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.