KEELOQ® Code Hopping Encoder* Security Programmable 28-bit s

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KEELOQ® Code Hopping Encoder* Security Programmable 28-bit s

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HCS200
KEELOQ® Code Hopping Encoder*
Security
Programmable 28-bit serial number Programmable 64-bit encryption Each transmission unique 66-bit transmission code length 32-bit hopping code 28-bit serial number, 4-bit function code, VLOW indicator transmitted Encryption keys read protected
PACKAGE TYPES
PDIP, SOIC HCS200
Operating
3.5-13.0V operation Three button inputs seven functions available Selectable baud rate Automatic code word completion Battery signal transmitted receiver Non-volatile synchronization data
BLOCK DIAGRAM
Oscillator Reset circuit Controller Power latching switching
Other
Easy programming interface On-chip EEPROM On-chip oscillator timing components Button inputs have internal pulldown resistors external component cost
EEPROM
Encoder
32-bit shift register
Button input port
Typical Applications
HCS200 ideal Remote Keyless Entry (RKE) applications. These applications include: Fixed code replacement Automotive systems Automotive alarm systems Automotive immobilizers Gate garage door openers Identity tokens Burglar alarm systems
HCS200 combines 32-bit hopping code generated non-linear encryption algorithm, with 28-bit serial number information bits create 66-bit transmission stream. length transmission eliminates threat code scanning, code hopping mechanism makes each transmission unique, thus rendering code capture resend schemes useless. encryption key, serial number, configuration data stored EEPROM which accessible external connection. This makes HCS200 very secure unit. HCS200 provides easy serial interface programming necessary security keys, system parameters, configuration data. encryption keys code combinations programmable read-protected. keys only verified after automatic erase programming operation. This protects against attempts gain access keys manipulate synchronization values.
DESCRIPTION
HCS200, from Microchip Technology Inc., code hopping encoder designed Remote Keyless Entry (RKE) systems. HCS200 utilizes Keeloq® code hopping technology, which incorporates high security, small package outline cost, make this device perfect solution replacement fixed code devices unidirectional remote keyless entry systems access control systems.
KeeLoq trademark Microchip Technology Inc. *Code hopping encoder patents issued Europe,
1996 Microchip Technology Inc.
Preliminary
This document created with FrameMaker
DS40138A-page
HCS200
HCS200 operates over wide voltage range volts 13.0 volts three button inputs 8-pin configuration. This allows system designer freedom utilize seven functions. only components required device operation buttons circuitry, allowing very system cost. system meant carried user operated gain access vehicle restricted area. HCS200 requires very external components (Figure 2-1). Most low-end keyless entry systems transmit same code from transmitter every time button pushed. number possible code combinations system also relatively small number. These shortcomings provide means sophisticated thief create device that `grabs' transmission re-transmits later, device that scans possible combinations until correct found. HCS200 employs KEELOQ code hopping encryption algorithm achieve high level security. Code hopping method which code transmitted from transmitter receiver different every time button pushed. This method, coupled with transmission length bits, virtually eliminates code `grabbing' code `scanning'. indicated block diagram page one, HCS200 small EEPROM array which must loaded with several parameters before use. most important these values are: 28-bit serial number which meant unique every encoder 16-bit configuration value encryption that generated time production 16-bit synchronization value serial number each transmitter programmed manufacturer time production. generation encryption done using generation algorithm (Figure 1-1). Typically, inputs generation algorithm serial number transmitter 64-bit manufacturer's code. manufacturer's code chosen system manufacturer must carefully controlled. manufacturer's code pivotal part overall system security.
SYSTEM OVERVIEW
Terms
Manufacturer's code 64-bit word, unique each manufacturer, used produce unique encryption each transmitter (encoder). Encryption unique 64-bit generated programmed into encoder during manufacturing process. encryption controls encryption algorithm stored EEPROM encoder device.
