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Lab Power Supply Turn ON and OFF Characteristics

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mahi:

--- Quote from: Furna on October 06, 2024, 08:19:11 pm ---Looking at the datasheet I realized this PSU has also sense wires; did you try using sense?
--- End quote ---

The sense terminals are always in use. In the HMP4040 they are connected to the output terminals via 1.5 kohm resistors inside the power supply. The only moment it makes sense to run separate sense wires to the DUT, is when losses in the wires are relevant. That is not the case in this test.

3isenhorn:
I love the idea of collecting some data, so here is my share:

1) Keysight E3640A

The control loop ramps up and then goes slowly to the limit. Since this supply has a low and high voltage mode (8V/20V), You see the results for turning on in low mode in Fig. 1 and for high mode in Fig. 2.

2) Agilent E3614A
Although similar in number, this has not a dedicated output  button. When the supply is turned on, the output is on.
When we turn on, as shown in  Fig. 3, we see some ripple below 0.5V in the beginning, due to the mechanical turn-on switch.
However, the control loop has a severe overshoot up to 6V for 116us, as shown in detail in Fig. 4.

3) Korad KD3005P

The supply also has no dedicated outpouring on/off. Which led to a  massive overshoot up to 8V and a small hick-up of around 0.2V in the beginning. As shown in Fig. 5.

Figs. 6, 7, 8 and 9 show the corresponding tune-off behavior, with nothing too special.

Hope this is helpful.

mhsprang:
Today I received a reply from Rohde & Schwarz: a UPS label and an RMA form to return the unit.

I replied that I won't be returning my PSU because the problem is not exemplary but a design error. I told them they can take any NGE100 or other model from their inventory and reproduce this problem.

I also included the links to both threads on this forum.

Whenever I hear more from them, I will post it here.

Furna:

--- Quote from: mahi on October 07, 2024, 04:57:54 am ---
--- Quote from: Furna on October 06, 2024, 08:19:11 pm ---Looking at the datasheet I realized this PSU has also sense wires; did you try using sense?
--- End quote ---

The sense terminals are always in use. In the HMP4040 they are connected to the output terminals via 1.5 kohm resistors inside the power supply. The only moment it makes sense to run separate sense wires to the DUT, is when losses in the wires are relevant. That is not the case in this test.

--- End quote ---

Thank you for your answer; next time I will also read better the datasheet and the manual  :)
Different brand's sense is implemented differently and can be enabled/disabled ...
Now the point is: what is the MCU doing before realizing it is time to lower the voltage?

mhsprang:

--- Quote from: Furna on October 07, 2024, 09:13:26 am ---
--- Quote from: mahi on October 07, 2024, 04:57:54 am ---
--- Quote from: Furna on October 06, 2024, 08:19:11 pm ---Looking at the datasheet I realized this PSU has also sense wires; did you try using sense?
--- End quote ---

The sense terminals are always in use. In the HMP4040 they are connected to the output terminals via 1.5 kohm resistors inside the power supply. The only moment it makes sense to run separate sense wires to the DUT, is when losses in the wires are relevant. That is not the case in this test.

--- End quote ---

Thank you for your answer; next time I will also read better the datasheet and the manual  :)
Different brand's sense is implemented differently and can be enabled/disabled ...
Now the point is: what is the MCU doing before realizing it is time to lower the voltage?

--- End quote ---

Sense wires have no effect in CC mode. The PSU drives a constant current into the load, no matter what the resistance is. Current flowing through a string of resistors is the same in every single resistor. The test leads are resistors in that chain.

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