MAX3535ECWI+T

Overview

The MAX3535ECWI+T is a full-duplex isolated RS-485/RS-422 transceiver providing 2500VRMS galvanic isolation between the logic side and the interface side. It supports data rates up to 1000kbps with a single +3V to +5.5V power supply. The device includes one differential driver and one receiver, utilizing internal high-voltage capacitors for signal transmission across the barrier. Power transfer to the isolated side is achieved via an external transformer driven by a 420kHz oscillator on pins ST1 and ST2. It features ±15kV ESD protection, pin-selectable slew-rate limiting, and open-line/shorted-line fail-safe inputs.

Feature Summary

• Integrated high-voltage capacitors provide 2500VRMS of galvanic isolation without requiring external components for data transmission.
• Pin-selectable slew-rate limiting controls electromagnetic interference (EMI) and reduces reflections on improperly terminated cables.
• Hot-swap capability protects the driver-enable input during system insertion or removal.
• Isolation-barrier fault detection circuitry alerts the processor when communication across the barrier fails.

Applications

• Isolated RS-485 systems
• Systems with large common-mode voltages
• Industrial-control local area networks
• Telecommunications systems

Procurement Notes

Verify the specific suffix 'C' indicates the commercial temperature range of 0°C to +70°C. Confirm the '+T' designation corresponds to tape-and-reel packaging if required for automated assembly. Ensure the ordering code matches the exact package width specified in the manufacturer's documentation.

Selection Notes

Select this component when a single-supply isolated RS-485 solution is required. The MAX3535E operates from +3V to +5.5V, allowing step-down transformers for power savings compared to higher voltage requirements. Verify that the application requires full-duplex communication and can accommodate the necessary external isolation transformer for power delivery.

Part Context

This part belongs to the MAX3535E/MXL1535E family of isolated transceivers. The MXL1535E is a functionally compatible improvement of the LTC1535 but requires a +4.5V to +5.5V supply. The MAX3535E offers improved secondary supply ranges for better efficiency at +5V operation using step-down transformers.

Replacement Considerations

MXL1535ECWI: Functionally similar but requires +4.5V to +5.5V logic supply.

FAQ

How is power transferred to the isolated side?

Power is transferred using an external transformer connected to the ST1 and ST2 pins, which are driven by an integrated 420kHz transformer driver.

What is the receiver load characteristic?

The receivers are 1/8 unit load, allowing up to 256 devices to be connected on the same bus.

How does the device handle open or shorted lines?

It features true fail-safe circuitry that ensures the receiver output remains in a logic-high state when the inputs are open, shorted, or disconnected.