Learn
product family facilitates several learn strategies implemented decoder. following examples what done. must pointed that their exists some third-party patents learning strategies implementation. 1.1.1 NORMAL LEARN
receiver uses same information that transmitted during normal operation derive transmitter's secret key, decrypt discrimination value synchronization counter. 1.1.2 SECURE LEARN*
transmitter activated through special button combination transmit stored 48-bit value (random seed) that used generation part key. Transmission random seed disabled after learning completed. HCS200 code hopping encoder device that designed specifically keyless entry systems, primarily vehicles home garage door openers. meant cost-effective, secure solution such systems. encoder portion keyless entry
FIGURE 1-1:
CREATION STORAGE ENCRYPTION DURING PRODUCTION
HCS200 EEPROM Array
Serial Number Encryption Sync Counter
Transmitter Serial Number
Manufacturer's Code
Generation Algorithm
Encryption
Code Hopping learn patents pending.
DS40138A-page
Preliminary
1996 Microchip Technology Inc.
HCS200
16-bit synchronization value basis transmitted code changing each transmission, updated each time button pressed. Because complexity code hopping algorithm, change synchronization value will result large change actual transmitted code. There relationship (Figure 1-2) between values EEPROM they used encoder. Once encoder detects that button been pressed, encoder reads button updates synchronization counter. synchronization value then combined with encryption encryption algorithm output bits encrypted information. This data will change with every button press, hence, referred hopping portion code word. 32-bit hopping code combined with button information serial number form code word transmitted receiver. code word format explained detail Section 4.3. type controller used receiver, typically microcontroller with compatible firmware that allows receiver operate conjunction with transmitter based HCS200. Section provides more detail integrating HCS200 into total system. Before transmitter used with particular receiver, transmitter must `learned' receiver. Upon learning transmitter, information stored receiver that track transmitter, including serial number transmitter, current synchronization value that transmitter, same encryption that used transmitter. receiver receives message valid format, serial number checked, and, from learned transmitter, message decrypted, decrypted synchronization counter checked against what stored. synchronization value verified, then button status checked what operation needed. Figure shows relationship between some values stored receiver values received from transmitter.
FIGURE 1-2:
BASIC OPERATION TRANSMITTER (ENCODER)
Transmitted Information KeeLoq Encryption Algorithm Bits Encrypted Data Serial Number Button Press Information
EEPROM Array Encryption Sync Counter Serial Number
FIGURE 1-3:
BASIC OPERATION RECEIVER (DECODER)
Check Match EEPROM Array Encryption Sync Counter Serial Number Manufacturer Code Check Match KEELOQ Decryption Algorithm Decrypted Synchronization Counter
Button Press Information
Serial Number
Bits Encrypted Data
Received Information
1996 Microchip Technology Inc.
Preliminary
DS40138A-page
HCS200
DEVICE OPERATION
shown Figure 2-1, HCS200 simple device use. requires only addition buttons circuitry transmitter your security application. description each described Table 2-1.
Note: When 9.0V driving capacitive loads, resistor with minimum value should used line with VDD. This prevents clamping 9.0V event overshoot. high security level HCS200 based patented KEELOQ technology. block cipher based block length bits length bits used. algorithm obscures information such that even transmission information (before coding) differs only from information previous transmission, next coded transmission will totally different. Statistically, only 32-bit string information changes, approximately percent coded transmission will change. HCS200 will wake upon detecting switch closure then delay approximately switch debounce (Figure 2-2). synchronization information, fixed information, switch information will encrypted form hopping code. encrypted hopping code portion transmission will change every time, even same button pushed again. code that been transmitted will occur again more than transmissions. This will provide more than years typical before code repeated based operations day. Overflow information sent from encoder used decoder extend number unique transmissions more than 192K. transmit process detected that button(s) been pressed, reset will immediately forced
FIGURE 2-1:
+12V (Note
TYPICAL CIRCUITS
code word will completed. Please note that buttons removed will have effect code word
unless buttons remain pressed which case code word will completed power down will occur.
button remote control
+12V (Note
FIGURE 2-2:
ENCODER OPERATION
button been pressed)
Power
Reset Debounce Delay
Sample Inputs Update Sync Info Encrypt With Encryption Load Transmit Register
button remote control (Note) Note functions implemented pressing more than button simultaneously using suitable diode array. Resistor recommended current limiting.
