Author Topic: SPD3303X stability  (Read 659 times)

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Offline mawyatt

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SPD3303X stability
« on: November 06, 2020, 03:16:57 pm »
Been considering the SPD3303X to replace my aging EMCO linear supply and also use as a somewhat precision variable voltage source. So interested in things like measured stability, noise levels and such. I didn't see anything in the data sheet that indicated small temperature change (+-10C) performance around room temperature.

Noted during Dave's teardown, what was Siglent thinking by using non-standard plug spacing :palm:  but also on the + side they are using the AD7792 24 bit ADC & PGA and a decent reference voltage source. If these are utilized in the direct control of the output I suspect the stability & temperature performance should be pretty good.

Anyway, I know this is a "Power Supply" but seems it potentially could be good enough to consider use as a moderately accurate and stable variable voltage reference, thus my inquiry.

Best, 
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Online tautech

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Re: SPD3303X stability
« Reply #1 on: November 06, 2020, 07:56:02 pm »
Tapped secondaries and a smart fan makes for quiet use. Essentially completely quiet at low loads.

Sold a good few over the years and just that one has had a problem....operator induced !
A customer popped a channel while powering a motor and trying to do regenerative braking without a protection diode .....but he is a young bloke and learnt that lesson: how high can back EMF go...as high as it needs to until something breaks down !  :-DD

Member HendriXML has had some fun with his:
https://www.eevblog.com/forum/testgear/battery-charging-using-a-siglent-sds1104x-and-spd3303x/
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Offline mawyatt

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Re: SPD3303X stability
« Reply #2 on: November 06, 2020, 08:27:00 pm »
Good info, thanks :-+

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike
 

Offline maginnovision

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Re: SPD3303X stability
« Reply #3 on: November 06, 2020, 08:59:07 pm »
Just recently my unit failed to manage CC where my other power supplies did not so I'd recommend getting one to try before you buy.
 
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Offline mawyatt

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Re: SPD3303X stability
« Reply #4 on: November 06, 2020, 09:02:27 pm »
Just recently my unit failed to manage CC where my other power supplies did not so I'd recommend getting one to try before you buy.

Not sure I understand what you are saying here, could you please provide more details?

Thanks,

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike
 

Offline maginnovision

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Re: SPD3303X stability
« Reply #5 on: November 06, 2020, 09:35:24 pm »
I connected the output of channel 1 or 2 to a MAX 60W 12V DC load. It can accept 12V/5A or any lower current with no issues. It can also accept up to 24V also up to 60W.

Rather than cut voltage back it would drop to 0V once it hit 3.2A and reset. So back to 12V and 0 A. Ramp to 3.2A then V drops to 0V and resets. None of my other power supplies exhibited the same behaviour.

As far as being a reference... I don't think so. Even using it as the supply for my LTZ1000 or even my DMMCheck was visible in the recordings but I don't know what you're looking for in terms of performance.
« Last Edit: November 06, 2020, 09:39:23 pm by maginnovision »
 

Offline mawyatt

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Re: SPD3303X stability
« Reply #6 on: November 07, 2020, 02:10:04 am »
Thanks for the explanation on the way it works, agree that is not Constant Current as I would have thought where the voltage is modulated to keep the current constant within a max voltage level.

Wasn't thinking about LTZ1000 or LM399 performance levels, but if your seeing effects using this as a supply for the LTZ1000 that's something to consider, as well as if it's not good enough for just a quick DMM validation where it just needs to maintain a voltage at a fixed level and not drift or have too much noise. I recall some old lab power supplies we had while I was working that could be dialed to levels of 10uv out of 10 volts, were very low noise and stable, so was hoping for something along these performance levels, maybe at the mv level.

The specs don't say much about short or long term drift, or temperature performance, so don't have much to go on. The use of the mentioned 24 bit ADC and a good reference one would think should produce a stable output. 1mv out of 32V is only 15 bits resolution, well within the capability of the ADC.

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike
 

Online tautech

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Re: SPD3303X stability
« Reply #7 on: November 07, 2020, 04:47:10 am »
I connected the output of channel 1 or 2 to a MAX 60W 12V DC load. It can accept 12V/5A or any lower current with no issues. It can also accept up to 24V also up to 60W.

Rather than cut voltage back it would drop to 0V once it hit 3.2A and reset. So back to 12V and 0 A. Ramp to 3.2A then V drops to 0V and resets. None of my other power supplies exhibited the same behaviour.
Nor should a SPD3303X-E.

SPD3303X-E firmware version please ?

12V halogen headlight lamp with both filaments in series draws 3.1A @ 12V and SPD3303X-E goes into CC with a 13V setting.
FW version  V1.01.01.02.05

Mucked around for ages with a falling trigger trying to discover your drop to 0V and there isn't one !
Even with a single shot trigger set barely below the output voltage captures of any significant voltage foldback where unable to be captured. A play with Normal triggering didn't prove anything either, certainly nothing repeatable or consistant so I'm calling BS on your reset to 0V.

Of the many attempts to capture bad CC behaviour this is the very worst I could manage which is hardly a foldback and die:

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Offline maginnovision

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Re: SPD3303X stability
« Reply #8 on: November 07, 2020, 05:31:18 am »
I'll get you the FW version when I have a chance.

EDIT: FW 1.01.01.02.05. HW 3.0. In about a week when tests are done I can make you a video. Until then the DUT can't be touched.
« Last Edit: November 07, 2020, 06:06:15 am by maginnovision »
 
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Offline mawyatt

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Re: SPD3303X stability
« Reply #9 on: November 07, 2020, 08:43:19 pm »
If someone has the SPD3303X or -E  PS could I request you setup a test to supply say 10.000VDC and maybe 1.000VDC with no load and monitor the voltage & noise with a good hi res DMM over an hour or so to see how much it drifts and how much output noise unloaded (maybe look with a DSO). If you have the time and want to also load the supply with a very heavy load to increase the internal temperature, then remove the load and repeat the above test to see how the voltage stabilizes as the temperature slowly returns to normal.

Thanks in advance for any help,

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike
 

Online 2N3055

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Re: SPD3303X stability
« Reply #10 on: November 08, 2020, 12:39:22 am »
I don't have Siglent PSU, but here is Rigol DP831, set to 12V. No load, about 55 mins, temp was around 23C.
Histogram in attachment.
 
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Offline doppelgrau

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Re: SPD3303X stability
« Reply #11 on: November 15, 2020, 04:14:32 am »
Didn't look at the clock, guess was about 20-30 minutes each for the SPD3303X-E. Sigent SDM3055 measured it.
For comparison a few minutes a SPF1168X. Hope that helps.

Edit: Removed the screenshots from the Rigol, that noise seems to have an other source, a test with the power supply disconneted showed similar results.
« Last Edit: November 15, 2020, 10:50:50 am by doppelgrau »
 
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