Question: about Imax of LDO design?

[twteng]

Hi
Most of papers relate to LDO design for SOC application which designing the Imax around 100mA or less ,
Does anybody know why it can't be larger? is it about stability issue or area concern?
thanks a lot.

 

[sijukrishnan]

I think the reason behind would be the general demerits of linear supply. Even the LDO does'nt have much drop-out(Vdo=Vin-Vout) voltage, in most of the cases, supplying to the SOC would be from 5V or 9V or 12V adaptor. Hence, to manage the extra voltage, the LDO should dissipate the extra power at the input as heat. To keep the junction temperature below absolute maximum of the LDO, thermal resistance should be very small. To make a low value thermal resistance type device, the package would be very huge which cannot be affordable by most of the designs employing an SOC. I believe this would be the reason, LDOs do not possess current more than 100mA, and hence designs.