TABLE 2-1:
Name Number
DESCRIPTIONS
Transmit Description Switch input Switch input Switch input 2/Clock when programming mode Ground reference connection Pulse width modulation (PWM) output pin/Data programming mode Positive supply voltage connection Buttons Added Buttons Released Complete Code Word Transmission Stop
DS40138A-page
Preliminary
1996 Microchip Technology Inc.
HCS200
EEPROM MEMORY ORGANIZATION
SER_0, SER_1 (Encoder Serial Number)
HCS200 contains bits 16-bit words) EEPROM memory (Table 3-1). This EEPROM array used store encryption information, synchronization value, etc. Further descriptions memory array given following sections.
SER_0 SER_1 lower upper words device serial number, respectively. Although there bits allocated serial number, only lower order bits transmitted. serial number meant unique every transmitter.
TABLE 3-1:
WORD ADDRESS
EEPROM MEMORY
MNEMONIC KEY_0 KEY_1 KEY_2 KEY_3 SYNC Reserved SER_0 SER_1 SEED_0 SEED_1 Reserved CONFIG DESCRIPTION 64-bit encryption (word 64-bit encryption (word 64-bit encryption (word 64-bit encryption (word 16-bit synchronization value 0000H Device Serial Number (word Device Serial Number (word Seed Value (word Seed Value (word 0000H Config Word
SEED_0, SEED_1 (Seed Word)
This 2-word (32-bit) seed code that will transmitted when three buttons pressed same time. This allows system designer implement secure learn feature this fixed code word part different generation/tracking process.
Configuration Word
configuration word 16-bit word stored EEPROM array that used device store information used during encryption process, well status option configurations. Further explanations each bits described following sections.
TABLE 3-2:
Number 3.6.1
CONFIGURATION WORD
Description Discrimination Discrimination Discrimination Discrimination Discrimination Discrimination Discrimination Discrimination Discrimination Discrimination Discrimination Discrimination Voltage Trip Point Select (VLOW SEL) Baudrate Select (BSL0) Reserved Reserved
Key_0 Key_3 (64-Bit Encryption Key)
64-bit encryption used transmitter create encrypted message transmitted receiver. This created programmed time production using generation algorithm. generation algorithm different from KEELOQ algorithm. Inputs generation algorithm serial number particular transmitter being used 64-bit manufacturer's code. While generation algorithm supplied from Microchip typical method used, user elect create their method generation. This done providing that decoder programmed with same means creating decryption purposes.
DISCRIMINATION VALUE (DISC0 DISC11)
SYNC (Synchronization Counter)
This 16-bit synchronization value that used create hopping code transmission. This value will changed after every transmission.
Reserved
Must initialized 0000H.
Bits should zero. discrimination value programmed with value serve post decryption check decoder end. typical system, this will programmed with least significant bits serial number constant value, which will also stored receiver system after transmitter been learned. discrimination bits part information that form encrypted portion transmission. After receiver decrypted transmission, discrimination bits checked against stored value verify that decryption process valid.
1996 Microchip Technology Inc.
Preliminary
DS40138A-page
HCS200
3.6.2 BAUD RATE SELECT BITS (BSL0)
TRANSMITTED WORD
Transmission Format
BSL0 selects speed transmission code word blanking. Table shows bits used select different baud rates Section provides detailed explanation code word blanking.
TABLE 3-3:
BSL0 3.6.3
BAUD RATE SELECT
Basic Pulse Element Code Words Transmitted
VOLTAGE TRIP POINT SELECT
voltage trip point select used tell HCS200 what level being used. This information will used device determine when send voltage signal receiver. When this one, level assumed operating from volt 12.0 volt level. low, then level assumed volts. Refer Figure voltage trip point. VLOW tested 3.5V 13.0V.
HCS200 transmission made several parts (Figure 4-1). Each transmission begins with preamble header, followed encrypted then fixed data. actual data bits which consists bits encrypted data bits fixed data. Each transmission followed guard period before another transmission begin. Refer Table transmission timing requirements. encrypted portion provides four billion changing code combinations includes button status bits (based which buttons were activated) along with synchronization counter value some discrimination bits. fixed portion comprised status bits, function bits, 28-bit serial number. fixed encrypted sections combined increase number combinations 7.38 1019.
