HCS301 Datasheet, PDF (1/20 Pages) Microchip Technology – KEELOQ CODE HOPPING ENCODER

HCS301
KEELOQ^® Code Hopping Encoder*
FEATURES
Security
• 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)
• Encryption keys are read protected
Operating
• 3.5V - 13.0V operation
• Four button inputs
- 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
Other
• Functionally identical to HCS300
• 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
• Low external component cost
Typical Applications
The HCS301 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
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 secu-
rity, a small package outline, and low cost, to make this
device a perfect solution for unidirectional remote key-
less entry systems and access control systems.
KeeLoq is a registered trademark of Microchip Technology Inc.
*Code hopping encoder patents issued for Europe, U. S. A., and R. S. A.
PACKAGE TYPES
PDIP, SOIC
S0 1
S1 2
S2 3
S3 4
8 VDD
7 LED
6 PWM
5 ^VSS
HCS301 BLOCK DIAGRAM
Oscillator
Reset circuit
Controller
LED
LED driver
Power
latching
and
switching
PWM
EEPROM
Encoder
32-bit shift register
VSS
VDD
Button input port
S₃ S₂ S₁ S₀
The HCS301 combines a 32-bit hopping code
generated by a non-linear encryption algorithm, with a
28-bit serial number and six status bits to create a
66-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 HCS301 a
very secure unit. The HCS301 provides an easy to use
serial interface for programming the necessary security
keys, system parameters, and configuration data.
The encryption keys and code combinations are pro-
grammable but read-protected. The keys can only be
verified after an automatic erase and programming
operation. This protects against attempts to gain
access to keys and manipulate synchronization values.
© 1996 Microchip Technology Inc.
Preliminary
DS21143A-page 1
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