Divide by 16 Counter 74LS93

A divide-by-16 counter, also called divide-by-sixteen counter, is a counter circuit used in the field of digital electronics, which produces a single pulse at the output for every 16 pulses at the input.

Block Diagram

This is a 4-bit ripple type decade binary counter, which consists of four master/slave JK flip-flops connected to provide a divide-by-two section and a divide-by-eight section. Each section has a separate clock input, which initiates state changes of the counter on the high-to-low clock transition.

In the diagram above, you can see that the output of the first section pin 12 (Q0) is not internally connected to the input of the second section pin 1 (CP1). The manufacturers have intentionally designed this to make the counter more versatile. This way the first flip-flop provides a divide-by-2 function, whilst the rest provide a divide-by-8 function. However, in this application I need to connect the output from the first stage to the second stage, because I need all the stages to make a divide-by-16 counter.

Circuit Implementation

In this circuit implementation, I have configured a standard 74LS93 to count up to 16 in a ripple through fashion. For every 16 pulses at the input, it will generate one pulse at the output.

Pin 1 connects to pin 12 so that the output of the first stage is fed to the input of the second stage. The input is at pin 14 (CP), and the final output is at pin 11 (Q3).

Truth Table

Here is a truth table showing the input count and the ripple through outputs from the four JK flip-flops.

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