Looking for a hardware recommendation on USBC power analyzer

Gough reviewed the FNB58 USB Power Tester here

https://goughlui.com/2023/04/29/review-tested-fnirsi-fnb58-usb-fast-charge-tester/

May be of interest.

I have bought several of the cheap devices and none are very good at all.

You can get them easily enough from Amazon or other places:

I have:

FNB58 - comes with very limited instructions but you can download a manual. It's popular so you can get help on the web. I would recommend it BUT - in pass though mode it stops some things from working at all.

Unit-T 658DUAL - cheap, limited.

Yojock (or whatever its called today) cross shaped thing, limited, poor instructions but prospect of community web support.

STM32 G0 - weird - good, BUT - you will need to download lots of quirky software to use it as an analyser - you can get all the source code - it uses quite good TI current and voltage measuring chips.

Ones I've looked at but not bought:

https://www.infineon.com/cms/en/product/evaluation-boards/cy4500/ looks similar to the ST - if you prefer Infineon to ST then might be quite good

https://www.teledynelecroy.com/protocolanalyzer/usb-voyager-m310e - the one you really want but if you need to ask the price then you can't afford it !

https://www.ellisys.com/products/usbex350/index.php - the other one you really want, but you'll need very deep pockets

If you only want to measure volts and amps the Yojock is quite good (although I've not used for C - C connecting because its connectors are the wrong gender for the job I was doing).

The fact that the FNB58 didn't work with some things and other dongles did might still be because the things (mostly a Belkin power bank) were wrong rather than it ! Gough liked the FNB58 more than I did !

USB C + PD is a total can of worms !

MK

"The fact that the FNB58 didn't work with some things and other dongles did might still be because the things (mostly a Belkin power bank) were wrong rather than it !"

That's an interesting observation. I'm not sure what you meant by "didn't work" - but the FNB58 and USB-C in general introduces some limitations.

When passing through USB-C PD (i.e. USB-C in and USB-C out), the reversibility "feature" breaks. As a result, you'll find it doesn't always work and it need flipping of either the input side or output side wiring or both.

The other thing is the position of the PD-COM switch. If it's set to ON, then the FNB58 may interfere with the signalling of your downstream device. When connected to a downstream USB-C PD device, I believe it should be switched OFF.

As power is lost during negotiation, the FNB58 may behave strangely in some cases - you need to power it by plugging in a 5V power source on the PC (micro USB-B port) to ensure the unit stays "alive" during negotiation, if you want to trace the PD negotiation. I've had to do this to trace a power-role-swap and it's vendor-defined messages (in HEX). It worked, but it was a bit of an unwieldy setup.

There may be genuinely some USB-C PD devices it cannot work with, but I haven't had the need to test one as yet. As for other analysers, I've not had the luck of using, but TI seems to do some good work there. If you just want to sniff, this might do the trick, but I've not had the chance to use one, so I can't say how well or not it will work - www.infineon.com/.../

- Gough

Gough Lui  Thanks very much for your comments. I wasn't aware of the loss of reverse-ability issue. It could easily have been that, and I didn't deliberately try reversing when things didn't work.

MK

Great insight folks. Thank BD for the link. I did a search of E14 before throwing up the question. G was playing in another sandbox for the post.

I was thinking cheap and portable for testing power. It seems there is more to these devices than I was expecting. I've some requirements learning to do:(