Synchronous Transmission Mode
Synchronous transmission mode used clock code word using external clock. enter synchronous transmission mode, programming mode start-up sequence must executed shown Figure 4-3. either falling edge device enters synchronous transmission mode. this mode, functions normal transmitter, with exception that timing data string controlled externally that extra bits transmitted with code word. button code will value falling edge timing data string controlled supplying clock should exceed kHz. code word same mode with reserved bits word. reserved bits ignored. When synchronous transmission mode should toggled until internal processing been completed shown Figure 4-3.
FIGURE 3-1:
Volts
VOLTAGE TRIP POINTS CHARACTERIZATION
VLOW
VLOW
VLOW
Code Word Organization
HCS200 transmits 66-bit code word when button pressed. 66-bit word constructed from Fixed Code portion Encrypted Code portion (Figure 4-2). Encrypted Data generated from button bits, discrimination bits, 16-bit sync value (Figure 4-2). Fixed Code Data made from status bit, fixed bit, button bits, 28-bit serial number.
Temp
DS40138A-page
Preliminary
1996 Microchip Technology Inc.
HCS200
FIGURE 4-1: CODE WORD TRANSMISSION FORMAT
LOGIC LOGIC Period Preamble Header Encrypted Portion Transmission THOP Fixed Portion Transmission TFIX Guard Time
FIGURE 4-2:
CODE WORD ORGANIZATION
Fixed Code Data Encrypted Code Data Button Status bits) Discrimination bits bits) 16-bit Sync Value
Fixed bit)
VLOW bit)
Button Status bits)
28-bit Serial Number
Status Fixed
Serial Number Button Status bits)
bits Encrypted Data
bits Data Transmitted
FIGURE 4-3:
SYNCHRONOUS TRANSMISSION MODE
S[1:0]
"01,10,11"
FIGURE 4-4:
Reserved
TRANSMISSION WORD FORMAT DURING SYNCHRONOUS TRANSMISSION MODE
Padding Function Code Serial Number Data Word Sync Counter
Transmission Direction
1996 Microchip Technology Inc.
Preliminary
DS40138A-page
HCS200
SPECIAL Code Word Completion
Code word completion automatic feature that makes sure that entire code word transmitted, even button released before transmission complete. HCS200 encoder powers itself when button pushed powers itself down after command finished, user already released button. button held down beyond time transmission, then multiple transmissions will result. another button activated during transmission, active transmission will aborted code will generated using button information.
power that transmitted device, BACW effectively prevents continuous transmission only allowing transmission every second word. This reduces average power transmitted hence, assists approval transmitter device.
Seed Transmission
order increase level security system, possible receiver implement what known secure learn function. This done utilizing seed value HCS200 which stored EEPROM only transmitted when three button inputs pressed same time (Table 5-1). Instead normal generation method being used create encryption key, this seed value used.
Blank Alternate Code Word
VLOW: Voltage indicator
Federal Communications Commission (FCC) part rules specify limits fundamental power harmonics that transmitted. Power calculated worst case average power transmitted window. therefore advantageous minimize duty cycle transmitted word. This achieved minimizing duty cycle individual bits blanking consecutive words. Blank Alternate Code Word (BACW) used reducing average power transmission (Figure 5-1). This selectable feature that determined conjunction with baud rate selection BSL0. Using BACW allows user transmit higher amplitude transmission transmission length shorter. puts constraints aver-
VLOW transmitted with every transmission (Figure Figure 8-5) will transmitted zero operating voltage above voltage trip point. VLOW signal transmitted receiver give indication user that transmitter battery low.
FIGURE 5-1:
BLANK ALTERNATE CODE WORD (BACW)
Amplitude 100ms 100ms Code Word 100ms 100ms
BACW Disabled (All words transmitted)
BACW Enabled transmitted)
TABLE 5-1:
ACTIVATION TABLE
External Internal
Standby after
Fixed
DS40138A-page
Preliminary
1996 Microchip Technology Inc.
HCS200
PROGRAMMING HCS200
When using HCS200 system, user will have program some parameters into device including serial number secret before used. programming cycle allows user input bits serial data stream, which then stored internally EEPROM. Programming will initiated forcing line high, after line been held high appropriate length time line (Table Figure 6-1). After program mode entered, delay must provided device automatic bulk write cycle complete. This will write locations EEPROM zeros pattern. device then programmed clocking bits time, using clock line data line. Data clocked falling edge After each 16-bit word loaded, programming delay required internal program cycle complete. programming cycle, device verified (Figure 6-2) reading back EEPROM. Reading done clocking line reading data bits PWM. Falling edge initiated reading. security reasons, possible execute verify function without first programming EEPROM. verify operation only done immediately following program cycle. Note: ensure that device does accidentally enter programming mode (resulting bulk erase), should never pulled high circuit connected Special care should taken when driving transistors.
