HCS201
®
KEELOQ Code Hopping Encoder
FEATURES
Security
DESCRIPTION
The HCS201 from Microchip Technology Inc. is a code
hopping encoder designed for secure Remote Keyless
Entry (RKE) systems. The HCS201 utilizes the KEELOQ
code hopping technology, incorporating high security, a
small package outline and low cost. The HCS201 is 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
• Encryption keys are read protected
PDIP, SOIC
8
7
6
5
V
DD
S0
S1
1
2
3
4
Operating
STEP
DATA
• 3.5V-13V operation
(2.0V min. using the Step up feature)
S2
VSS
• Three button inputs
V
DDB
• 7 functions available
• Selectable baud rate
• Automatic code word completion
• Battery low signal transmitted to receiver
• Non-volatile synchronization data
HCS201 BLOCK DIAGRAM
VDDB
Step Up
Controller
VDD
STEP
Other
Power
latching
and
Oscillator
• Simple programming interface
• On-chip EEPROM
Controller
switching
RESET circuit
• On-chip oscillator and timing components
• Button inputs have internal pull-down resistors
• Minimum component count
EEPROM
Encoder
• Synchronous Transmission mode
• Built-in step up regulator
DATA
32-bit shift register
Typical Applications
V
SS
Button input port
S2 S1 S0
• The HCS201 is ideal for Remote Keyless Entry
(RKE) applications. These applications include:
V
DD
• Automotive RKE systems
• Automotive alarm systems
• Automotive immobilizers
• Gate and garage door openers
• Identity tokens
The HCS201 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.
DS41098C-page 1