Siglent SPD3303D review

[FrankBuss]

Looks like the SPD3303C is very similar. Some modes are missing, like the wave display or the timer, but if you just need a normal power supply, the LED panel should work, too. But the contrast and brightness of the display of the SPD3303D is very good, so it is a matter of taste, if you prefer good old LED digits.

[g0hjq]

Thanks for the review Frank,

I've just received my SDP3303D, which cost a 240 GB Pounds from Barsoom.eu on Amazon. Surprisingly it was sent by DHL direct from China, and arrived in 5 days.

From what I've seen so far, it looks like a nice power supply - reasonably compact, easy to use, 3 isolated outputs, very quiet, and the problems with glitches on Channel 3 seem to have been fixed.

NewFile1.png shows channel 3 (top) and 1 (bottom) at power on from cold with no load. Output 3 spikes at up to 1.7 volts, then drops down to about one volt. I can't imagine this causing problems with the 3.3 or 5v logic loads it's obviously intended for.

NewFile2.png shows channels 3 (top) and 1 (bottom) when the outputs are switch on.

NewFile3.png shows channel 3 recovering from a short circuit. Removing a 2 amp load causes just a few tens of milivolts ripple before setting down.

The LCD display is gorgeous - very clear and easy to read, but I'm not really sure it's worth the extra cost over the SPD3303C with the LED display.

Gary.

[artelse]

Thanks for the response! I am still undecided about getting the Rigol DP832 or the Siglent SPD3303D.. The good thing about the Siglent is the small footprint while the Rigol is quite a beast, but has more options.

[FrankBuss]

The Siglent is cheaper than the Rigol. If the Siglent has all features you need, then it might be better for you.

But I think the user interface of the Rigol is better, sometimes you just want to enter the voltage, not turning a knob endlessly (the SPD3303D has no acceleration function, at least not in my firmware version, but might be not a good idea for voltage adjustments anyway). An advantage for some applications is that all three channels of the SPD3303D are isolated. The DP832 has just two fully isolated channels, the GND of channel 3 is shared with GND of channel 2. But on the SPD3303D there is no display for the current for channel 3, just a LED for overload.

[Siglent]

Thanks for the review Frank,

I've just received my SDP3303D, which cost a 240 GB Pounds from Barsoom.eu on Amazon. Surprisingly it was sent by DHL direct from China, and arrived in 5 days.

From what I've seen so far, it looks like a nice power supply - reasonably compact, easy to use, 3 isolated outputs, very quiet, and the problems with glitches on Channel 3 seem to have been fixed.

NewFile1.png shows channel 3 (top) and 1 (bottom) at power on from cold with no load. Output 3 spikes at up to 1.7 volts, then drops down to about one volt. I can't imagine this causing problems with the 3.3 or 5v logic loads it's obviously intended for.

NewFile2.png shows channels 3 (top) and 1 (bottom) when the outputs are switch on.

NewFile3.png shows channel 3 recovering from a short circuit. Removing a 2 amp load causes just a few tens of milivolts ripple before setting down.

The LCD display is gorgeous - very clear and easy to read, but I'm not really sure it's worth the extra cost over the SPD3303C with the LED display.

Gary.

Dear Gary,
thank you very much for the review, SPD3303D is better than SPD3303C. not only for the screen, but also for the programming function. more information here.http://siglent.blog.com/2013/05/16/use-siglent-programmable-dc-power-supply-to-complete-a-variety-of-test-solutions/

[willd1971]

If anyone's interested I have a couple of SPD3303C units in stock at Labtronix in the UK at £190ea.  They are new stock so don't expect the CH3 problems described above.  Here's the link:

http://labtronix.co.uk/drupal/shop/powersupply/spd3303C

[Murray]

Does anyone know what the output capacitance of this supply is?

The Rigol DP832 has 1000uf directly across the output, which seems to me like it could defeat the usefulness of the current limit in some cases. The Korad programmable thing has 330uf. I was wondering what this one had.

Thanks

[FrankBuss]

Does anyone know what the output capacitance of this supply is?

That's an interesting question. I measured it:



Test setup: Channel 1 on, current limit set to 10 mA with "fine" adjustment, voltage to 1 V. Then I connected a scope to a 10 ohm resistor and then the resistor leads to the power supply output while it was on. As you can see, it needs 2.3 ms to discharge to 37%, so with t=RC <=> C=t/R I think the output capacitor is 230 uF.

But the interesting part is the 4.7 ms delay before we can see the current limitation. So I tested it with 100 ohm and 5 V output voltage:



For 40 ms twice the selected output current is not good.

