The HEF4017BT is a 5-stage Johnson Decade Counter with ten spike-free decoded active high outputs (Q0 to Q9), an active low carry output from the most significant flip-flop (Q5\\-9), active high and active low clock inputs (CP0, CP1\\) and an overriding asynchronous master reset input (MR). The counter is advanced by either a low-to-high transition at CP0 while CP1\ is low or a high-to-low transition at CP1\ while CP0 is high. When cascading counters, the Q5\\-9 output, which is low while the counter is in states 5, 6, 7, 8 and 9, can be used to drive the CP0 input of the next counter. A high on MR resets the counter to zero (Q0 = Q5\\-9 = high, Q1 to Q9 = low) independent of the clock inputs (CP0, CP1\\). Automatic counter code correction is provided by an internal circuit: following any illegal code the counter returns to a proper counting mode within 11 clock pulses. Schmitt trigger action makes the clock inputs highly tolerant of slower rise and fall times.
