DM74LS491数据手册TI中文资料规格书

描述 Description

General Description
The ten-bit counter can count up, count down, set, and load 2 LSB’s, 2 MSB’s and 6 middle bits high or low as a group. All operations are synchronous with the clock. SET overrides LOAD, COUNT and HOLD. LOAD overrides COUNT. COUNT is conditional on CIN, otherwise it holds.
All outputs are enabled when OE is low, otherwise HIGH-Z. The 24 mA IOL outputs are suitable for driving RAM/PROM address lines in video graphics systems.Features/Benefits
■ CRT vertical and horizontal timing generation
■ Bus-structured pinout
■ 24-pin SKINNYDIP saves space
■ TRI-STATEÉ outputs drive bus lines
■ Low current PNP inputs reduce loading