同步向上/向下计数器, DOWN / UP模式控制 SYNCHRONOUS UP/DOWN COUNTERS WITH DOWN/UP MODE CONTROL
description/ordering information
The CD54/74HC190 are asynchronously presettable BCD decade counters, whereas the CD54/74HC191 and CD54/74HCT191 are asynchronously presettable binary counters.
• 2-V to 6-V VCC Operation ’HC190, 191
• 4.5-V to 5.5-V VCC Operation ’HCT191
• Wide Operating Temperature Range of −55°C to 125°C
• Synchronous Counting and Asynchronous Loading
• Two Outputs for n-Bit Cascading
• Look-Ahead Carry for High-Speed Counting
• Balanced Propagation Delays and Transition Times
• Standard Outputs Drive Up To 15 LS-TTL Loads
• Significant Power Reduction Compared to LS-TTL Logic ICs