Which factor is directly related to dynamic power but not static?

Which factor is directly related to dynamic power but not static?

• A. Leakage.
• B. Idle state length.
• C. Temperature.
• D. Switching activity.

Answer: (D)

Dynamic power comes from charging and discharging the capacitive loads as signals toggle. The energy per transition is tied to the load, voltage, and frequency, but how much energy is used overall in a given period depends on how often those transitions happen. That is captured by switching activity—the average fraction of gates that switch per clock cycle. So, as switching activity increases, dynamic power rises directly and predictably. Leakage is static power: it flows even when nothing is switching, and it’s mainly governed by temperature and device leakage characteristics, not by how often the circuit toggles. The length of the idle state can influence how many transitions occur (and thus dynamic energy), but the fundamental, direct factor that links to dynamic power is switching activity. Temperature can affect leakage and device behavior, but it’s not the direct driver of dynamic power in the same way.

Dynamic power comes from charging and discharging the capacitive loads as signals toggle. The energy per transition is tied to the load, voltage, and frequency, but how much energy is used overall in a given period depends on how often those transitions happen. That is captured by switching activity—the average fraction of gates that switch per clock cycle. So, as switching activity increases, dynamic power rises directly and predictably.

Leakage is static power: it flows even when nothing is switching, and it’s mainly governed by temperature and device leakage characteristics, not by how often the circuit toggles. The length of the idle state can influence how many transitions occur (and thus dynamic energy), but the fundamental, direct factor that links to dynamic power is switching activity. Temperature can affect leakage and device behavior, but it’s not the direct driver of dynamic power in the same way.