5-stage Johnson counter in a 16-SSOP
The NXP 74HC4017DB,112 is a 5-stage Johnson decade counter — it walks a logic high through ten decoded outputs in sequence, one clock edge at a time. That makes it the go-to for LED chasers, sequential timing chains, and state-machine step generation in 74HC-based logic designs. Rated for an 83 MHz count rate, it keeps up with fast clock sources without missing edges — useful when the upstream oscillator or MCU clock runs well into the tens of megahertz.
The asynchronous master reset (pin MR) pulls all outputs low regardless of the clock state — a single pulse clears the counter without waiting for the next clock edge, which simplifies power-on reset circuits.