HCS300
Code Hopping Encoder*
FEATURES
PACKAGE TYPES
PDIP, SOIC
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
8
7
6
5
VDD
LED
PWM
VSS
S0
S1
1
2
3
4
S2
S3
Operating
HCS300 BLOCK DIAGRAM
• 2.0—6.3V operation
• Four button inputs
- No additional circuitry required
- 15 functions available
Oscillator
Power
latching
and
Controller
Reset circuit
switching
LED
• Selectable baud rate
LED driver
• Automatic code word completion
• Battery low signal transmitted to receiver
• Non-volatile synchronization data
EEPROM
Encoder
Other
• Easy to use programming interface
• On-chip EEPROM
PWM
32-bit shift register
• On-chip oscillator and timing components
• Button inputs have internal pulldown resistors
• Current limiting on LED output
• Minimum component count
VSS
Button input port
VDD
• Synchronous transmission mode
Typical Applications
S2
S3
S1 S0
The HCS300 is ideal for Remote Keyless Entry (RKE)
applications. These applications include:
The HCS300 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.
• Automotive RKE systems
• Automotive alarm systems
• Automotive immobilizers
• Gate and garage door openers
• Identity tokens
• Burglar alarm systems
The encryption key, serial number, and configuration
data are stored in EEPROM which is not accessible via
any external connection. This makes the HCS300 a
very secure unit. The HCS300 provides an easy to use
serial interface for programming the necessary security
keys, system parameters, and configuration data.
DESCRIPTION
The HCS300, from Microchip Technology Inc., is a code
hopping encoder designed for secure Remote Keyless
Entry (RKE) systems. The HCS300 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.
The encyrption 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.
KeeLoq is a trademark of Microchip Technology Inc.
*Code hopping encoder patents allowed and pending.
1996 Microchip Technology Inc.
Preliminary
DS21137D-page 1
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