Microchip Technology MCS3142-I/ST

The MCS3142 combines Classic KEELOQ and Ultimate KEELOQ encoding modes in one remote transmitter device. It provides four switch inputs, an RF output and configurable modulation and data formatting. Ultimate mode uses an AES-128 block cipher with a programmable 128-bit key; Classic mode uses the KEELOQ 32-bit block cipher with a programmable 64-bit key. The transmitter and trained receiver must use matching mode, keys and synchronization rules.

LCDChip records 20-TSSOP (0.173", 4.40mm Width); the normalized package name is 20-TSSOP. Microchip's product identification section confirms that the /ST suffix selects TSSOP, and its data sheet shows a 20-lead TSSOP pin diagram and package marking for MCS3142-I/ST.

Layout checks

• Check the manufacturer's 20-lead TSSOP outline and pin-one mark.
• Place supply bypassing and oscillator components to suit RF layout guidance.
• Route the RF output and antenna matching network for the selected band.

The local JPG is absent and the production package URL returns HTTP 404; keep this draft unpublished until the correct image is restored and inspected.

Microchip's 20-TSSOP pin table lists VDD on pins 1 and 8; SOSCI/SOSCO on 2/3; SW3 on 4; PGC/PGD on 5/6; pin 7 as no connection to be tied to VSS; CTRL_IN on 9; RFOUT on 10; VSS on 11 and 20; DATA_IN on 12; XTAL on 13; CTRL_OUT on 14; DATA_OUT on 15; active-low LED on 16; and SW2/SW1/SW0 on 17/18/19. Follow the detailed transmitter and programming diagrams before routing.

RF frequency, transmit current and modulation settings depend on the selected crystal, band and programmed configuration; use the complete manufacturer tables for final design.

Another remote encoder is not automatically compatible with the transmitter or learned receiver. Compare cipher mode, key and serial provisioning, code word, synchronization, RF frequency, modulation, pinout, supply and temperature grade. No internal replacement is linked without an exact API product match and manufacturer-supported equivalence.

Microchip's MCS3142 Dual KEELOQ Technology Encoder Data Sheet, DS40001747A, provides the feature list, 20-TSSOP pin description, electrical limits, package marking and exact -I/ST identification. Confirm the latest controlled revision and applicable RF approvals for the target market.

Check device marking, lot traceability and 20-TSSOP dimensions. Validate programmed keys, serial numbers, button assignments, oscillator accuracy and actual RF emissions. Test receiver learning, rolling-code synchronization and reset/failure behavior on the complete system.

Verify key-management procedures, receiver synchronization, RF band and modulation configuration, antenna matching, 20-TSSOP footprint and regulatory requirements. Restore and inspect the production JPG before formal publication.