Features
• Positive or Negative Edge Triggering
• Synchronous Internal Carry Propagation
• Fanout (Over Temperature Range)
- Standard Outputs . . . . . . . . . . . . . . . 10 LSTTL Loads
- Bus Driver Outputs . . . . . . . . . . . . . 15 LSTTL Loads
• Wide Operating Temperature Range . . . -55oC to 125oC
• Balanced Propagation Delay and Transition Times
• Significant Power Reduction Compared to LSTTL
Logic ICs
• HC Types
- 2V to 6V Operation
- High Noise Immunity: NIL = 30%, NIH = 30% of VCC
at VCC = 5V
• HCT Types
- 4.5V to 5.5V Operation
- Direct LSTTL Input Logic Compatibility,
VIL= 0.8V (Max), VIH = 2V (Min)
- CMOS Input Compatibility, Il ≤ 1μA at VOL, VOH

Description
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 negativegoing
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.