PIC32 USB issue

[Peter Truman]

Hi All - understanding that Proton doesn't support a PIC32 (shame I say!)

I'm on a hardware project that requires a PIC32MZ to act as a host (just using a thumb drive and bootloader to update code). But I'm having the devil of a time with the suggested high side switch.

See attached diagram.

The problem is - I have checked that I specified the correct part number on my BOM (TPS2051BDBVR), this one has the Active high enable (so 3.3v from the PIC) - I've read every word of the datasheet but no matter what I do I can't get the expected 5v out of pin 1 (I've also attached a snip of my schematic - I am aware that my schematic shows this part with an active low enable - my bad!)

I'm at a loss! I worry that perhaps the board house fitted the wrong part (I'm not able to see the part numbers even under microscope)

So I wonder if anyone has any experience of this - failing that, can anyone see any really good reason why I can't power Pin 1 of the USB Type A socket with a SS relay or another FET of my own choice, or even just hardwire it to its own 5v supply?

I'd appreciate any suggestions - I'm a bit stuck!

[John Lawton]

Hi Peter,

have you checked that pin 4 of the TPS2051BDBVR is actually going high as expected to turn on the device. If so then I too am at a loss to explain why the output isn't going high, unless there is an overload situation there for some reason.

As you say it is possible that the fitted device is not correct. Maybe try out known correct example of the part on an adaptor pc board?

John

[david]

It's a SOT-23 so should be fairly easy to see the product code (PLJI) on the device with a modest magnifier.  This may allow you to confirm the right part was fitted.
The OC active low output should go low (with a pull-up fitted) when there's a current overload. 
Like John has hinted - there's not much there to go wrong.

David

[Peter Truman]

I spend the day with my head mounted magnifier (and glasses) that is usually enough to read most things. In this case I had to break out my trusty USB microscope. Seems I have managed to scratch the surface with all of my poking around so nothing left to read I'm afraid.

I don't have another untouched board to look at - these were expensive so I only had 2 made - the other is with the siftware guy in Sydney. He's posting that down to me so I might have a chance with that one.

I'm of the same view - this should be simple! SO I remain at a loss until I get the other board.

Thanks for the help

[david]

No one in Sydney with a magnifier? A SOT-23 should be quite easy to read (ok it's black on black) but at the right angle you should clearly see the laser marking.   Be thankful it's not a chipscale package. Good luck and keep us posted.

David