2-V to 6-V VCC Operation (’HC190, 191)

4.5-V to 5.5-V VCC Operation (’HCT191)

Wide Operating Temperature Range of

−55°C to 125°C

Synchronous Counting and Asynchronous

Loading

Two Outputs for n-Bit Cascading

Look-Ahead Carry for High-Speed Counting

Balanced Propagation Delays and

Transition Times

Standard Outputs Drive Up To 15 LS-TTL

Loads

Significant Power Reduction Compared to

LS-TTL Logic ICs

description/ordering information

The CD54/74HC190 are asynchronously presettable BCD decade counters, whereas the CD54/74HC191 and

CD54/74HCT191 are asynchronously presettable binary counters.

Presetting the counter to the number on preset data inputs (A−D) is accomplished by a low asynchronous

parallel load (LOAD) input. Counting occurs when LOAD is high, count enable (CTEN) is low, and the down/up

(D/U) input is either high for down counting or low for up counting. The counter is decremented or incremented

synchronously with the low-to-high transition of the clock.