74系列逻辑芯片/74HC191D
GENERAL DESCRIPTION
The 74HC/HCT191 are high-speed Si-gate CMOS devices and are pin compatible with low power Schottky TTL LSTTL. They are specified in compliance with JEDEC standard no. 7A.
The 74HC/HCT191 are asynchronously presettable 4-bit binary up/down counters. They contain four master/slave flip-flops with internal gating and steering logic to provide asynchronous preset and synchronous count-up and count-down operation.
FEATURES
• Synchronous reversible counting
• Asynchronous parallel load
• Count enable control for synchronous expansion
• Single up/down control input
• Output capability: standard
• ICC category: MSI