MAX3243EWI

Overview

The MAX3243EWI is a +3.0V to +5.5V RS-232 transceiver featuring three drivers and five receivers in a 28-pin Wide SO package. It incorporates AutoShutdown technology, reducing supply current to 1µA when no valid signal is detected on receiver inputs for 30µs. The device operates within an industrial temperature range of -40°C to +85°C. It utilizes internal dual charge pumps to generate ±5.5V from a single supply, requiring only 0.1µF capacitors at 3.3V. The guaranteed data rate is 120kbps with worst-case loads, while typical operation supports up to 235kbps.

Feature Summary

• AutoShutdown functionality reduces power consumption by disabling the onboard power supply and drivers upon detecting invalid signal levels on all receiver inputs.
• Integrated dual charge-pump circuitry eliminates the need for external ±12V supplies, enabling operation from a single +3.0V to +5.5V source.
• Includes an always-active complementary receiver output (R2OUTB) that monitors RS-232 activity even when other receivers are in a high-impedance shutdown state.

Applications

• Battery-powered equipment
• Hand-held devices
• Portable diagnostics equipment

Procurement Notes

Verify the specific ordering suffix against the manufacturer's official documentation to confirm package type and temperature rating. Ensure compatibility with system voltage requirements and interface standards before procurement. Cross-reference part numbers with authorized distributors to confirm availability and authenticity.

Selection Notes

Select this component for applications requiring low-power standby modes and single-supply operation. Verify that the required data rates do not exceed the guaranteed 120kbps limit under worst-case loading conditions. Confirm that the 28-pin Wide SO package fits the available PCB space and thermal constraints.

Part Context

This device belongs to the MAX3221/MAX3223/MAX3243 family of +3V to +5.5V RS-232 transceivers. While sharing core features like AutoShutdown and integrated charge pumps, the MAX3243 variant specifically provides three drivers and five receivers, distinguishing it from the lower-channel MAX3221 and MAX3223 models.

Replacement Considerations

MAX3243CWI+

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 present on any receiver input for a duration of 30µs. Upon detection of a valid level, the system automatically reactivates.

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

R2OUTB is a complementary, always-active receiver output. It allows monitoring of external RS-232 devices, such as Ring Indicators, without forward-biasing protection diodes on other connected logic devices during shutdown.

Can the MAX3243 drive serial mice directly?

Yes, the MAX3243 is designed to drive serial mice. However, because AutoShutdown may interfere with mouse wake-up signals, FORCEOFF and FORCEON should typically be tied to VCC to keep the transmitters active.