IC-Mart Your Trusted Source for RS-232 Interface Chips

(from leading manufacturers)

Major Manufacturers and Typical RS-232 ICs

1. Analog Devices (ADI)

• MAX232: The original standard. 5V supply, 2Tx/2Rx standard transceiver.
• MAX3232 / MAX3232E: The industry’s most popular wide-voltage (3.0V-5.5V) 2Tx/2Rx transceiver. The “E” denotes ±15kV ESD protection.
• MAX3221: Single-channel 1Tx/1Rx compact transceiver. Ideal for space-constrained designs.
• MAX3243: 3Tx/5Rx full serial port transceiver. Features Auto-Powerdown. Commonly used in industrial PCs.
• MAX3237: High-speed RS-232 transceiver. Supports data rates up to 1Mbps.
• ADM3251E: ADI’s premium native product. A single-chip RS-232 transceiver with integrated 2.5kV power and signal isolation.
• LTM2882: A micro-module from the Linear Technology portfolio. Integrates highly reliable isolated power with an RS-232 transceiver.

2. Texas Instruments (TI)

• SN75188: Classic 4-channel RS-232 standalone driver. Requires dual power supplies.
• SN75189: Classic 4-channel RS-232 standalone receiver.
• SN65C3232: TI’s standard 3.3V/5V 2Tx/2Rx transceiver.
• TRS3232E: TI’s 3.3V/5V transceiver with ±15kV ESD protection.
• MAX232 / MAX3232 / MAX3221 / MAX3243: Pin-to-pin replacements for Maxim’s models. Engineered for high cost-effectiveness.

3. Renesas Electronics

• HIN232: Classic 5V 2Tx/2Rx transceiver originally launched by Intersil.
• ISL3232E: 3.3V/5V standard 2Tx/2Rx transceiver. Features ultra-low shutdown current and high ESD protection.
• ISL4241E: 3Tx/5Rx full serial port transceiver. Perfect for industrial equipment requiring full handshake signals.

4. STMicroelectronics

• SN75189: 4-channel RS-232 receiver compatible with TI models.
• ST232: ST’s version of the standard 5V 2Tx/2Rx transceiver.
• ST3232: ST’s version of the wide-voltage 3.3V/5V 2Tx/2Rx transceiver.

5. MaxLinear

• SP3232E: A renowned 3.3V/5V 2Tx/2Rx transceiver with high ESD protection. Widely used in industrial and telecom motherboards.

Leading Chinese RS-232 IC Manufacturers and Typical Models

1. SIT (Hunan Xinlite Electrical)

• Overview: SIT focuses exclusively on automotive and industrial bus interfaces (RS485/RS232/CAN). Their chips are known in the industrial control sector for outstanding lightning surge immunity, anti-interference, and robust ESD protection.
• Typical Model: SIT3232E
• Classification: Wide voltage (3.3V-5.5V) + Basic configuration (2Tx/2Rx) + High ESD protection (±15kV)
• Logic: A perfect domestic drop-in replacement for the TI TRS3232E or Maxim MAX3232E. It features an internal charge pump requiring only four 0.1uF external capacitors. Designed to prevent static breakdown during hot-plugging in harsh industrial environments.

2. 3PEAK

• Overview: A top-tier domestic supplier of analog signal chain ICs. Their product line covers Op-Amps, ADCs/DACs, and interfaces. Their interface ICs emphasize high speed and stability. They are widely used in telecom base stations and high-end industrial equipment.
• Typical Model: TPT3232E
• Classification: Wide voltage (3V-5.5V) + Standard configuration (2Tx/2Rx)
• Logic: Supports data rates up to 250kbps. Fully complies with the TIA/EIA-232-F standard. Available in SOP and TSSOP packages. It serves as a highly versatile core transceiver for standard serial communication between MCUs and external peripherals.

3. Shanghai Belling

• Overview: A veteran state-owned enterprise in China’s microelectronics industry. Belling offers a mature portfolio of standard analog, logic, and interface ICs. They are known for high cost-effectiveness and stable high-volume supply.
• Typical Model: BL13232E (and variants like BL13232ETS)
• Classification: Wide voltage (3.0V-5.5V) + Standard configuration (2Tx/2Rx) + Protection mechanisms
• Logic: Integrates a dual charge pump. Features ±12kV IEC 61000-4-2 contact discharge protection. This chip covers most basic 5V/3.3V communication needs. Widely used in smart meters, security systems, and general instruments.

4. MORNSUN

• Overview: Traditionally a leading manufacturer of industrial power and micro-power modules. Leveraging their expertise in power isolation, they use System-in-Package (SiP) technology to integrate isolated power and interface ICs. This creates highly integrated isolated interface products.
• Typical Model: TD541S232H / TD041S232H
• Classification: High-end protection + Electrical isolation + Specialized physical package (DFN)

RS-232 Interface IC Typical Application Scenarios

USB and wireless communication are everywhere today. However, RS-232 retains an irreplaceable position in demanding professional fields. This is due to its physical characteristics: simple structure, extreme stability, true plug-and-play capability, and no need for complex protocol stacks.

Here are its four core applications:

1. Industrial Automation This is the largest market for RS-232 chips. Industrial environments are filled with electromagnetic interference from motors and inverters. They require absolutely reliable point-to-point communication.

• Programmable Logic Controllers (PLCs): Engineers use RS-232 serial ports to program, debug, and read logs from PLCs.
• CNC Machines and Robot Chassis: Used for data exchange between the main control board and servo motor drives, or various industrial sensors (like displacement sensors and precision scales).