This made me wonder what happens if you turn on the channel with load, when it should go to CC mode immediatly. New test setup: 10 ohm and scope connected to the channel 1 output, channel 1 is turned off, current limit set to 10 mA. Then I turn on channel 1:



As you can see, it starts with 2 V, which means for the first millisecond there is a current of 200 mA instead of 10 mA. And after 10 ms the output voltage drops down to nearly 0 V, then rising again to the expected 0.1 V for the CC mode. Same problem for 100 mA current limit, it starts with 200 mA. But I guess no problem for most circuits, even a low current fast fuse would not blow in a millisecond.

But it is worse with 1 ohm (screwed to the power supply output terminals) and 100 mA current limit, output voltage set to 10 V:



Within the first few microseconds there is a peak of 3.2 A, the maximum output of the power supply, 32 times the selected limit. Again, it is too short to harm most DUTs, so I can live with that, but looks like there is room for improvement for Siglent how to implement the current limitation.

[rf-loop]

Does anyone know what the output capacitance of this supply is?

The Rigol DP832 has 1000uf directly across the output, which seems to me like it could defeat the usefulness of the current limit in some cases. The Korad programmable thing has 330uf. I was wondering what this one had.

Thanks

Output capacitors are 220uF  (+/- tolerances)


Here also tiny test with SPD3303S  for test it for load step response. Here Load change from 0.375A to 0.75A

Step change in load using FET switcher (Switch FET is there IRF540N) unit controlled By Siglent SDG805 pulses and dummy load resistor set. (2kHz  170us pulses higher load)  Switcth unit setup so that load rise and fall time roughly around 3-4us. (some amount softened switch so that dummy load resistors and wiring reactances do not produce ringing and disturb test.). CH4 is connected to switch D and S.

Compared with equal test setup (including wiring) with Agilent 6632B  what is 1x 0-20V 5A well known very good linear PSU.

Agilent regulation set for FAST mode using  switch in Agilent PSU rear panel. (as can see it is quite fast). Both was set for 7.5V and 3A limit so it means that both run full time in CV mode of course.
Agilent have also sense lines. Connected just for "self happy" with jumpers between output terminal. Not sensed over real loa wires.  But oscilloscope is connected to terminals, not after wiring to load. (same also with Siglent, measurement direectly from output binding posts and separate line to load.

Of course Siglent loose this game but it was very clear before I get result. But Siglent result is not at all bad. It is also good to note that this Agilent list price strating from US$ 2,800)

Images are self explanating.

deleted (wrong information due to problem in this test demo unit.)


I'm doing more many kind of tests but due to lack of time for this, I do  these later.


EDIT: This test totally obsolete. After tests it more I have found that this SPD3303S have problem.
After then control board is changed as warranty issue. This case have delayed due to my own  lack of time for this case.
 Later new tests.

[rf-loop]

In meant time before more tests.
SPD3303S
Mains voltage 230Ac

6 hour:
CH1 and CH2  total out 195W.
Independent mode, both channels running in CV (constant voltage) to dummy load.
~31.22V and current ~3.122A)
Room temp 22 celsius.

No any signs of any kind of temperature problems.
Also measured exhausted air temp. 41 - 42 celsius.


3 hour:
CH1 and CH2
Independent mode.
Both channels adjusted for 32V and 3.2A.
Output terminals short circuited.
Room temp 22-23 celsius.

After 3 hour not any kind of signs about any kind of temperature problems.
Exhausted air temp 40 - 41 celsius.

[Sang]

My CH3 is a bit high,

CH1 (set to 12V) outputs 12,000 according to my Fluke 87V
CH2 (set to 12V) outputs 11,999

but CH3 outputs either 2,523 3,325 or 5,022 volt

that is out of spec isn't it?

Both with or without a load

[rf-loop]

My CH3 is a bit high,

CH1 (set to 12V) outputs 12,000 according to my Fluke 87V
CH2 (set to 12V) outputs 11,999

but CH3 outputs either 2,523 3,325 or 5,022 volt

that is out of spec isn't it?

Both with or without a load

It is well inside specifications.  (even if there is decimal point error and 8% is 0.8% is it is just inside specs and it is good it is small amount up due to fact it do not have sense lines for compensate V drop due to wire resistances. (also small drop in internal wires from regulator to output terminals))

Just for example: 3A load, wires to load 1m lenght (2 wires). Wire: 1mm2 copper. Loop resistance 0.034 ohm.  Voltage total drop in these wires ~102mV !


CH3 specifications:

[Sang]

Good point, Thank you.

I could not find that in the paper manual it came with.

[rf-loop]

My some old tests was "garbage" due to problem on the SPD3303S control board. Also there was small problem in IRF540 based power switch unit used in test.