TABLE 6-1:
PROGRAMMING/VERIFY TIMING REQUIREMENTS
Symbol TPH1 TPH2 TPBW TPROG TCLKL TCLKH Min. Max.
5.0V 10%, 25°C Parameter Program mode setup time Hold time Hold time Bulk Write time Program delay time Program cycle time Clock time Clock high time Data setup time Data hold time Data valid time
Units
FIGURE 6-1:
PROGRAMMING WAVEFORMS
TPBW TCLKH
Enter Program Mode
(Clock) TPH1 (Data) TPH2 TCLKL
Data Word (KEY_0) Repeat each word times)
Data Word
Note Unused button inputs held ground during entire programming sequence. must taken ground after program/verify cycle.
FIGURE 6-2:
VERIFY WAVEFORMS
Data Word
Bit190 Bit191
Begin Verify Cycle Here Programming Cycle (Data) (Clock) Note:
Bit190 Bit191
verify operation done, then must immediately follow program cycle.
1996 Microchip Technology Inc.
Preliminary
DS40138A-page
HCS200
INTEGRATING HCS200 INTO SYSTEM
FIGURE 7-1: TYPICAL LEARN SEQUENCE
Enter Learn Mode Wait Reception Valid Code Generate from Serial Number Generated Decrypt Compare Discrimination Value with Fixed Value
HCS200 system requires compatible decoder. This decoder typically microcontroller with compatible firmware. Microchip will provide (via license agreement) firmware routines that accept transmissions from HCS200 decrypt hopping code portion data stream. These routines provide system designers means develop their decoding system.
Learning transmitter receiver
order transmitter used with decoder, transmitter must first `learned'. Several learning strategies followed decoder implementation. When transmitter learned decoder, suggested that decoder stores serial number current synchronization value EEPROM. decoder must keep track these values every transmitter that learned (Figure 7-1). maximum number transmitters that learned only function much EEPROM memory storage available. decoder must also store manufacturer's code order learn transmission transmitter, although this value will change typical system usually stored part microcontroller code. Storing manufacturer's code part code also better security reasons. must stated that some learning strategies have been patented care must taken infringe.
Equal
Wait Reception Second Valid Code Generated Decrypt Compare Discrimination Value with Fixed Value
Equal Counters Sequential
Learn successful. Store: Serial number Encryption Synchronization counter
Learn Unsuccessful
Exit
DS40138A-page
Preliminary
1996 Microchip Technology Inc.
HCS200
Decoder operation Synchronization with Decoder
typical decoder operation (Figure 7-2), generation decoder side done taking serial number from transmission combining that with manufacturer's code create same secret that used transmitter. Once secret obtained, rest transmission decrypted. decoder waits transmission immediately check serial number determine learned transmitter. takes encrypted portion transmission decrypts using stored uses discrimination bits determine decryption valid. everything this point valid, synchronization value evaluated. KEELOQ technology features sophisticated synchronization technique (Figure 7-3) which does require calculation storage future codes. stored counter value that particular transmitter counter value that just decrypted within formatted window counter stored command executed. counter value within single operation window, within double operation window window, transmitted synchronization value stored temporary location goes back waiting another transmission. When next valid transmission received, will check value with temporary storage. values sequential, assumed that counter just gotten single operation `window', back sync, synchronization value stored command executed. transmitter somehow gotten double operation window, transmitter will work must re-learned. Since entire window rotates after each valid transmission, codes that have been used part `blocked' (32K) codes longer valid. This eliminates possibility grabbing previous code re-transmitting gain entry. Note: synchronization method described this section only typical implementation because usually implemented firmware, altered needs particular system
FIGURE 7-2:
TYPICAL DECODER OPERATION
Start
Transmission Received
Does Serial Number Match
Decrypt Transmission Decryption Valid Counter Within Counter Within Save Counter Temp Location Execute Command Update Counter
FIGURE 7-3:
