The ripple current in the output caps is a significant compared to the output current in a buck convertor running in current mode with a not too large output inductor in fact the peak to peak ripple current could be say 30 of the output current in this orthodox setup so at 40 amps dc you need caps to handle almost 7 amps peak now the approx.
Ceramic capacitor rms current.
A note of caution.
Equation 2 calculates the root mean square rms value of the ripple current.
The rms value of the peak to peak ripple voltage can be calculated from the equation.
There is no allowable current ripple specification for ceramic capacitors but you should carefully follow the points below and confirm them in the actual circuit before use.
The selected ceramic capacitors must also meet the ripple current limitation.
Capacitors ceramic capacitors multilayer ceramic chip capacitors mlcc with dipped radial lead.
For this reason this parameter is usually measured at room temperature.
Given that i o 12a δipp 3 625a and d 10 the rms value of the input ripple is 3 615a rms.
The ripple current of ceramic capacitor varies depending on the temperature of operation.
Ceramic capacitors operating at higher temperatures have less ripple current capability compared to those operating at lower temperatures.
Vrms vpp 1 2 2 the ripple current in the capacitor can then be calculated by applying ohm s law if the capacitor s esr is known.