MAX3243EEAI+

Overview

The MAX3243EEAI+ is a +3.0V to +5.5V RS-232 transceiver featuring AutoShutdown technology that reduces supply current to 1µA when no valid signal is detected on receiver inputs for 30µs. It integrates three drivers and five receivers in a 28-pin SSOP package, operating within an industrial temperature range of -40°C to +85°C. The device utilizes a dual charge pump with four 0.1µF capacitors to generate internal ±5.5V supplies from a single voltage source. It supports data rates up to 235kbps and includes an always-active complementary receiver output (R2OUTB) for external monitoring during shutdown.

Feature Summary

• AutoShutdown functionality automatically disables the onboard power supply and drivers upon detecting invalid signal levels, significantly reducing power consumption.
• Integrated dual charge-pump circuitry generates required RS-232 voltages using only four small external capacitors, eliminating the need for external ±12V supplies.
• Includes a dedicated complementary receiver output that remains active during shutdown states to monitor external devices without forward-biasing connected logic.

Applications

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

Procurement Notes

Verify the specific suffix 'E' confirms the extended temperature rating (-40°C to +85°C) and 'I' indicates the SSOP package type. Confirm the '+' suffix denotes RoHS compliance status as per manufacturer standards. Ensure the ordering information matches the exact pinout and electrical characteristics defined in the official datasheet before finalizing procurement.

Selection Notes

Select this component when designing systems requiring low-power standby modes via automatic signal detection. It is suitable for interfacing with 3.3V or 5V logic families while maintaining true RS-232 performance. Consider the integrated complementary receiver if the design requires monitoring serial activity while the main system is powered down.

Part Context

This part belongs to the MAX3221/MAX3223/MAX3243 family of 3V-powered EIA/TIA-232 transceivers. While the MAX3221 offers one driver/receiver and the MAX3223 provides two, the MAX3243 specifically accommodates three drivers and five receivers. All variants share the same AutoShutdown architecture and capacitor requirements.

Replacement Considerations

Public confirmed substitute part numbers include MAX3243EAI and MAX3243EUI. These alternatives maintain identical electrical specifications but differ in package type, such as Wide SO or TSSOP configurations.

FAQ

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

The device enters AutoShutdown mode when it senses no valid signal levels on all receiver inputs for a duration of 30µs. This typically occurs if the RS-232 cable is disconnected or peripheral transmitters are turned off.

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 receiver activity even when the other receivers are in a high-impedance state due to shutdown, preventing current paths through UART protection diodes.

Can the MAX3243 drive serial mice directly?

Yes, the MAX3243 is designed to drive serial mice from low-voltage supplies. However, because the AutoShutdown feature may interfere with mouse operation, FORCEOFF and FORCEON should be tied to VCC to keep the transmitters enabled.