SYNCHRONIZATION WINDOW
Entire Window rotates eliminate previously used codes Blocked Codes
Current Position
Open Codes Current window codes
1996 Microchip Technology Inc.
Preliminary
DS40138A-page
HCS200
ELECTRICAL CHARACTERISTICS
ABSOLUTE MAXIMUM RATINGS
Item Rating Units
TABLE 8-1:
Symbol
Note:
Supply voltage -0.3 13.3 Input voltage -0.3 13.3 VOUT Output voltage -0.3 IOUT output current TSTG Storage temperature +125 (Note) TLSOL Lead soldering temp (Note) VESD rating 4000 Stresses above those listed under "ABSOLUTE MAXIMUM RATINGS" cause permanent damage device.
TABLE 8-2:
CHARACTERISTICS
Commercial (C): Tamb +70°C Industrial (I): Tamb -40°C +85°C 3.5V 13.0V Parameter Operating current (avg) Sym. Typ* -0.3 0.5VDD 0.08 12.0 VDD+ 0.15 Unit -2.0mA 2.0mA 4.0V 4.0V Conditions 3.5V 6.6V 13.0V
Standby current High level Input voltage level input voltage High level output voltage level output voltage Resistance; S0-S2 Resistance; Note:
ICCS RS0-2 RPWM
Typical values 25°C.
DS40138A-page
Preliminary
1996 Microchip Technology Inc.
HCS200
FIGURE 8-1: TYPICAL CURVE HCS200 WITH EXTERNAL RESISTORS
12.0 10.0
VBAT
External 12.0 10.0
VBAT
External 12.0 10.0
VBAT LEGEND
Typical Maximum Minimum
1996 Microchip Technology Inc.
Preliminary
DS40138A-page
HCS200
FIGURE 8-2: POWER TRANSMIT TIMING
Code Word Transmission Button Press Detect Code Word Code Word Code Word Code Word
TABLE 8-3:
POWER TRANSMIT TIMING REQUIREMENTS
+3.5 13.0V Commercial (C): Tamb +70°C Industrial (I): Tamb -40°C +85°C Parameter Time second button press Transmit delay from button detect Debounce Delay Auto-shutoff time-out period Symbol Code Word Code Word Unit Remarks (Note
(Note Note time which second button pressed without completion first code word intention press combination buttons. auto-shutoff time-out period tested.
FIGURE 8-3:
FORMAT
LOGIC LOGIC Preamble Header Encrypted Portion Transmission THOP Fixed portion Transmission TFIX Guard Time
FIGURE 8-4:
PREAMBLE/HEADER FORMAT
Preamble Header Data Word Transmission
DS40138A-page
Preliminary
1996 Microchip Technology Inc.
HCS200
FIGURE 8-5: DATA WORD FORMAT
Serial Number Header Button Code Status VLOW
Fixed Code Word Guard Time
Hopping Code Word
TABLE 8-4:
CODE WORD TRANSMISSION TIMING REQUIREMENTS
Code Words Transmitted Number Min. 26.9 28.6 10.9 75.6 1190 Typ. 1200 38.4 40.8 15.6 108.0 Max. 1860 14.3 59.5 63.2 24.2 167.4 Min. 13.4 14.3 37.8 2381 Typ. 19.2 20.4 54.0 1667 Max. 29.8 31.6 12.1 83.7 1075 Units
+3.5 13.0V Commercial (C): Tamb +70°C Industrial (I): Tamb -40°C +85°C Symbol THOP TFIX Note: Characteristic Basic pulse element pulse width Preamble duration Header duration Hopping code duration Fixed code duration Guard Time Total Transmit Time data rate
timing parameters tested derived from oscillator clock.
FIGURE 8-6:
HCS200 TEMP CHARACTERIZATION)
Typical Max.
3.5V
5.0V
5.0V
Min. TEMPERATURE
1996 Microchip Technology Inc.
Preliminary
DS40138A-page
HCS200
HCS200 Product Identification System
order obtain information (e.g., pricing delivery), please listed part numbers, refer factory listed sales offices.
