器件名称:
74HC191
功能描述:
Presettable synchronous 4-bit binary up/down counter
文件大小:
108.17KB 共14页
简 介:
INTEGRATED CIRCUITS DATA SHEET For a complete data sheet, please also download: The IC06 74HC/HCT/HCU/HCMOS Logic Family Specifications The IC06 74HC/HCT/HCU/HCMOS Logic Package Information The IC06 74HC/HCT/HCU/HCMOS Logic Package Outlines 74HC/HCT191 Presettable synchronous 4-bit binary up/down counter Product specication File under Integrated Circuits, IC06 December 1990 Philips Semiconductors Product specication Presettable synchronous 4-bit binary up/down counter FEATURES Synchronous reversible counting Asynchronous parallel load Count enable control for synchronous expansion Single up/down control input Output capability: standard ICC category: MSI 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. Asynchronous parallel load capability permits the counter to be preset to any desired number. Information present on the parallel data inputs (D0 to D3) is loaded into the counter and appears on the outputs when the parallel load (PL) input is LOW. As indicated in the function table, this operation overrides the counting function. Counting is inhibited by a HIGH level on the count ena……
