IC-Mart Your Trusted Source for RS-422 Interface Chips

(from leading manufacturers)

Top Global RS-422 Interface IC Manufacturers

1. Texas Instruments (TI)

Chip Model	Core Function	Number of Channels	Operating Voltage	Key Features / Applications
AM26C31	Driver	Quad	5V	The industry’s most classic quad driver. Standard TTL input.
AM26C32	Receiver	Quad	5V	Quad receiver paired with the AM26C31.
AM26LV31	Driver	Quad	3.3V	Classic 3.3V model specifically designed for modern low-power MCUs/FPGAs.
AM26LV32	Receiver	Quad	3.3V	Official companion receiver for the AM26LV31.
SN75179B	Transceiver	Full-duplex 1:1	5V	Classic full-duplex chip. High-durability industrial standard.
THVD1406	Transceiver	Full-duplex 1:1	3.3V/5V	Wide-voltage logic compatible. Supports 1.8V logic interfaces. High ESD protection.
THVD1550	Transceiver	Full/Half-duplex	5V	50 Mbps high-speed model. Includes high ESD protection. Ideal for high-speed servo control.
ISO35T	Isolated Transceiver	Full-duplex 1:1	3.3V/5V	High isolation. Integrates 2.5 kVrms digital isolation. Specifically handles high-voltage surges.

2. Analog Devices (ADI)

Chip Model	Core Function	Number of Channels	Operating Voltage	Key Features / Applications
MAX490	Transceiver	Full-duplex 1:1	5V	4-wire full-duplex benchmark. Low power. Slew-rate limited to reduce EMI.
MAX3490E	Transceiver	Full-duplex 1:1	3.3V	High ESD protection ($\pm15\text{kV}$). Designed for hot-swappable interfaces.
MAX3040 / MAX3042	Driver	Quad	5V	Quad driver with high ESD protection. Commonly replaces TI’s AM26 series.
MAX3280E	Receiver	Single	3.3V/5V	True 50 Mbps high-speed receiver. Designed for backplanes and high-speed serial ports.
MAX3293	Driver	Single	3.3V/5V	Slew-rate limited high-speed single driver. Used in extremely space-constrained interfaces.
ADM2587E	Isolated Transceiver	Full-duplex 1:1	3.3V/5V	Fully integrated flagship. Combines digital isolation and isolated DC-DC power in one chip. No external isolated power needed on the PCB.

3. STMicroelectronics (ST)

Chip Model	Core Function	Number of Channels	Operating Voltage	Key Features / Applications
ST442AB	Receiver	Quad	5V	High-speed quad differential receiver. High interference immunity. Widely used in industrial PLC inputs.
ST3485 / ST490A	Transceiver	Full-duplex 1:1	3.3V / 5V	Classic general-purpose full-duplex chip. Cost-effective primary choice for industrial replacement.

4. Renesas (formerly Intersil)

Chip Model	Core Function	Number of Channels	Operating Voltage	Key Features / Applications
ISL32470E	Transceiver	Full-duplex 1:1	3.3V/5V	Ultra-high fault-protected model. Bus pins tolerate up to $\pm60\text{V}$ overvoltage faults. Features $\pm15\text{kV}$ ESD protection.

Mainstream RS-422/RS-485 Interface IC Manufacturers in China

1. Ruimeng Technology

• Vendor Positioning: Focuses on general analog circuits and interface chips. It is one of the most comprehensive domestic manufacturers for replacing classic quad industrial legacy chips. If you need an alternative to the AM26 series for industrial motor control or encoders, Ruimeng is the top choice.
• Typical Models:
  • MS2374 (Quad Driver): Perfect domestic replacement for TI’s classic AM26LS31 / AM26C31.
  • MS2375 (Quad Receiver): Perfect domestic replacement for TI’s classic AM26LS32 / AM26C32. Features integrated fail-safe protection. Ensures a high output state when inputs are open.
  • MS2583 (Single Transceiver): 5 Mbps low-power RS-422 interface circuit. Ideal for power-sensitive handheld industrial devices.

