SN74HC138DBR datasheet by Texas Instruments

SN74HC138DBR Frequently Asked Questions (FAQs)

• What is the maximum frequency of operation for the SN74HC138DBR?
  The maximum frequency of operation for the SN74HC138DBR is typically around 25 MHz, but it can vary depending on the specific application and operating conditions.
• How do I ensure that the SN74HC138DBR 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 and 10uF capacitors. Additionally, use a 10kΩ pull-up resistor on the enable pins (E1, E2, and E3) to prevent floating inputs.
• What is the maximum current that the SN74HC138DBR can sink or source?
  The SN74HC138DBR can sink or source up to 25mA of current per output pin, but it's recommended to limit the current to 10mA or less to ensure reliable operation.
• How do I handle the enable pins (E1, E2, and E3) to ensure proper operation?
  The enable pins (E1, E2, and E3) are active-low inputs. To enable the decoder, connect the enable pins to a logic low (GND) or use a pull-down resistor to ensure they are not floating. When the enable pins are high, the decoder is disabled.
• What is the propagation delay of the SN74HC138DBR?
  The propagation delay of the SN74HC138DBR is typically around 10-15ns, but it can vary depending on the specific application and operating conditions.