HG232
RS-232 transceiver with ±15kV ESD protection, 250kbps data rate, and integrated charge pump for PC communication
Product Overview
Description
HG232 is a 3-driver/5-receiver RS-232 transceiver designed for PC communication and serial data interfaces requiring robust ESD protection.
Operating from a single 3.0V to 5.5V supply, the device uses an integrated charge pump to generate the ±5V RS-232 signal levels, eliminating the need for dual supplies.
With ±15kV ESD protection on RS-232 pins, 250kbps data rate, and low power shutdown mode, this transceiver is ideal for PC peripherals, industrial equipment, and portable devices.
Product Series
HG
Primary Application
PC peripherals and accessories
Key Features
- Single 3.0V to 5.5V supply operation
- Integrated charge pump - no external capacitors needed
- ±15kV ESD protection on RS-232 pins
- 250kbps data rate for standard serial communication
- 3 drivers and 5 receivers for full modem support
- Low power shutdown mode (1μA)
- Auto-shutdown feature for power saving
- Meets EIA/TIA-232E specifications
Specifications
| Supply Voltage Range | 3.0V to 5.5V |
|---|---|
| Data Rate | Up to 250kbps |
| ESD Protection | ±15kV HBM on RS-232 pins |
| Drivers | 3 (TXD, RTS, DTR) |
| Receivers | 5 (RXD, CTS, DSR, DCD, RI) |
| Output Swing | ±5V typical |
| Supply Current | 5mA typical (operating) |
| Shutdown Current | 1μA max |
| Package | SSOP-28, TSSOP-28 |
Applications
PC peripherals and accessories
Electronic system design
Industrial control systems
Industrial automation and control
Point-of-sale equipment
Electronic system design
Network switches and routers
Communication and interface
Test and measurement equipment
Data acquisition and conversion
Portable devices with serial ports
Electronic system design
Legacy serial equipment
Electronic system design
FAE Expert Insights
"HG232 is my go-to choice for RS-232 interfaces requiring robust ESD protection. The ±15kV rating eliminates external protection components in most applications, saving BOM cost and board space. The integrated charge pump works reliably across the full 3-5.5V range, making it versatile for both 3.3V and 5V systems. I've used this in numerous industrial applications where equipment gets handled frequently - the ESD protection has prevented field failures. The auto-shutdown feature is useful for battery-powered devices. For best EMI performance, place charge pump capacitors close to the IC. This is a cost-effective alternative to MAX3232 with equivalent functionality."
±15kV ESD protection with integrated charge pump
— Michael Zhang, BeiLuo
Frequently Asked Questions
What external capacitors does HG232 require?
HG232 requires four external capacitors for the charge pump: one between V+ and VCC (positive pump capacitor), one between V- and GND (negative pump capacitor), and two reservoir capacitors (V+ to GND and V- to GND). Recommended values are 0.1μF to 1μF ceramic capacitors with X5R or X7R dielectric. Lower values (0.1μF) are suitable for 3.3V operation, while 1μF provides better performance at 3.0V. Place all capacitors as close as possible to the IC pins with short traces. The charge pump operates at approximately 200kHz.
Use 0.1μF-1μF ceramic capacitors close to IC. Contact our FAE team for charge pump capacitor selection guidelines.
How does the auto-shutdown feature work?
HG232 auto-shutdown feature automatically enters low-power mode (1μA) when no valid RS-232 signals are detected for 30 seconds. The device monitors the receiver inputs for transitions. When activity is detected, the device wakes up within 100μs. This feature is enabled by connecting the auto-shutdown pin to VCC. For manual control, the shutdown pin can be driven by a microcontroller. In shutdown mode, the charge pump turns off, receivers are disabled, and drivers enter high-impedance state. This feature is particularly useful for battery-powered devices connected intermittently to PCs.
Enable auto-shutdown for battery-powered applications. Contact our FAE team for power management strategies.
What is the maximum cable length for RS-232 with HG232?
RS-232 maximum cable length depends on data rate and cable quality. At 9600bps, maximum length is approximately 100 feet (30m). At 115.2kbps, maximum is about 50 feet (15m). At 250kbps (HG232 maximum), keep cable under 25 feet (8m) for reliable operation. Use shielded cable in noisy environments. RS-232 is designed for point-to-point communication within a room or equipment rack. For longer distances, consider RS-485 (HG485) which supports 4000 feet at lower data rates. HG232's ±5V output swing provides good noise margin for reliable communication at maximum data rates.
Keep RS-232 cables under 25 feet at 250kbps. For longer distances, use RS-485. Contact our FAE team for interface selection guidance.
Can HG232 operate at 3.3V with 5V logic levels?
HG232 can operate from 3.3V supply while interfacing with 5V logic on the TTL side. The digital inputs (TXD, RTS, DTR) are 5V tolerant, accepting logic high up to 5.5V. The digital outputs (RXD, CTS, DSR, DCD, RI) swing to VCC (3.3V), which meets 5V CMOS input high threshold (3.5V minimum) marginally. For reliable 5V interface, ensure 5V system uses CMOS input levels (not TTL). Alternatively, add pull-up resistors to 5V on outputs. The RS-232 side always uses ±5V levels regardless of supply voltage, ensuring compatibility with all RS-232 devices.
Inputs are 5V tolerant. Outputs may need pull-ups for 5V TTL. Contact our FAE team for mixed-voltage interface design.
How do I protect HG232 from overvoltage on RS-232 lines?
HG232 includes ±15kV ESD protection on RS-232 pins, adequate for human body model ESD. For additional protection against sustained overvoltage or lightning: Use external TVS diodes (e.g., SMAJ series) for transients above ±25V; Add series resistors (10-100Ω) to limit current; Use isolation transformers for galvanic isolation; and Consider optocouplers for complete electrical isolation. For most indoor applications, the internal ±15kV protection is sufficient. Industrial or outdoor applications may require additional protection. Always follow good grounding practices and use shielded cables.
Internal ±15kV protection adequate for most applications. Add external TVS for harsh environments. Contact our FAE team for protection design.
What is the difference between HG232 and HG485?
HG232 is an RS-232 transceiver for point-to-point serial communication up to 50 feet, using single-ended ±5V signaling. It supports full-duplex communication with 3 drivers and 5 receivers. HG485 is an RS-485 transceiver for multi-drop industrial networks up to 4000 feet, using differential 2-wire signaling. RS-485 supports up to 256 nodes (32 with standard transceivers) with half-duplex communication. Choose RS-232 for short-distance PC communication. Choose RS-485 for long-distance industrial networks with multiple devices. Some systems use both: RS-232 for local PC interface and RS-485 for remote device network.
Use HG232 for PC serial ports. Use HG485 for industrial networks. Contact our FAE team for system interface design.