2. NOVOSENSE Microelectronics

• Vendor Positioning: The absolute leader in domestic digital isolation chips. If your RS-422 application faces severe electromagnetic environments like heavy industrial plants, EVs, or large power grids, and requires breaking ground loop interference, NOVOSENSE is the top-tier domestic choice.
• Typical Models:
  • NSI83086E (Isolated Full-Duplex Transceiver): Integrates up to 5 kVrms digital isolation. Data rates reach 16 Mbps. Often used to benchmark or upgrade against ADI’s isolated chips (like the ADM2587E or ADM2795E series).
  • NSI83085 (Isolated Half-Duplex Transceiver): Primarily used for RS-485. Highly common in 2-wire RS-422 downgraded applications.

3. SIT Core (Now merged into OMNIVISION Group)

• Vendor Positioning: Specializes in industrial and automotive communication interface (CAN, LIN, RS485/422) chips. Massive shipping volume. Its products highlight high electrostatic discharge (ESD) protection and full voltage range coverage.
• Typical Models:
  • SIT3490E (Full-Duplex Transceiver): 3.3V/5V compatible. 14 Mbps high-speed full-duplex RS-422/485 chip. Features $\pm15\text{kV}$ ESD protection. A perfect alternative to ADI/Maxim’s MAX3490E.
  • SIT65HVD75DR (Half/Full-Duplex Compatible): Benchmarks against TI’s SN65HVD series. Strong anti-interference capability. Suitable for long-cable transmission.

4. Chipanalog

• Vendor Positioning: A rising star in high-performance analog chips. Its interface product line focuses on “fault-protection” and high common-mode voltage tolerance. Highly suitable for complex industrial terminal blocks.
• Typical Models:
  • CA-IF4820HS / CA-IF48XX Series (Full/Half-Duplex Transceivers): The biggest highlight is $\pm30\text{kV}$ ultra-high ESD protection. They offer an extended common-mode voltage range up to $\pm15\text{V}$ (standard chips are usually -7V to +12V). This ensures stable communication even with significant ground voltage offsets on-site.
  • CA-IS3088 (Isolated Transceiver): Isolated interface chip with high common-mode transient immunity (CMTI).

5. 3PEAK and SGMICRO

• Vendor Positioning: Two giants in China’s comprehensive high-performance analog chip market. Despite broad product lines, their massive interface portfolios include many high-quality RS-422/485 standard parts. They focus on premium quality and stable supply chains.
• Typical Models:
  • TP75176E (3PEAK): A tribute and upgrade to the industry’s legendary TI SN75176. Offers improved ESD protection and a wider operating temperature range.

Legacy Chip (International Brand)	Core Features	Recommended Chinese Alternative (Drop-in Replacement)
TI AM26C31 / MAX3042	Quad Driver	Ruimeng MS2374
TI AM26C32 / ST442AB	Quad Receiver	Ruimeng MS2375
TI SN75176 / ADM485	Classic Full/Half-Duplex Standard	3PEAK TP75176E / SIT Equivalent Models
MAX3490E	3.3V Full-Duplex, High ESD Protection	SIT SIT3490E
TI ISO35T / ADM2587E	High-End Digital Isolated RS-422	NOVOSENSE NSI83086E / Chipanalog CA-IS3088

RS-422 Interface IC Core Functions and Mechanics

The core function of an RS-422 chip is to act as an “amplifier and translator”:

• Transmitter (Driver): Converts weak digital logic signals from the main controller into robust differential signals. It sends them across long cables.
• Receiver: At the cable’s other end, it filters and restores the noisy differential signals. It converts them back into weak logic signals for the receiving “brain.”

Core Technology: What is a Differential Signal?

Traditional RS-232 uses high/low voltage on a single wire to represent 0 and 1. This makes it highly susceptible to external interference. RS-422 uses a “two wires for one signal” model. It represents logic 0 or 1 through the voltage difference between these two wires. When heavy factory machinery starts up and creates EMI, the noise overlays equally onto both wires. Their voltage difference remains identical. This mechanism grants RS-422 exceptional anti-interference capabilities. It enables transmission distances up to 1,200 meters (4,000 feet) and speeds up to 10 Mbps.

