agilent power supply

[electros6]

HI guys,
           I have post a part of the circuit from the agilent E3634 ser power supply. please tell me what is the P channel mosfet Q7 is doing here.

[prasimix]

I asked the same question some time ago (check here). From current perspective I'd like to say that is possibly added as a simple "down-programmer".

[dom0]

It is. Re. it's location is before the current shunt so as to not measure this quiescent current. This current serves some different purposes, including fast down-programming with light loads and better regulation with light loads, or when a heavy load is disconnected.

[sorin]

I think that is for drawing constant current,
the system will not stable with output current =0.

[bson]

Looks like a protective feature against reverse polarities on the terminals.  Like an inductive load, or a battery attached backwards, or the effects of a blown power rail cap.

[prasimix]

Looks like a protective feature against reverse polarities on the terminals.  Like an inductive load, or a battery attached backwards, or the effects of a blown power rail cap.

It employs reverse connected diodes for that...