MICROCHIP HCS361-I/P

The HCS361 is an encoder designed specifically for secure Remote Keyless Entry (RKE) systems. The HCS361 utilizes KEELOQ hopping code technology, which combines high security, small package size, and low cost, making it an ideal solution for one-way RKE and access control systems.

The HCS361 creates a 67-bit transmission stream by combining a 32-bit hopping code generated by a nonlinear encryption algorithm with a 28/32-bit serial number and 7/3 status bits. The key, serial number, and configuration data are stored in an EEPROM array that cannot be accessed through any external connection. EEPROM data is programmable but read-protected. Data can only be verified after an auto-erase and programming operation is performed, preventing attempts to retrieve the key or manipulate synchronization values. The HCS361 provides an easy-to-use serial interface for programming the necessary keys, system parameters, and configuration data.

The HCS361 encoder is particularly suited for keyless entry systems, primarily used in vehicles and home garage door openers. The encoding portion of a keyless entry system is integrated into a transmitter that the user carries and operates to gain access to a vehicle or restricted area. The HCS361 is designed to be a cost-effective and secure solution requiring minimal external components.

Most low-end keyless entry transmitters are assigned a fixed identification code that is transmitted identically with each button press. The number of unique identification codes in low-end systems is typically relatively small. These shortcomings provide opportunities for technically sophisticated thieves to create devices that "grab" a transmitted signal and retransmit it later, or rapidly "scan" through all possible identification codes until the correct one is found.

In contrast, the HCS361 employs KEELOQ hopping code technology combined with a 66-bit transmission length, virtually eliminating the possibility of using "grabbed" or "scanned" codes. The high security of the HCS361 is based on the patented KEELOQ technology. It uses a block cipher based on a 32-bit block length and a 64-bit key length. The algorithm scrambles information in such a way that even if the transmission information (before encoding) differs by only one bit compared to the previous transmission, the next encoded transmission will be completely different. Statistically, if only one bit changes in a 32-bit information string, more than 50% of the encoded transmission bits will change.

• Automotive remote keyless entry systems
• Automotive alarm systems
• Automotive immobilizers
• Door and garage door openers
• Identity tokens
• Burglar alarm systems