SNVS953G December 2012 – May 2021 LM25018
A simplified waveform for secondary output current (IOUT2) is shown in Figure 8-7.
The secondary output current (IOUT2) is sourced by COUT2 during on-time of the buck switch, TON. Ignoring the current transition times in the secondary winding, the secondary output capacitor ripple voltage can be calculated using Equation 29.
For a 1:1 transformer turns ratio, the primary and secondary voltage ripple equations are identical. A COUT2 value of 2.2 μF is selected for this design example.
If lower output voltage ripple is required, a higher value must be selected for COUT1 and COUT2.