MAX491ESD

MAX491ESD is an ESD protection diode array from Maxim Integrated (now part of Analog Devices) designed to shield high-speed data interfaces from electrostatic discharge. It provides multiple low-capacitance TVS diodes that clamp transients to supply rails or ground, preserving signal integrity on lines such as USB, HDMI, camera interfaces (e.g., MIPI), or general microcontroller I/O. The device offers fast response and small package options with various channel counts and working voltages. Use MAX491ESD when you need close-proximity protection without adding significant loading or distortion to the signal; place it near the connector or protected device and route lines carefully to minimize trace length. When selecting, compare channel count, working voltage, clamp voltage, capacitance, leakage, and ESD ratings (HBM/CDM), as well as package and footprint. For exact performance, refer to the latest MAX491ESD datasheet and any application notes, since variants exist with different ratings.

Equivalent RS-485/RS-422 transceivers with ESD protection include:
- TI SN65HVD178 / SN65HVD178A
- Analog Devices ADM485
- STMicroelectronics ST485 / ST3485
- NXP PCA82C250 / PCA82C251
- Microchip MCP4851
- Onsemi NCV485
- Maxim MAX485 (reference family)

Here are typical features of the MAX491ESD:
- ESD-protected RS-485/RS-422 transceiver (bus pins protected against electrostatic discharge)
- Half-duplex, 2-wire differential signaling
- 1/4 unit load on the bus (enables more devices on a single network)
- Single-supply operation (typical 3.3–5V)
- Fail-safe receiver: guarantees a known high output when inputs are open, shorted, or idle
- Separate driver enable (DE) and receiver enable (RE) for easy tri-state control
- Low quiescent power for battery-powered or remote-sensor applications
- Robust operation with transient/bus protections for harsh environments
- TTL/CMOS-compatible input thresholds
Note: For exact electrical specs (voltage ranges, data rate, and protections), please refer to the official datasheet.

Pin count: 8 pins (8‑pin package).
Function: MAX491ESD is an RS-485/RS-422 transceiver with built‑in ESD protection. It provides a driver/receiver pair: DI (data in) drives the differential bus A/B, RO (data out) is the receiver output, DE enables the driver, and /RE (or RE) enables the receiver. Vcc and GND power the device. Bus pins: A and B.

- Manufacturer: Maxim Integrated (the MAX491ESD is a Maxim part; Maxim Integrated is now a subsidiary of Analog Devices).
- Company type: A semiconductor company that designs and manufactures analog and mixed-signal integrated circuits (American-origin, global supplier).

Applications of MAX491ESD:
- Industrial automation and process control (RS-485/RS-422 multi-drop networks; Modbus, similar protocols)
- Building automation (HVAC, lighting, security)
- Remote telemetry, data acquisition, and SCADA over long cable runs
- Distributed instrumentation in harsh/noisy or ESD-prone environments
- Point-to-point or multipoint RS-485/RS-422 links needing rugged differential signaling with ESD protection (DMX512, BACnet, etc.)
Note: It provides robust bus protection and differential signaling suitable for rugged field installations.

MAX491ESD is available in an 8-pin SOIC (surface-mount) package.