT8297A/B Lead Plating System Z : ECO (Ecological Element with Halogen Free and Pb free) A : 340kHz B : 800kHz Note : Richtek products are : RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. Applications Industrial and Commercial Low Power Systems Computer Peripherals LCD Monitors and TVs Green Electronics/Appliances Point of Load Regulation for High-Performance DSPs, FPGAs, and ASICs Pin Configuration (TOP VIEW) Suitable for use in SnPb or Pb-free soldering processes. Marking Information RT8297AZQW 00 : Product Code 00W SW VIN BOOT EN 1 2 3 4 GND Package Type QW : WDFN-8L 2x2 (W-Type) 9 8 7 6 5 GND GND PGOOD FB WDFN-8L 2x2 W : Date Code RT8297BZQW 71 : Product Code 71W W : Date Code Copyright (c) 2018 Richtek Technology Corporation. All rights reserved. DS8297A/B-07 June 2018 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT8297A/B Typical Application Circuit RT8297A VIN 4V to 17V 2 VIN BOOT 3 CIN 10F CBOOT 10nF SW 1 6 PGOOD PGOOD Chip Enable 7, 8, 9 (Exposed Pad) R1 110k FB 5 4 EN L 15H VOUT 3.3V 1.5A COUT 22F x 2 R2 36k GND RT8297B VIN 4V to 17V 2 VIN BOOT 3 CIN 10F CBOOT 10nF SW 1 6 PGOOD PGOOD Chip Enable 7, 8, 9 (Exposed Pad) R1 47k FB 5 4 EN L 6.8H VOUT 3.3V 1.5A COUT 22F x 2 R2 15k GND Table 1. Recommended Component Selection RT8297A VOUT (V) L (H) R1 (k) R2 (k) COUT (F) 1.2 4.7 110 220 22 x 2 2.5 10 110 51 22 x 2 3.3 15 110 36 22 x 2 5 22 120 22 22 x 2 VOUT (V) L (H) R1 (k) R2 (k) COUT (F) 1.2 3.6 47 91 22 x 2 2.5 4.7 47 22 22 x 2 3.3 6.8 47 15 22 x 2 5 10 62 12 22 x 2 RT8297B Copyright (c) 2018 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DS8297A/B-07 June 2018 RT8297A/B Functional Pin Description Pin No. Pin Name Pin Function 1 SW 2 VIN 3 BOOT 4 EN 5 FB Feedback input pin. For an adjustable output, connect an external resistive voltage divider to this pin. 6 PGOOD Power good indicator. The output of this pin is low if the output voltage is 12.5% less than the nominal voltage. Otherwise, it is an open drain. GND Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. 7, 8, 9 (Exposed Pad) Switch node. Connect to external L-C filter. Input supply voltage. Must bypass with a suitably large ceramic capacitor. Bootstrap for high side gate driver. Connect 0.01F or greater ceramic capacitor from BOOT to SW pin. Chip enable. A logic-high enables the converter; a logic-low forces the RT8297A/B into shutdown mode, reducing the supply current to less than 5A. Attach this pin to VIN with a 100k pull up resistor for automatic startup. Functional Block Diagram VIN Internal Regulator EN Enable Comparator + 2.5V 5k 3V 1V 0.4V OSC 340kHz/800kHz VA VCC Slope Comp + Current Sense Amplifier Foldback Control VA + BOOT OV OV Comparator + + UV - - UV Comparator 0.8V FB - S Q R Current Comparator Q 145m SW 140m + Error Amp PGOOD Comparator + 35pF 400k - 1pF GND 0.7V FB PGOOD Copyright (c) 2018 Richtek Technology Corporation. All rights reserved. DS8297A/B-07 June 2018 is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT8297A/B Absolute Maximum Ratings (Note 1) Supply Voltage, VIN ----------------------------------------------------------------------------------------SW --------------------------------------------------------------------------------------------------------------BOOT to SW -------------------------------------------------------------------------------------------------All Other Pins ------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25C WDFN-8L 2x2 ------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2) WDFN-8L 2x2, JA -------------------------------------------------------------------------------------------WDFN-8L 2x2, JC -------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) -----------------------------------------------------------------Junction Temperature ---------------------------------------------------------------------------------------Storage Temperature Range ------------------------------------------------------------------------------ESD Susceptibility (Note 3) HBM (Human Body Model) --------------------------------------------------------------------------------MM (Machine Model) ---------------------------------------------------------------------------------------- Recommended Operating Conditions -0.3V to 19V -0.3V to (VIN + 0.3V) -0.3V to 6V -0.3V to 6V 0.833W 120C/W 8.2C/W 260C 150C -65C to 150C 2kV 200V (Note 4) Supply Input Voltage, VIN ---------------------------------------------------------------------------------- 4V to 17V Junction Temperature Range ------------------------------------------------------------------------------- -40C to 125C Ambient Temperature Range ------------------------------------------------------------------------------- -40C to 85C Electrical Characteristics (VIN = 12V, TA = 25C, unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit Shutdown Supply Current ISHDN VEN = 0V -- 1 5 A Supply Current IOUT VEN = 3V, VFB = 0.9V -- 0.6 1 mA 0.788 0.800 0.812 V -- 10 -- nA RDS(ON)1 -- 145 -- m RDS(ON)2 -- 140 -- m 2.45 3 4.65 A -- 1 -- A For RT8297A 300 340 380 For RT8297B 700 800 900 VFB = 0V, For RT8297A -- 95 -- VFB = 0V, For RT8297B -- 170 -- VFB = 0.7V, For RT8297A -- 93 -- % VFB = 0.7V, For RT8297B -- 84 -- % Feedback Reference Voltage VREF 4V VIN 17V Feedback Current High Side Switch On Resistance Low Side Switch On Resistance VFB = 0.8V IFB Upper Switch Current Limit Min. duty cycle, VBOOT VSW = 4.8V maximum loading = 1.5A Lower Switch Current Limit From drain to source Oscillation Frequency fOSC1 Short-Circuit Oscillation Frequency fOSC2 Maximum Duty Cycle DMAX Copyright (c) 2018 Richtek Technology Corporation. All rights reserved. www.richtek.com 4 kHz kHz is a registered trademark of Richtek Technology Corporation. DS8297A/B-07 June 2018 RT8297A/B Parameter Minimum On-Time Input Under Voltage Lockout Threshold Input Under Voltage Lockout Threshold Hysteresis EN Threshold Voltage Symbol Test Conditions Min Typ Max Unit tON -- 100 125 ns VUVLO -- 3.5 -- V VUVLO -- 200 -- mV 2.7 -- -- -- -- 0.4 -- 1 -- A Logic-High VIH Logic-Low VIL EN Pull Low Current VEN = 2V, VFB = 1V V Soft-Start Period tSS -- 1 -- ms Thermal Shutdown TSD -- 150 -- C Thermal Shutdown Hysteresis Power Good Threshold Rising Power Good Threshold Hysteresis Power Good Pull Down Resistance Output OVP Trip Threshold TSD -- 15 -- C -- 0.7 -- V -- 130 -- mV -- 12 -- -- 125 -- %VREF Output OVP Prop Delay -- 10 -- s Output UVP Trip Threshold -- 50 -- %VREF Output UVP Prop Delay -- 2 -- s Note 1. Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may affect device reliability. Note 2. JA is measured at TA = 25C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. JC is measured at the exposed pad of the package. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions. Copyright (c) 2018 Richtek Technology Corporation. All rights reserved. DS8297A/B-07 June 2018 is a registered trademark of Richtek Technology Corporation. www.richtek.com 5 RT8297A/B Typical Operating Characteristics Efficiency vs. Output Current Efficiency vs. Output Current 100 100 90 90 80 VOUT = 5V VOUT = 3.3V VOUT = 1.2V 70 60 Efficiency (%) Efficiency (%) 80 50 40 30 20 70 VOUT = 5V VOUT = 3.3V VOUT = 1.2V 60 50 40 30 20 10 10 RT8297A, VIN = 12V 0 0.01 0.10 1.00 RT8297B, VIN = 12V 0 0.01 10.00 0.10 Output Current (A) Output Voltage vs. Output Current 5.10 3.40 5.06 3.36 Output Voltage (V) Output Voltage (V) 10.00 Output Current (A) Output Voltage vs. Output Current 5.02 4.98 3.32 3.28 3.24 4.94 RT8297B, VIN = 12V, VOUT = 3.3V RT8297A, VIN = 12V, VOUT = 5V 3.20 4.90 0.0 0.3 0.6 0.9 1.2 0.0 1.5 0.3 0.5 