Electronics > Projects, Designs, and Technical Stuff
Lab Power Supply - The Lost Current
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C:

Think of a load like a esp32, sleep, running & transmit.
very fast change and too much drop and big problems.

Todays loads change very fast, and you need to test the dynamics  of the supply. Lack of fast change leads to larger cap across output which is bad for CC mode
xavier60:
This is a load transient test I did at 3A while the output capacitor was 1uF. The voltage dip on the top trace is upside down because I am measuring everything with respect to the + output.
This response is comparable to that of my U8002A, and I suspect that it has a 100uf output capacitor. I wish I could be certain about this.
C:

A transient lets things settle.

To know what you have, you need to test with repeated changes.

So what I see in picture is a slow response.
xavier60:

--- Quote from: C on March 01, 2018, 01:57:50 am ---
A transient lets things settle.

To know what you have, you need to test with repeated changes.

So what I see in picture is a slow response.

--- End quote ---
Keep in mind that I tested my regulator with only 1uF on the output.
This is the same test done on my Agilent U8002A, a well respected model.
I think it would be very difficult to get it much faster than this.
Maybe the new op-amps will help.
xavier60:

--- Quote from: C on February 27, 2018, 03:02:10 pm ---If you look at that HP supply you will see a whole bunch of differential connected op amps.

And you can create a dual differential mixer using an op amp
I call this a mixer as used in audio but it is actually a summer.

Think differential output -  differential reference.

In addition to working it also lowers noise some.

--- End quote ---
The ORing is done in a clever way in the U8002A. The CC op-amp,IC9, can take control of the CV op-amp,IC8, via D42 to pin 8. Pin 8 is one of the op-amp's compensation pins that provides a connection to the point where the transconductance amplifier's output connects to the input of the output stage.
So in both CV and CV modes, IC8's output has full source/sink control of the Gate.
http://d1.amobbs.com/bbs_upload782111/files_39/ourdev_638271E5Q049.pdf
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