DS485
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SNLS122C –JULY 1998–REVISED APRIL 2013
DS485 Low Power RS-485/RS-422 Multipoint Transceiver
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1FEATURES DESCRIPTION
The DS485 is a low-power transceiver for RS-485
• Meets TIA/EIA RS-485 Multipoint Standard and RS-422 communication. The device contains one
• ensured Full Load Output Voltage (V OD3)driver and one receiver. The drivers slew rate allows
• Low Quiescent Current: 200 μA typ for operation up to 2.5 Mbps (see Applications
Information section).
•−7V to +12V Common-Mode Input Voltage
Range The transceiver draws 200 μA of supply current when
unloaded or fully loaded with the driver disabled and
• TRI-STATE Outputs on Driver and Receiver operates from a single +5V supply.
• AC Performance: The driver is short-circuit current limited and is
– Driver Transition Time: 25 ns typ protected against excessive power dissipation by
– Driver Propagation Delay: 40 ns typ thermal shutdown circuitry that places the driver
– Driver Skew: 1 ns typ outputs into TRI-STATE (High Impedance state)
under fault conditions. The driver ensures a minimum
– Receiver Propagation Delay: 200 ns typ of 1.5V differential output voltage with maximum
– Receiver Skew: 20 ns typ loading across the common mode range (VOD3).
• Half-Duplex Flow Through Pinout The receiver has a failsafe feature that ensures a
• Operates From a Single 5V Supply logic-high output if the input is open circuit.
• Allows Up To 32 Transceivers on the Bus The DS485 is available in 8-pin SOIC and PDIP
• Current-Limiting and Thermal Shutdown For packages and is characterized for Industrial and
Driver Overload Protection Commercial temperature range operation.
• Industrial Temperature Range Operation
• Pin and Functional Compatible With MAX485
and LTC485
TRUTH TABLE
Connection and Logic Diagram DRIVER SECTION
RE* DE DI A B
X H H H L
X H L L H
X L X Z Z
RECEIVER SECTION
RE* DE A-B RO
L L ≥+0.2V H
L L ≤−0.2V L
H X X Z
L L OPEN*(1) H
(1) Non Terminated, Open Input only
Figure 1. 8-Pin SOIC or PDIP X = indeterminate
See D or P Package Z = TRI-STATE
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.
PRODUCTION DATA information is current as of publication date. Copyright © 1998–2013, 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.
DS485
SNLS122C –JULY 1998–REVISED APRIL 2013
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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)
Supply Voltage (VCC) +12V
Enable Input Voltage (RE*, DE) −0.5V to (VCC + 0.5V)
Driver Input Voltage (DI) −0.5V to (VCC + 0.5V)
Driver Output Voltage (A, B) −14V to +14V
Receiver Input Voltage (A, B) −14V to +14V
Receiver Output Voltage (RO) −0.5V to (VCC + 0.5V)
Maximum Package Power Dissipation @ +25°C SOIC Package 1.19W
PDIP Package 0.74W
Derate SOIC Package 9.5 mW/°C above +25°C
Derate PDIP Package 6.0 mW/°C above +25°C
Maximum Package Power Dissipation @ +70°C SOIC Package 0.76W
PDIP Package 0.47W
Storage Temperature Range −65°C to +150°C
Lead Temperature Range Soldering, 4 sec +260°C
ESD (HBM) ≥2 kV
(1) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and
specifications.
(2) Absolute Maximum Ratings are those values beyond which the safety of the device cannot be ensured. They are not meant to imply that
the devices should be operated at these limits. The table of ELECTRICAL CHARACTERISTICS specifies conditions of device operation.
