Power Regulator capacitors

[bunrockter]

When looking at reference designs for power regulators (LDO/Linear, switching, etc.) why are the input and ceramic output capacitors generally a 1206 case size? I can find a capacitor that is 0402 or 0603 with the same/similar voltage and ESR, the only difference I see is the temperature (X5R Vs. X7R).

The chip that I am looking at specifically calls out an 0805 P/N as an example in the datasheet, and the reference board that uses it populated a 1206 P/N. I found a 0603 that has the same ESR and the rated voltage is a little less but is still 4x more than the output voltage.


Thanks.

 

[D.A.(Tony)Stewart]

As I recall;
the smaller the part, the higher the SRF for ceramic caps, but also geometry of MLM is a big factor, layers and stack orientation.
Choose types for SMPS rated for such with ESR or ripple current and never Gen Purpose.

Size may affect heat loss rating but also ESL

>=1206 for >=1kV and more ripple current, less leakage
<=805 for VHF,
<=603 for UHF , microwave

bigger parts tend to have higher voltage ratings and lower ESR with cheaper materials.