MAX249CQH+D

Overview

The MAX249CQH+D is a multichannel RS-232 transceiver from the MAX220–MAX249 family, designed for EIA/TIA-232E and V.28/V.24 interfaces. It operates on a single +5V supply using integrated charge-pump circuitry to generate internal ±10V rails, eliminating the need for external bipolar supplies. The device features three drivers and three receivers with independent enable controls. Electrical specifications include a data rate of up to 120 kbps, an output voltage swing of ±7.5V under load, and receiver input protection up to ±25V. It is housed in a 44-pin PLCC package and supports commercial temperature ranges.

Feature Summary

• Integrated dual charge-pump DC-DC converters convert a single +5V supply into internal ±10V rails for RS-232 driver operation without requiring external bipolar power sources.
• Features three independent transmitter outputs and five independent receiver inputs, each equipped with dedicated control pins (ENTA, ENTB, ENRA, ENRB) for granular power management and shutdown states.
• Provides robust signal integrity through TTL/CMOS-compatible logic thresholds and includes high-voltage tolerance on receiver inputs to protect against line faults.

Applications

• Multidrop RS-232 networks
• Portable diagnostics equipment
• Interface translation systems

Procurement Notes

Verify the specific suffix 'CQH' against the manufacturer's current ordering information table to confirm the exact package type and temperature grade. Confirm RoHS compliance status as indicated by the '+' designation. Check production status for availability, as older Maxim Integrated components may have limited stock or end-of-life implications.

Selection Notes

Select this component when designing systems requiring multiple independent RS-232 channels controlled individually via software. Ensure the application can accommodate the 44-pin PLCC footprint. Verify that the required data rates do not exceed 120 kbps and that the system operates within the specified single-supply voltage range.

Part Context

This part belongs to the MAX220–MAX249 family of +5V-powered, multichannel RS-232 drivers and receivers. The family offers various channel counts and package options to suit different board space constraints. The MAX249 specifically provides a high channel count with individual enable capabilities, distinguishing it from simpler dual-channel variants like the MAX232.

Replacement Considerations

Direct replacements within the same family include other MAX24x series parts such as the MAX244, MAX245, MAX246, MAX247, and MAX248, depending on the required number of drivers and receivers. Cross-reference the pinout and control logic configurations carefully before substitution.