4-bit binary counter with parallel load using JK flip flop

4-bit binary counter with parallel load:

Counters employed in digital systems quite often require a parallel load capability for transferring an initial binary number before the count operation. It shows that the logic diagram of a binary counter has a parallel load capability and can also be cleared to 0 synchronous with the clock. When equal to I, the clear input sets all the K inputs to I, thus clearing all flip-flops with the next clock transition.

The input load control when equal to I disables the count operation and causes a transfer of data from the four parallel inputs into the four flip-flops (provided that the clear input is 0). If the clear and load inputs are both 0 and the increment input is I, the circuit operates as a binary counter.

The operation of the circuit is summarized below in Table. With the clear, load, and increment inputs all at 0, the outputs do not change even when pulses are applied to the C terminals. If the clear and load inputs are maintained at logic 0, the increment input controls the operation of the counter and the outputs change to the next binary count for each positive transition of the clock. The input data are loaded into the flip-flops when the load control input is equal to I provided that the clear is disabled, but the increment input can be 0 or I. The register is cleared to 0 with the clear control regardless of the values in the load and increment inputs.