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LT1785IS8#TRPBF
Public Made by Adomby adom
Analog Devices RS-485/RS-422 ICs, SO-8. Pinout cross-checked by two models against the datasheet, KiCad symbol/footprint/3D.
3D Model
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Symbol & Footprint
Schematic Symbol
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PCB Footprint
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Datasheet
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README
markdownLT1785IS8#TRPBF
Analog Devices · RS-485/RS-422 ICs · SO-8
LT1785IS8#TRPBF 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 high when A is at least 200mV above B and low when A is at least 200mV below B, and it goes high impedance when RE is high. |
| 2 | RE | input | Receiver output enable: a logic low enables the receiver output RO and a logic high places RO in high impedance. |
| 3 | DE | input | Driver output enable: a logic high enables the driver outputs A and B and a logic low places them in high impedance. |
| 4 | DI | input | Driver input: a logic high drives output A high and B low, and a logic low gives complementary output states. |
| 5 | GND | power_in | Ground reference for the device. |
| 6 | A | bidirectional | Receiver input and driver output A, with receiver inputs protected against voltage faults between ±60V. |
| 7 | B | bidirectional | Receiver input and driver output B, with receiver inputs protected against voltage faults between ±60V. |
| 8 | VCC | power_in | Positive supply input, 4.75V ≤ VCC ≤ 5.25V for RS422 or RS485 operation, to be 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 |
|---|---|---|---|---|---|---|---|
| Differential Driver Output Voltage (Unloaded) | VOD1 | 4.1 | 5 | V | IO = 0 | 4 | |
| Differential Driver Output Voltage (With Load) | VOD2 | 2 | 2.7 | V | R = 50Ω (RS422), Figure 1 | 4 | |
| Differential Driver Output Voltage (With Load) | 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 for Complementary Output States | 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 for Complementary Output States | Δ/VOC/ | 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 | VTH | -0.2 | 0.2 | V | LT1785/LT1791: -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 | -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 | ISC | 35 | 250 | mA | VOUT = HIGH, Force VO = -7V | 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 | -0.2 | 0.3 | mA | -7V ≤ VO ≤ 12V | 4 | ||
| Driver Three-State Output Current | -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 | ||
| Supply Voltage | VCC | 18 | V | 2 | |||
| Receiver Enable Input Voltage | -0.3 | 6 | V | 2 | |||
| Driver Enable Input Voltage | -0.3 | 6 | V | 2 | |||
| Driver Input Voltage | -0.3 | 18 | V | 2 | |||
| Receiver Input Voltage | -60 | 60 | V | 2 | |||
| Driver Output Voltage | -60 | 60 | V | 2 | |||
| Operating Temperature Range (I grade) | -40 | 85 | °C | LT1785I/LT1785AI | 2 | ||
| Storage Temperature Range | -65 | 150 | °C | 2 | |||
| Lead Temperature (Soldering, 10 sec) | 300 | °C | 2 | ||||
| Maximum Junction Temperature | TJMAX | 150 | °C | 2 | |||
| Thermal Resistance, Junction to Ambient | θJA | 150 | °C/W | S8 package | 2 | ||
| Supply Voltage for RS422/RS485 Operation | VCC | 4.75 | 5 | 5.25 | V | RS422 or RS485 operation | 7 |
CAD (KiCad official)
- Symbol:
LT1785IS8#TRPBF - Footprint:
Package_SO:SOIC-8_3.9x4.9mm_P1.27mm - 3D model: SO-8 (KiCad packages3D, STEP)
- 3D model files:
lt1785is8-trpbf-etched.step/lt1785is8-trpbf-etched.glbcarry the MPN laser-etched on the die in a toggleableAdom.LaserEtchgroup (Fusion-ready);lt1785is8-trpbf.step/lt1785is8-trpbf.glbare 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, primaryclaude-haiku-5-5(text), consensusclaude-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).