Usually, bulk capacitors are placed on the output due to various reasons, such as uninterrupted operation during power interruption or micro-short at the input, holdup requirements for doing a memory dump before turning of the module, and filtering requirements as well. This design considers minimum bulk capacitors requirements for meeting functional status A during LV124 E10 test case 2 100-µs input interruption. To achieve functional pass status A, acceptable voltage drop in the output of LM74722-Q1 is based on the UVLO settings of downstream DC/DC converters. For this design, 2.5-V drop in output voltage for 100 µs is considered and the minimum holdup capacitance required is calculated by

Minimum holdup capacitance required for 1-V drop in 100 µs is 470 µF.