SN74HC191NSR datasheet by Texas Instruments

SN74HC191NSR Frequently Asked Questions (FAQs)

• What is the maximum clock frequency that the SN74HC191NSR can handle?
  The maximum clock frequency of the SN74HC191NSR is 30 MHz, but it can vary depending on the operating voltage and load capacitance. It's recommended to check the timing characteristics in the datasheet for specific frequency limits.
• How do I ensure that the SN74HC191NSR is properly powered and decoupled?
  To ensure proper power and decoupling, connect the VCC pin to a stable 2-6V power supply, and decouple the power pins with 0.1uF ceramic capacitors. Additionally, use a 10uF bulk capacitor to filter out noise and voltage drops.
• What is the maximum input voltage that the SN74HC191NSR can tolerate?
  The maximum input voltage that the SN74HC191NSR can tolerate is 7V, but it's recommended to keep the input voltage within the recommended operating range of 2-6V to ensure reliable operation.
• Can I use the SN74HC191NSR in a 3.3V system?
  Yes, the SN74HC191NSR can be used in a 3.3V system, but it's essential to ensure that the input signals are within the recommended voltage range of 0.8V to 2.7V. Additionally, the output voltage will be limited to 3.3V, which may affect the noise margin.
• How do I handle the asynchronous clear (CLR) input?
  The asynchronous clear (CLR) input should be tied to VCC through a pull-up resistor (e.g., 1kΩ) to prevent unwanted clearing of the counter. When CLR is low, the counter will reset to zero, regardless of the clock input.