2. Networking and Telecom (The Lifeline) Step into an enterprise server room, and nearly every core device relies on RS-232.

• Console Ports: Cisco routers, core switches, massive firewalls, and servers all feature an RS-232-based console port on the back. When a network completely crashes and IP remote access fails, IT engineers must connect directly to this port via an RS-232 cable for base-level system recovery and configuration.

3. Medical and Scientific Instruments Medical and scientific fields demand zero-latency, authentic data. They avoid the unpredictability of complex USB drivers.

• Medical Devices: Blood analyzers, ECG machines, and multi-parameter monitors use isolated RS-232 chips. These transmit real-time data to a host computer. The isolation ensures patients are safe from electrical shock, even if the motherboard leaks current.
• Lab Instruments: Precision tools like gas chromatographs and spectrometers have long used RS-232 as their standard output interface.

4. Point of Sale (POS) and Terminals At supermarkets and malls, checkout peripherals rely on RS-232 communication.

• POS Peripherals: Receipt printers, legacy barcode scanners, magnetic stripe/chip card readers, and customer displays connect to the host via RS-232. Unlike USBs, RS-232 connectors feature screw locks. They won’t accidentally pull loose.

Detailed Classification

I. Core Function and Integration

This is the fundamental physical logic. It determines whether the chip operates unidirectionally or bidirectionally.

1. Standalone Driver / Standalone Receiver

• Features: Used in legacy or ultra-minimalist designs. The motherboard supplies dual voltage (e.g., ±12V). The chip only handles one-way level conversion (TTL/CMOS to RS-232, or vice versa).
• Typical Models:
  • SN75188: 4-channel RS-232 driver. — Texas Instruments (TI)
  • SN75189: 4-channel RS-232 receiver. — TI / STMicroelectronics

2. Transceiver

• Features: The absolute standard in modern designs. A single chip integrates both transmit (Tx) and receive (Rx) channels.
• Typical Models: Covers almost all chips in the following categories (e.g., the classic MAX232 — Analog Devices).

II. Supply Voltage and Charge Pump Technology

This is the core baseline for hardware design. The RS-232 standard requires ±12V levels, but modern MCUs usually operate on 5V or 3.3V. Internal “charge pumps” divide these ICs into two main camps.

1. Legacy 5V Supply Series

• Features: Supports only 5V systems. An internal charge pump boosts and inverts the 5V to generate the required RS-232 levels.
• Typical Models:
  • MAX232: The industry’s founding RS-232 chip. — Analog Devices, TI, and others.
  • HIN232: — Renesas (formerly Intersil).

2. Wide/Low Voltage Supply Series (3.0V – 5.5V)

• Features: Uses a highly efficient dual charge pump architecture. Supports 5V and perfectly matches modern 3.3V MCUs (like the STM32). This is the highest volume category today.
• Typical Models:
  • MAX3232: The 3.3V upgrade to the MAX232. — Analog Devices, TI.
  • SP3232E: — MaxLinear.

III. Channel Configuration

This depends on how many RS-232 signal lines your device requires.

1. Basic Configuration (1Tx / 1Rx)

• Features: Minimalist communication. Connects only TX, RX, and GND. Extremely compact.
• Typical Models:
  • MAX3221: — TI, Analog Devices.

2. Standard Configuration (2Tx / 2Rx)

• Features: The most common setup. Supports basic transmission plus an additional set of hardware flow control signals (like RTS/CTS).
• Typical Models:
  • MAX3232, SN65C3232: — TI.

3. Full Serial Port / Multi-Channel (3Tx / 5Rx or more)

• Features: Implements a complete 9-pin (DB9) RS-232 standard. Supports all handshake and control signals (TX, RX, RTS, CTS, DTR, DSR, DCD, RI).
• Typical Models:
  • MAX3243: 3Tx/5Rx. Common in industrial PC motherboards. — Analog Devices, TI.
  • ISL4241E: 3Tx/5Rx. — Renesas.

IV. Protection and Isolation

Specialized designs for industrial control, automotive electronics, or harsh environments.

1. High ESD Protection

• Features: Provides ±15kV or higher ESD protection on RS-232 pins. Prevents chip breakdown from human touch or hot-plugging. Usually denoted by an “E” suffix.
• Typical Models:
  • MAX3232E: ±15kV ESD. — Analog Devices.
  • TRS3232E: ±15kV ESD. — TI.

2. Isolated RS-232

• Features: Integrates a digital isolation layer and isolated power (transformer or capacitor based). Completely severs electrical connections. Prevents ground loop interference or high-voltage surges from damaging the motherboard.
• Typical Models:
  • ADM3251E: Single-chip 2.5kV fully isolated RS-232. — Analog Devices.
  • LTM2882: Micro-module with integrated isolated power. — Analog Devices.

V. Advanced Features

1. High Speed

• Features: Standard RS-232 usually runs around 120kbps. High-speed versions feature optimized drivers reaching 250kbps, 460kbps, or even 1Mbps.
• Typical Models:
  • MAX3237: Supports up to 1Mbps. — Analog Devices, TI.

2. Auto-Powerdown / Low Power

• Features: Automatically shuts down the internal charge pump when the RS-232 cable is unplugged or no signal is detected. Enters a microamp-level standby mode. Drastically extends battery life in portable devices.
• Typical Models:
  • MAX3243: Features Auto-Powerdown. — Analog Devices.
  • ISL3232E: Features ultra-low shutdown current. — Renesas.