IC-Mart Your Trusted Source for RS-422/RS-485 Interface Interface Chips

(from leading manufacturers)

Mainstream RS-422/RS-485 Chip Manufacturers

1. Texas Instruments (TI)

Chip Model	Duplex Mode	Data Rate	Node Capacity	Core Features & Selection Guide
SN75176B	Half-Duplex	10 Mbps	1 UL (32 nodes)	Industry Fossil: Decades-old standard. Extremely low cost. No special protection. Only for board-level or stable indoor short-distance communication.
AM26LS31 / 32	Simplex	25 Mbps	–	Classic Quad-Channel: 31 is a quad driver; 32 is a quad receiver. Used for motor encoders and RS-422 point-to-point multi-wire transmission.
SN65HVD12	Full-Duplex	1 Mbps	1/8 UL (256 nodes)	Classic Full-Duplex: 3.3V supply. Supports high node count. Widely used in legacy 4-wire industrial control systems.
THVD1500	Half-Duplex	500 kbps	1/8 UL (256 nodes)	Modern Cost-Effective: 5V supply. Slew-rate limited for excellent anti-interference and EMI performance. Top choice for long-distance Modbus routing.
THVD1450	Half-Duplex	50 Mbps	1/8 UL (256 nodes)	Modern High-Speed Benchmark: Supports up to 50 Mbps. Integrates robust 16kV IEC ESD protection.
THVD2450	Half-Duplex	50 Mbps	1/8 UL (256 nodes)	Ultimate Fault Protection: Features ±70V bus overvoltage protection. Prevents damage from accidental 24V/48V industrial power shorts.
ISO1410	Half-Duplex	50 Mbps	1/8 UL (256 nodes)	Digital Isolation: Uses TI’s capacitive silicon dioxide ($\text{SiO}_2$) isolation technology. Integrates up to $5\text{kV}_{\text{RMS}}$ signal isolation.
ISOW1412	Half-Duplex	50 Mbps	1/8 UL (256 nodes)	Full Isolation (Built-in Power): Single-chip integrated digital isolation and micro DC-DC transformer. Works without an external isolated power supply.

2. Analog Devices (ADI)

Chip Model	Duplex Mode	Data Rate	Node Capacity	Core Features & Selection Guide
MAX485	Half-Duplex	2.5 Mbps	1 UL (32 nodes)	5V Classic Benchmark: The industry’s most widely used and cloned 5V chip. SOP-8 package.
MAX3485	Half-Duplex	10 Mbps	1 UL (32 nodes)	3.3V Classic Benchmark: The 3.3V version of MAX485. The default choice for almost all MCU (like STM32) development boards.
MAX483	Half-Duplex	250 kbps	1/4 UL (128 nodes)	Low-Power Slew-Rate Limited: Limits waveform slope. Designed for low-speed, ultra-long distance, and high anti-reflection scenarios.
MAX491 / 3491	Full-Duplex	2.5/10 Mbps	1 UL (32 nodes)	Classic Full-Duplex: 14-pin package. Supports simultaneous RX/TX. Commonly used for RS-422.
ADM1485	Half-Duplex	30 Mbps	1 UL (32 nodes)	Legacy High-Speed: 5V supply. Early 30 Mbps high-speed interface IC.
ADM3072E	Half-Duplex	250 kbps	1/8 UL (256 nodes)	High-Protection Dense Node: Integrates ±15kV ESD and hot-swap fault protection. Supports 256 nodes.
LT1785A	Half-Duplex	250 kbps	1/4 UL (128 nodes)	Former Linear Tech Ace: ±60V fault protection. Renowned for high-voltage surge and short-circuit resistance in harsh factory environments.
ADM2483	Half-Duplex	500 kbps	1/8 UL (256 nodes)	Magnetic Isolation Benchmark: Classic iCoupler magnetic isolation chip. Widely used in inverters and power meters.
ADM2587E	Half-Duplex	500 kbps	1/8 UL (256 nodes)	All-in-One Full Isolation: Industry’s most famous single-chip solution with built-in isolated power. Star model for industrial meters and BMS.

Mainstream Chinese RS-422/RS-485 Chip Manufacturers

1. NOVOSENSE

Leading domestic enterprise in isolation and interface chips. Its core advantage is capacitive digital isolation technology. It holds a high market share in renewable energy (solar, storage), automotive, and industrial control. The product line directly competes with TI and ADI’s high-end isolation series.

Typical Model	Category & Features	Core Parameters & Positioning	International Equivalent
NSI83085	Non-Isolated / Half-Duplex	3.3V/5V wide supply, ±18kV ESD protection, 1/8 load (256 nodes). Ideal for standard high-reliability industrial communication.	MAX3485 / SN65HVD485
NSI8141	Pure Isolation	500kbps rate. Offers 5kVrms high-voltage electrical isolation. Requires external isolated power.	ADM2483 / ISO1410
NSI8241W	Integrated Isolated Power	Ultimate single-chip solution. Integrates digital isolation and micro-transformer. Directly outputs isolated power and 485 signals.	ADM2587E / ISOW1412

2. Chipanalog

Focuses on high-end analog and isolation chips. Features a comprehensive layout in digital isolators and isolated interfaces. A major domestic player in the high-end isolated RS-485 market.

