- Bits (#)4Technology
- VCC (Min) (V)4.75
- VCC (Max) (V)5.25
- Input typeTTL
- Output typeCMOS
- Programmable Look-Ahead Up/Down Binary Counters
- Fully Synchronous Operation for Counting and Programming
- Internal Look-Ahead for Fast Counting
- Carry Output for n-Bit Cascading
- Fully Independent Clock Circuit
These synchronous presettable counters feature an internal carry look-ahead for cascading in high speed counting applications. The ‘LS169B and ‘S169 are 4-bit binary counters. Synchronous operation is provided by having all flip-flops clocked simultaneously so that the outputs change coincident with each other when so instructed by the count-enable inputs and internal gating. This mode of operation helps eliminate the output counting spikes that are normally associated with asynchronous (ripple-clock) counters. A buffered clock input triggers the four master-slave flip-flops on the rising (positive-going) edge of the clock waveform.
These counters are fully programmable; that is the outputs may each be preset to either level. The load input circuitry allows loading with the carry-enable output of cascaded counters. As loading is synchronous, setting up a low level at the load input disables the counter and causes the outputs to agree with the data inputs after the next clock pulse.