LSI/CSI UL ® LS7220 LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747 (631) 271-0400 FAX (631) 271-0405 A3800 DIGITAL LOCK FOR AUTOMOTIVE IGNITIONS OPERATING DESCRIPTION: (Refer to Figures 2, 3, 4 and 5.) When the Sense input goes high, the LS7220 is enabled. The Lock Status output turns on and Save Status and LOCK outputs remain off. When the programmed four-digit combination is entered from the keypad, in proper sequence, LOCK turns on and Lock Status turns off. If the Sense input is interrupted for a period of time greater than the Convenience Delay, the operating sequence must start over. If the Sense input is interrupted for a period of time less than the Convenience Delay, the operation of the LS7220 is unaffected. A momentary high at the Save input sets the Save Memory and causes the LS7220 to save an Unlock condition (Sequential Memory is set) for any time duration interruption of the Sense input (i.e., valet parking). The Save Status output turns on when Save Memory is set. The Lock input is used to reset the Save Memory and return the LS7220 to normal operation. NOTE: Using a 3 x 4 keypad, the ✳ key can be connected to the Lock input and the # key to the Save input. Lock Status and Save Status outputs can be used to drive red and green LED indicators, respectively. INPUT/OUTPUT DESCRIPTION: (Refer to Figure 4) SENSE INPUT (Pin 1) A high at this input causes CONVENIENCE DELAY to transition high and enables recognition of the SELECTED KEYS when they are inputted in proper sequence. Control logic for LOCK, LOCK STATUS and SAVE STATUS outputs is also enabled. A low at this input keeps all outputs off and resets the Sequential Memory if Save Memory is not set. VDD (Pin 9) Supply voltage negative terminal. Vss (Pin 14) Supply voltage positive terminal. 1 SENSE IN UNSELECTED KEYS (RESET) 14 V SS (+V) 2 13 LOCK OUT 3 12 CONVENIENCE DELAY 11 SAVE IN I 1 I 2 4 I 3 5 10 SAVE STATUS OUT I 4 6 9 V DD (-V) 7 8 SELECTED KEYS (IN SEQUENCE) LOCK IN LS 7220 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. PIN ASSIGNMENT - TOP VIEW LSI 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 LOCK STATUS OUT FIGURE 1. UNSELECTED KEYS (RESET) INPUT (Pin 2) A high at this input resets the Sequential Detector for the SELECTED KEYS inputs. This input must be wired to all digit keys which are not part of the Four-Digit Combination. SELECTED KEYS INPUTS (Pins 3, 4, 5, 6) When these inputs are brought high in correct sequence, (i.e.,I1, I2, I3, I4) the Sequential Memory is set if SENSE input is high. LOCK output turns on and LOCK STATUS output turns off when the Sequential Memory is set. LOCK INPUT (Pin 7) A high at this input resets the Save Memory. The SAVE STATUS output turns off when this occurs. LOCK STATUS OUTPUT (Pin 8) This output is the complement of LOCK output when the SENSE input is high. See NOTE. SAVE STATUS OUTPUT (Pin 10) This output turns on when Save Memory is set and SENSE input is high. See NOTE. SAVE INPUT (Pin 11) A high at this input sets the Save Memory. If Save Memory is set and Sequential Memory is set, the Save Memory will prevent the Sequential Memory from being reset as a result of a change at the SENSE Input. (See SAVE STATUS OUTPUT.) CONVENIENCE DELAY I/O (Pin 12) An external capacitor placed on this pin will delay the effect of changes at the SENSE Input from affecting the outputs and the condition of the Sequential Detector and Sequential Memory. (See Figure 2) LOCK OUTPUT (Pin 13) This output turns on when the Sequential Memory is set and SENSE input is high. See NOTE. NOTE: Outputs are off when SENSE input is low. 7220-012703-1 January 2003 ABSOLUTE MAXIMUM RATINGS: PARAMETER DC Supply Voltage Any Input Voltage Operating Temperature Storage Temperature SYMBOL VSS - VDD VIN TA TSTG VALUE +20 VSS - 20 to VSS + 0.5 -25 to +85 -65 to +150 UNIT V V °C °C TRANSIENT CHARACTERISTICS: (See Figure 3) (TA = -25°C to +85°C, VSS = +5V to +18V) PARAMETER SENSE High Delay to Outputs Enabled SYMBOL TSE MIN - MAX 1 UNIT µs CONDITION No external capacitor, Pin 12 SENSE Low Delay to Outputs Disabled TSD - 10 µs No external capacitor, Pin 12 Input Pulse Widths (except SENSE) TPW 25 - µs - Valid Combination Entry to LOCK Output Enabled TCE - 10 µs SENSE High DC ELECTRICAL CHARACTERISTICS: (All voltages referenced to VDD; TA = -25°C to +85°C unless otherwise specified.) PARAMETER Supply Voltage Supply Current SYMBOL VSS ISS Vss voltages = 5V, 9V, 12V, 15V, 18V MIN +5 - MAX +18 20, 30, 40, 50, 70 UNIT V µA CONDITION VSS voltages 2, 3, 4, 6, 8.5 VSS V