Power Supply Ripple Calculator Formula

Understand the math behind the power supply ripple calculator. Each variable explained with a worked example.

Use the Power Supply Ripple Calculator

Formulas Used

Ripple Voltage (Vpp)

ripple_vpp = load_current_a / (cap_farads * frequency_hz)

Ripple Voltage (Vrms)

ripple_vrms = load_current_a / (cap_farads * frequency_hz) / (2 * sqrt(3))

Variables

VariableDescriptionDefault
load_current_aLoad Current(A)1
filter_cap_ufFilter Capacitance(µF)1000
frequency_hzRipple Frequency(Hz)120
cap_faradsDerived value= filter_cap_uf / 1000000calculated

How It Works

Power Supply Ripple

Formula

V_ripple = I_load / (C x f)

Where f is the ripple frequency (120 Hz for full-bridge rectifier on 60 Hz mains). Larger capacitance or lower current reduces ripple.

Worked Example

1 A load, 1000 uF filter cap, 120 Hz ripple (full-bridge on 60 Hz).

load_current_a = 1filter_cap_uf = 1000frequency_hz = 120
  1. 01C = 1000 / 1000000 = 0.001 F
  2. 02V_ripple = 1 / (0.001 x 120) = 8.33 Vpp
  3. 03V_rms = 8.33 / (2 x 1.732) = 2.406 V

Ready to run the numbers?

Open Power Supply Ripple Calculator