Author Topic: Lab Power Supply Turn ON and OFF Characteristics  (Read 7402 times)

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Offline KungFuJosh

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Re: Lab Power Supply Turn ON and OFF Characteristics
« Reply #75 on: October 10, 2024, 08:31:45 pm »
Here's the on and off characteristics of my v6.2 hw 3303X. As I mentioned in the other thread, there's no spike above the V&A settings when set above 30mA.

This is CH1. There's always a fast spike to ~29mA when the channel is activated.

Thanks,
Josh
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Offline KungFuJosh

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Re: Lab Power Supply Turn ON and OFF Characteristics
« Reply #76 on: October 10, 2024, 08:47:44 pm »
Similar performance with CH2.


Going back to my previous comment about Settings vs. Limits (since this is not actually limits that we're adjusting). I can set OCP to 30mA or whatever below the 40mA channel setting, and it will shut off the PSU output promptly after I activate it.

Thanks,
Josh
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Online Martin72

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Re: Lab Power Supply Turn ON and OFF Characteristics
« Reply #77 on: October 11, 2024, 02:08:47 pm »
Peaktech 6227

8V, 40mA, 47 Ohm Resistor.
LeCroy WS3024Z, Siglent CP6030.

Very controlled power-on process. When switching off, you can clearly see that an electrolytic capacitor discharges at the output of the power supply.
Remedy: mechanical switch between power supply and DUT.
« Last Edit: October 11, 2024, 08:31:12 pm by Martin72 »
 
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Offline radar_macgyver

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Re: Lab Power Supply Turn ON and OFF Characteristics
« Reply #78 on: October 12, 2024, 12:08:52 am »
Here are some plots from an Agilent U8001A. Load is 47 ohm non-inductive. MXO4 with RT-ZP11 probes. I set the voltage to 15V, with various current limits. At 500 mA, the supply was in CV mode, all others were CC. I toggled the on/off switch rapidly to see both rise and fall slopes. I noticed a glitch would sometimes show up, I captured one on the 500 mA setting, though it did happen at others too.

It seems quite well behaved, but I think this PS had killed a board I was testing due to transients during CC/CV switching.

edit: sorry, filenames say '10V' but the supply was set for 15V.
 

Offline thm_w

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Re: Lab Power Supply Turn ON and OFF Characteristics
« Reply #79 on: October 12, 2024, 12:29:54 am »
Here are some plots from an Agilent U8001A. Load is 47 ohm non-inductive. MXO4 with RT-ZP11 probes. I set the voltage to 15V, with various current limits.

But did you test the settings as specified in the OP... 8V and 40mA?
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Offline mhsprang

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Re: Lab Power Supply Turn ON and OFF Characteristics
« Reply #80 on: October 12, 2024, 09:48:04 am »
Here are some plots from an Agilent U8001A. Load is 47 ohm non-inductive. MXO4 with RT-ZP11 probes. I set the voltage to 15V, with various current limits.

But did you test the settings as specified in the OP... 8V and 40mA?
Thas it indeed important as on the R&S NGE 103 the problem disappears above 150 mA. This behaviour is all about low currents. My tests were all done at 10 mA, when testing (and frying) some LEDs.
 

Offline radar_macgyver

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Re: Lab Power Supply Turn ON and OFF Characteristics
« Reply #81 on: October 12, 2024, 06:43:08 pm »
But did you test the settings as specified in the OP... 8V and 40mA?
Ah crap, will re-do with those settings, that was at work so it'll be a couple of days. In the meantime, here's the results from my home bench, with a TTi MX100TP and a Siglent SDS2104X Plus. The 40mA test shows an overshoot, and interestingly, the overshoot behavior at higher current limits starts to show a pattern, its like the control loop stays in CV mode till the voltage reaches 2.5V before it switches to CC mode. I tried various ranges supported and they all showed the same behavior (this supply lets you internally combine its three outputs to create several ranges). No difference between the output channels either.
 
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Offline AVGresponding

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Re: Lab Power Supply Turn ON and OFF Characteristics
« Reply #82 on: October 13, 2024, 09:05:24 am »
HP 6633B here. Quite a bit slower to regulate than others:

nuqDaq yuch Dapol?
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Offline AndyC_772

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Re: Lab Power Supply Turn ON and OFF Characteristics
« Reply #83 on: October 13, 2024, 10:19:23 am »
I carried out quite a detailed investigation of this effect on the 6632B some years ago...

https://www.eevblog.com/forum/beginners/first-bench-supply-ripplenoise-problems/msg141522/#msg141522

Online tautech

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Re: Lab Power Supply Turn ON and OFF Characteristics
« Reply #84 on: October 13, 2024, 10:21:33 am »
Siglent SPS5042X < 40V 60A capable.
Set to 8V 40mA > 56 Ohm 10W < first to hand.....

