rfHCS362F

Application

• Automotive Remote Keyless Entry (RKE) systems
• Automotive alarm systems
• Automotive immobilizers
• Community gate and garage door openers
• Identity tokens with usage counters
• Burglar alarm systems
• Building access


Description

The rfHCS362G/362F is a code hopping encoder plus UHF transmitter designed for secure wireless command and control systems. The rfHCS362G/362F utilizes the KEELOQ® code hopping technology which incorporates high security in a small package outline a low cost to make this device well suited for unidirectional remote keyless entry systems and access control systems. The rfHCS362G/362F combines a 32-bit hopping code generated by a nonlinear encryption algorithm with 28/32-bit serial number and 9/5 status bits to create 69-bit transmission stream.

The length of the rfHCS362G/362F transmission strongly resists the threat of code scanning. The code hopping mechanism makes each transmission unique, thus rendering code capture and resend (code grabbing) schemes virtually useless. The encryption 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 rfHCS362G/362F provides an easy to use serial interface for programming the necessary keys, system parameters and configuration data. The transmitter is a fully integrated UHF ASK/FSK transmitter consisting of crystal oscillator, Phase- Locked Loop (PLL), open-collector differential-output Power Amplifier (PA), and mode control logic. External components consist of bypass capacitors, crystal, and PLL loop filter. There are no internal electrical connections between the encoder and the transmitter. The encoder oscillator is independent from the transmitter crystal oscillator. The rfHCS362G is capable of Amplitude Shift Keying (ASK) modulation by turning the PA on and off. The rfHCS362F is capable of ASK or Frequency Shift Keying (FSK) modulation by employing an internal FSK switch to pull the transmitter crystal via a second load capacitor.