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LT1785AIS8#PBF

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Analog Devices RS-485/RS-422 ICs, SO-8. Pinout cross-checked by two models against the datasheet, KiCad symbol/footprint/3D.

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Contents

README

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LT1785AIS8#PBF

Analog Devices · RS-485/RS-422 ICs · SO-8

LT1785AIS8#PBF from Analog Devices, in a SO-8. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin Name Type Function
1 RO output Receiver output is TTL level, high when receiver input A is at least 200mV above B and low when A is at least 200mV below B, goes high impedance when RE is high or the part is powered off, and is protected from output shorts from ground to 6V.
2 RE input Receiver output enable is a TTL level input where logic low enables RO and logic high places RO in high impedance, and it must be tied low for CAN bus applications to prevent shutdown.
3 DE input Driver output enable is a TTL level input where logic high enables the driver outputs A and B (Y and Z on LT1791) and logic low places them in high impedance, and it is the data input in CAN bus operation.
4 DI input Driver input is a TTL level input where logic high drives output A or Y high and B or Z low, with complementary states for logic low, and it should be tied low for CAN bus applications.
5 GND power_in Ground reference pin for the transceiver.
6 A bidirectional Driver output A and receiver input A, protected against voltage faults between ±60V, with the receiver forcing RO high when V(A) ≥ V(B) + 200mV and low when V(A) ≤ V(B) - 200mV.
7 B bidirectional Driver output B and receiver input B, protected against voltage faults between ±60V, with the receiver forcing RO low when V(A) ≤ V(B) - 200mV and high when V(A) ≥ V(B) + 200mV.
8 VCC power_in Positive supply input requiring 4.75V ≤ VCC ≤ 5.25V for RS422 or RS485 operation, decoupled with a 0.1µF low ESR capacitor directly at this pin.

Key specifications

Parameter Value
Manufacturer Analog Devices
Package SO-8
Category Communication Interface Chip/UART/485/232
Pins 8

Electrical characteristics

Limits as printed in the datasheet (page.json metadata.characteristics carries them as data).