Typical Application Scenarios for RS-422 Interface ICs

Thanks to its full-duplex capability (independent, simultaneous transmit and receive), long-distance reach, and high interference immunity, the RS-422 chip holds an irreplaceable position. It is essential in heavy manufacturing, automation control, and highly reliable communication fields.

1. Industrial Automation: Servo Motors and Absolute Encoders (Largest Market)

In CNC machines, robotic arms, or automated assembly lines, motors must rotate and report their exact position with extreme precision.

• Application Logic: Optical or magnetic encoders at the motor’s rear generate high-frequency pulse signals (Phases A, B, and Z). These signals must transmit back to the servo drive with ultra-low latency and zero error rates.
• Chip Role: Quad driver chips (like the AM26LS31) are typically used. They convert the encoder’s parallel signals into RS-422 differential signals. These travel stably over long cables back to the control cabinet. This is the most classic industrial control use case.

2. Factory Floors: PLCs and Distributed Control Systems (DCS)

In large factories, the central control room is often hundreds of meters away from node machinery.

• Application Logic: Programmable Logic Controllers (PLCs) need real-time communication with widespread sensors, inverters, and remote I/O modules.
• Chip Role: RS-422 chips resist heavy motor start/stop interference over hundreds of meters of cable. When crossing between factory buildings with different power supplies, digitally isolated RS-422 chips are specifically used. This prevents ground potential differences from sparking and destroying equipment.

3. Internal Communication in Heavy Equipment and Special Vehicles

This applies to construction machinery (like concrete pump trucks, large excavators) and mining equipment.

• Application Logic: The vehicle chassis’s main control unit must communicate with the cabin HMI or rear monitoring modules. The vehicle interior contains massive diesel engines or generators. The electromagnetic environment is extremely harsh.
• Chip Role: Wide-voltage RS-422 transceivers with high ESD protection and anti-vibration features are used. They ensure control commands remain completely intact amidst intense EMI.

4. Aerospace and Marine Instruments

In these fields, zero downtime is the top priority.

• Application Logic: Communication is critical between aircraft cockpit dashboards and belly sensors, or between a ship’s bridge and engine room radar/sonar.
• Chip Role: RS-422 remains the foundation for many military and aerospace buses (like physical layers in some ARINC protocols). Its simple point-to-multipoint broadcast structure and extreme physical-layer reliability outperform many complex modern digital networks.

5. Security Surveillance and Broadcast Control (PTZ Control)

• Application Logic: In large venues or security systems, central consoles must remotely control pan, tilt, and zoom (PTZ) functions of HD cameras hundreds of meters away.
• Chip Role: Many security systems are now networked. However, in broadcast-level studios or high-reliability security grids, RS-422 is still used for precise, low-latency hardwired control.

RS-422 Interface IC Classifications

Category 1: By Core Function

This is the most basic classification dictated by system architecture. It depends on whether your device is a transmitter, a receiver, or requires bidirectional communication.

1. Driver (Transmitter)

• Function: Converts single-ended digital logic (TTL/CMOS) from the MCU into RS-422 differential signals for transmission.
• Typical Chips:
  • AM26C31 / Manufacturer: Texas Instruments (TI) – The absolute industry benchmark. Almost every RS-422 engineer has used it.
  • MAX3040 / Manufacturer: Analog Devices (ADI / formerly Maxim).

2. Receiver

• Function: Restores incoming RS-422 differential signals from long cables back to single-ended logic signals for the MCU.
• Typical Chips:
  • AM26C32 / Manufacturer: Texas Instruments (TI) – Typically paired with the AM26C31.
  • ST442AB / Manufacturer: STMicroelectronics (ST).

