DC-DC recomendations for PMA5-83-2W+ sequencer

Current peaks will depend on the slew rate or RdsOn of the source and effective load capacitance. Ripple voltage will depend on the impedance ratio and spectral content.

You have the LTC1261 driving some unknown 1 uF and 100 pF caps

A low ESR Cap will typ. have Tau = 0.5 to 10 us results.
For 1uF tells me ESR specs will be 0.5 to 10 ohms.
Using my formula f-3dB= 0.5/Tau = 1 MHz to 100 kHz

Using C0G/NP0 100 pF cap data from Murata's GRM series;
These low ESR ceramic caps have a minimum 200 mohms at 280 MHz.
Since the charge pump has no spectrum at this frequency it is useless for absorbing ripple.


Source ESR could be the open cct V / short cct current that limits output current.
The 100 pF NP0 cap would be useful if the driver resistance degraded to approach the ESR of the bulk 1uF cap then the lower ESR ceramic cap can shunt momentarily.

The "logic" required is to judge the spectrum of the ripple to be impeded and the impedance ratio of each cap relative to the source to understand the benefit..