Add a decoupling capacitor from
VCC to GND. The capacitor needs to be placed physically close to
the device and electrically close to both the VCC and GND pins. An
example layout is shown in the Layout section.
Ensure the capacitive load at the
output is ≤ 50 pF. This is not a hard limit; it will, however, ensure optimal
performance. This can be accomplished by providing short, appropriately sized
traces from the SN74LV138A to one or more of the
receiving devices.
Ensure the resistive load at the
output is larger than (VCC / IO(max)) Ω. This will ensure
that the maximum output current from the Absolute Maximum Ratings is not
violated. Most CMOS inputs have a resistive load measured in MΩ; much larger
than the minimum calculated previously.
Thermal issues are rarely a
concern for logic gates; the power consumption and thermal increase, however,
can be calculated using the steps provided in the application report, CMOS
Power Consumption and Cpd Calculation.