SN75176 - Differential Bus Transceiver RS-485/RS-422 | Texas Instruments
N.º da peça: SN75176 ✓ Ativo| Qtd. | Preço unitário | Total |
|---|---|---|
| 1 | $0.94 | $0,94 |
| 10 | $0.84 | $8,40 |
| 100 | $0.71 | $71,00 |
| 500 | $0.63 | $315,00 |
| 1.000 | $0.55 | $550,00 |
SN75176 Visão geral
What is a differential bus transceiver? A differential bus transceiver is a mixed-signal interface IC that converts logic-level signals into balanced differential voltage pairs for transmission over twisted-pair cabling, then converts them back to single-ended logic at the far end. Differential signalling rejects common-mode noise and ground shifts, enabling reliable data transfer over hundreds or thousands of metres. RS-422 supports point-to-point simplex links, while RS-485 enables multipoint half-duplex buses with up to 32 unit loads.
Key features of the SN75176 include independent driver and receiver enable pins that allow half-duplex operation, thermal-shutdown protection that disables the driver output when junction temperature exceeds safe limits, and short-circuit current limiting on both driver outputs and receiver output. The receiver failsafe design forces a logic-high output when the bus is idle (no differential voltage present), preventing erroneous data on open or shorted lines.
The SN75176 uses a bipolar process that delivers high drive strength (±60 mA) and wide common-mode range (-7 V to +12 V), at the cost of higher quiescent current (typical 30 mA enabled, 1 µA shutdown) than newer CMOS RS-485 parts. The architecture mirrors the original Motorola MC3486-era transceivers, which established the de-facto pinout this TI part inherits.
Typical applications of the SN75176 include industrial RS-485 multidrop networks, factory automation sensor buses, building-automation HVAC control, point-of-sale terminal daisy chains, and legacy RS-422 point-to-point links. Designers choose it primarily for retrofits of existing systems, low-cost designs where CMOS low-power parts are unnecessary, and as a known-good baseline for new RS-485 prototyping.
When designing with the SN75176, observe the bus-termination requirement (120 Ω resistor at each far end of the cable) and keep stub lengths below the standard's recommendations. The driver enable (DE) and receiver enable (RE-bar) pins must be coordinated to prevent bus contention; pull RE-bar high when the receiver is not needed to reduce quiescent supply current toward 1 µA.
Alternativas drop-in para SN75176 — mesmo encapsulamento, compatível pino a pino. Peças de encapsulamento diferente que exigem retrabalho na PCB são excluídas.
Ferramenta de comparação rápida — selecione peças alternativas para comparação lado a lado:
SN75176A
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
SN75176AP
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
SN75176BP
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
MAX485EPA+
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
ADM485JN
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
SP485EN-L
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
SN75176 Especificações
| Função | Transceiver |
| Protocol | RS-422, RS-485 |
| Number of Drivers/Receivers | 1/1 |
| Duplex | Half |
| Receiver Hysteresis | 50 mV (typical) |
| Supply Voltage (Vcc) | 4.75 V to 5.25 V |
| Temperatura de operação | 0 °C to +70 °C |
| Driver Output Current | ±60 mA (max) |
| Common-Mode Input Range | -7 V to +12 V |
| Differential Input Threshold | ±200 mV |
| Quiescent Supply Current (enabled) | 30 mA (typical) |
| Shutdown Supply Current | 1 µA (typical) |
| Encapsulamento | 8-pin PDIP (P) |
| Tipo de montagem | Through-Hole |
| Standards Compliance | ANSI TIA/EIA-422-B, TIA/EIA-485-A, ITU V.11, ITU X.27 |
| Status RoHS | Compliant |
Configuração de pinos do SN75176
| Pino 1 | R — Receiver data output (logic level, referenced to GND) |
| Pino 2 | RE-bar — Receiver Enable, active low. Low = receiver enabled; high = receiver output high-impedance |
| Pino 3 | DE — Driver Enable, active high. High = driver enabled; low = driver outputs high-impedance |
| Pino 4 | D — Driver data input (logic level) |
| Pino 5 | GND — Ground reference for logic and bus |
| Pino 6 | A — Non-inverting differential bus line (driver output / receiver input) |
| Pino 7 | B — Inverting differential bus line (driver output / receiver input) |
| Pino 8 | Vcc — 5 V supply input (4.75 V to 5.25 V) |
Aplicações típicas
SN75176 é adequado para 7 aplicaçãos: RS-485 Multidrop Industrial Bus, Building Automation HVAC Network, Point-of-Sale (POS) Daisy Chain, Security & Surveillance PTZ Control, RS-422 Point-to-Point Link, Microcontroller UART Expansion Board, Energy Metering Submeter Networks.
