Pull-down resistor caution: What is the primary concern when biasing an input with a pull-down resistor?

Introduction / Context:
Pull-down resistors bias an input to logic LOW when undriven. While useful, they can increase steady-state current draw and power loss, especially when the node is driven HIGH for significant time.

Given Data / Assumptions:

• VCC is present and the signal may be HIGH for long durations.
• Pull-down connects the node to ground through a resistor.
• Input leakage is small but nonzero.

Concept / Approach:
When the node is driven HIGH, current flows from VCC through the driver into the resistor to ground, dissipating power P = V^2 / R approximately (neglecting driver drop). Choosing too small a resistor leads to unnecessary power and thermal stress.

Step-by-Step Solution:

Verification / Alternative check:
Thermal check of resistor and supply current measurements validate the choice.

Why Other Options Are Wrong:

• Low power dissipation: The concern is the opposite—excess dissipation.
• Keeps a floating terminal LOW: That is a benefit, not a concern.
• False triggering: Possible with poor values, but the primary design worry is wasted power.

Common Pitfalls:
Copying pull-up values without considering asymmetry, using very small resistances, and ignoring battery life impacts.

Final Answer:
the high power dissipation of the resistor