The above equation can be transformed into another equation to get a ripple current value in accordance with the frequency of the rated ripple current, each of ESRf1, ---ESRfn is approximately equal to ESRfo divided by square value of the frequency multiplier (Ff1---Ffn). Here ESRfo is the value at the frequency of the rated ripple current and Ff1---Ffn is a conversion coefficient from one frequency to another in accordance with the frequency f1---fn. ESRf1 = ESRfo / (Ff1)2 … …
ESRfn = ESRfo / (Ffn)2
Relationship of W = (IRipple)2 * RESR leads IX as following:
IX = √W/ESRfo
The above is rewritten in the following equation:
IX = √(If1/Ff1)2 + (If2/Ff2)2 + …… (Ifn/Ffn)2
Where:
IX = Ripple current in accordance with the frequency of
the rated ripple current
If1……Ifn = Operating ripple currents at every frequency f1……fn
Ff1……Ffn = Frequency multipliers for every frequency f1……fn
prescribed in the catalog, based on the fact that the internal
resistance of a capacitor varies with frequency.