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Keysight New instruments
EEVblog:
--- Quote from: bd139 on March 03, 2021, 09:23:25 pm ---Or just stuff a diode in series. :-//
--- End quote ---
That's what the manual tells you to do.
Unfortunately no external sense to compensate for the drop.
EEVblog:
--- Quote from: floobydust on March 03, 2021, 07:07:19 pm ---I think a decent PSU doesn't need OVP, it's supposed to be reliable lol. Put the money into a beefier pass-transistor and heatsink or backfeed-diode.
But here we have firmware and memory leaks which the OVP might need to cover.
I can't easily tell if the new PSU can source/sink (push-pull) output. It's likely just a source-only.
Is it an SCR crowbar? Must be.
--- End quote ---
The manual says is "program the output to zero", that implies software control of theo utput, not a real hardware crowbar.
nctnico:
--- Quote from: EEVblog on March 04, 2021, 12:03:23 am ---
--- Quote from: floobydust on March 03, 2021, 07:07:19 pm ---I think a decent PSU doesn't need OVP, it's supposed to be reliable lol. Put the money into a beefier pass-transistor and heatsink or backfeed-diode.
But here we have firmware and memory leaks which the OVP might need to cover.
I can't easily tell if the new PSU can source/sink (push-pull) output. It's likely just a source-only.
Is it an SCR crowbar? Must be.
--- End quote ---
The manual says is "program the output to zero", that implies software control of theo utput, not a real hardware crowbar.
--- End quote ---
No. Even on analog controlled PSUs (the HP 6012A for example) HPAK calles a current sink circuit a 'down programmer'. This circuit is intended to discharge the output capacitors in order to ramp the output voltage down in a controlled manner. Kind of a 2 quadrant operation.
If you look at the manual for the HP 6012A you'll notice that HP calls applying analog voltages to set the output voltage / current 'programming'. There is no software involved; it is all analog.
bdunham7:
--- Quote from: EEVblog on March 04, 2021, 12:03:23 am ---The manual says is "program the output to zero", that implies software control of theo utput, not a real hardware crowbar.
--- End quote ---
What is "the overvoltage condition"? Is it the output exceeding the set point by a certain amount or is it exceeding a fixed limit above the maximum output of the PSU?
If the former, then it must be at least partly software controlled, if not it could be a standalone circuit that triggers it. I assume there is no separate OVP control.
If 'program the output to zero' means the same thing as shorting it out (which is what they are warning about) then that implies that there is either a crowbar or that the main PSU outputs can sink current.
I'd sure like to know what the explanation would be for setting up a lab PSU in this manner.
SilverSolder:
I just looked at the manual for a supply designed by our ancestors (6200B) and it claims that back-powering it leads to "loss of regulation and possible damage to the output capacitor", presumably if you back-power it at a voltage that exceeds the rating of the capacitor...
So, a battery would just cause "loss of regulation", presumably. I guess our ancestors weren't so dumb?
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