HCS200
Package: Plastic (300 Body), 8-lead Plastic SOIC (150 Body), 8-lead Blank +70°C -40°C +85°C HCS200 HCS200T Code Hopping Encoder Code Hopping Encoder (Tape Reel)
Temperature Range: Device:
AMERICAS
Corporate Office Microchip Technology Inc. 2355 West Chandler Blvd. Chandler, 85224-6199 Tel: 786-7200 Fax: 786-7277 Technical Support: 786-7627 Web: http://www.microchip.com Atlanta Microchip Technology Inc. Sugar Mill Road, Suite 200B Atlanta, 30350 Tel: 640-0034 Fax: 640-0307 Boston Microchip Technology Inc. Mount Royal Avenue Marlborough, 01752 Tel: 480-9990 Fax: 480-8575 Chicago Microchip Technology Inc. Pierce Road, Suite Itasca, 60143 Tel: 285-0071 Fax: 285-0075 Dallas Microchip Technology Inc. 14651 Dallas Parkway, Suite Dallas, 75240-8809 Tel: 991-7177 Fax: 991-8588 Dayton Microchip Technology Inc. Suite Prestige Place Miamisburg, 45342 Tel: 291-1654 Fax: 291-9175 Angeles Microchip Technology Inc. 18201 Karman, Suite 1090 Irvine, 92715 Tel: 263-1888 Fax: 263-1338 York Microchip Technology Inc. Motor Parkway, Suite Hauppauge, 11788 Tel: 273-5305 Fax: 273-5335
AMERICAS (continued)
Jose Microchip Technology Inc. 2107 North First Street, Suite Jose, 95131 Tel: 436-7950 Fax: 436-7955 Toronto Microchip Technology Inc. 5925 Airport Road, Suite Mississauga, Ontario 1W1, Canada Tel: 405-6279Fax: 405-6253
EUROPE
United Kingdom Arizona Microchip Technology Ltd. Unit Courtyard Meadow Bank, Furlong Road Bourne End, Buckinghamshire Tel: 850303 Fax: 850178 France Arizona Microchip Technology SARL Zone Industrielle Bonde Buisson Fraises 91300 Massy France Tel: Fax: Germany Arizona Microchip Technology GmbH Gustav-Heinemann-Ring D-81739 Muenchen, Germany Tel: Fax: Italy Arizona Microchip Technology Centro Direzionale Colleoni Palazzo Taurus Colleoni 20041, Agrate Brianza, Milan Italy Tel: 9939 Fax: 9883
ASIA/PACIFIC
Hong Kong Microchip Technology 3801B, Tower Metroplaza, Hing Fong Road, Kwai Fong, N.T., Hong Kong Tel: 1200 Fax: 3431 Korea Microchip Technology 168-1, Youngbo Bldg. Floor Samsung-Dong, Kangnam-Ku, Seoul, Korea Tel: 7200 Fax: 5934 Singapore Microchip Technology Middle Road #10-03 Prime Centre Singapore 188980 Tel: 8870 Fax: 8850 Taiwan Microchip Technology 10F-1C Tung North Road Taipei, Taiwan, Tel: 7175 Fax: 0139
JAPAN
Microchip Technology Intl. Inc. Benex 3-18-20, Shin Yokohama Kohoku-Ku, Yokohama Kanagawa Japan Tel: 6166 Fax: 6122 6/14/96
rights reserved. 1996, Microchip Technology Inc.,USA, 5/96
Information contained this publication regarding device applications like intended through suggestion only superseded updates. representation warranty given liability assumed Microchip Technology Incorporated with respect accuracy such information, infringement patents other intellectual property rights arising from such otherwise. Microchip's products critical components life support systems authorized except with express written approval Microchip. licenses conveyed, implicitly otherwise, under intellectual property rights. Microchip logo name registered trademarks Microchip Technology Inc. rights reserved. other trademarks mentioned herein property their respective companies.
DS40138A-page
Preliminary
1996 Microchip Technology Inc.

KEELOQ® Code Hopping Encoder* Security Programmable 28-bit s

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