SN74HC191DR datasheet by Texas Instruments

SN74HC191DR Frequently Asked Questions (FAQs)

• What is the maximum clock frequency that the SN74HC191DR can handle?
  The SN74HC191DR can handle clock frequencies up to 40 MHz.
• How do I ensure that the counter is properly reset?
  To ensure proper reset, the reset input (R) should be held low for at least 10 ns, and then released while the clock input (CP) is low.
• What is the maximum count value that the SN74HC191DR can store?
  The SN74HC191DR is a 4-bit synchronous up/down counter, so it can store a maximum count value of 15 (1111 in binary).
• Can I use the SN74HC191DR as a divide-by-n counter?
  Yes, the SN74HC191DR can be used as a divide-by-n counter by connecting the Q0 output to the CP input and using the load input (LD) to load the desired count value.
• How do I handle the asynchronous load input (LD) and the synchronous count enable input (ENP, ENT)?
  The load input (LD) is asynchronous, meaning it can be changed at any time. The count enable inputs (ENP, ENT) are synchronous, meaning they should only be changed while the clock input (CP) is low.