Gate Drive Power⚠ unverified
Electrical / Power Electronics · Compute the gate drive power dissipation
Parameters
| Input | Symbol | Unit | Default | Description |
|---|---|---|---|---|
| Qg | Qg | C | 1.0 | Total gate charge |
| Vgs | Vgs | V | 1.0 | Gate-to-source drive voltage |
| f | f | Hz | 1.0 | Switching frequency |
| Output | Symbol | Unit | Description |
|---|---|---|---|
| result | P | W | Gate drive power dissipation, in watts (W) |
The science & history
Understanding the Parameters
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$Q_g$ — total gate charge from the datasheet at the chosen $V_{gs}$ (and often specified at a given $V_{DS}$). Includes $C_{iss}$ charge plus Miller (plateau) charge during the switching transition. Use the $Q_g$ for your drive voltage, not an arbitrary datasheet condition.
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$V_{gs}$ — peak gate voltage the driver applies (e.g. 10 V or 12 V for many Si MOSFETs; logic- level parts lower; some GaN drivers use 5–6 V).
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$f$ — switching frequency. Gate power scales linearly with $f$, which is why multi-MHz converters care about $Q_g$ even when conduction loss is small.
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$P$ — power drawn from the driver bias supply (for a simple push-pull driver that dumps gate energy resistively). Some resonant or energy-recovery drivers recover part of this energy.
Derivation (Approaching a Proof)
To raise the gate from 0 to $V_{gs}$, the driver must supply charge $Q_g = \int i_g\,dt$. The energy delivered by a constant-voltage gate supply during that charge is
$$E_{on} = Q_g\,V_{gs}.$$
(If the gate is a linear capacitor $C_{iss}$, then $Q_g = C_{iss}V_{gs}$ and $E = C V^2$, of which $\tfrac12 C V^2$ is stored on the gate and $\tfrac12 C V^2$ is lost in the series resistance — total drawn from the supply is still $C V^2 = Q_g V_{gs}$.) Discharging the gate on the next edge typically dissipates the stored energy in the pull-down path; for a full cycle the supply still provided $Q_g V_{gs}$ once per turn-on. At frequency $f$,
$$P = E_{cycle}\,f = Q_g\,V_{gs}\,f.$$
For complementary half-bridge drivers, count both devices (or use total $Q_g$ appropriately).
History
Gate-charge specifications and the $Q_g V f$ power estimate became standard as power MOSFETs replaced bipolars (no large continuous base current, but capacitive gate charge every cycle). Driver ICs and isolated gate-drive supplies are sized around this budget plus quiescent current.
Related Concepts: Switching Loss, Conduction Loss, Efficiency Total, Watt's Law
Notes: Registry calculator gate-drive-power (unverified). $Q_g$ in coulombs (1 nC = $10^{-9}$ C).
Simple model: no driver quiescent current, no overlapping cross-conduction in the driver stage.