Screenshots in this order:
Small step and some ripple at ON.
Clean ramp down at off.
Close in analysis of the power ON step.
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Offline AVGresponding

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Re: Lab Power Supply Turn ON and OFF Characteristics
« Reply #85 on: October 14, 2024, 05:21:51 am »
This appears to show the SPS5042X not going in to CC..?   :-//
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Online tautech

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Re: Lab Power Supply Turn ON and OFF Characteristics
« Reply #86 on: October 14, 2024, 05:36:17 am »
This appears to show the SPS5042X not going in to CC..?   :-//
;D
Study the V/div settings.  ;)
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Offline Kean

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Re: Lab Power Supply Turn ON and OFF Characteristics
« Reply #87 on: October 14, 2024, 05:45:56 am »
This appears to show the SPS5042X not going in to CC..?   :-//
;D
Study the V/div settings.  ;)

The first trace shows it exceeding 2.24V (40mA over 56ohms) for at least 40ms, and hitting the 8V CV setting.
The second trace (ramp down at power off) shows it was eventually in CC mode, but you don't show a longer timescale from power on to see it going from CV to CC mode.
It also looks like it was in CC at about 2.4V so probably closer to 45mA than 40mA.
 
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Online tautech

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Re: Lab Power Supply Turn ON and OFF Characteristics
« Reply #88 on: October 14, 2024, 05:57:35 am »
This appears to show the SPS5042X not going in to CC..?   :-//
;D
Study the V/div settings.  ;)

The first trace shows it exceeding 2.24V (40mA over 56ohms) for at least 40ms, and hitting the 8V CV setting.
The second trace (ramp down at power off) shows it was eventually in CC mode, but you don't show a longer timescale from power on to see it going from CV to CC mode.
It also looks like it was in CC at about 2.4V so probably closer to 45mA than 40mA.
OSD = 44mA
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Offline mawyattTopic starter

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Re: Lab Power Supply Turn ON and OFF Characteristics
« Reply #89 on: October 14, 2024, 04:00:27 pm »
Rob,

We agree with Kean.

This looks as if the CC is attempting in the 1st graph at ~5V, but voltage across 56Ω resistor continues up to 8V which is Voltage setting. If true CC Mode were active, then the voltage across the 56Ω resistor would limit at 40ma*56Ω = 2.24V and not continue to 8V.

Edit: Added response with 56Ω Resistor with SPD3303X, showing voltage across resistor. Note how the response approached the CC Setting of 40mA as set (2.24V across R) with the CV is set to 8V.

Can you rerun this 1st plot with time scale at 50ms/div (or longer if necessary) to show the supply output returning to the proper CC set to 40mA*56Ω or 2.24V?

Best,
« Last Edit: October 14, 2024, 05:01:22 pm by mawyatt »
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Offline David Hess

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Re: Lab Power Supply Turn ON and OFF Characteristics
« Reply #90 on: October 14, 2024, 06:11:16 pm »
Here are the waveforms for a Tektronix PS503A power supply set for 8 volts and 80 milliamps.  This power supply has 50 microfarads of output capacitance.  The output control switch operates by controlling the reference.  Neither the voltage or current control loops are clamped.

The current waveform had some variation so I recorded multiple examples with my DSO set to accumulate them.  The peak excursion with current limiting was 1 volt higher than the nominal 4 volt output into 50 ohms.  I have no idea why this variation exists.
 

Offline radar_macgyver

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Re: Lab Power Supply Turn ON and OFF Characteristics
« Reply #91 on: October 14, 2024, 06:32:45 pm »
Startup for the Agilent U8001A again, this time with 8V and 40mA settings. The only 'odd' thing I see is the fast rise to ~250 mV before the much slower rise to the final 2V. The behavior is similar on other current limit settings and in constant voltage mode.
 
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Online Aldo22

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Re: Lab Power Supply Turn ON and OFF Characteristics
« Reply #92 on: October 17, 2024, 01:11:34 pm »
Fnirsi DPS-150

Nice behavior when switching on and off with the button, but full 8V at the beginning if you just plug in the cable.

 

Offline BennoG

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Re: Lab Power Supply Turn ON and OFF Characteristics
« Reply #93 on: October 17, 2024, 02:08:15 pm »
Fnirsi DPS-150
Nice behavior when switching on and off with the button, but full 8V at the beginning if you just plug in the cable.

The hard cable connection is expected because the PSU has some capacitors that needs to be discharged before current limiting can start.

Benno
 
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Online Aldo22

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Re: Lab Power Supply Turn ON and OFF Characteristics
« Reply #94 on: October 17, 2024, 02:30:31 pm »
The hard cable connection is expected because the PSU has some capacitors that needs to be discharged before current limiting can start.

Thank you.
I don't know how other "better" PSUs behave.
Anyway, you should keep in mind that you are probably not absolutely safe from overcurrent if the connection is interrupted for a short time.
« Last Edit: October 17, 2024, 02:44:40 pm by Aldo22 »
 


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