what kind of feedback topology does LDO circuit act?

[Josephchiang]

Dear all,

I was confused that what kind of feedback topology does LDO circuit act.

I think that the error amplifier sense the feedback voltage from resistor dividers and judge the output voltage going either larger or less by compare the sensed voltage with reference voltage.So the topology should be series-shunt feedback.

But something weird is that the power MOSFET supply current to output loading.

The feedback block of resistor divider seems weird to sense the output current provided by power MOS.

How to illustrate the weird thing?

Am I right? Please correct me if I am wrong.

Any help is sincerely appreciate.

 

[shar2013]

LDO feedback is series-shunt samples voltage and returns voltage. The output stage MOS current goes of course to the load. Think of it as a capacitor which the load drains and the LDO fills. The voltage sense determines if the
you need to increase/decrease the charge "flow".

 

[Josephchiang]

Good illustration.

Thanks a lot.