RECOMMENDED OPERATING CONDITIONS Min Typ Max Units
Supply Voltage (VCC) +4.75 +5.0 +5.25 V
Operating Free Air Temperature (TA) DS485 0 +25 +70 °C
DS485T −40 +25 +85 °C
Bus Common Mode Voltage −7 +12 V
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SNLS122C –JULY 1998–REVISED APRIL 2013
ELECTRICAL CHARACTERISTICS
Over Supply Voltage and Operating Temperature Ranges, unless otherwise specified(1)(2)
Symbol Parameter Conditions Pin Min Typ Max Units
VOD1 Differential Driver Output Voltage (No Load) A, B 5 V
VOD2 Differential Driver Output Voltage RL= 50Ω, (RS422), See Figure 2 2 2.8 V
with Load RL= 27Ω, (RS485), See Figure 2 1.5 2.3 5 V
ΔVOD Change in Magnitude of Output RL= 27Ωor 50Ω(3) 0.2 |V|
Differential Voltage
VOD3 Differential Driver Output Voltage— R1 = 54Ω, R2 = 375Ω1.5 2.0 5 V
Full Load with Max VCM VTEST =−7V to +12V, See Figure 6
VOC Driver Common-Mode Output Voltage RL= 27Ωor 50Ω, See Figure 2 3 V
ΔVOC Change in Magnitude of Common-Mode RL= 27Ωor 50Ω, See Figure 2(3) 0.2 |V|
Output Voltage
VIH Input High Voltage DI, 2.0 V
DE,
VIL Input Low Voltage 0.8 V
RE*
IIN1 Input Current VIN = 0V or VCC ±2 μA
IIN2 Input Current(4) VIN = +12V A, B 1.0 mA
DE = 0V, VCC = 0V or 5.25V VIN =−7V −0.8 mA
VTH Receiver Differential Threshold Voltage −7V ≤VCM ≤+12V −0.2 0.2 V
ΔVTH Receiver Input Hysteresis VCM = 0V 70 mV
VOH Receiver Output High Voltage IO=−4 mA, VID = 0.2V RO 3.5 V
VOL Receiver Output Low Voltage IO= 4 mA, VID =−0.2V 0.4 V
IOZR TRI-STATE Output Current at Receiver 0.4V ≤VO≤2.4V ±1 μA
RIN Receiver Input Resistance −7V ≤VIN ≤+12V A, B 12 kΩ
ICC No-Load Supply Current(5) DE = VCC, RE* = 0V or VCC VCC 200 900 μA
DE = 0V, RE* = 0V or VCC 200 500 μA
IOSD1 Driver Short Circuit Current, VO= HIGH −7V ≤VO≤+12V A, B 35 250 mA
IOSD2 Driver Short Circuit Current, VO= LOW −7V ≤VO≤+12V 35 250 mA
IOSR Receiver Short Circuit Current 0V ≤VO≤VCC RO 7 85 mA
(1) Current into device pins is defined as positive. Current out of device pins is defined as negative. All voltages are referenced to ground
except VOD1/2/3 and VID.
(2) All typicals are given for: VCC = +5.0V, TA= +25°C.
(3) Δ|VOD| and Δ|VOC| are changes in magnitude of V OD and VOC respectively, that occur when the input changes state.
(4) IIN2 includes the receiver input current and driver TRI-STATE leakage current.
(5) Supply current specification is valid for loaded transmitters when DE = 0V or enabled (DE = H) with no load.
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SWITCHING CHARACTERISTICS
Over Supply Voltage and Operating Temperature Ranges, unless otherwise specified(1)(2)(3)
Symbol Parameter Conditions Min Typ Max Units
tPLHD Driver Differential Propagation Delay—Low to High RL= 54Ω, CL= 100 pF 10 40 65 ns
tPHLD Driver Differential Propagation Delay—High to Low 10 39 65 ns
tSKEW Differential Skew |tPHLD −tPLHD| 1 10 ns
trDriver Rise Time 3 25 40 ns
tfDriver Fall Time 3 25 40 ns
tZH Driver Enable to Output High CL= 100 pF 170 ns
tZL Driver Enable to Output Low CL= 100 pF 170 ns
tLZ Driver Disable from Output Low CL= 15 pF 170 ns
tHZ Driver Disable from Output High CL= 15 pF 170 ns
tPLHD Receiver Differential Propagation Delay—Low to High CL= 15 pF (RO) 70 190 320 ns
tPHLD Receiver Differential Propagation Delay—High to Low 70 210 320 ns
tSKEW Differential Skew |tPHLD −tPLHD| 20 50 ns
tZH Receiver Enable to Output High CL= 15 pF 110 ns
tZL Receiver Enable to Output Low 110 ns
tLZ Receiver Disable from Output Low 110 ns
tHZ Receiver Disable from Output High 110 ns
fmax Maximum Data Rate See (4) 2.5 Mbps
(1) All typicals are given for: VCC = +5.0V, TA= +25°C.
(2) f = 1 MHz, trand tf≤6 ns, ZO= 50Ω.
(3) CLincludes jig and probe capacitance.
(4) fmax is the ensured data rate for 50 ft of twisted pair cable. f max may be conservatively determined from the ratio of driver transition time
(tr) to the data rate unit interval (1/fmax). Using a 10% ratio yields fmax = (0.1)/40 ns = 2.5 Mb/s. Higher data rates may be supported by
allowing larger ratios.
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SNLS122C –JULY 1998–REVISED APRIL 2013
Figure 14.
PIN DESCRIPTIONS
Pin # I/O Name Function
1 O RO Receiver Output: If A > B by 200 mV, RO will be high; If A < B by 200 mV, RO will be low. RO will be high also if
the inputs (A and B) are open (non-terminated).
