This data sheet describes the features and functions of the CD74AC191 and CD74ACT191 asynchronous presettable four-bit binary up/down counters.
The CD74AC191 and CD74ACT191 are asynchronously presettable binary up/down synchronous counters that utilize Harris Advanced CMOS Logic technology (now Texas Instruments). These devices feature buffered inputs, a terminal count output for look-ahead carry in high-speed cascading applications, and a ripple clock output. They operate with supply voltages ranging from 1.5V to 5.5V for AC types.
| Typical Propagation Delay | 12.8ns |
|---|---|
| Output Drive Current | #24mA |
| Fanout Capability | 15 FAST™ ICs |
The Terminal Count (TC) output goes HIGH and remains HIGH for one clock cycle.
This is a 4-bit binary up/down synchronous counter.