Parameter Symbol Min Typ Max Unit Conditions Page
Supply Voltage VCC 18 V 2
Receiver Enable Input Voltage RE -0.3 6 V 2
Driver Enable Input Voltage DE -0.3 6 V 2
Driver Input Voltage DI -0.3 18 V 2
Receiver Input Voltage A, B -60 60 V 2
Driver Output Voltage Y, Z -60 60 V 2
Receiver Output Voltage RO -0.3 V Maximum is VCC + 6V as printed 2
Storage Temperature Range -65 150 °C 2
Lead Temperature 300 °C Soldering, 10 sec 2
Operating Temperature Range TA -40 85 °C LT1785AI (this MPN, -40°C to 85°C) 2
Supply Voltage for RS422/RS485 operation VCC 4.75 5 5.25 V For RS422 or RS485 operation 7
Junction-to-ambient thermal resistance θJA 150 °C/W S8 package 2
Maximum Junction Temperature TJMAX 150 °C 2
Differential Driver Output Voltage (Unloaded) VOD1 4.1 5 V IO = 0 4
Differential Driver Output Voltage (With Load, RS422) VOD2 2 2.7 V R = 50Ω (RS422), Figure 1 4
Differential Driver Output Voltage (With Load, RS485) VOD2 1.5 2.45 V R = 27Ω (RS485), Figure 1 4
Differential Driver Output Voltage (With Load) VOD2 1.2 2.2 V R = 18Ω 4
Change in Magnitude of Driver Differential Output Voltage VOD 0.2 V R = 27Ω or R = 50Ω, Figure 1 4
Driver Common Mode Output Voltage VOC 2 2.5 3 V R = 27Ω or R = 50Ω, Figure 1 4
Change in Magnitude of Driver Common Mode Output Voltage ΔVOC 0.2 V R = 27Ω or R = 50Ω, Figure 1 4
Input High Voltage VIH 2 V DI, DE, RE 4
Input Low Voltage VIL 0.8 V DI, DE, RE 4
Input Current IIN1 5 µA DI, DE, RE 4
Differential Input Threshold Voltage for Receiver (LT1785A) VTH -0.2 0 V LT1785A/LT1791A: -7V ≤ VCM ≤ 12V 4
Receiver Input Hysteresis ΔVTH 20 mV -7V < VCM < 12V 4
Receiver Output High Voltage VOH 3.5 4 V IO = -400µA, VID = 200mV 4
Receiver Output Low Voltage VOL 0.3 0.5 V IO = 1.6mA, VID = -200mV 4
Three-State (High Impedance) Output Current at Receiver IOZR -1 1 µA 0V < VOUT < 6V; RE > 2V or Power Off 4
Receiver Input Resistance (LT1785) RIN 50 90 kΩ LT1785 -7V ≤ VCM ≤ 12V 4
Driver Short-Circuit Current (VOUT HIGH) ISC 35 250 mA VOUT = HIGH, Force VO = -7V 4
Driver Short-Circuit Current (VOUT LOW) ISC 35 250 mA VOUT = LOW, Force VO = 12V 4
Driver Output Fault Current -6 6 mA VO = 60V / VO = -60V 4
Receiver Short-Circuit Current -35 35 mA 0V ≤ VO ≤ VCC 4
Driver Three-State Output Current (-7V to 12V) -0.2 0.3 mA -7V ≤ VO ≤ 12V 4
Driver Three-State Output Current (-60V to 60V) -6 6 mA -60V ≤ VO ≤ 60V 4
Supply Current ICC 5.5 9 mA No Load, RE = 0V, DE = 5V 4
Supply Current ICC 4.5 8 mA No Load, RE = 0V, DE = 0V 4
Supply Current ICC 0.2 0.3 mA No Load, RE = 5V, DE = 0V 4
Driver Input to Output (rising) tPLH 700 2000 ns Figures 3, 5 5
Driver Input to Output (falling) tPHL 700 2000 ns Figures 3, 5 5
Driver Output to Output Skew tSKEW 100 ns Figures 3, 5 5
Driver Rise or Fall Time tr, tf 200 800 2000 ns Figures 3, 5 5
Driver Enable to Output High tZH 500 3000 ns Figures 4, 6 5
Driver Enable to Output Low tZL 800 3000 ns Figures 4, 6 5
Driver Disable Time from Low tLZ 200 5000 ns Figures 4, 6 5
Driver Disable Time from High tHZ 800 5000 ns Figures 4, 6 5
Receiver Input to Output (rising) tPLH 400 900 ns Figures 3, 7 5
Receiver Input to Output (falling) tPHL 400 900 ns Figures 3, 7 5
Differential Receiver Skew tSKD 200 ns 5
Receiver Enable to Output Low tZL 300 1000 ns Figures 2, 8 5
Receiver Enable to Output High tZH 300 1000 ns Figures 2, 8 5
Receiver Disable from Low tLZ 400 1000 ns Figures 2, 8 5
Receiver Disable from High tHZ 400 1000 ns Figures 2, 8 5
Maximum Data Rate fMAX 250 kbps 5
Time to Shut Down tSHDN 3 µs Figures 2, 6, 8 5
Driver Enable from Shutdown to Output High tZH(SHDN) 12 µs Figures 2, 6; RE = 5V 5
Driver Enable from Shutdown to Output Low tZL(SHDN) 12 µs Figures 2, 6; RE = 5V 5
Receiver Enable from Shutdown to Output High tZH(SHDN) 4 µs Figures 2, 8; DE = 0V 5
Receiver Enable from Shutdown to Output Low tZL(SHDN) 4 µs Figures 2, 8; DE = 0V 5

CAD (KiCad official)

  • Symbol: LT1785AIS8#PBF
  • Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
  • 3D model: SO-8 (KiCad packages3D, STEP)
  • 3D model files: lt1785ais8-pbf-etched.step / lt1785ais8-pbf-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); lt1785ais8-pbf.step / lt1785ais8-pbf.glb are the bare package body.

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

  • Datasheet: Analog Devices datasheet (18 pp, sha256 50c2d3317a147414, retrieved 2026-10-28, tier: manufacturer)
  • Extractor: parts-factory 2.0.0 / extract_pins 0.3, primary claude-haiku-5-5 (text), consensus claude-sonnet-5-5 (agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish.
  • CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF