MAX3244CAI+T

Overview

The MAX3244CAI+T is a true RS-232 transceiver manufactured by Analog Devices Inc./Maxim Integrated, housed in a 28-pin SSOP package. It operates on a single +3.0V to +5.5V supply and features three drivers and five receivers for full-duplex communication. The device guarantees a maximum data rate of 250kbps and achieves a typical supply current of 1µA through AutoShutdown Plus technology. It includes an internal dual charge pump requiring four small capacitors, provides ±15kV ESD protection on I/O pins, and offers a READY output signal indicating charge pump regulation status.

Feature Summary

• AutoShutdown Plus functionality automatically reduces supply current to 1µA when the interface is idle or disconnected, waking up upon valid signal transitions without BIOS modifications.
• Integrated dual charge pump generates required RS-232 voltage levels from low-voltage supplies using minimal external capacitance.
• Dedicated R2OUTB pin provides an always-active noninverting receiver output to monitor ring indicator signals during shutdown states.

Applications

• Notebook, subnotebook, and palmtop computers
• Cellular phones and handheld equipment
• Battery-powered peripherals and printers

Procurement Notes

Verify the specific suffix 'CAI+T' against official documentation to confirm the commercial temperature range, SSOP-28 packaging, and tape-and-reel delivery format. Ensure compatibility with system power requirements and check for lead-free/RoHS compliance markings as indicated by the plus sign.

Selection Notes

Select this component for applications requiring low-power standby modes and high noise immunity. The MAX3244 variant is appropriate where 250kbps throughput suffices; choose the MAX3245 if 1Mbps operation is necessary. Verify that the 28-pin SSOP footprint fits the PCB layout constraints.

Part Context

This part belongs to the MAX3224–MAX3227/MAX3244/MAX3245 family of 1µA RS-232 transceivers. It shares core architecture with the MAX3245 but differs in guaranteed data rate specifications. The CAI designation indicates the commercial temperature range and SSOP package type within the Maxim Integrated product line.

Replacement Considerations

Public confirmed substitutes include MAX3244EEAI+T (extended temperature) and MAX3244CAP+T (different package). Cross-reference electrical characteristics and pinouts before implementation.

FAQ

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

The device enters shutdown mode when no valid signal transition is detected on any receiver or transmitter input for more than 30 seconds, typically due to cable disconnection or peripheral inactivity.

What is the function of the INVALID output pin?

The INVALID output goes low when no valid RS-232 voltage levels are detected on all receiver inputs, indicating the absence of a valid signal regardless of the FORCEON/FORCEOFF states.

Why is the R2OUTB pin included in the MAX3244 design?

R2OUTB is an always-active noninverting output that allows monitoring of receiver activity, such as Ring Indicator signals, even when other receiver outputs are in a high-impedance shutdown state.