ADM222AN

Overview

The ADM222AN is a high-speed RS-232 line driver and receiver manufactured by Analog Devices Inc. It operates from a single +5 V power supply and utilizes an internal charge pump to generate the required bipolar voltage levels for RS-232 communication. The device features two drivers and two receivers, supporting transmission rates up to 200 kB/s. It includes a shutdown (SHDN) function that reduces quiescent current to 0.1 µA when disabled. The component is housed in an 18-lead plastic dual in-line package (N-18) and meets EIA-232-E and V.28 specifications.

Feature Summary

• Integrates on-board DC-to-DC converters using small external capacitors to generate ±9 V output swing from a single 5 V supply.
• Includes a shutdown pin that disables all transmit and receive functions to minimize power consumption.
• Features Schmitt trigger inputs on receivers to ensure noise immunity and error-free reception.
• Pin-compatible with industry-standard MAX222/MAX232A/MAX242 devices.

Applications

• Computers
• Peripherals
• Modems
• Printers
• Instruments

Procurement Notes

Verify the specific ordering suffix against the manufacturer's official documentation to confirm package type and compliance status. Ensure the procurement channel provides valid traceability for the Analog Devices part number. Confirm RoHS compliance requirements match the specific batch or revision being ordered.

Selection Notes

Select this component when a single 5 V supply is available and low power consumption during idle states is required. The integrated shutdown feature makes it suitable for battery-operated systems. Verify that the 200 kB/s data rate meets the application requirements and that the 18-lead DIP package fits the design constraints.

Part Context

The ADM222 is part of the ADM222/ADM232A/ADM242 family of CMOS RS-232 drivers and receivers. This family shares common architecture but differs in control features; the ADM222 specifically focuses on shutdown capability without an enable pin, distinguishing it from the ADM242 which adds an enable function.

Replacement Considerations

The datasheet confirms pin compatibility with MAX222, MAX232A, and MAX242. These parts may serve as direct replacements if electrical characteristics align with the system requirements.

FAQ

What is the effect of the SHDN pin on the ADM222?

When the SHDN pin is asserted, all transmitter and receiver functions are disabled, reducing the supply current to 0.1 µA.

How does the ADM222 generate RS-232 voltage levels?

It uses an internal charge pump voltage converter that requires four external 0.1 µF capacitors to generate ±10 V from the single 5 V input supply.

Are unused TTL/CMOS inputs left floating?

No, each TTL/CMOS input has an internal 400 kΩ pull-up resistor to VCC, which pulls unconnected inputs high and forces the outputs into a low state.