DESCRIPTION
The HCS361 is a code hopping encoder designed for secure Remote Keyless Entry (RKE) systems. The HCS361 utilizes the KEELOQ code hopping technology, which incorporates high security, a small package outline and low cost, to make this device a perfect solution for unidirectional remote keyless entry systems and access control systems.
The HCS361 combines a 32-bit hopping code generated by a nonlinear encryption algorithm, with a 28/32-bit serial number and 7/3 status bits to create a 67-bit transmission stream. The length of the transmission eliminates the threat of code scanning and the code hopping mechanism makes each transmission unique, thus rendering code capture and resend (code grabbing) schemes useless.
The encryption key, serial number, and configuration data are stored in EEPROM which is not accessible via any external connection. This makes the HCS361 a very secure unit. The HCS361 provides an easy to use serial interface for programming the necessary security keys, system parameters, and configuration data.

FEATURES
Security
• Programmable 28/32-bit serial number
• Programmable 64-bit encryption key
• Each transmission is unique
• 67-bit transmission code length
• 32-bit hopping code
• 35-bit fixed code (28/32-bit serial number,
   4/0-bit function code, 1-bit status, 2-bit CRC)
• Encryption keys are read protected

Operating
• 2.0-6.6V operation
• Four button inputs
   - 15 functions available
• Selectable baud rate
• Automatic code word completion
• Battery low signal transmitted to receiver
• Nonvolatile synchronization data
• PWM and VPWM modulation

Other
• Easy to use programming interface
• On-chip EEPROM
• On-chip oscillator and timing components
• Button inputs have internal pulldown resistors
• Current limiting on LED output
• Minimum component count

Enhanced Features Over HCS300
• 48-bit seed vs. 32-bit seed
• 2-bit CRC for error detection
• 28/32-bit serial number select
• Two seed transmission methods
• PWM and VPWM modulation
• Wake-up signal in VPWM mode
• IR modulation mode

Typical Applications
The HCS361 is ideal for Remote Keyless Entry (RKE)
applications. These applications include:
• Automotive RKE systems
• Automotive alarm systems
• Automotive immobilizers
• Gate and garage door openers
• Identity tokens
• Burglar alarm systems