DIGITAL LOCK FOR AUTOMOTIVE IGNITIONS
LSI/CSI
LS7220
U® L LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747 (631) 271-0400 FAX (631) 271...
Description
LSI/CSI
LS7220
U® L LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747 (631) 271-0400 FAX (631) 271-0405
A3800
DIGITAL LOCK FOR AUTOMOTIVE IGNITIONS January 2003
FEATURES: 5040 Four-Digit Combinations (for a 10 digit Keypad) Combinations are Hard-Wire Programmed Sense Input Enables Operation Save Memory Feature for Valet Parking Convenience Delay Controlled by External Capacitor Static or Momentary Lock Control Output Save Memory and Lock Status Outputs +5V to +18V Operation (Vss - VDD) LS7220 (DIP), LS7220-S (SOIC) - See Figure 1
DESCRIPTION: The LS7220 is a MOS digital lock circuit. When wired to a ten-digit keypad, the circuit will recognize one four-digit combination out of a possible 5040 combinations. The LS7220 is configured with the features required for an Automotive Ignition Anti-Theft Digital Lock (See Figure 5). These features include Sense input which enables the IC, Save Memory for Valet Parking, Convenience Delay to maintain Unlock condition for short term interruptions of the Sense input and Save Status and Lock Status outputs which can be used for direct drive of LED indicators.
LS 7220
LSI
PIN ASSIGNMENT - TOP VIEW
SENSE IN 1
14 V SS (+V)
UNSELECTED KEYS 2 (RESET)
I1 3
13 LOCK OUT 12 CONVENIENCE
DELAY
SELECTED KEYS (IN SEQUENCE)
I2 4 I3 5
I4 6
11 SAVE IN 10 SAVE STATUS OUT 9 VDD (-V)
LOCK IN 7
FIGURE 1.
8 LOCK STATUS OUT
UNSELECTED KEYS (RESET) INPUT (Pin 2) A high at this input resets the Sequential De...
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