0.8 1.0 1.3 1.5 Output Current (A) Output Current (A) Reference Voltage vs. Temperature Reference Voltage vs. Temperature 1.00 1.00 0.95 0.95 Reference Voltage (V) Reference Voltage (V) 1.00 0.90 0.85 0.80 0.75 0.70 0.90 0.85 0.80 0.75 0.70 0.65 0.65 RT8297A, VIN = 12V, IOUT = 0A RT8297B, VIN = 12V, IOUT = 0A 0.60 0.60 -50 -25 0 25 50 75 100 Temperature (C) Copyright (c) 2018 Richtek Technology Corporation. All rights reserved. www.richtek.com 6 125 -50 -25 0 25 50 75 100 125 Temperature (C) is a registered trademark of Richtek Technology Corporation. DS8297A/B-07 June 2018 RT8297A/B Frequency vs. Input Voltage 860 350 850 345 Frequency (kHz)1 Frequency (kHz)1 Frequency vs. Input Voltage 355 340 335 330 325 320 840 830 820 810 800 790 315 RT8297A, VOUT = 3.3V, IOUT = 0.3A RT8297B, VOUT = 3.3V, IOUT = 0.3A 310 780 4 6 8 10 12 14 16 18 4 6 8 Frequency vs. Temperature 14 16 18 900 875 Frequency (kHz)1 375 Frequency (kHz)1 12 Frequency vs. Temperature 400 350 325 300 275 850 825 800 775 750 725 RT8297A, VOUT = 3.3V, IOUT = 0.3A 250 RT8297B, VOUT = 3.3V, IOUT = 0.3A 700 -50 -25 0 25 50 75 100 125 -50 -25 0 25 50 75 100 125 Temperature (C) Temperature (C) Quiescent Current vs. Input Voltage Quiescent Current vs. Input Voltage 1000 900 950 850 Quiescent Current (A) Quiescent Current (A) 10 Input Voltage (V) Input Voltage (V) 800 750 700 650 900 850 800 750 700 650 RT8297B, VEN = 3.3V, VFB = 0.85V RT8297A, VEN = 3.3V, VFB = 0.85V 600 600 4 6 8 10 12 14 16 Input Voltage (V) Copyright (c) 2018 Richtek Technology Corporation. All rights reserved. DS8297A/B-07 June 2018 18 4 6 8 10 12 14 16 18 Input Voltage (V) is a registered trademark of Richtek Technology Corporation. www.richtek.com 7 RT8297A/B Quiescent Current vs. Temperature 0.90 0.85 0.85 Quiescent Current (mA) Quiescent Current (mA) Quiescent Current vs. Temperature 0.90 0.80 0.75 0.70 0.65 0.80 0.75 0.70 0.65 RT8297A, VIN = 12V, VEN = 3.3V, VFB = 0.85V RT8297B, VIN = 12V, VEN = 3.3V, VFB = 0.85V 0.60 0.60 -50 -25 0 25 50 75 100 -50 125 -25 0 Temperature (C) RT8297A 3.8 3.6 Current Limit (A) Current Limit (A) 3.2 3.0 VOUT = 1.2V 2.6 RT8297B 125 VOUT = 3.3V 3.2 3.0 2.8 2.6 2.4 2.2 2.2 2.0 VOUT = 1.2V 3.4 2.4 2.0 4 6 8 10 12 14 16 18 4 6 8 Input Voltage (V) 10 12 14 16 18 Input Voltage (V) Current Limit vs. Temperature 3.9 100 3.6 VOUT = 3.3V 2.8 75 Current Limit vs. Input Voltage 4.0 3.4 50 Temperature (C) Current Limit vs. Input Voltage 3.8 25 Current Limit vs. Temperature 4.0 RT8297A RT8297B 3.7 3.3 Current Limit (A) Current Limit (A) 1 3.6 3.0 2.7 2.4 2.1 3.4 3.1 2.8 1.8 VIN = 12V, VOUT = 1.2V 1.5 -50 -25 0 25 50 75 100 Temperature (C) Copyright (c) 2018 Richtek Technology Corporation. All rights reserved. www.richtek.com 8 125 VIN = 12V, VOUT = 1.2V 2.5 -50 -25 0 25 50 75 100 125 Temperature (C) is a registered trademark of Richtek Technology Corporation. DS8297A/B-07 June 2018 RT8297A/B Load Transient Response Load Transient Response RT8297A RT8297B VOUT (100mV/Div) VOUT (50mV/Div) IOUT (1A/Div) IOUT (1A/Div) VIN = 12V, VOUT = 3.3V, IOUT = 0.1A to 1.5A VIN = 12V, VOUT = 3.3V, IOUT = 0.1A to 1.5A Time (1ms/Div) Time (1ms/Div) Switching Switching RT8297A RT8297B VSW (10V/Div) VSW (10V/Div) VOUT (5mV/Div) VOUT (5mV/Div) IL (1A/Div) IL (1A/Div) VIN = 12V, VOUT = 3.3V, IOUT = 1.5A VIN = 12V, VOUT = 3.3V, IOUT = 1.5A Time (5s/Div) Time (500ns/Div) Power On from EN Power On from EN RT8297A RT8297B, VIN = 12V, VOUT = 3.3V, IOUT = 1.5A VEN (5V/Div) VEN (5V/Div) PGOOD (5V/Div) PGOOD (5V/Div) VOUT (2V/Div) VOUT (2V/Div) IOUT (2A/Div) IOUT (2A/Div) VIN = 12V, VOUT = 3.3V, IOUT = 1.5A Time (500s/Div) Copyright (c) 2018 Richtek Technology Corporation. All rights reserved. DS8297A/B-07 June 2018 Time (500s/Div) is a registered trademark of Richtek Technology Corporation. www.richtek.com 