Switching Regulator Efficiency Calculator Formula
Understand the math behind the switching regulator efficiency calculator. Each variable explained with a worked example.
Formulas Used
Input Power
input_power_w = v_out * load_current_a / eff_fractionInput Current
input_current_a = v_out * load_current_a / (eff_fraction * v_in)Power Lost
power_lost_w = v_out * load_current_a / eff_fraction - v_out * load_current_aVariables
| Variable | Description | Default |
|---|---|---|
v_in | Input Voltage(V) | 12 |
v_out | Output Voltage(V) | 3.3 |
load_current_a | Output Current(A) | 2 |
efficiency_pct | Efficiency(%) | 90 |
eff_fraction | Derived value= efficiency_pct / 100 | calculated |
How It Works
Switching Regulator Efficiency
Formulas
P_in = P_out / Efficiency
I_in = P_out / (Efficiency x V_in)
Switching regulators convert voltage using rapid switching and an inductor. They achieve 85-95% efficiency regardless of voltage ratio, far better than linear regulators for large step-downs.
Worked Example
12 V to 3.3 V at 2 A with 90% efficiency.
v_in = 12v_out = 3.3load_current_a = 2efficiency_pct = 90
- 01P_out = 3.3 x 2 = 6.6 W
- 02P_in = 6.6 / 0.9 = 7.33 W
- 03I_in = 7.33 / 12 = 0.611 A
- 04Power lost = 7.33 - 6.6 = 0.73 W
Ready to run the numbers?
Open Switching Regulator Efficiency Calculator