74139 Dual Decoder/Demux IC
The 74HC39 counter circuits contain independent ripple carry counters and utilize advanced silicon-gate CMOS technology. The MM74HC393 contains two 4-bit ripple carry binary counters, which can be cascaded to create a single divide-by-256 counter. Each of the two 4-bit counters is incremented on the HIGH- to-LOW transition (negative edge) of the clock input, and each has an independent clear input. When clear is set HIGH all four bits of each counter are set to a low level. This enables count truncation and allows the implementation of divide-by-N counter configurations.
- Typical operating frequency: 50 MHz
- Typical propagation delay: 13 ns (Ck to QA)
- Wide operating supply voltage range: 2–6V
- Low input current: <1 µA
- Low quiescent supply current: 80 µA maximum(74HC Series)
- Fanout of 10 LS-TTL loads