9 RT8297A/B Power Off from EN Power Off from EN RT8297A RT8297B, VIN = 12V, VOUT = 3.3V, IOUT = 1.5A VEN (5V/Div) VEN (5V/Div) PGOOD (5V/Div) PGOOD (5V/Div) VOUT (2V/Div) VOUT (2V/Div) IOUT (2A/Div) VIN = 12V, VOUT = 3.3V, IOUT = 1.5A Time (100s/Div) Copyright (c) 2018 Richtek Technology Corporation. All rights reserved. www.richtek.com 10 IOUT (2A/Div) Time (100s/Div) is a registered trademark of Richtek Technology Corporation. DS8297A/B-07 June 2018 RT8297A/B Application Information The RT8297A/B is a synchronous high voltage buck converter that can support the input voltage range from 4V to 17V and the output current can be up to 1.5A. Output Voltage Setting The resistive divider allows the FB pin to sense the output voltage as shown in Figure 1. VOUT R1 FB R2 RT8297A/B GND Thermal Shutdown Thermal shutdown is implemented to prevent the chip from operating at excessively high temperatures. When the junction temperature is higher than 150C, the whole chip is shutdown. The chip is automatically re-enable when the junction temperature cools down by approximately 15 degrees. Over Voltage Protection (OVP) The RT8297A/B provides Over Voltage Protection function when output voltage over 125%. The internal MOS will be turned off. The control will return to normal operation if over voltage condition is removed. Figure 1. Output Voltage Setting Under Voltage Protection (UVP) The output voltage is set by an external resistive divider according to the following equation : R1 VOUT = VREF 1 R2 Where VREF is the feedback reference voltage (0.8V typ.). External Bootstrap Diode Connect a 10nF low ESR ceramic capacitor between the BOOT pin and SW pin. This capacitor provides the gate driver voltage for the high side MOSFET. It is recommended to add an external bootstrap diode between an external 5V and the BOOT pin for efficiency improvement when input voltage is lower than 5.5V or duty ratio is higher than 65%. The bootstrap diode can be a low cost one such as 1N4148 or BAT54. The external 5V can be a 5V fixed input from system or a 5V output of the RT8297A/B. Note that the external boot voltage must be lower than 5.5V 5V BOOT RT8297A/B 10nF SW Figure 2. External Bootstrap Diode Copyright (c) 2018 Richtek Technology Corporation. All rights reserved. DS8297A/B-07 June 2018 For the RT8297A/B, it provides Hiccup Mode Under Voltage Protection (UVP). When the FB voltage drops below 50% of the feedback reference voltage, the UVP function will be triggered and the RT8297A/B will shut down for a period of time and then recover automatically. The Hiccup Mode UVP can reduce input current in short-circuit conditions. Inductor Selection The inductor value and operating frequency determine the ripple current according to a specific input and output voltage. The ripple current IL increases with higher VIN and decreases with higher inductance. V V IL = OUT 1 OUT VIN f L Having a lower ripple current reduces not only the ESR losses in the output capacitors but also the output voltage ripple. High frequency with small ripple current can achieve highest efficiency operation. However, it requires a large inductor to achieve this goal. For the ripple current selection, the value of IL = 0.2(IMAX) will be a reasonable starting point. The largest ripple current occurs at the highest VIN. To guarantee that the ripple current stays below the specified maximum, the inductor value should be chosen according to the following equation : VOUT VOUT L= 1 f IL(MAX) VIN(MAX) is a registered trademark of Richtek Technology Corporation. www.richtek.com 11 RT8297A/B Table 2. Suggested Inductors for Typical Application Circuit Component Supplier TDK TDK TAIYO YUDEN Series Dimensions (mm) VLF10045 SLF12565 10 x 9.7 x 4.5 12.5 x 12.5 x 6.5 NR8040 8x8x4 CIN and