My "demo" SPD3303S is  repaired and it have  now new control board.  (long delay to repair it in my workshop was just my own reason, not Siglent.  (just lack of time for working with this, and because this is my demo unit  what is not used for lab work and failure was not "fatal class")


In all next tests HW version is 1.2. (also on PCB, printed version new)  And FW version 1.01.01.06R2.


First 2 images.
Both power supplies with same settings. 20V and current limit 3A
Load. Continuous 1A  and load step to 2A, step duration 300us.  Oscilloscope CH1 show switch control signal from Siglent SDG5082 to switch unit what control PSU load.   Load is set of selectable power resistors)
Switching period is 2ms. 1A 1.7ms and 0.3ms 2A.  It need note that switch turn on and off  edges are quite fast (enough for this purpose)



(just note oscilloscope scale. 100mV/div and Voltage is 20VDC (oscilloscope input AC coupled)
Result is good.




This is Agilent 6632B 20V 5V very good quality linear system power supply.




Next image. Short circuit.

(not "copper rod short" but short using  power switch unit (it use IRF540 as switch.)
CH1 is switch control signal from Siglent SDG5082
SPD3303S settings: 20V and 3A.







Next three images: SPD3303S.
Channel output tur ON with different voltages for look if there is any voltage where is gives some peak. (it is good to know that there is 4 internal primary voltage levels before output regulation stages. It is nessessary for reduce power dissipation with different voltages and load currents. So it steps to desired transsformer tap with different output voltages.

No any noticeable or worrying voltage peaks during the run-up ramp. Just smooth turn on.











Next. Voltage set for 32V and current limit 3.0A
Connected different loads ("0" ohm, 0.5 ohm to 10 ohm) to output using switch module.
Also there is trace with output off and output continuously on. (just for ref)
This show how it switch from CV mode to CC mode and recover to CV.






Next two images:

Recovery from 1ms output short with different current limits. (CV --> Shorted (CC) --> recover back to CV)
1. 0.6A to 3.0A  with 32V
2. 0.1A to 1A with 32V and 16V







Then next CH1 and 2 Series connected mode (full 64V)
From off to ON






Next four images about CH3.


Short circuit recovery, No Load




Short Circuit recovery, 10 ohm Load (@5V  0.5A)




CH3 turn ON with 10 ohm load



CH3 turn ON with NO load. (exept scope probe)

[Zbig]

The images don't show. I'm sorry, they do. Just some corporate proxy issues. Thank you for the analysis.

[Marblefish]

Hi,
My first post - just discovering electronics as a hobby after a break of a few decades. I am in the process of selecting a bench power supply as an upgrade to my current ‘ hobbled together supply’ as a birthday present to myself. After reading the excellent review by Frank, I wondered if when setting the unit up to provide a positive & negative supply (20v) is it best to use the Siglent in Independent mode & link Ch1- to Ch2+ together and use the ground as 0v rail or in Series mode with ground as 0v? I was thinking that in Independent mode you only have to adjust one channel & the 2nd channel follows accordingly.

Many thanks.

[Zbig]

It's the other way round: you only have to adjust the voltage on one channel while in Series mode. In Independent mode, the channels are... well, independent I'd personally use Series mode in this scenario as it saves you from using a shorting bar and ensures both channels are sharing the load equally (and your 0V indeed sits in the middle). Also, trying to keep both channels' voltages in sync manually could turn to be a bit tedious (same knob shared by two channels).

[monz]

This is correct, in series mode it automatically connects + on channel 1 to - on channel 2 (becomes the common connection) and the voltage and current adjustment track each other.  I was disappointed to find that in series mode the channel 2 current is not measured. The current reading on channel 1 is simply duplicated to channel 2. So if I have a load between common and channel 1 - it displays current (and shows the same reading for channel 2, which has nothing connected) and if I connect a load from common to channel 2 + it displays no current. I don't know if this is a software bug or hardware limitation. I would think the relay inside just connects the two channels together just as if this was done externally with a jumper. Or maybe they incorrectly assumed in the software a load would only be across both with com never connected.

This and the bug where it saves the power on count when presets are saved make me wonder about the quality of the firmware.

Other than that annoyance, it has been very good, there have been no issues and the output voltage is very accurate. It's also not as deep as many and takes up less room on the shelf.

[FrankBuss]

I think it is a feature, because the series mode is intended for a higher output voltage, so it makes sense to show the same current.

[monz]

This would make sense when connecting across both supplies in series for situations where higher voltages are needed since the current would be the same, it should then show double the voltage and only display the total.

But since a common connection is provided (labeled com along the gray line showing the series output connections below binding posts), this can't be assumed since there would be different loads between the negative side and ground and the positive side and ground as shown in the photos.

