The CD74HC4518 is a dual BCD up-counter. The ’HC4520 and CD74HCT4520 are dual binary up-counters. Each device consists of two independent internally synchronous 4-stage counters. The counter stages are D-type flip-flops having interchangeable CLOCK and ENABLE lines for incrementing on either the positive-going or the negative-going transition of CLOCK. The counters are cleared by high levels on the MASTER RESET lines. The counter can be cascaded in the ripple mode by connecting Q₃ to the ENABLE input of the subsequent counter while the CLOCK input of the latter is held low.