8-Bit Negative-Edge Binary Ripple Counter with Clock Enable and Asynchronous Clear

CR8CE is an 8-bit, cascadable, clearable, binary, ripple counter. The asynchronous clear (CLR), when High, overrides all other inputs and causes the outputs (Q7 – Q0) to go to logic level zero. The counter increments when the clock enable input (CE) is High during the High-to-Low clock (C) transition. The counter ignores clock transitions when CE is Low.

Larger counters can be created by connecting the Q7 output of the first stage to the clock input of the next stage. CLR and CE inputs are connected in parallel. The clock period is not affected by the overall length of a ripple counter. The overall clock-to-output propagation is n(TC - Q), where n is the number of stages and TC - Q is the C-to-Q7 propagation delay of each stage.

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