器件名称:
DM74LS491N
功能描述:
10-Bit Counter
文件大小:
136.78KB 共4页
简 介:
DM54LS491 74LS491 10-Bit Counter July 1989 DM54LS491 74LS491 10-Bit Counter 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 Y Y Y Y Y CRT vertical and horizontal timing generation Bus-structured pinout 24-pin SKINNYDIP saves space TRI-STATE outputs drive bus lines Low current PNP inputs reduce loading Connection Diagram Top View Standard Test Load TL L 8332 – 2 TL L 8332 – 1 Order Number DM54LS491J DM74LS491J or DM74LS491N See NS Package Number J24F or N24C Function Table OE CK SET LD CNT CIN UP D9-D0 H L L L L L L X Q9-Q0 Operation X H L L L L L X X L H H H H X X X H L L L X X X X H L L X X X X X L H X X D X X X X Z Hi-Z H Set all HIGH D LOAD D Q HOLD Q HOLD Q plus 1 Count UP Q minus 1 Count DN u u u u u u TRI-STATE is a registered trademark of National Semiconductor Corp C1995 National Semiconductor Corporation TL L 8332 RRD-B30M115 Printed in U S A Absolute Maximum Ratings If Military Aerospace specified devices are required please contact the National Semiconductor Sales Office Distributors for availability and specifications Supply Voltage VCC 7V Input Voltag……
