+3V to +5V, 2500VRMS Isolated RS-485/RS-422 Transceivers with ±15kV ESD Protection

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Part Details
Part Models 4
1ku List Price Starting From $7.90
  • 2500VRMS RS-485 Bus Isolation Using On-Chip High-Voltage Capacitors
  • 1000kbps Full-Duplex RS-485/RS-422 Communication
  • +3V to +5.5V Power-Supply Voltage Range (MAX3535E)
  • +4.5V to +5.5V Power-Supply Voltage Range (MXL1535E)
  • 1/8 Unit Receiver Load, Allowing 256 Devices on Bus
  • ±15kV ESD Protection Using HBM
  • Pin-Selectable Slew-Rate Limiting Controls EMI
  • Hot-Swap-Protected Driver-Enable Input
  • Undervoltage Lockout
  • Isolation-Barrier Fault Detection
  • Short-Circuit Protected
  • Thermal Shutdown
  • Open-Line and Shorted-Line Fail-Safe Receiver Inputs
Additional Details
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The MAX3535E/MXL1535E isolated RS-485/RS-422 full-duplex transceivers provide 2500VRMS of galvanic isolation between the RS-485/RS-422 side and the processor or control logic side. These devices allow fast, 1000kbps communication across an isolation barrier when the common-mode voltages (i.e., the ground potentials) on either side of the barrier are subject to large differences. Isolation is achieved through integrated high-voltage capacitors. The MAX3535E/MXL1535E also feature a 420kHz transformer driver that allows power transfer to the RS-485 side using an external transformer.

The MAX3535E/MXL1535E include one differential driver, one receiver, and internal circuitry to send the RS-485 signals and control signals across the isolation barrier (including the isolation capacitors). The MAX3535E/MXL1535E RS-485 receivers are 1/8 unit load, allowing up to 256 devices on the same bus.

The MAX3535E/MXL1535E feature true fail-safe circuitry. The driver outputs and the receiver inputs are protected from ±15kV electrostatic discharge (ESD) on the interface side, as specified in the Human Body Model (HBM).

The MAX3535E/MXL1535E feature driver slew-rate select that minimizes electromagnetic interference (EMI) and reduces reflections. The driver outputs are short-circuit and overvoltage protected. Other features are hot-swap capability and isolation-barrier fault detection.

The MAX3535E operates with a single +3V to +5.5V power supply. The improved secondary supply range of the MAX3535E allows the use of step-down transformers for +5V operation, resulting in considerable power savings. The MXL1535E operates with a single +4.5V to +5.5V power supply. The MXL1535E is a function-/pin-compatible improvement of the LTC1535. The MAX3535E/MXL1535E are available over the commercial 0°C to +70°C and extended -40°C to +85°C temperature ranges.


  • Industrial-Control Local Area Networks
  • Isolated RS-485 Systems
  • Systems with Large Common-Mode Voltages
  • Telecommunications Systems
Part Models 4
1ku List Price Starting From $7.90

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Software & Part Ecosystem

Software & Part Ecosystem

Evaluation Kit

Evaluation Kits 1


MAX3535E Evaluation Kit



MAX3535E Evaluation Kit

MAX3535E Evaluation Kit

Features and Benefits

  • Designed for 2500VRMS Isolation
  • 1/8 RS-485 Unit Load
  • 1000kbps Full-Duplex RS-485/RS-422 Communication (Configurable for Half Duplex)
  • +3.0V to +5.5VDC Input Range
  • Isolated VCC2 Output
  • Center-Tapped, Full-Wave Rectifier Output
  • 420kHz Switching Frequency
  • Undervoltage Lockout (UVLO) and Thermal Shutdown
  • Low-Cost Integrated-FET H-Bridge Design
  • Fully Assembled and Tested

Product Detail

The MAX3535E evaluation kit (EV kit) is a fully assembled and tested PCB that contains a 2500VRMS isolated RS-485/RS-422 transceiver with ESD protection. The EV kit circuit features a differential driver and one receiver. The circuit’s receiver is a 1/8 unit load for the RS-485 bus and communicates up to 1000kbps. The MAX3535E fail-safe circuitry and driver slew-rate features are demonstrated and easily reconfigured.

Additionally, the EV kit features an H-bridge DC-DC converter to power the isolated section of the MAX3535E RS-485/RS-422 circuit. Input power to the circuit is supplied by a +3V to +5.5VDC source. This circuit uses a full-wave rectifier on the unregulated output and provides unregulated voltage to the MAX3535E internal, linear low-dropout (LDO) regulator. Using an H-bridge design minimizes input ripple current and radiated noise. Undervoltage lockout (UVLO) and thermal shutdown provide for a robust, isolated RS-485/RS-422 transceiver circuit and power supply. The surface-mount transformer provides up to 2500VRMS galvanic isolation and the output is powered from a center-tapped, full-wave rectifier circuit to reduce output voltage ripple.

The isolated H-bridge DC-DC converter operation at 420kHz allows the use of ceramic-only output capacitors and a small transformer.

Tools & Simulations

Tools & Simulations 1

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