COUT Selection The input capacitance, C IN, is needed to filter the trapezoidal current at the source of the high side MOSFET. To prevent large ripple current, a low ESR input capacitor sized for the maximum RMS current should be used. The RMS current is given by : V IRMS = IOUT(MAX) OUT VIN VIN 1 VOUT This formula has a maximum at VIN = 2VOUT, where IRMS = IOUT/2. This simple worst-case condition is commonly used for design because even significant deviations do not offer much relief. Choose a capacitor rated at a higher temperature than required. Several capacitors may also be paralleled to meet size or height requirements in the design. For the input capacitor, a 10F low ESR ceramic capacitor is recommended. For the recommended capacitor, please refer to table 3 for more detail. The selection of COUT is determined by the required ESR to minimize voltage ripple. Moreover, the amount of bulk capacitance is also a key for COUT selection to ensure that the control loop is stable. Loop stability can be checked by viewing the load transient response as described in a later section. The output ripple, VOUT , is determined by : 1 VOUT IL ESR 8fCOUT The output ripple will be highest at the maximum input voltage since IL increases with input voltage. Multiple capacitors placed in parallel may be needed to meet the ESR and RMS current handling requirement. Dry tantalum, special polymer, aluminum electrolytic and ceramic capacitors are all available in surface mount packages. Special polymer capacitors offer very low ESR value. However, it provides lower capacitance density than other Copyright (c) 2018 Richtek Technology Corporation. All rights reserved. www.richtek.com 12 types. Although Tantalum capacitors have the highest capacitance density, it is important to only use types that pass the surge test for use in switching power supplies. Aluminum electrolytic capacitors have significantly higher ESR. However, it can be used in cost-sensitive applications for ripple current rating and long term reliability considerations. Ceramic capacitors have excellent low ESR characteristics but can have a high voltage coefficient and audible piezoelectric effects. The high Q of ceramic capacitors with trace inductance can also lead to significant ringing. Higher values, lower cost ceramic capacitors are now becoming available in smaller case sizes. Their high ripple current, high voltage rating and low ESR make them ideal for switching regulator applications. However, care must be taken when these capacitors are used at input and output. When a ceramic capacitor is used at the input and the power is supplied by a wall adapter through long wires, a load step at the output can induce ringing at the input, VIN. At best, this ringing can couple to the output and be mistaken as loop instability. At worst, a sudden inrush of current through the long wires can potentially cause a voltage spike at VIN large enough to damage the part. Checking Transient Response The regulator loop response can be checked by looking at the load transient response. Switching regulators take several cycles to respond to a step in load current. When a load step occurs, VOUT immediately shifts by an amount equal to ILOAD (ESR) also begins to charge or discharge COUT generating a feedback error signal for the regulator to return VOUT to its steady-state value. During this recovery time, VOUT can be monitored for overshoot or ringing that would indicate a stability problem. Thermal Considerations For continuous operation, do not exceed absolute maximum junction temperature. The maximum power dissipation depends on the thermal resistance of the IC package, PCB layout, rate of surrounding airflow, and difference between junction and ambient temperature. The maximum power