SN74LS123DR datasheet by Texas Instruments

SN74LS123DR Frequently Asked Questions (FAQs)

• What is the maximum frequency of operation for the SN74LS123DR?
  The maximum frequency of operation for the SN74LS123DR is 10 MHz.
• Can I use the SN74LS123DR in a 3.3V system?
  No, the SN74LS123DR is a 5V device and is not compatible with 3.3V systems. You may need to use a level shifter or a different device that is compatible with 3.3V systems.
• How do I handle the reset pin (MR) in my design?
  The reset pin (MR) is an active-low input that resets the counter to zero. You can tie it to VCC through a resistor to prevent accidental resets, or connect it to a reset signal in your system.
• What is the purpose of the enable inputs (ENP and ENT) in the SN74LS123DR?
  The enable inputs (ENP and ENT) allow you to enable or disable the counter. When ENP is low and ENT is high, the counter is enabled. When ENP is high or ENT is low, the counter is disabled.
• How do I cascade multiple SN74LS123DR devices to create a larger counter?
  To cascade multiple SN74LS123DR devices, connect the carry-out (CO) of one device to the clock input (CLK) of the next device. Make sure to connect the clock inputs of all devices to a common clock signal.