2 I RE* Receiver Output Enable: RO is enabled when RE* is low; RO is in TRI-STATE when RE* is high.
3 I DE Driver Output Enable: The driver outputs (A and B) are enabled when DE is high; they are in TRI-STATE when DE
is low. Pins A and B also function as the receiver input pins (see below).
4 I DI Driver Input: A low on DI forces A low and B high while a high on DI forces A high and B low when the driver is
enabled.
5 NA GND Ground
6 I/O A Non-inverting Driver Output and Receiver Input pin. Driver output levels conform to RS-485 signaling levels.
7 I/O B Inverting Driver Output and Receiver Input pin. Driver output levels conform to RS-485 signaling levels.
8 NA VCC Power Supply: 4.75V ≤VCC ≤5.25V
Related TI Low Power RS-485 Transceivers
Part Number Temperature Range Number of XCVRs on Bus Comments
DS36C278 0°C to +70°C 128 Ultra Low Power Transceiver
DS36C278T −40°C to +85°C 64 Ultra Low Power Transceiver
DS36C279 0°C to +70°C 128 Auto-Sleep Mode
DS36C279T −40°C to +85°C 64 Auto-Sleep Mode
DS36C280 0°C to +70°C 128 Adjustable Slew Rate Control
DS36C280T −40°C to +85°C 64 Adjustable Slew Rate Control
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APPLICATIONS INFORMATION
The DS485 is a low power transceiver designed for use in RS-485 multipoint applications. The DS485 can
transmit data up to 2.5 Mbps based on a ratio of driver transition time to the unit interval (bit time) of 10%. This
maximum data rate may be further limited by the interconnecting media. The DS485 provides a standard unit
load to the RS-485 bus across the common mode range of −7V to +12V. This allows up to 32 transceivers
(standard unit load) to be connected to the bus. More transceivers may be connected to the bus if they support a
reduced unit load (see Related TI Low Power RS-485 Transceivers). The DS485 also ensures the driver's output
differential voltage into a worst case load that models standard termination loads and 32 unit loads referenced to
the maximum common mode voltage extremes. With a minimum of 1.5V swing into this load, a 1.3V differential
noise margin is supported along with the standard common mode rejection range of the receivers.
Due to the multipoint nature of the bus, contention between drivers may occur. This will not cause damage to the
drivers since they feature short-circuit protection and also thermal shutdown protection. Thermal shutdown
senses die temperature and puts the driver outputs into TRI-STATE if a fault condition occurs that causes
excessive power dissipation which can elevate the junction temperature to +150°C.
A typical multipoint application is shown in the following figure. Note that termination is typically required but is
only located at the two ends of the cable (not on every node). Commonly pull up and pull down resistors may be
required at one end of the bus to provide a failsafe bias. These resistors provide a bias to the line when all
drivers are in TRI-STATE. See Application Note AN-847(SNLA031) for a complete discussion of failsafe biasing
of differention buses.
Figure 15. Multipoint RS-485 Application
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SNLS122C –JULY 1998–REVISED APRIL 2013
REVISION HISTORY
Changes from Revision B (April 2013) to Revision C Page
• Changed layout of National Data Sheet to TI format ............................................................................................................ 8
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PACKAGE OPTION ADDENDUM
www.ti.com 25-Aug-2017
Addendum-Page 1
PACKAGING INFORMATION
Orderable Device Status
(1)
Package Type Package
Drawing Pins Package
Qty Eco Plan
(2)
Lead/Ball Finish
(6)
MSL Peak Temp
(3)
Op Temp (°C) Device Marking
(4/5)
Samples
DS485M LIFEBUY SOIC D 8 95 TBD Call TI Call TI 0 to 70 DS485
M
DS485M/NOPB LIFEBUY SOIC D 8 95 Green (RoHS
& no Sb/Br) CU SN Level-1-260C-UNLIM 0 to 70 DS485
M
DS485MX/NOPB LIFEBUY SOIC D 8 2500 Green (RoHS
& no Sb/Br) CU SN Level-1-260C-UNLIM 0 to 70 DS485
M
DS485N/NOPB LIFEBUY PDIP P 8 40 Green (RoHS
& no Sb/Br) CU SN Level-1-NA-UNLIM 0 to 70 DS485
N
DS485TM LIFEBUY SOIC D 8 95 TBD Call TI Call TI -40 to 85 DS485
TM
DS485TM/NOPB LIFEBUY SOIC D 8 95 Green (RoHS
& no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 85 DS485
TM
DS485TMX/NOPB LIFEBUY SOIC D 8 2500 Green (RoHS
& no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 85 DS485
TM
(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.
PACKAGE OPTION ADDENDUM
www.ti.com 25-Aug-2017
Addendum-Page 2
(6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish
value exceeds the maximum column width.
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