Typical Model	Category & Features	Core Parameters & Positioning	International Equivalent
CA-IF4888	Non-Isolated / Full-Duplex	Up to 25Mbps rate. High overvoltage protection. Used for high-speed RS-422 encoders or point-to-point buses.	MAX491 / SN65HVD12
CA-IS2082B	Pure Isolation / Half-Duplex	Offers 3kVrms isolation voltage and ±100kV/μs ultra-high Common-Mode Transient Immunity (CMTI).	ADM2483
CA-IS2092A	Integrated Isolated Power	RS-485 transceiver with built-in DC-DC isolated power. Designed for space-constrained, harsh industrial environments.	ADM2587E

3. 3PEAK

A leading domestic enterprise in high-performance analog signal chains. Its RS-485 line focuses on high-reliability basic interface replacements. Widely used in security, instrumentation, and building automation.

Typical Model	Category & Features	Core Parameters & Positioning	International Equivalent
TPT3485 / TPT485	Non-Isolated / Basic	3.3V and 5V standard replacements. Good contact discharge immunity. Massive shipment volume.	MAX3485 / MAX485
TPT75176	Non-Isolated / Basic	5V supply. Direct replacement for the industry’s oldest standard model. Optimized thermal shutdown protection.	SN75176B
TPT147x Series	Non-Isolated / Half-Duplex	Emphasizes high ESD protection and wider common-mode voltage range. Ideal for long-cable transmission.	SN65HVD147x

4. MORNSUN

Originally a well-known domestic power module giant. Leveraged its power magnetic isolation expertise to launch highly competitive interface chips with integrated power isolation.

Typical Model	Category & Features	Core Parameters & Positioning	International Equivalent
SCM3401A	Pure Isolation / Half-Duplex	500kbps rate. Used with Mornsun’s fixed-voltage isolation modules for a complete power+signal isolation solution.	ADM2483
SCM3406A	Integrated Isolated Power	Integrates Mornsun’s signature micro-isolated power technology. Effectively resolves system ground loop interference.	ADM2587E

5. Shanghai Belling

Veteran state-owned semiconductor enterprise. Known for comprehensive product lines and high cost-effectiveness. Ideal for high-volume, cost-sensitive commercial or general industrial applications.

Typical Model	Category & Features	Core Parameters & Positioning	International Equivalent
BL3485 / BL485	Non-Isolated / Basic	Extremely low cost. The most common domestic pin-to-pin replacement in consumer electronics, standard meters, and simple access control.	MAX3485 / SP3485
BL3085A / B	High Node Support	Supports 1/8 unit load. Allows 256 nodes per bus. Built-in fail-safe protection.	SN65HVD3085E

6. Innovative Niche Manufacturers

Some domestic companies target specific application pain points with micro-innovations:

• Cosm – COS13487EESA:
  • Innovation: Features automatic transmit/receive control. Traditional RS-485 requires an extra MCU GPIO pin (DIR/DE) to toggle states. This chip integrates automatic recognition logic. It switches to transmit when data is present and reverts to receive automatically. This drastically simplifies isolation circuit design (only TX and RX lines need isolation; control lines do not).

RS-422/RS-485 Interface IC Core Working Mechanism: Differential Transmission

Upon receiving an MCU’s logic signal, these ICs convert it into a differential signal. Instead of transmitting data via voltage relative to a ground line, it uses the voltage difference between two wires (typically A and B) to represent logic 0 and 1.

Electromagnetic interference (like noise from heavy motor startups) usually affects both wires equally. This is called common-mode interference. When the receiving chip calculates the voltage difference, the interference is subtracted out. This gives RS-422/RS-485 chips two core advantages:

• Extreme Anti-Interference: Survives highly noisy electromagnetic environments.
• Ultra-Long Transmission Distance: At suitable rates, communication can reach up to 1,200 meters (4,000 feet). Allows multiple devices on a single bus.

Typical Applications

Due to low cost, high reliability, and long-distance capabilities, RS-422/RS-485 is the most widely used PHY layer in the industry. Many famous industrial protocols (Modbus, Profibus-DP, BACnet) rely on these chips.

