MCS3122-I/ST

Specialized ICS Overview

The MCS3122-I/ST is a specialized encoder IC from Microchip Technology, designed for secure Remote Keyless Entry (RKE) and access control systems. It implements Advanced KeeLoq technology using the AES-128 block cipher to generate hopping codes. The device operates on a supply voltage ranging from 2.0 V to 3.7 V and features three switch inputs, one active-low LED drive, and configurable RF transmission parameters. Encoded data includes a 32-bit serial number, a 128-bit encrypted portion, and an optional 32-bit authorization check. It is housed in a 14-pin TSSOP package.

Specialized ICS Feature Summary

• Advanced KeeLoq encryption utilizing AES-128 with programmable 128-bit crypt key and 32-bit serial number
• Configurable transmitter supporting FSK/OOK modulation and PWM/Manchester encoding
• Integrated synchronization counter with dual-copy storage and checksum protection
• Three switch inputs with internal pull-ups and configurable seed transmission button combinations

Specialized ICS Applications

• Automotive Remote Keyless Entry (RKE) Systems
• Automotive Alarm Systems
• Gate and Garage Door Openers
• Home Security Systems
• Wireless Sensors and Remote Keypads

Specialized ICS Procurement Notes

Verify the specific suffix 'I' indicates industrial temperature range (-40°C to +85°C). Confirm the package type is 14-TSSOP. Ensure programming tools are compatible with the serial interface required for loading the Flash configuration data, including the crypt key and synchronization counters.

Specialized ICS Selection Notes

Select this component for unidirectional authentication requiring high security against code-grabbing attacks. The MCS3122 supports both FSK and OOK modulation, allowing flexibility in RF front-end design. Verify that the system frequency band (e.g., 315 MHz or 433.92 MHz) matches the crystal oscillator specifications required by the device configuration.

Specialized ICS Part Context

This part belongs to the Microchip MCS3122 family of Advanced KeeLoq encoders. The '-I/' designation typically denotes the industrial temperature grade and the TSSOP-14 surface-mount package variant. It serves as a cost-effective solution for replacing fixed-code transmitters in legacy systems with rolling-code security.

Specialized ICS Replacement Considerations

Direct pin-to-pin replacements within the same manufacturer's lineup may include other variants of the MCS3122 series differing only in packaging or temperature ratings. Cross-manufacturer substitution requires careful evaluation of the AES-128 implementation and RF modulation compatibility.