RS-485 Multidrop Industrial Bus
The SN75176's TIA/EIA-485-A compliance, ±60 mA driver output, and ±12 V common-mode range make it a robust transceiver for half-duplex multidrop buses in factory-automation networks. Placed at each PLC, sensor, or motor-drive node on a single twisted pair, it converts 5 V TTL logic from the host MCU into the ±1.5 V minimum differential required by the standard. The receiver's 50 mV hysteresis rejects common-mode noise injected by 24 V motor wiring and VFD inverters, and the failsafe receiver output (logic-high on idle bus) prevents false framing bytes when no node is driving. Compared to newer CMOS parts, the SN75176 trades power efficiency for ruggedness in electrically noisy industrial cabinets.
Recomendado
Building Automation HVAC Network
HVAC control panels typically talk to rooftop units, variable-air-volume boxes, and air-handlers over RS-485 buses running up to 1200 m at 100 kbps. The SN75176 supports these topologies with its ±60 mA driver that can drive up to 32 unit loads on a single bus. The DE (Driver Enable) and RE-bar (Receiver Enable) pins are tied together so the host MCU controls half-duplex direction with a single GPIO, simplifying firmware. Built-in thermal shutdown protects the IC if a wiring fault shorts the bus to 24 VAC. Engineers also value the part's decades-long track record and wide availability across distributors, simplifying facility-management installations and service-stock inventory.
Recomendado
Point-of-Sale (POS) Daisy Chain
POS terminals in retail environments are typically daisy-chained over RS-485 to share a single back-office POS controller, running 9600 to 115200 bps with up to 32 nodes per bus. The SN75176's 5 V single-supply operation, 8-pin PDIP footprint, and proven TIA/EIA-485-A compliance have made it a long-time default in cash-register and barcode-scanner links. The receiver's wide common-mode input (-7 V to +12 V) tolerates the ground-potential differences that occur across long store runs, and the part's 30 mA quiescent current is acceptable for always-on commercial equipment. For battery-powered tablets, designers should pick a CMOS 3.3 V alternative instead.
Recomendado
Security & Surveillance PTZ Control
Pan-tilt-zoom (PTZ) camera control links have used RS-485 for decades because of its immunity to ground loops in buildings and its ability to drive 1200 m of CAT5 between control room and cameras. The SN75176, paired with an external 120 Ω termination, reliably delivers PELCO-D or VISCA command frames at 2400 to 38400 bps over typical 24 V-rail installations. The transceiver's ±60 mA driver strength keeps signal rise time below the bus's required 30 % unit-interval budget even on the shortest stubs in dense daisy chains. Its bipolar drive stages outperform CMOS parts when driving long, capacitance-heavy legacy cables in older security installations.
Recomendado
RS-422 Point-to-Point Link
Although the SN75176 is most often used on RS-485 buses, it is fully TIA/EIA-422-B compliant and works as a point-to-point driver/receiver on simplex links up to 1200 m at 10 Mbps. Typical pairings include a CNC machine controller to a remote operator panel, where the differential pair rejects motor-bearing noise. In this configuration, DE is tied high (always enabled) and RE-bar is tied low (always enabled), making the part behave as a single bidirectional RS-422 transceiver. Designers should remember that RS-422 requires a 100 Ω terminator at the receiver, not the 120 Ω used for RS-485.
Recomendado
Microcontroller UART Expansion Board
Microcontroller boards (Arduino, STM32 Nucleo, ESP32 dev kits) frequently add an RS-485 shield to expose a UART bus to industrial peripherals. The SN75176, in its 8-pin PDIP package, is the classic through-hole transceiver for hobby and education-grade shields because it can be hand-soldered into a 0.1-inch prototype board. Driven by a single UART TX/RX pair plus one GPIO for direction control, it converts the 5 V logic levels into the differential signals expected by industrial sensors and actuators. For battery-powered IoT nodes, the SN75176's 30 mA quiescent draw is excessive, so a 3.3 V CMOS transceiver should be substituted in that scenario.
Recomendado
Energy Metering Submeter Networks
Commercial submetering systems for tenant billing typically chain electricity, water, and gas meters on a single RS-485 bus running through a building's electrical closet. The SN75176's wide -7 V to +12 V common-mode range tolerates ground offsets between the meter's reference plane and the building's main distribution ground, even when large loads cause ground potential shifts. Its 30 mA quiescent current is acceptable on a 5 V always-powered bus, and the receiver's 50 mV hysteresis rejects pulse-width-modulation noise from adjacent VFD motor leads. Pairing the SN75176 with a TVS diode on the bus side further improves reliability in harsh electrical environments.