Applications are concentrated in areas requiring long cabling and facing electromagnetic interference:

1. Industrial Automation and Heavy MachineryThe primary market for RS-485. Factory floors and heavy machinery (construction equipment, fluid control, robots) generate heavy electromagnetic interference from motors and inverters.
   • Examples: Bus communication between PLCs, HMIs, sensors (temperature, pressure, flow), and inverters. Controllers send parameters or collect data via RS-485.
2. Renewable Energy and Power SystemsPower systems demand strict isolation and high-voltage safety. Isolated RS-485 chips are heavily used here.
   • Examples: Solar inverters (sending data to control centers), BMS (cascading data between battery clusters in storage racks), and smart meter AMR systems.
3. Building Automation and SecurityModern buildings have scattered equipment. Cables run through entire structures. RS-485’s long-distance, multi-node features are a perfect match.
   • Examples: HVAC thermostat networking, access control board synchronization, elevator dispatching, and PTZ camera control in security systems.
4. Servo Motors and Motion ControlFull-duplex RS-422 chips dominate this area.
   • Examples: Absolute motor encoders. CNC machines and robotic arms need precise rotor position feedback sent to servo drives at high speeds. RS-422 provides megabit-level point-to-point data feedback while resisting noise.
5. Commercial Automation and TerminalsCommon in lightweight scenarios sensitive to wiring costs.
   • Examples: Supermarket POS networks, highway toll booth control, and parking lot guidance light networks.

Four Core Physical and Application Classifications

1. Basic Physical Topology (Duplex Mode)

Dictated directly by the communication architecture (2-wire vs. 4-wire). The first step in chip selection.

Category Name	Features & Scenarios	Typical Models	Manufacturers
Half-Duplex	One differential pair (A/B). Shared RX/TX toggled via DE/RE pins. Classic RS-485 mode. Saves wiring, supports multi-node.	MAX485 / MAX3485 THVD1429 NSI83085	Analog Devices (Maxim) Texas Instruments (TI) NOVOSENSE
Full-Duplex	Two differential pairs (TX+/TX-, RX+/RX-). Independent RX/TX. For RS-422 systems or high-speed point-to-point RS-485.	MAX491 / MAX3491 SN65HVD12 CA-IF4888	Analog Devices (Maxim) Texas Instruments (TI) Chipanalog
Simplex (Independent)	Chip contains purely drivers or purely receivers. Used for multi-channel data acquisition or dedicated multi-wire communication.	AM26LS31 (Quad Driver) AM26LS32 (Quad Receiver)	Texas Instruments (TI) Classic Series

2. Electrical Anti-Interference & Safety (Isolation and Protection)

Determines the chip’s survivability in harsh environments like industrial, power, and outdoor settings.

Category Name	Features & Scenarios	Typical Models	Manufacturers
Non-Isolated Standard	Low cost, small footprint (often SOP-8). Used inside chassis, board-level, or stable short-distance environments with no ground potential difference.	SP3485 SN75176B	MaxLinear (Exar) Texas Instruments (TI)
Signal Isolated	Integrates magnetic or capacitive isolation (e.g., iCoupler). Breaks ground loops. Requires external isolated power.	ADM2483 ISO1410	Analog Devices (ADI) Texas Instruments (TI)
Full Isolation	Ultimate single-chip solution. Isolates signals and integrates a micro-transformer. Outputs isolated 3.3V/5V power directly, simplifying PCB design.	ADM2587E ISOW1412 NSI8241W	Analog Devices (ADI) Texas Instruments (TI) NOVOSENSE
Fault-Protected	Bus pins withstand high overvoltage. The chip survives accidental contact with 24V industrial power or 60V high voltage on long wire runs.	LT1785A (±60V rating) THVD2450 (±70V rating)	Analog Devices (Linear) Texas Instruments (TI)

3. Signal Transmission Performance (Speed and Slew-Rate)

Determines how fast and how far the data can travel.

Category Name	Features & Scenarios	Typical Models	Manufacturers
Slew-Rate Limited	Intentionally slows signal rising edges. Speeds usually 115kbps ~ 500kbps. Suppresses high-frequency harmonics, reflections, and EMI. Top choice for long cables or unterminated buses.	MAX483 (250kbps) THVD1500 (500kbps)	Analog Devices (Maxim) Texas Instruments (TI)
High-Speed	Maximizes speed. Rates reach 10Mbps ~ 50Mbps or higher. Ideal for short-distance, massive data transfers. Requires strict PCB routing and impedance matching.	ADM1485 (30Mbps) MAX3460 (20Mbps) THVD1450 (50Mbps)	Analog Devices (ADI) Analog Devices (Maxim) Texas Instruments (TI)

4. Bus Capacity (Input Impedance and Node Count)

Determines exactly how many devices (nodes) can connect to a single RS-485 bus.

Category Name	Features & Scenarios	Typical Models	Manufacturers
Standard (1 UL)	~12kΩ input impedance. Strict standard compliance. Max 32 nodes per bus. Common in legacy chips.	SN75176B	Texas Instruments (TI)
1/4 Unit Load (1/4 UL)	~48kΩ input impedance. Draws less bus current. Allows up to 128 nodes per bus.	MAX487 MAX3430	Analog Devices (Maxim)
1/8 Unit Load (1/8 UL)	>96kΩ input impedance. Minimal leakage current. Allows up to 256 nodes per bus. Ideal for large building automation (BACnet) and dense industrial networks.	ADM3072E THVD1410	Analog Devices (ADI) Texas Instruments (TI)