MAX3325EAI

Overview

The MAX3325EAI is a dual RS-232 transceiver with an integrated LCD supply and contrast controller, manufactured by Analog Devices Inc./Maxim Integrated. It operates on a single +3.0V to +3.6V supply and provides a regulated +5.0V output at up to 11mA for logic or display power. The device supports data rates up to 250kbps, compliant with EIA-232E specifications. It features a 6-bit DAC for LCD contrast adjustment, selectable positive or negative bias, and a temperature sensor for compensation. Shutdown current is typically 1µA. It is housed in a 28-pin SSOP package.

Feature Summary

• Integrates dual RS-232 transceivers with a dedicated LCD supply and contrast control circuitry
• Provides a regulated +5.0V output from a single +3.0V to +3.6V supply using small capacitors
• Includes a 6-bit digital-to-analog converter with UP/DOWN interface for precise LCD contrast adjustment
• Features internal temperature sensing to automatically compensate LCD contrast against ambient changes

Applications

• PDAs and Palmtop Computers
• Handy Terminals
• GPS Receivers
• Hand-Held Medical Equipment
• Industrial Test Equipment

Procurement Notes

Verify the component marking and pin configuration against the official datasheet before installation. Confirm that the operating voltage range matches the system requirements of +3.0V to +3.6V. Ensure appropriate decoupling capacitors are used as specified in the application circuit to maintain stability and performance.

Selection Notes

Select this component when a single-supply solution is required for both RS-232 communication and LCD bias generation. It is suitable for battery-powered devices needing low shutdown current and adjustable contrast control. Verify that the 28-pin SSOP package fits the PCB layout constraints and that the 250kbps data rate meets the communication speed requirements.

Part Context

The MAX3325 belongs to Maxim's family of 3V RS-232 transceivers designed for portable electronics. Unlike standard transceivers, it combines serial communication with power management functions specifically tailored for LCD displays. This integration reduces component count and board space in compact handheld devices requiring both data connectivity and visual output.

Replacement Considerations

MAX3325CAI

FAQ

How does the MAX3325 handle LCD contrast temperature compensation?

The device includes an internal temperature sensor (TEMP pin) that outputs a voltage varying with temperature. This signal can be connected via a resistor network to the feedback loop of the LCD regulator to automatically adjust the contrast voltage, minimizing deviation due to ambient temperature changes.

What is the maximum data rate supported by the RS-232 section?

The RS-232 transmitters and receivers support a maximum data rate of 250kbps while meeting all EIA-232E specifications under worst-case load conditions.

Can the RS-232 and LCD sections be powered down independently?

Yes, the device allows independent shutdown control. The SD232 pin disables the RS-232 transmitters, while the SDLCD pin disables the analog circuitry including the regulators, references, DAC, and temperature sensors, allowing for tailored power consumption.