Recomendado
Resumo dos produtos recomendados
Dados de referência de engenharia para SN75176 — comparação, orientação de projeto e informações de conformidade.
Guia de seleção
Comparação com alternativas
| Parâmetro | Este produto | SN75176A | SN75176BP | MAX485EPA+ | ADM485JN | SP485EN-L |
|---|---|---|---|---|---|---|
| Package | PDIP-8 (P) | PDIP-8 (P) - same | PDIP-8 (P) - same | PDIP-8 (P) - same | PDIP-8 (P) - same | PDIP-8 (P) - same |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Maxim Integrated | Analog Devices | MaxLinear |
| Process Technology | Bipolar | Bipolar | Bipolar | CMOS | CMOS | CMOS |
| Quiescent Supply Current (enabled) | 30 mA (typical) | 30 mA | 30 mA | 0.3 mA | 0.4 mA | 0.4 mA |
| Driver Output Current | ±60 mA (max) | ±60 mA | ±60 mA | ±35 mA | ±35 mA | ±35 mA |
| Bus ESD Rating | ±2 kV HBM (typical) | ±2 kV | ±15 kV | ±15 kV | ±15 kV | ±15 kV |
| Supply Voltage | 4.75 V to 5.25 V | 4.75 V to 5.25 V | 4.75 V to 5.25 V | 4.75 V to 5.25 V | 4.75 V to 5.25 V | 4.75 V to 5.25 V |
| Receiver Hysteresis | 50 mV (typical) | 50 mV | 50 mV | 20 mV | 20 mV | 20 mV |
| Common-Mode Input Range | -7 V to +12 V | -7 V to +12 V | -7 V to +12 V | -7 V to +12 V | -7 V to +12 V | -7 V to +12 V |
| Number of Drivers/Receivers | 1/1 | 1/1 | 1/1 | 1/1 | 1/1 | 1/1 |
| Unit Price (1 pc, USD, as of 2026-10-20) | $0.94 | $0.94 | $1.05 | $3.20 | $3.65 | $1.15 |
Principais diferenciais
- Bipolar drive strength (±60 mA) for robust long-cable performance (vs MAX485EPA+)
- Wide 50 mV receiver hysteresis for noisy industrial environments (vs MAX485EPA+)
- DECADES-LONG proven legacy pinout and supply design (vs SP485EN-L)
Notas de projeto
Place a 100 nF decoupling capacitor as close as possible to pin 8 (Vcc) and pin 5 (GND), with traces shorter than 5 mm to suppress switching transients that the bipolar driver can generate. Keep the A and B bus traces at least 2 mm from any digital clock or switching-power-supply traces, and ideally parallel-route them with a ground-fill underneath to maintain 100 Ω differential impedance. With the 8-pin PDIP package, leave at least 1.0 mm between bus pins (6, 7) and any keep-out zone so that hand-solder rework does not lift adjacent pads.
Estimate: at 5 V Vcc, 30 mA quiescent, and 0.94 USD unit price, the SN75176 costs roughly 4.6 mW in standby, which is acceptable for always-on mains-powered industrial designs but unacceptable for battery-powered IoT nodes - those should pick a 3.3 V CMOS alternative. Failure to tie RE-bar low when the receiver is desired typically leaves the receiver output high-impedance, and the host UART reads '1' as the active-idle state - which is fine for RS-485 but masks a real configuration bug. Finally, omitting the 120 Ω termination resistor at each end of a long bus results in reflections that corrupt the first few bits of every packet; always terminate.
On buses longer than 100 m at rates above 1 Mbps, the SN75176's bipolar driver strength (±60 mA) is a benefit: it can charge and discharge the cable capacitance faster than CMOS parts (typical ±35 mA). However, the steeper edges generate more EMI; add a series resistor of 10–33 Ω between each driver output and the bus pin to slow the edge rate if radiated emissions fail CE/FCC. The receiver's 50 mV hysteresis provides good noise rejection on industrial lines - tighter hysteresis parts (e.g. 20 mV on MAX485) are more susceptible to false triggering near noisy VFDs.
Informações de conformidade
RoHS compliant per TI product page. The legacy SN75176 base ordering code is superseded by SN75176A (PDIP-8) and SN75176B (DIP/SOIC) revisions; lead-free Pb-free variants are denoted with the 'P' (PDIP) and 'D' (SOIC) suffixes.