It seems like an incorrect assumption is being made in the software. Maybe I'm wrong, just doesn't seem right. I would think pressing the series button simply puts the two in series via a relay, the same as connecting them internally, then sets the software so the control tracks.

neg-- -- com --  -- pos, couldn't resist using the meter thing !

[leonerd]

Just to add my thoughts on this unit:

Hardware-wise it's nice. A good shape, size, the buttons are useable, and so on.

However, software-wise the UI is quite a let-down. Given the size of the TFT screen, Siglent haven't made good use of it at all. It's little more than four large numbers and some status indications - a TFT-shaped translation of the actual LED digit displays on the 3303C.

When you're using the dial to adjust the setting of voltage/current, there's no onscreen indication that the numbers you're adjusting are the settings, and not live readout. After a short timeout, it goes back to live readout, with no display of the setting. To say again more clearly: While setting, you cannot see the live readouts. While displaying live readouts, you cannot see the set values.

The coarse/fine button makes it very inconvenient to enter such voltages as  5.50V. You have to dial to 5.00V in coarse, then in 0.01V increments all the way up from .00V to .50V - that's fifty clicks of the wheel. There are some "cursor left/right" buttons just below the wheel that could be used to move the adjustment position between 10V, 1V, 0.1V and 0.01V.

The operation of the "All on/off" button is less than ideal. When fewer than all three channels are turned on (which is fairly likely), pressing this button turns them all on. That feels rather unsafe to me - I would hope that if any channel is on, the button works as "All off". Only when all are off, does pressing it turn them all on. And even then I would want a confirmation, or maybe force me to long-press it to turn them all on. In its present mode of operation I don't think I'd ever be brave enough to touch it.

Speaking of "all three channels" - I know it's only really a two channel PSU with a cut-down 5V third, but there is no indication on the screen as to the status of the third channel. I don't know if the hardware itself has the capability to measure the live current being sourced by Ch3, or even know what voltage it is set to, but given as the button LED and the "All on/off" button respond to the status of Ch3, I suspect the management CPU is at least aware whether Ch3 is on or not. Could that be displayed on the screen too?

This is supposed to be fairly simply bench PSU - you should be able to set voltage and current levels, see live measurements of them, and turn on and off channels. And yet the UI on the screen fails to be useful at any of these basic operations.

All of these are software issues on the embedded - and upgradeable - firmware. All of these could be fixed. I see that Siglent themselves are a contributor on this forum; indeed on this very thread.

Siglent - I would love to see some improvements in this UI. For that matter, I'd love to help you make some improvements. All the hardware is there on this device, it just needs some nicer software to round it off into a really great PSU. I could throw a few mockups of display screens into this (or maybe a different) thread, see what people think to the ideas. I don't want to just complain for the sake of complaining; I'd like to help make it better. Maybe between us we can all work on improving the user experience with this device.

[tautech]

Welcome to the forum leonerd.

One has to ask what FW version is installed?

[leonerd]

One has to ask what FW version is installed?

I did once manage to make it tell me:

Code: [Select]

SCPI> *IDN?
    < Siglent Technologies,SPD3303,SPD30CE4xxxxxx,1.01.01.01.06R1,V1.2
I do have an r2 image file, but lacking any change or release notes I can't tell if reflashing it would make a difference here. I don't have easy access to a Windows machine to run the Windows software to update it, so any reflash operation is going to involve either moving the heavy PSU, moving an even-heavier computer, or finding a Linux program that can do it.

[FrankBuss]

Unfortunately last time I tried to update it, it didn't work, I got the messages "Failed to search device". Where can I download the latest firmware version and firmware update program? And what was changed?

Would be really nice to set the voltage in 0.1 V steps. Usually I need to set 3.3 V, 5 V etc., and almost never 0.01 V steps and then it is annyoing and time consuming to setup the voltage. Don't know if the arrow keys should be used for selecting the finer steps, maybe a short press on "Fine" selects 1 V and 0.1 V, and a long press on "Fine" selects 0.01 V steps. Shouldn't be much work to implement it. And fixing the problem with the wheel that it misses counts when turning fast would be nice, too. Then it would be a perfect power supply for me Changing the display format is a matter of taste, I can live with the current concept that it shows the set value when you turn the wheel and after a timeout the output value.

[leonerd]

Unfortunately last time I tried to update it, it didn't work, I got the messages "Failed to search device". Where can I download the latest firmware version and firmware update program? And what was changed?

The latest firmware can be found by searching in

  http://www.siglent.com/ENs/gjjrj.aspx?id=15

Specfically, the file required seems to live currently at

  http://www.siglent.com/ENs/gjjrj-xq.aspx?id=1019&tid=15

I don't know of a program to update it, other than the original Windows control software supplied on the CD with the PSU.

The firmware updates don't appear to come with a list of changes or release notes, so it's hard to tell what's been changed.