© 1996 Microchip Technology Inc.

Preliminary

DS40146C-page 1

M

FEATURES

Security

• Programmable 28/32-bit serial number

• Programmable 64-bit encryption key

• Each transmission is unique

• 67-bit transmission code length

• 32-bit hopping code

• 35-bit fixed code (28/32-bit serial number,

4/0-bit function code, 1-bit status, 2-bit CRC)

• Encryption keys are read protected

Operating

• 2.0-6.6V operation

• Four button inputs

- 15 functions available

• Selectable baud rate

• Automatic code word completion

• Battery low signal transmitted to receiver

• Nonvolatile synchronization data

• PWM and VPWM modulation

Other

• 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

• Minimum component count

Enhanced Features Over HCS300

• 48-bit seed vs. 32-bit seed

• 2-bit CRC for error detection

• 28/32-bit serial number select

• Two seed transmission methods

• PWM and VPWM modulation

• Wake-up signal in VPWM mode

• IR modulation mode

Typical Applications

The HCS361 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

PACKAGE TYPES

HCS361 BLOCK DIAGRAM

DESCRIPTION

The HCS361 is a code hopping encoder designed for

secure Remote Keyless Entry (RKE) systems. The

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.

The HCS361 combines a 32-bit hopping code

generated by a nonlinear encryption algorithm, with a

28/32-bit serial number and 7/3 status bits to create a

67-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.

1

2

3

4

8

7

6

5

S0

S1

S2

S3

LED

PWM

PDIP, SOIC

Oscillator

Reset circuit

LED driver

Controller

Power

latching

and

switching

Button input port

32-bit shift register

Encoder

EEPROM

PWM

LED

*Code hopping encoder patents issued in Europe, U. S. A., R. S. A. — US: 5,517,187; Europe: 0459781

HCS361

Code Hopping Encoder*