SN54AS869JT

同步8位加/减计数器 SYNCHRONOUS 8-BIT UP/DOWN COUNTERS

description

These synchronous, presettable, 8-bit up/down counters feature internal-carry look-ahead circuitry for cascading in high-speed counting applications. Synchronous operation is provided by having all flip-flops clocked simultaneously so that the outputs change coincidentally with each other when so instructed by the count-enable ENP, ENT inputs and internal gating. This mode of operation eliminates the output counting spikes normally associated with asynchronous ripple clock counters. A buffered clock CLK input triggers the eight flip-flops on the rising positive going edge of the clock waveform.

• Fully Programmable With Synchronous Counting and Loading

• SN74ALS867A and ′AS867 Have Asynchronous Clear; SN74ALS869 and ′AS869 Have Synchronous Clear

• Fully Independent Clock Circuit Simplifies Use

• Ripple-Carry Output for n-Bit Cascading

• Package Options Include Plastic

   Small-Outline DW Packages, Ceramic Chip Carriers FK, and Standard Plastic NT and Ceramic JT 300-mil DIPs