© 1996 Microchip Technology Inc.

Preliminary

DS40138A-page 1

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

• 28-bit serial number, 4-bit function code,

• Encryption keys are read protected

Operating

• 3.5–13.0V operation

• Three button inputs

- seven functions available

• Selectable baud rate

• Automatic code word completion

• Battery low signal transmitted to receiver

• Non-volatile synchronization data

Other

• Easy to use programming interface

• On-chip EEPROM

• On-chip oscillator and timing components

• Button inputs have internal pulldown resistors

• Low external component cost

Typical Applications

The HCS200 is ideal for Remote Keyless Entry (RKE)

applications. These applications include:

• Fixed code replacement

• Automotive RKE systems

• Automotive alarm systems

• Automotive immobilizers

• Gate and garage door openers

• Identity tokens

• Burglar alarm systems

DESCRIPTION

The HCS200, from Microchip Technology Inc., is a code

hopping encoder designed for Remote Keyless Entry

(RKE) systems. The HCS200 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 replacement of fixed code devices

in unidirectional remote keyless entry systems and

access control systems.

PACKAGE TYPES

BLOCK DIAGRAM

The HCS200 combines a 32-bit hopping code

generated by a non-linear encryption algorithm, with a

28-bit serial number and 6 information 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 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 HCS200 a

very secure unit. The HCS200 provides an easy to use

serial interface for programming the necessary security

keys, system parameters, and configuration data.

All 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.

1

2

3

4

8

7

6

5

S0

S1

S2

PWM

PDIP, SOIC

NC

NC

Vss

Oscillator

Reset circuit

Controller

Power

latching

and

switching

Button input port

32-bit shift register

Encoder

EEPROM

PWM

S2 S1 S0

HCS200

KeeLoq is a trademark of Microchip Technology Inc.

*Code hopping encoder patents issued in Europe, U. S. A., and R. S. A.

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