MAX3243ECUI+T

Overview

The MAX3243ECUI+T is a +3.0V to +5.5V RS-232 transceiver featuring three drivers and five receivers in a 28-pin TSSOP package. It supports full-duplex communication with a guaranteed data rate of 120kbps and typical operation up to 235kbps. The device incorporates AutoShutdown technology, reducing supply current to 1µA when no valid signal is detected on receiver inputs for 30µs. It includes an always-active complementary receiver output (R2OUTB) for external monitoring during shutdown. ESD protection is rated at ±15kV (HBM). Operating temperature range is -40°C to +85°C.

Feature Summary

• AutoShutdown functionality reduces power consumption by disabling the onboard power supply and drivers when valid RS-232 signals are absent.
• Integrated dual charge-pump circuitry generates required voltage levels from a single low-voltage supply without external transformers.
• Complementary receiver output remains active during shutdown to monitor serial activity while other outputs are high-impedance.

Applications

• Battery-powered equipment requiring extended standby life
• Hand-held devices and portable diagnostics equipment
• Serial mouse driveability applications

Procurement Notes

Verify the specific suffix 'CUI' corresponds to the 28-pin TSSOP package and industrial temperature grade (-40°C to +85°C). Confirm that the '+T' designation indicates tape-and-reel packaging suitable for automated surface-mount assembly processes. Cross-reference the manufacturer's latest ordering guide to ensure component availability and compliance status.

Selection Notes

Select this component when interfacing CMOS logic to RS-232 ports in space-constrained designs. It is suitable for systems requiring low quiescent current during idle periods. Ensure external capacitors match the specified values for the target supply voltage to maintain stable charge-pump operation and signal integrity.

Part Context

This part belongs to the MAX3221/MAX3223/MAX3243 family of RS-232 transceivers. While sharing core features like AutoShutdown and single-supply operation, it differs from the MAX3221 (1 driver/1 receiver) and MAX3223 (2 drivers/2 receivers) by providing additional channels and a dedicated complementary receiver output for system management.

Replacement Considerations

MAX3243EAI+T: Alternative package variant (SSOP-28) with identical electrical specifications and pinout compatibility.

FAQ

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

The device enters AutoShutdown mode if no valid RS-32 signal levels are present on all receiver inputs 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 receiver output that remains active even when the main receivers are disabled during shutdown. This allows continuous monitoring of serial activity without forward-biasing connected UART protection diodes.

Can the MAX3243 directly drive a serial mouse?

Yes, the MAX3243 is specifically designed to drive serial mice. However, the AutoShutdown feature must be disabled by connecting FORCEON and FORCEOFF to VCC to prevent the transmitters from turning off during mouse operation.