SN74ALS161BN | Texas Instruments

Synchronous 4-Bit Binary Counter, SN74ALS161BN, Texas Instruments

This synchronous, presettable, 4-bit binary counter features internal carry look-ahead circuitry for application in high-speed counting designs. The SN74ALS161BN is a 4-bit binary counter. Synchronous operation is provided by having all flip-flops clocked simultaneously so that the outputs change coincidentally with each other when instructed by the count-enable (ENP, ENT) inputs and internal gating. This mode of operation eliminates the output counting spikes normally associated with asynchronous (ripple-clock) counters.

A buffered clock (CLK) input triggers the four flip-flops on the rising (positive-going) edge of the clock input waveform. This counter is fully programmable; it can be preset to any number between 0 and 15. Because presetting is synchronous, setting up a low level at the load (LOAD) input disables the counter and causes the outputs to agree with the setup data after the next clock pulse, regardless of the levels of the enable inputs.

Features

• Internal Look-Ahead Circuitry for Fast Counting
• Carry Output for n-Bit Cascading
• Synchronous Counting
• Synchronously Programmable