SN74LS138N datasheet by Texas Instruments

SN74LS138N Frequently Asked Questions (FAQs)

• What is the maximum frequency of operation for the SN74LS138N?
  The maximum frequency of operation for the SN74LS138N is typically around 20-25 MHz, but this can vary depending on the specific application and operating conditions.
• How do I ensure that the SN74LS138N is properly powered and decoupled?
  To ensure proper operation, the SN74LS138N should be powered with a stable 5V supply, and decoupling capacitors (e.g. 0.1uF and 10uF) should be placed close to the device to filter out noise and reduce electromagnetic interference (EMI).
• What is the maximum current that the SN74LS138N can sink or source?
  The SN74LS138N can sink up to 24mA and source up to 12mA per output, but it's recommended to keep the current within the absolute maximum ratings to ensure reliable operation.
• How do I handle the enable inputs (E1, E2, E3) to ensure proper operation?
  The enable inputs (E1, E2, E3) should be driven with a valid logic level (either high or low) to enable or disable the decoder outputs. Floating or undefined enable inputs can cause unpredictable behavior.
• What is the propagation delay of the SN74LS138N?
  The propagation delay of the SN74LS138N is typically around 10-15ns, but this can vary depending on the specific application and operating conditions.