FEDEVEL
Platform forum

Kalaslas , 08-25-2025, 01:23 PM

Hi! I've been looking at getting a dongle to measure USB-A and USB-C power consumption and do protocol analysis. However, i've tested some before and been very disappointed in the crappy accuracy some of them have. Does anyone have a good recommendation for a good analyzer like this?

Robert Feranec , 08-27-2025, 11:59 PM

I am interested in this too. There are many available, but I don't know any proper brand, it's usually just some random stuff.

Kalaslas , 08-29-2025, 12:12 PM

Yeah, a colleague has one that he bought from AliExpress or something similar, and did some measurements with it. I suspected the accuracy of those measurements and did a second take with a PSU. His USB dongle told me the device under test was pulling ~100 mA when the benchtop PSU told me 450 mA, so he is now forbidden from using his dongle again in any official capacity 😅

Mini , 08-29-2025, 11:55 PM

What you mean by protocol analysis? Like PD? Fnirsi has a lot of different meters for example. I'm sure they are not that off.

QDrives , 08-31-2025, 03:35 PM

But is the PSU corrent?

Kalaslas , 08-31-2025, 04:25 PM

I trust a benchtop PSU from a reputable brand, which I've used for several years without any issues more than a random no-name USB dongle from AliExpress. But the PSU isn't calibrated, so who knows really 😅

QDrives , 08-31-2025, 07:13 PM

You have 2 measurements that do not match. And no, I do not trust a current measurement from a power supply, even if it is from a reputable brand.
Do a measurement with an oscilloscope (high frequency) or multimeter (DC). You can simply add a 10mΩ resistor in series for this.