I completely removed my diode a week or so ago and the effect on the digital inputs was like night vs. day.
There’s no way I’d go back to the way it was before, ESD protection or not.
The only problem is finding a replacement…
(and being able to solder it in - I only have a very basic setup).
Problem is … it’s only 1mm long.
Yes. It will be fiddly / difficult and need to be done under a microscope.
I am also interested in other methods before I have a go. You had mentioned using the PESD3V3U1UT in conjunction with a secondary ESD diode but I am not sure how that works. Doesn’t the low capacitance of that device rely on the internal diode so that if it is connected as in the original circuit then the channel connected to the ESD diode will still have a high capacitance.
OK. What about this one? TPD2E009DBZR
uk.farnell.com/texas-instruments … /1755715RL
This has pretty much the same characteristics of the USB3 one I mentioned before but the DBZ is in a SOT-23 package.
Looking at the photo in previous posts carefully it looks to me like the board was actually designed out for a SOT-23 package and the SOT-523 device has been stretched by the soldering to fit.
Anyway I’ve now ordered the SOT-23 device as it will be much easier to handle than the smaller usb30 one.
We’re waiting with baited breath. Let us know how you get on…!
No problem. I ordered it from eBay for UKP 2.50 and should get it in the next couple of days. Hope to fit it next weekend.
OK. So I have fitted this part (TPD2E009DBZR) now replacing the previous one. It is a perfect fit and was fairly easy to do, but obviously one needs a very fine tip soldering iron, good magnification and a steady hand. I actually found the most time consuming bit was getting the unit back into the case juggling all the buttons.
Initial tests show high frequency logic now goes through but I haven’t explored the limits yet.
I’ve just done mine as well with the same part. I used one of those stands with magnifying glass and crocodile clips and a fairly average soldering iron, it wasn’t too difficult.
I’ve been using mine for a week or so with no diode. Adding this diode didn’t seem to be any difference, which is good! An 8mHz square wave generated by my Arduino displays perfectly. I haven’t got a higher frequency signal to look at, that’s basically the bandwidth I needed though…
Before the mod I had trouble seeing a 1mHz signal and a 2mHz signal showed a flat line (I thought it was a bug in my software at first, or a problem with the Arduino outputs!)
I removed the D5. Negative side protection may be a bit worse, but otherwise looks good:
