4位同步向上/向下二进制计数器 4-BIT SYNCHRONOUS UP/DOWN BINARY COUNTERS
description/ordering information
The ’HC191 devices are 4-bit synchronous, reversible, up/down binary counters. Synchronous counting operation is provided by having all flip-flops clocked simultaneously so that the outputs change coincident with each other when instructed by the steering logic. This mode of operation eliminates the output counting spikes normally associated with asynchronous ripple-clock counters.
● Wide Operating Voltage Range of 2 V to 6 V
● Outputs Can Drive Up To 10 LSTTL Loads
● Low Power Consumption, 80-µA Max ICC
● Typical tpd = 13 ns
● ±4-mA Output Drive at 5 V
● Low Input Current of 1 µA Max
● Single Down/Up Count-Control Line
● Look-Ahead Circuitry Enhances Speed of Cascaded Counters
● Fully Synchronous in Count Modes
● Asynchronously Presettable With Load Control
