Re: LDO at full load
Hi
You said that You have designed a LDO regulator, I'm guessing from discreete component. That could be tricky. There are few configuration. The most common one is with use of PNP transistor, in operation with common emiter. That means in order to control the emiter current your Base potencial will be lover than emiter. In LDO any of the intermadiate control voltages cannot be abowe the input voltage.
In your case could be that your gain of transistor is not enought, simple use a darlington transistor and see what happen.
The best would be if you can use monolitic LDO regulator, there are plenty of those on the market.
Arek