Power Supply Filter Capacitor Equation

Why the capacitor in your power supply filter is too big january 21 2016 by david williams the job of the capacitor in the output filter of a dc power supply is to maintain a constant dc value by removing as much power ripple as possible.

Power supply filter capacitor equation.

Depending on the power supply the smoothing capacitor is combined with other circuits. Regardless of the frequency with which the input voltage is applied a capacitor is used in order to reduce the remaining resistance after rectification. This large current may damage the diode and at the same time it causes greater heating of the power transformer resulting in decreased efficiency. A capacitive power supply usually has a rectifier and filter to generate a direct current from the reduced alternating voltage.

In the following section we will try to evaluate the formula for calculating filter capacitor in power supply circuits for ensuring minimum ripple at the output depending on the connected load current spec. Putting it to work a practical example. This is an assumption in cases where the capacitor is oversize it will be perhaps 80 but this is close enough for government work and not very critical. F input frequency of ac.

Because these capacitors have a dc value they are actually storing a lot of energy that never gets used. Simple shunt capacitor filter reduces the ripple voltage but increases the current through the diode. Where i load current. Probably the most widely used application of smoothing capacitors is the construction of power supplies.

C i 2 x f x vpp. L c filters power supply filters.