MAX3243ECAI+T

Overview

The MAX3243ECAI+T is a low-voltage RS-232 transceiver featuring three drivers and five receivers in a 28-pin SSOP package. It operates from a single +3.0V to +5.5V supply, utilizing an internal dual charge pump to generate ±5.5V for RS-232 signaling without external ±12V rails. The device supports data rates up to 235kbps with typical propagation delays of 0.3µs. It incorporates AutoShutdown technology, reducing supply current to 1µA when no valid signal is detected on receiver inputs for 30µs. An always-active complementary receiver output (R2OUTB) allows monitoring during shutdown.

Feature Summary

• AutoShutdown functionality reduces power consumption by disabling the onboard power supply and drivers when no valid RS-232 signal is present on receiver inputs.
• Integrated dual charge-pump circuitry generates required RS-232 voltage levels from a single low-voltage supply, eliminating the need for external negative voltage sources.
• Includes a complementary always-active receiver output that remains functional during shutdown mode to monitor external devices without forward-biasing connected logic.

Applications

• Battery-powered equipment requiring extended standby life
• Hand-held portable devices with serial communication interfaces
• Portable diagnostic equipment

Procurement Notes

Verify the component matches the specific Analog Devices/Maxim Integrated part number MAX3243ECAI+T. Confirm the 'E' suffix indicates the -40°C to +85°C industrial temperature range and the 'AI' suffix corresponds to the 28-pin SSOP package. Ensure the '+T' designation aligns with the required reel packaging format for surface-mount assembly processes.

Selection Notes

Select this component when interfacing 3.3V or 5V logic systems with RS-232 ports where power efficiency is critical. The MAX3243ECAI+T is suitable for applications needing multiple transmitter and receiver channels within a compact footprint. Consider the 1µA shutdown current for battery-operated designs and verify that the 235kbps data rate meets the system's communication speed requirements.

Part Context

This component belongs to the MAX3221/MAX3223/MAX3243 family of low-voltage RS-232 transceivers. While sharing the same core AutoShutdown architecture and charge-pump technology, the MAX3243 differs by providing three drivers and five receivers compared to the one-driver/one-receiver MAX3221 and two-driver/two-receiver MAX3223.

Replacement Considerations

MAX3243CAI+T: Identical electrical specifications but limited to commercial temperature range (0°C to +70°C).

FAQ

How does the AutoShutdown feature determine when to enter low-power mode?

The device enters AutoShutdown mode if no valid RS-232 signal levels are detected on all receiver inputs for a duration of 30µs. Valid levels are defined as voltages greater than +2.7V or less than -2.7V.

What is the function of the R2OUTB pin on the MAX3243?

R2OUTB is a complementary, always-active receiver output. It allows the system to monitor RS-232 activity even when the main receivers are in a high-impedance state due to shutdown, preventing current flow through protection diodes of connected peripherals.

Can the MAX3243 drive serial mice directly?

Yes, the MAX3243 is designed to drive serial mice. However, because the AutoShutdown feature may interfere with mouse operation, FORCEOFF and FORCEON should be tied to VCC to keep the transmitters active continuously.