MAX3158CPI+

Overview

The MAX3158CPI+ is a high CMRR RS-485/RS-422 data-communications interface providing ±60V isolation in a hybrid microcircuit. It operates on a single +5V supply (4.75V to 5.25V) and supports data rates up to 250kbps. The device contains one transmitter and one receiver, with drivers featuring short-circuit current limiting and thermal shutdown protection. Supply current typically draws 25mA when active and drops to 25µA in shutdown mode. It is housed in a 28-pin PDIP package and operates within a temperature range of 0°C to +70°C.

Feature Summary

• Provides ±60V isolation between logic and cable grounds using external charge-pump capacitors.
• Features fail-safe circuitry that guarantees a logic-high receiver output if inputs are open or shorted.
• Includes independently programmable receiver and transmitter output phase pins to correct for twisted-pair reversal.
• Offers pin-selectable operation between half-duplex and full-duplex modes.

Applications

• Industrial control systems requiring isolated communication.
• Telecommunications equipment interfaces.
• Local area networks utilizing RS-485 or RS-422 protocols.
• Level translation applications involving ground potential differences.

Procurement Notes

Verify the specific ordering suffix 'CPI+' corresponds to the commercial temperature range and PDIP package configuration. Confirm component authenticity through authorized distributors or direct manufacturer channels. Ensure the procurement documentation matches the exact part number to avoid confusion with similar variants like the MAX3157 or other temperature grades.

Selection Notes

Select this component when galvanic isolation is required between a microcontroller system and an RS-485/RS-422 bus. It serves as a low-cost replacement for opto-isolated transceivers. Ensure the application environment stays within the 0°C to +70°C operating range. Verify that the available space accommodates the necessary external 100V capacitors for the internal charge pump.

Part Context

This part belongs to the MAX3158 family of high CMRR RS-485 transceivers. The 'C' suffix indicates the commercial temperature grade (0°C to +70°C), while 'P' denotes the 28-pin plastic dual in-line package. The '+' suffix signifies compliance with RoHS standards. It is functionally related to the MAX3157 but provides higher isolation capabilities.

Replacement Considerations

Public confirmed substitute part numbers include MAX3158CAI, MAX3158EAI, and MAX3158EPI. These variants share identical electrical characteristics but differ in package type (SSOP vs. PDIP) or operating temperature range (Extended vs. Commercial).

FAQ

How is the half-duplex/full-duplex mode selected?

The mode is selected via the H/F pin. Connecting H/F to ISOCOM selects full-duplex mode, while connecting it to ISOVCC selects half-duplex mode.

What happens if the receiver inputs are left open?

The fail-safe feature guarantees a logic-high receiver output if the inputs are open, shorted, or connected to a terminated transmission line with all drivers disabled.

How does the device handle driver overload?

Drivers are protected by short-circuit current limiting and thermal shutdown circuitry. If excessive power dissipation occurs, the thermal shutdown places the driver outputs into a high-impedance state.