3. Transceiver (Bidirectional)

• Function: Integrates both a driver and a receiver within a single chip. RS-422 typically uses 4-wire full-duplex transceivers.
• Typical Chips:
  • MAX490 / Manufacturer: Analog Devices (ADI).
  • SN75179B / Manufacturer: Texas Instruments (TI).

Category 2: By Number of Channels

Depends on how many signals your bus must transmit simultaneously (e.g., just TX/RX, or including clock signals CLK, enable signals EN, etc.).

1. Single (1 TX or 1 RX)

• Applications: Extremely space-saving basic serial communication.
• Typical Chip: MAX3293 (Single Driver) / Manufacturer: Analog Devices (ADI).

2. Dual (2 TX or 2 RX)

• Applications: Dual clocks or dual data streams.
• Typical Chip: SN75158 (Dual Driver) / Manufacturer: Texas Instruments (TI).

3. Quad (4 TX or 4 RX)

• Applications: The most classic RS-422 format. Widely used for servo motor encoders (Phases A, B, Z, U). One chip handles all signals.
• Typical Chips:
  • AM26LS31 (Quad Driver, historic classic) / Manufacturer: TI or AMD (legacy).
  • MAX3042 (Quad Driver) / Manufacturer: Analog Devices (ADI).

Category 3: By Supply Voltage

Constrained by your mainboard’s power design. It must match the MCU/FPGA IO level.

1. 5V Standard Supply

• Features: Strong driving capability. Good anti-interference. Suitable for traditional industrial PCs.
• Typical Chips: AM26C31, MAX490.

2. 3.3V Low-Voltage Supply

• Features: Fits modern ARM Cortex MCUs or FPGAs. No level conversion needed. Models usually feature “LV” (Low Voltage) or 3xxx naming.
• Typical Chips:
  • AM26LV31 (3.3V Quad Driver) / Manufacturer: Texas Instruments (TI).
  • ISL32470E / Manufacturer: Renesas (formerly Intersil).

3. Wide-Voltage Logic Compatible (1.8V – 5V)

• Features: The chip itself may use a 3.3V/5V supply, but logic IO pins (V_logic) support 1.8V. Connects directly to low-power DSPs/SOCs.
• Typical Chip: THVD1406 / Manufacturer: Texas Instruments (TI).

Category 4: By Protection & Isolation

Dictated by the device’s operating environment and safety requirements.

1. Standard (No Special Protection)

• Features: Lowest cost. Suitable for ideal environments within the same PCB or enclosure.
• Typical Chips: Base models like AM26C31 or MAX490.

2. High ESD Protection ($\pm15\text{kV}$ or higher)

• Features: Used when interfaces are exposed outside the enclosure. Prevents human static discharge from destroying the chip when touching cables. Models often carry an “E” (ESD) suffix.
• Typical Chips:
  • MAX3490E / Manufacturer: Analog Devices (ADI).
  • SP3490E / Manufacturer: MaxLinear (formerly Exar).

3. Galvanic Isolation

• Features: Integrates internal transformers (magnetic) or capacitive isolation layers. Blocks multi-kilovolt surges and ground loop currents. Used in harsh factory floors, lightning-prone areas, or cross-building communication.
• Typical Chips:
  • ADM2587E (RS-422/485 chip with built-in isolated power) / Manufacturer: Analog Devices (ADI).
  • ISO35T / Manufacturer: Texas Instruments (TI).

Category 5: By Data Rate

Selected based on data throughput needs after meeting the above conditions.

1. Standard / Low Rate ($\le$ 10 Mbps)

• Features: Limited slew rate creates smooth rising edges. The advantage is minimal EMI. Ideal for long-cable transmission over hundreds of meters.
• Typical Chip: MAX490 (2.5 Mbps) / Manufacturer: Analog Devices (ADI).

2. High Rate (20 Mbps to 50 Mbps and above)

• Features: Suitable for short-distance, high-throughput backplane buses or precision servo controls.
• Typical Chips:
  • MAX3280E (50 Mbps Receiver) / Manufacturer: Analog Devices (ADI).
  • THVD1550 (50 Mbps Transceiver) / Manufacturer: Texas Instruments (TI).