Siglent SPD3303X-E PSU Constant Current Bug or Fault? - Page 1
Forum section: electronics / repair

author: t1d
author_rank: Super Contributor
timestamp: October 08, 2023, 06:25:00 pm
content: I have always thought that my Siglent PSU had various glitches. I think I may have identified one, while testing a Joule Thief.Model = SPD3303X-E (Not modified)Current Software = V1.01.01.03.10 ADSSerial Number = SPD3XHBX3R1089Purchased November 2019Setup- The circuit was powered with Ch1 of my Siglent PSU.- The Constant Current was set @ 0.01A/10mA.- The Voltage was swept between 0.5V and 1.5V.- DUT = Joule Thief with a Red LED. I forget the LED’s Vf and If; sorry.The Joule Thief illuminates its Red LED at 0.6V. At 0.7V, the Constant Current engages. Here's where the glitch occurs.In the transition to Constant Current, the Red DUT LED flashes more brightly, for a moment. So, my guess is that the DUT is seeing some unbridled voltage and/or current. (This is not good.) This is repeatable and consistent. I can't remember, if I tried CH2. Is this a known problem?I can’t imagine that the Joule Thief has anything to do with the problem. But, maybe? Back EMI being created by the transition?Obviously, more research and testing is required. The Joule Thief circuit should be removed from the equation. Channel 2 should be confirmed. Do you have any other testing protocol suggestions?What simple test circuit do you suggest? Just a LED and a current limiting resistor?Thank you for your help!

author: t1d
author_rank: Super Contributor
timestamp: October 08, 2023, 06:45:30 pm
content: Here's the Joule Thief schematic, if it is of any help...

author: 2N3055
author_rank: Super Contributor
timestamp: October 08, 2023, 10:10:46 pm
content: Power supply has large capacitor on output. CC circuit cuts in but capacitor needs to discharge..If you want to model the battery with PSU you also need to insert serial resistance between PSU and load to mimic internal impedance of battery..

author: tautech
author_rank: Super Contributor
timestamp: October 09, 2023, 01:56:23 am
content: Quote from: t1d on October 08, 2023, 06:25:00 pmHW version ?FYI, FW V1.01.01.03.10 release notes:1. This firmware version only supports V6.1 hardware version of SPD3303X /X E

author: electr_peter
author_rank: Unknown
timestamp: October 09, 2023, 03:08:59 pm
content: Why do you think brighter LED means that there is a fault/bug in PSU? How does voltage & current looks on oscilloscope?From what is described, you have a very dynamic load which triggers current limit on PSU in burst which in turn affects load.This does not indicate bug or fault with PSU (yet).Quote from: 2N3055 on October 08, 2023, 10:10:46 pmGood advice. If OP expects PSU to work as a battery, add resistor in series. Then it will behave more like a battery and mask PSU non-ideal aspects (reaction delay, output capacitance, current overshoot etc.).PSU current limit functionality can simply be tested by shorting leads or using resistors. Or add resistor in series and then short the outputs and check it on s scope as well.

author: t1d
author_rank: Super Contributor
timestamp: October 10, 2023, 04:37:58 am
content: Quote from: 2N3055 on October 08, 2023, 10:10:46 pmThank you so much, 2N3005! This makes me feel much better. It explains the effects that I am seeing and means that there is likely not a problem, at all. I will try the resistor and the additional tests suggested by others.

author: t1d
author_rank: Super Contributor
timestamp: October 10, 2023, 04:42:59 am
content: Quote from: tautech on October 09, 2023, 01:56:23 amThanks, tautech! I was hoping that you would help me!You are correct; my apologies. I got the SW# from my computer files, not from my PSU. Now that you point out the hardware discrepancy, I remember encountering this, the last time I updated.The correct information is:SW# = 1.01.01.02.05HW# = V3.0Thank you.

author: t1d
author_rank: Super Contributor
timestamp: October 10, 2023, 04:46:05 am
content: Quote from: electr_peter on October 09, 2023, 03:08:59 pmThank you, electr_peter, for the additional test methods. I will give them a try.

author: tautech
author_rank: Super Contributor
timestamp: October 10, 2023, 06:17:15 am
content: Quote from: t1d on October 10, 2023, 04:42:59 amThen most recent for yours is V1.01.01.02.07R2https://int.siglent.com/upload_file/zip/firmware/Power_Supply/SPD3303X-E_V1.01.01.02.07R2_EN.zip

author: t1d
author_rank: Super Contributor
timestamp: October 10, 2023, 07:26:23 am
content: Quote from: tautech on October 10, 2023, 06:17:15 amThanks, tautech! I will get that updated.Not to highjack my own thread... lol But, my next step is to upgrade the PSU to "X." However, I am not much good on computers, so installing some of the needed programs is intimidating... NI-Visa and EasyPower... When I attempt it, I will post on the appropriate thread.

author: tautech
author_rank: Super Contributor
timestamp: October 10, 2023, 07:34:15 am
content: Quote from: t1d on October 10, 2023, 07:26:23 amYeah it's a PITA needing NIVISA and EasyPower just to update FW.Have a hunt for just NIVISA RUNTIME as its a much smaller download with only the connectivity drivers you need plus 1000's of others.Be sure to install any NIVISA package before connecting the PC to PSU or Windoze that thinks it knows best will auto-install its own drivers and not the ones you need.Consult the EasyPower install instructions for guidance and IIRC there's a link to NI Runtime within.

author: t1d
author_rank: Super Contributor
timestamp: October 10, 2023, 10:01:10 am
content: Quote from: tautech on October 10, 2023, 07:34:15 amThanks for these tips!Yep, this is all outside of my knowledge base. I finished installing EasyPower and NI-Visa (I think???,) while you were typing. I didn't know about the NI-Visa driver issues and just accepted the default settings. So, I need to investigate what drivers I ended up with.

author: tautech
author_rank: Super Contributor
timestamp: October 10, 2023, 06:44:27 pm
content: Quote from: t1d on October 10, 2023, 10:01:10 amNot really unless they are of interest.Just connect the PSU to PC and boot EasyPower and see how things go.The FW install notes guide you on the install.