V VSS voltages VSS voltages *INPUT VOLTAGES: SENSE Low SENSE High VIL VIH 0 3.5, 5.5, 6.5, 9, 11.5 CONVENIENCE DELAY Low CONVENIENCE DELAY High VIL VIL 0.7Vss 0.3Vss - - Typical Typical All Other Inputs: Low High VIL VIH 0 Vss - 1 Vss - 3 Vss V V - *NOTE 1: All inputs have pull down resistors to VDD. Typical input sink current is 12µA with input at Vss (Vss - VDD = +12V) OUTPUT CURRENT: ***LOCK STATUS Source Current Vo = +1.7V IO 0.4, 2.5, 5, 9, 14 1.3, 6, 12, 20, **30 mA Vss voltages ***SAVE STATUS Source Current Vo = +1.7V IO 0.8, 5, 10, 18, 28 2.6, 12, 24, **30, **30 mA Vss voltages CONVENIENCE DELAY IO 0.1, 0.5, 0.7, 1, 1.2 0.5, 1.1, 1.6, 2.1, 2.4 mA Vss voltages LOCK IO 1.3, 6.5, 9.1, 13, 15.6 6.5, 14.7, 21, 27.3, **30 mA Vss voltages CIN - pF - Inupt Capacitance 10 **NOTE 2: Limit current to 30mA maximum ***NOTE 3: LOCK STATUS and SAVE STATUS output currents are balanced to achieve equal brightness for red and green LEDs 7220-012703-2 FIGURE 2. CONVENIENCE DELAY TIME vs POWER SUPPLY (with External Capacitor C, Pin 12) 14 Typical Curve for C = 5µF T A = 25 ° C T SD, seconds 12 10 8 6 4 2 0 5 10 15 18 (V SS-V DD ), Volts SENSE Input T PW I1 T PW I2 T PW I3 T PW I4 T SE LOCK T CE T SD T SD T SE LOCK STATUS T SE SAVE Input SAVE STATUS T SE LOCK Input FIGURE 3. LS7220 TIMING DIAGRAM SELECTED KEYS (IN SEQUENCE) SAVE INPUT FIGURE 4. LS7220 BLOCK DIAGRAM 11 POWER ON RESET I4 I3 I2 I1 6 5 4 3 SEQUENTIAL DET EC T O R R CORRECT SEQUENCE INCORRECT SEQUENCE LOCK INPUT S R SAVE MEMORY Q 7 R S SEQUENTIAL MEMORY Q Q 2 UNSELECTED KEYS (RESET) 13 SENSE INPUT (ENABLE) LOGIC "1" LEVEL RESTORE 1 LOCK V SS 8 LOCK STATUS 10 SA VE ST AT U S V SS V SS 14 (+V) V DD 9 (-V) V DD Capacitor Discharge Current V SS 7220-012703-3 V SS 12 CONVENIENCE DELAY C + V SS External Capacitor FIGURE 5. TYPICAL ANTI-THEFT DIGITAL LOCK SEE NOTE 2 NC (CONVENIENCE DELAY) KEYPAD FROM IGNITION SWITCH C (See Note 1) +12V +12V NO +12V 1 2 3 4 5 6 7 .05µF,25V SENSE IN VSS UNSELECTED KEYS (RESET) LOCK 13 CONVENIENCE 12 DELAY I2 SAVE IN - C1 (See Note 2) + +12V 11 SAVE 10 STATUS I3 I4 LS7220 LOCK IN RELAY COIL (UNLOCK RELAY) 14 I1 VDD LOCK STATUS To .05µF Starter 250V Solenoid or Starter Motor or Hood Lock GREEN LED (SAVE INDICATIOR) 9 8 RED LED (LOCK INDICATOR) Note 1: C is optional. It may be required to prevent ignition noise from generating a false reset. (Typical values range from 0.1µF to 0.47µF) Note 2: See Figure 2 to select C1 value for desired Convenience Delay Time. If Convenience Delay is not desired, wire Keypad to +12V instead of CONVENIENCE DELAY and eliminate C1. A typical automotive anti-theft digital lock circuit is shown in Figure 5. When the Ignition Switch is turned on the SENSE input (Pin 1) goes high and the circuit is ready to accept the unlocking input sequence at I1, I2, I3 and I4 (Pins 3, 4, 5 and 6, respectively). If the keys associated with these inputs are depressed exactly in sequence, the LOCK output (Pin 13) turns ON and the Unlock Relay is energized. This state is indicated by the OFF condition of the LOCK STATUS output (Pin 8) which turns the red LED OFF (indicates unlock condition). If the keys are depressed in any sequence other than as described above, the internal sequential detector resets and the entire sequence must be repeated (See Figure 4). In order to save the ON condition of the LOCK output before the ignition switch is turned Off (i.e., when the SENSE input becomes low) the key associated with the SAVE input (Pin 11) has to be depressed. The "SAVE" status is indicated by a high at the SAVE STATUS output (Pin 10), which turns the green LED On. If the ignition switch is turned Off when the green LED is On, all the output status are preserved in the internal memory, so that when the ignition switch is turned on again there is no need to go through the input sequence again. This feature could be used for valet parking and garage service. Status saving may be cancelled by depressing the LOCK input key followed by turning the ignition switch Off for a time greater than the CONVENIENCE DELAY (See Figure 2). This also turns OFF the LOCK output. +12V .0 5 µ F 0 1 KEYPAD 1 2 2 3 3 V SS UNSELECTED KEYS I1 LOCK CONVENIENCE DELAY 14 5 5 6 6 7 8 9 7220-012703-4 7 TO LOCK CONTROL CIRCUIT 13 12 4 4 See Note 1 - C1 (See Note 1) + +12V I2 11 See Note 1 10 I3 VDD I4 LS7220 9 8 NOTE 1: C1 value determines the Combination Entry Time and duration of Momentary LOCK Output (See Figure 4). Select C1 value from Figure 2. Code shown is 4179. FIGURE 6. DIGITAL LOCK WITH MOMENTARY OUTPUT