MAX3243EWI+

Overview

The MAX3243EWI+ is a full-duplex RS-232 transceiver manufactured by Analog Devices Inc./Maxim Integrated. It integrates three drivers and five receivers in a 28-pin Wide SO package, operating within a +3.0V to +5.5V supply range. The device features AutoShutdown technology, reducing supply current to 1µA when no valid signal is detected on receiver inputs for 30µs. It supports data rates up to 235kbps with typical propagation delays of 0.3µs. The internal dual charge pump generates ±5.5V from a single supply using four 0.1µF capacitors. It 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 standby power consumption.
• Integrated dual charge-pump circuitry eliminates the need for external ±12V supplies, enabling operation from a single low-voltage source.
• Complementary always-active receiver output allows continuous monitoring of RS-232 activity even when the main transceiver logic is powered down.

Applications

• Battery-powered equipment requiring extended standby life
• Hand-held and portable diagnostic devices
• Peripherals connected via serial interfaces

Procurement Notes

Verify the specific suffix 'EWI+' against the manufacturer's official ordering guide to confirm the Wide SO package type and temperature range (-40°C to +85°C). Confirm RoHS compliance status as indicated by the '+' suffix. Cross-reference the component with the latest datasheet revision to ensure pinout and electrical characteristics remain unchanged.

Selection Notes

Select this component for applications requiring full-duplex communication with multiple receiver lines. Ensure the system operates within the specified +3.0V to +5.5V voltage range. Verify that the required data rate does not exceed 235kbps under worst-case load conditions. Consider the thermal resistance characteristics of the 28-Wide SO package for heat dissipation requirements.

Part Context

This part belongs to the MAX32xx family of low-power RS-232 transceivers. It shares core architecture with the MAX3221 and MAX3223 but offers higher channel density with three drivers and five receivers. The 'E' designation indicates an extended industrial temperature range compared to the 'C' commercial grade variants.

Replacement Considerations

Public confirmed substitutes include MAX3243CAI, MAX3243CUI, MAX3243EAI, and MAX3243EUI. These alternatives share identical electrical specifications and pinouts but differ in package type or operating temperature range.

FAQ

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

The device enters AutoShutdown mode if all receiver inputs remain between +0.3V and -0.3V for at least 30µs. It wakes up when any receiver input exceeds +2.7V or drops below -2.7V.

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

R2OUTB is a noninverting, always-active receiver output. It monitors receiver activity while other receivers are in a high-impedance state during shutdown, preventing forward biasing of connected UART protection diodes.

Can the MAX3243 drive serial mice directly?

Yes, the MAX3243 is specifically designed to drive serial mice. However, the AutoShutdown feature must be disabled by connecting FORCEOFF and FORCEON to VCC to ensure continuous operation.