SN74LS138NE4 datasheet by Texas Instruments

SN74LS138NE4 Frequently Asked Questions (FAQs)

• What is the maximum frequency of operation for the SN74LS138NE4?
  The maximum frequency of operation for the SN74LS138NE4 is typically around 25 MHz, but it can vary depending on the specific application and operating conditions.
• How do I ensure that the SN74LS138NE4 is properly powered and decoupled?
  To ensure proper power and decoupling, connect the VCC pin to a stable 5V power supply, and decouple the power pins with 0.1uF ceramic capacitors to ground. Additionally, use a 10uF electrolytic capacitor to filter the power supply.
• What is the maximum current that the SN74LS138NE4 can sink or source?
  The SN74LS138NE4 can sink up to 16mA and source up to 2mA per output pin, with a total current limit of 100mA for all outputs combined.
• How do I handle the enable inputs (E1, E2, E3) to ensure proper operation?
  The enable inputs (E1, E2, E3) must be connected to a valid logic level (either VCC or GND) to ensure proper operation. Floating or unconnected enable inputs can cause unpredictable behavior.
• What is the propagation delay of the SN74LS138NE4?
  The propagation delay of the SN74LS138NE4 is typically around 10-15ns, but it can vary depending on the specific application and operating conditions.