What describes dynamic power?

What describes dynamic power?

• A. Dynamic power is consumed during switching as capacitances charge/discharge.
• B. Static power is due to leakage.
• C. Power is proportional to temperature.
• D. Power is unrelated to circuit activity.

Answer: (A)

Dynamic power comes from the activity of charging and discharging load capacitors as signals toggle. Each switching event moves charge from the supply into the circuit and then dissipates that energy as heat when the capacitor is discharged through the transistors. The average power spent scales with how often switching occurs (the activity), the total capacitance being driven, and the square of the supply voltage, often summarized as P_dynamic ≈ α C_L V^2 f. That’s why describing dynamic power as being consumed during switching as capacitances charge and discharge is the best match. Static power, by contrast, comes from leakage currents when transistors are on, not from switching. Temperature affects leakage more than dynamic power, and while power generally increases with circuit activity, the dynamic component specifically ties to switching, not to temperature alone.

Dynamic power comes from the activity of charging and discharging load capacitors as signals toggle. Each switching event moves charge from the supply into the circuit and then dissipates that energy as heat when the capacitor is discharged through the transistors. The average power spent scales with how often switching occurs (the activity), the total capacitance being driven, and the square of the supply voltage, often summarized as P_dynamic ≈ α C_L V^2 f. That’s why describing dynamic power as being consumed during switching as capacitances charge and discharge is the best match.

Static power, by contrast, comes from leakage currents when transistors are on, not from switching. Temperature affects leakage more than dynamic power, and while power generally increases with circuit activity, the dynamic component specifically ties to switching, not to temperature alone.