69 MHz count rate and dual 4-bit architecture
The 74HC4520D/S400118 is a dual 4-bit binary counter from NXP's 74HC series, each element counting up to 69 MHz — fast enough for digital frequency division, event counting, or time-delay generation in industrial logic chains.
Asynchronous reset and dual-edge trigger flexibility
Each counter element has an asynchronous reset (MR) that clears the outputs immediately, independent of the clock — useful for power-on initialization or emergency reset without waiting for a clock edge. The counter triggers on both positive and negative clock edges, giving the designer a choice of rising-edge or falling-edge counting without external inversion. This dual-edge capability simplifies interfacing with sensors or other asynchronous signals.