1 Features
• Fully static operation
• Buffered inputs
• Common reset
• Negative edge clocking
• Fanout (over temperature range)
– Standard outputs: 10 LSTTL loads
– Bus driver outputs: 15 LSTTL loads
• Wide operating temperature range: -55℃ to 125℃
• Balanced propagation delay and transition times
• Significant power reduction compared to LSTTL
Logic ICs
• HC types
– 2 V to 6 V operation
– High noise immunity: NIL = 30%, NIH = 30% of
VCC at VCC = 5 V
• HCT types
– 4.5 V to 5.5 V operation
– Direct LSTTL input logic compatibility, VIL = 0.8
V (max), VIH = 2 V (min)
– CMOS input compatibility, II ≤ 1 μA at VOL,VOH

2 Description
The ’HC4020 and ’HCT4020 are 14-stage ripple-carry
binary counters. All counter stages are controller/
peripheral flip- flops. The state of the stage advances
one count on the negative clock transition of each
input pulse; a high voltage level on the MR line resets
all counters to their zero state. All inputs and outputs
are buffered.