MAX3320AEAP+T

Overview

The MAX3320AEAP+T is a true RS-232 transceiver integrated with a microprocessor power-on reset circuit, manufactured by Analog Devices Inc./Maxim Integrated. It operates on a single +3V to +5.5V supply and supports data rates up to 250kbps using only four small external capacitors. The device features AutoShutdown Plus technology, reducing supply current to 4µA during inactivity while keeping receivers active. It includes two drivers and two receivers in a 20-pin SSOP package. The 'E' suffix indicates an extended temperature range of -40°C to +85°C, and the 'A' suffix sets the RESET threshold at 4.25V.

Feature Summary

• Integrates a precise power-on reset supervisor that asserts an active-low signal when VCC drops below a preset threshold, remaining valid down to 1V.
• Utilizes AutoShutdown Plus functionality to achieve ultra-low 4µA supply current by automatically disabling charge pumps and transmitters after 30 seconds of inactivity.
• Employs a proprietary low-dropout transmitter output stage to ensure true RS-232 performance with minimal external components.
• Features an INVALID output pin that detects the absence of valid RS-232 signal levels on receiver inputs.

Applications

• Palmtop Computers
• Portable/Battery-Powered Equipment
• Hand-Held Equipment

Procurement Notes

Verify the complete part number against official documentation to confirm specific configuration options. The ordering suffix determines critical parameters such as the operating temperature range and the exact voltage threshold for the power-on reset function. Ensure the selected variant matches the system's supply voltage requirements and environmental constraints before procurement.

Selection Notes

Select the appropriate reset threshold suffix based on the target VCC level: 'A' for 4.25V, 'B' for 2.85V, 'L' for 4.63V, or 'T' for 3.08V. Choose the 'E' suffix variant for industrial applications requiring operation between -40°C and +85°C. Confirm that the required data rate does not exceed 250kbps and that the system can accommodate the necessary external charge-pump capacitors.

Part Context

This component belongs to the MAX3320 family of RS-232 transceivers designed for low-power serial communication. It combines standard transceiver capabilities with integrated power management features. The specific AEAP+T designation identifies the extended temperature grade, SSOP packaging, and RoHS-compliant construction within this product line.

Replacement Considerations

Direct replacements include other variants from the MAX3320 family (MAX3320BEAP+, MAX3320LEAP+) which share identical electrical characteristics but differ in reset thresholds. Cross-family alternatives like the MAX3232 series offer similar functionality but may lack the integrated power-on reset supervisor or specific shutdown current specifications.

FAQ

How does the AutoShutdown Plus feature affect receiver operation?

When AutoShutdown Plus activates due to 30 seconds of input inactivity, it shuts down the internal charge pumps and transmitters to save power. However, the receivers remain fully active and continue to monitor the RS-232 lines for incoming signals.

What is the function of the INVALID output pin?

The INVALID output asserts high if no valid RS-232 signal levels are present on any receiver input for at least 90 microseconds. This allows the system to detect cable disconnections or peripheral failures.

Can the RESET output be guaranteed valid down to 0V?

The RESET output is guaranteed valid down to VCC = 1V. Below 1V, it becomes an open circuit. To ensure validity down to 0V, an external pull-down resistor must be connected to the RESET pin.