54HC191 Datasheet | SGS-THOMSON

DESCRIPTION The M54/74HC190/191 are high speed CMOS 4-BIT SYNCHRONOUS UP/DOWN COUNTERS fabricated in silicon gate C2MOS technology. They have the same high speed performance of LSTTL bined with true CMOS low power consumption. State changes of the counter are synchronous with the LOW-to-HIGH transition of the Clock Pulse input. An asynchronous parallel load input overrides counting and loads the data present on the DATA inputs into the flip-flops, which makes it possible to use the circuits as programmable counters. A countenable input serves as the carry/borrow input in multi-stage counters. Control input, Down/Up, determines whether a circuit counts up or down. A MAX/MIN output and a Ripple Clock output provide overflow/underflow indication and make possible a variety of methods for generating carry/borrow signals in multistage counter applications. All inputs are equipped with protection circuits against static discharge and transient excess voltage. NC = No Internal Connection October 1992 1/14 M54/M74HC190/191 INPUT AND OUTPUT EQUIVALENT CIRCUIT IEC LOGIC SYMBOL (HC190) PIN DESCRIPTION PIN No 3, 2, 6, 7 5 11 12 13 15, 1, 10, 9 8 16 SYMBOL NAME AND FUNCTION QA to QD Flip-Flop Outputs ENABLE Count Enable Input (Active LOW) U/D Parallel Data Input LOAD Load Input (Active LOW) MA/MI OUT Terminal Count Output RC Ripple Clock Output (Active LOW) CLOCK Cloack Input (LOW to HIGH, Edge-triggered) DA to DD Data Inputs Ground (0V) VCC Positive Supply Voltage IEC LOGIC SYMBOL (HC191) TRUTH TABLE INPUTS LOAD ENABLE D/U CLOCK L X X Xa H...