dissipation can be calculated by the following formula : is a registered trademark of Richtek Technology Corporation. DS8297A/B-07 June 2018 RT8297A/B PD(MAX) = (TJ(MAX) - TA ) / JA Layout Consideration where TJ(MAX) is the maximum junction temperature, TA is the ambient temperature, and JA is the junction to ambient thermal resistance. Follow the PCB layout guidelines for optimal performance of the RT8297A/B PD(MAX) = (125C - 25C) / (120C/W) = 0.833W for WDFN-8L 2x2 package The maximum power dissipation depends on the operating ambient temperature for fixed T J(MAX) and thermal resistance, JA. The derating curve in Figure 3 allows the designer to see the effect of rising ambient temperature on the maximum power dissipation. Keep the traces of the main current paths as short and wide as possible. Put the input capacitor as close as possible to the device pins (VIN and GND). SW node is with high frequency voltage swing and should be kept at small area. Keep sensitive components away from the SW node to prevent stray capacitive noise pickup. Place the feedback components to the FB pin as close as possible. The GND and Exposed Pad should be connected to a strong ground plane for heat sinking and noise protection. SW should be connected to inductor by wide and short trace. VOUT Keep sensitive components away from this trace. L COUT Maximum Power Dissipation (W) 0.9 Four-Layer PCB 0.8 0.7 0.6 CIN Input capacitor must be placed as close to the IC as possible. CBOOT SW VIN BOOT EN 1 2 3 4 GND For recommended operating condition specifications, the maximum junction temperature is 125C. The junction to ambient thermal resistance, JA, is layout dependent. For WDFN-8L 2x2 package, the thermal resistance, JA, is 120C/W on a standard JEDEC 51-7 four-layer thermal test board. The maximum power dissipation at TA = 25C can be calculated by the following formula : 9 8 7 6 5 GND GND PGOOD FB R1 R2 SW 0.5 0.4 0.3 VOUT GND The resistor divider must be connected as close to the device as possible. Figure 4. PCB Layout Guide 0.2 0.1 0.0 0 25 50 75 100 125 Ambient Temperature (C) Figure 3. Derating Curve of Maximum Power Dissipation Copyright (c) 2018 Richtek Technology Corporation. All rights reserved. DS8297A/B-07 June 2018 is a registered trademark of Richtek Technology Corporation. www.richtek.com 13 RT8297A/B Table 3. Suggested Capacitors for CIN and COUT Location Component Supplier Part No. Capacitance (F) Case Size CIN MURATA GRM31CR61E106K 10 1206 CIN TDK C3225X5R1E106K 10 1206 CIN TAIYO YUDEN TMK316BJ106ML 10 1206 COUT MURATA GRM32ER61E226M 22 1210 COUT MURATA GRM21BR60J226M 22 0805 COUT TDK C3225X5R0J226M 22 1210 COUT TAIYO YUDEN EMK325BJ226MM 22 1210 Copyright (c) 2018 Richtek Technology Corporation. All rights reserved. www.richtek.com 14 is a registered trademark of Richtek Technology Corporation. DS8297A/B-07 June 2018 RT8297A/B Outline Dimension D2 D L E E2 1 e SEE DETAIL A b 2 1 2 1 A A1 A3 DETAIL A Pin #1 ID and Tie Bar Mark Options Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated. Dimensions In Millimeters Dimensions In Inches Symbol Min Max Min Max A 0.700 0.800 0.028 0.031 A1 0.000 0.050 0.000 0.002 A3 0.175 0.250 0.007 0.010 b 0.200 0.300 0.008 0.012 D 1.950 2.050 0.077 0.081 D2 1.000 1.250 0.039 0.049 E 1.950 2.050 0.077 0.081 E2 0.400 0.650 0.016 0.026 e L 0.500 0.300 0.020 0.400 0.012 0.016 W-Type 8L DFN 2x2 Package Richtek Technology Corporation 14F, No. 8, Tai Yuen 1st Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Richtek products are sold by description only. Customers should obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnished by Richtek is believed to be accurate and reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Richtek or its subsidiaries. DS8297A/B-07 June 2018 www.richtek.com 15