ADM1181AARW

Overview

The ADM1181AARW is a robust, high-speed, dual-channel RS-232/V.28 interface transceiver manufactured by Analog Devices Inc. Operating from a single 5 V power supply (4.5 V to 5.5 V), it integrates internal charge-pump circuitry to generate the necessary positive and negative voltages for RS-232 signaling without external transformers. The device supports data rates up to 230 kbps with low power consumption of 6 mA typical no-load current. It features ±15 kV ESD protection on all I/O lines, ensuring compliance with IEC1000-4-2 standards, and includes internal 5 kΩ pull-down resistors on receiver inputs. Packaged in a 16-lead SOIC, it serves as an upgrade for legacy MAX202E and LT1181A designs.

Feature Summary

• Compliant with EU EMC directive 89/336/EEC, featuring low electromagnetic emissions and high immunity to fast transient bursts.
• Integrated charge-pump voltage converter eliminates the need for external transformers or multiple power supplies.
• Robust input/output protection against electrostatic discharge up to ±15 kV and electrical fast transients.
• Schmitt-trigger receivers provide noise immunity and error-free reception for signals with slow transition times.

Applications

• General-purpose RS-232 data links
• Portable instruments requiring low power consumption
• Personal Digital Assistants (PDAs)
• ISDN modem interfaces

Procurement Notes

Verify the specific package suffix 'ARW' corresponds to the 16-lead Wide SOIC format when sourcing. Confirm that the ordering part number matches the exact revision required for your design, as Analog Devices may update specifications without notice. Ensure compatibility with existing PCB footprints if replacing older generation transceivers like the MAX202E.

Selection Notes

Select this component for applications requiring pin-compatible upgrades to standard RS-232 drivers while demanding enhanced ESD protection. It is suitable for environments with frequent cable plugging/unplugging or harsh electrical conditions. Consider the 230 kbps maximum data rate and single-supply operation when designing power budgets for portable devices.

Part Context

The ADM1181A is part of the ADM202E/ADM1181A family, designed as a ruggedized enhancement to earlier RS-232 transceivers. It offers improved electromagnetic compatibility compared to traditional charge-pump devices. The device is functionally similar to the ADM202E but optimized for specific packaging and performance characteristics within the Analog Devices interface portfolio.

Replacement Considerations

The datasheet identifies the ADM1181A as a direct pin-compatible upgrade for the LTC1181A. It also serves as a modification for circuits originally using MAX202E or MAX232E sockets, though verification of specific operating conditions is recommended.

FAQ

What is the purpose of the internal 5 kΩ pull-down resistors?

The internal 5 kΩ pull-down resistors on each RS-232 receiver input ensure that unconnected inputs are pulled to ground, resulting in a Logic 1 output level and preventing floating input states.

How does the device achieve EMC compliance?

The ADM1181A achieves EMC compliance through controlled slew rates on transmitter outputs to minimize radiated emissions and integrated protection structures that handle ESD and fast transients, meeting EN55022 and IEC1000-4 standards.

Can larger capacitors be used for the charge pump?

Yes, while 0.1 µF capacitors are recommended for C1 through C4, larger capacitors up to 47 µF can be used to facilitate direct substitution with older generation charge-pump RS-232 transceivers.