Microchip Technology HCS412/SN

The HCS412 supports remote keyless entry designs that need both a unidirectional code-hopping transmission and a bidirectional transponder challenge-response path. Its encoder sends a 69-bit code word containing a 32-bit encrypted hopping portion and a 37-bit fixed portion. The transponder can respond to a 32-bit challenge through an inductive link. The /SN suffix identifies the 8-lead plastic SOIC package; this exact order code is the commercial-temperature option.

Microchip identifies /SN as an 8-lead plastic SOIC with a nominal 150 mil body. The site's normalized 8-SOIC registration corresponds to the existing 0.154-inch (3.90 mm) width entry. Check the manufacturer mechanical drawing and actual footprint before assembly.

Layout checks

• Confirm the 8-lead SOIC land pattern and pin-1 orientation.
• Route LC0 and LC1 to the inductive antenna network specified for the reader design.
• Keep VDD decoupling and the DATA transmitter connection consistent with the application circuit.

The normalized package registry entry and local JPG were checked. The illustration is not a dimensional drawing.

Microchip DS41099D, 8-pin SOIC pin table:

Multiplexed pin behavior depends on the selected operating and programming mode.

Electrical and timing design must follow the applicable operating-mode tables in DS41099D.

Do not substitute a different HCS device by package alone. Compare transmitted word format, learning method, key storage, challenge-response protocol, antenna interface, pinout, supply range, and temperature grade. The HCS412-I/SN uses an industrial-temperature ordering code and must be checked as a distinct part. No internal alternative is linked without a verified exact product record.

Microchip Technology publishes HCS412 datasheet DS41099D, including device operation, electrical limits, package identification, and application guidance. The /SN package and temperature interpretation above follow its product-identification table.

Check the full HCS412/SN order code, package marking, lot traceability, and programmed configuration. Validate encoder learning and transponder responses against the intended receiver and key-management process; a package match alone does not establish security compatibility.

Design the LF antenna and reader as a system. Confirm mode-specific pin multiplexing, programming sequence, key learning, code-hopping synchronization, battery-low behavior, and RF output coding against DS41099D. Protect manufacturing keys and validate the commercial-temperature requirement before release.