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Lab Power Supply Turn ON and OFF Characteristics

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Furna:

--- Quote from: mawyatt on October 07, 2024, 02:57:02 pm ---With the new Siglent SPD4000 series we find it interesting that the results from CH1 and CH2 are different wrt to the conditions discussed here as shown by Furna. We don't see this with the older SPD3303X as both channels behave the same as expected!! Also, haven't seen any post that indicate other supplies have different behavior with 2 main channels with same specs as one would "expect" the detailed design and implementation of the channels would be identical. 

Would be interesting to find out why, as this is quite puzzling?

Best

--- End quote ---

For whom is not following the Siglent SPD4000 series thread, my measurements of Siglent SPD4121X are available at
https://www.eevblog.com/forum/testgear/new-siglent-spd4000x-series-power-supply/msg5667709/#msg5667709
https://www.eevblog.com/forum/testgear/new-siglent-spd4000x-series-power-supply/msg5667823/#msg5667823

Siglent SPD4000 series has 4 channels that are inerhently different ...
SPD4121X in particular has
CH1-CH4 15V 1.5A are independent
CH2-CH3 12V 10A can be setup in series/parallel and both also have 4wire sense

Antonio90:
A few measurements from the GPD-4303S and the Yokogawa 7651 DC source.

Please note, all measurements done with standard 10X probes, and 8v 40mA, except channel 4 from the GPD, which only goes to 5.2V.
Resistor measured at around 54.17 Ohms.

Edit: The math trace is the current at 20mA/div (i think it is pink?)

_Wim_:
A few of the power supplies I own (for the fast ones, I also added a 2ms timebase). Test with 50ohm resistor / 8V / 40mA. Interesting is the GS200, which can work in current mode and voltage mode.

Martin72:

--- Quote from: nctnico on October 06, 2024, 11:07:20 pm ---1) The on/off button isn't driving a relay but simply forces the output voltage setting to 0 at the point where the setpoint is fed into the output stage. I have modified quite a few power supplies to add this feature. Simply short the voltage control potmeter to ground to disable the output using a toggle switch. But in a digitally controlled PSU it is a simple matter of having the DAC which drives the output stage output 0V. Same principle though.

2) The rapid discharge effect you are describing is a parallel power sinking circuit (Keysight calls this a downprogrammer https://docs.keysight.com/kkbopen/66xxa-down-programming-589741416.html) which kicks in when the output voltage is higher than then setpoint voltage. So when an output is switched off, this circuit will kick in because the output voltage is higher than the setpoint. But it will also kick in when power is fed into the power supply. Attach a fan and turn the output on / off. Chances are you see the current becoming negative due to the sink circuit absorbing the power from the fan while it is spinning down and working as a generator. However, this feature is not available in all power supplies so you need to check the specs. A way to tell whether a PSU has a sink circuit is when the voltage fall settling times are specified as well.

--- End quote ---

Regarding 2):
I may have expressed myself a little misleadingly (or the translator).
I actually wanted to explain how most of the off-state images here come about, using a practical test example on an assembly.
Be that as it may, I may get around to adding a few pictures of this this week, but of Peaktech power supplies... ;)

mawyatt:

--- Quote from: Furna on October 07, 2024, 04:57:00 pm ---
--- Quote from: mawyatt on October 07, 2024, 02:57:02 pm ---With the new Siglent SPD4000 series we find it interesting that the results from CH1 and CH2 are different wrt to the conditions discussed here as shown by Furna. We don't see this with the older SPD3303X as both channels behave the same as expected!! Also, haven't seen any post that indicate other supplies have different behavior with 2 main channels with same specs as one would "expect" the detailed design and implementation of the channels would be identical. 

Would be interesting to find out why, as this is quite puzzling?

Best

--- End quote ---

For whom is not following the Siglent SPD4000 series thread, my measurements of Siglent SPD4121X are available at
https://www.eevblog.com/forum/testgear/new-siglent-spd4000x-series-power-supply/msg5667709/#msg5667709
https://www.eevblog.com/forum/testgear/new-siglent-spd4000x-series-power-supply/msg5667823/#msg5667823

Siglent SPD4000 series has 4 channels that are inerhently different ...
SPD4121X in particular has
CH1-CH4 15V 1.5A are independent
CH2-CH3 12V 10A can be setup in series/parallel and both also have 4wire sense

--- End quote ---

That's unusual that CH1 and CH4 are the same and CH2 and CH3 are the same but different from CH1 and CH4, this explains the difference since CH1 (15V 1.5A) is not the same specification as CH2 (12V 10A) and thus one might expect a different response from such!!

Now looking at the Siglent page for the SPD4121X shown, this arrangement looks OK with terminals for CH1 logically on left then the channels proceed to right as 2 thru 4 (not like GPP 4323 where Instek placed CH4 on left, then 2 thru 4 1 thru 3 towards right  :o

The 4000 display shows 1 to 2 top and 3 to 4 below left to right which makes sense, however because of the arrangement the similar channels are diagonal not left to right as one would expect!!

Imagine using a typical analog supply arrangement of +-15V (or +-12V), then the important display channel parameters (V and I) are diagonal not left to right for the active channels. So glancing at the active channels in this common use case requires determining the individual channel parameters on diagonals rather than side by side!!

This makes no sense IMO, would like to hear the logic behind this arrangement from Siglent designers!!!

https://siglentna.com/power-supplies/spd4000x-series-programmable-linear-dc-power-supply/

Best,

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