HCS301
®
KEELOQ Code Hopping Encoder
FEATURES
Security
DESCRIPTION
The HCS301 from Microchip Technology Inc. is a code
hopping encoder designed for secure Remote Keyless
Entry (RKE) systems. The HCS301 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.
• Programmable 28-bit serial number
• Programmable 64-bit encryption key
• Each transmission is unique
• 66-bit transmission code length
• 32-bit hopping code
• 34-bit fixed code (28-bit serial number,
4-bit button code, 2-bit status)
PACKAGE TYPES
PDIP, SOIC
• Encryption keys are read protected
8
7
6
5
VDD
S0
S1
1
2
3
4
Operating
LED
PWM
VSS
• 3.5V - 13.0V operation
• Four button inputs
S2
S3
• No additional circuitry required
• 15 functions available
• Selectable baud rate
• Automatic code word completion
• Battery low signal transmitted to receiver
• Battery low indication on LED
• Non-volatile synchronization data
HCS301 BLOCK DIAGRAM
Oscillator
Power
latching
and
Controller
RESET circuit
switching
LED
Other
LED driver
• Functionally identical to HCS300
• Easy-to-use programming interface
• On-chip EEPROM
EEPROM
Encoder
• On-chip oscillator and timing components
• Button inputs have internal pull-down resistors
• Current limiting on LED output
• Low external component cost
PWM
32-bit shift register
Button input port
VSS
VDD
Typical Applications
The HCS301 is ideal for Remote Keyless Entry (RKE)
applications. These applications include:
S2
S3
S1 S0
• Automotive RKE systems
• Automotive alarm systems
• Automotive immobilizers
• Gate and garage door openers
• Identity tokens
The HCS301 combines a 32-bit hopping code,
generated by a nonlinear encryption algorithm, with a
28-bit serial number and 6 information bits to create a
66-bit code word. The code word length eliminates the
threat of code scanning and the code hopping mecha-
nism makes each transmission unique, thus rendering
code capture and resend schemes useless.
• Burglar alarm systems
2001 Microchip Technology Inc.
DS21143B-page 1