CD54HCT640F3A datasheet by Texas Instruments

CD54HCT640F3A Frequently Asked Questions (FAQs)

• What is the maximum frequency of operation for the CD54HCT640F3A?
  The maximum frequency of operation for the CD54HCT640F3A is 50 MHz, but it can operate up to 100 MHz with a reduced voltage supply (VCC) of 4.5V.
• How do I handle the output enable (OE) pin during power-up and power-down?
  It's recommended to tie the OE pin to VCC or GND through a pull-up or pull-down resistor to ensure a defined state during power-up and power-down. This prevents unwanted output transitions.
• What is the recommended termination scheme for the CD54HCT640F3A?
  Texas Instruments recommends using a series termination scheme with a 33-ohm resistor in series with each output and a 50-ohm pull-up resistor to VCC for each output. This helps reduce signal reflections and improves signal integrity.
• Can I use the CD54HCT640F3A with a 3.3V supply voltage?
  Yes, the CD54HCT640F3A can operate with a 3.3V supply voltage, but the output voltage levels will be reduced. Ensure that the receiving device can tolerate the reduced voltage levels.
• How do I ensure signal integrity when using the CD54HCT640F3A in a high-speed application?
  To ensure signal integrity, use controlled impedance PCB traces, keep signal traces short, and use a solid ground plane. Additionally, consider using a signal integrity analysis tool to simulate and optimize your design.