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 sys tems 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 crypt key, serial number and configuration data are stored in an EEPROM array which is not accessible via any external connection. The EEPROM data is programmable but read protected. The data can be verified only after an automatic erase and programming operation. This protects against attempts to gain access to keys or manipulate synchronization values. The HCS361 provides an easy-to-use serial interface for programming the necessary 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 pull-down 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