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LS7055 Datasheet(PDF) 1 Page - LSI Computer Systems |
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LS7055 Datasheet(HTML) 1 Page - LSI Computer Systems |
1 / 6 page 6 DECADE PREDETERMINING UP/DOWN COUNTER FEATURES: • +4.75V to +15V (Vss - VDD) • Preset, Presignal and Mainsignal Store • DC to 250kHz Count Frequency • Fully Synchronous Operation Three Comparators with Output Flags Automatic or Manual Preset/Reset Control • Thumbwheel Interface for Storage Selects • Prescale on Count Input Selectable • Count Inhibit • Up/Down Control • Scan Rate up to 150kHz • Scan Oscillator has Override Capability • Blanking Override for Decimal Point Operaton • Multiplexed 7 Segment and BCD Data Output • Output latches • Reset • Hysteresis on Count Input • CMOS Type Noise Immunity on all other inputs • LS7055, LS7056 (DIP) - See Figure 1 DESCRIPTION: The LS7055/LS7056 is a MOS synchronous 6 decade Up/Down counter. The circuit includes storages and comparators, zero de- tect, automatic presetting and resetting, output latches, multi- plexed output BCD and seven segment data. Thumbwheel switches can be used to provide BCD data to the storage net- works in the circuit. COUNT (Pin 40) Counter operates at speeds up to 250kHz and advances on the positive edge of the input count pulse. UP/DOWN (Pin 39) Counter operates in up or down mode. A high input causes the counter to operate in the up mode while a low input causes it to operate in the down mode. COUNT INHIBIT (Pin 1) A high input inhibits counting and the counter remains at its last count. A low input enables counting. DATA TRANSFER INPUT (Pin 37) A high input allows the seven segment display and BCD data to follow the count (the internal latches become transparent). A low input prevents updating of the latches as the count advances and the seven segment display and BCD data outputs remain fixed. RESET (Pin 4) A high input resets and holds all counter stages at zero. A low input allows counter operation. January 2003 7055-012703-1 LSI/CSI LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747 (631) 271-0400 FAX (631) 271-0405 LS7055 LS7056 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 FIGURE 1 PIN ASSIGNMENT - TOP VIEW COUNT INPUT UP/DOWN INPUT ZERO DETECT OUTPUT DATA TRANSFER INPUT PRESIGNAL OUTPUT B1 B2 B4 B8 BLANKING OVERRIDE g f e V SS (+V) c b LSD V DD (-V) RESET INPUT COUNT INHIBIT INPUT DIVIDE CONTROL INPUT 1 DIVIDE CONTROL INPUT 2 MAIN SIGNAL OUTPUT B8 B4 B2 B1 BCD DATA OUTPUTS DIGIT SELECT OUTPUTS LS7055 SEGMENT OUTPUTS INHIBIT INTERNAL RESET INPUT INHIBIT INTERNAL PRESET INPUT PRESET INPUT BCD DATA INPUTS SELECT STORAGE INPUT 1 SELECT STORAGE INPUT 2 LSD+1 LSD+2 LSD+3 LSD+4 SCAN OSCILLATOR INPUT MSD a d * OPTIONAL CHOICE-LAMP TEST (SPECIFY LS7056) DIGIT SELECT OUTPUTS INHIBIT INTERNAL RESET (Pin 5) A high input prevents the automatic reset of the counter to zero when in the up mode and when the counter reaches the number in the main signal store. PRESET (Pin 7) A high level presets the BCD counter to the number set in the preset store. A low input allows counter operation. INHIBIT INTERNAL PRESET (Pin 6) A high input prevents the automatic preset of the counter to the number set in preset store when in the down mode and the counter reaches zero. SELECT STORAGE OF DATA INPUTS (Pins 15, 16) Two inputs which allow BCD data to be stored in either the preset, presignal or main signal store. The proper method for loading the stores is depicted in Figure 4. PIN 15 PIN16 STORAGE 0 0 No Selection 1 0 Presignal 0 1 Main Signal 1 1 Preset UL ® A3800 * |
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