Author Topic: USB hub I designed keeps failing. Can somebody look at my design please?  (Read 607 times)

0 Members and 1 Guest are viewing this topic.

Offline 4flyerTopic starter

  • Contributor
  • Posts: 11
  • Country: us
I recently designed a US hub based around he USB2507. I am having an issue where when I power up the IC with 3.3, it seemingly dies and gets very hot and draws 200mA more than it should. I have even removed my 3.3V LDO and powered the IC directly from a power supply. I think I did a decent job on the board minus some impedance mismatches on the USB lines. Regardless, this issue is present even when all I have powered is the USB IC and its associated capacitors. Do I have something wrong with the schematic? Could bas capacitors cause the IC to fail? Attached is my schematic and datasheet. I am also attaching the demo board schematic provided by the vendor. Thanks for the help!
« Last Edit: March 14, 2023, 03:12:03 am by 4flyer »
 

Offline ajb

  • Super Contributor
  • ***
  • Posts: 2733
  • Country: us
Just at a quick look, the PRTPWR pins are outputs meant to control power to each downstream port, but you've got them strapped to +3v3. There may be other issues but that could certainly cause the problem you're seeing
 
The following users thanked this post: 4flyer, karpouzi9

Offline pcprogrammer

  • Super Contributor
  • ***
  • Posts: 4355
  • Country: nl
Another thing in your schematic that can give problems is the direct connection between the two host supplies. Not the reason for the board not working. That is more likely due to what ajb wrote.

Why the direct connection of the two host supplies can be a problem has to do with USB supplies coming from different computers not being at the same voltage level. By the looks of it you are only using it to detect if a host is connected, I would at least add diodes in series. But since you are using a switch to select which host is being used it would be cleaner to add some logic, that only the supply of the selected host is fed into the detection pin of the USB2507.

Offline 4flyerTopic starter

  • Contributor
  • Posts: 11
  • Country: us
Just at a quick look, the PRTPWR pins are outputs meant to control power to each downstream port, but you've got them strapped to +3v3. There may be other issues but that could certainly cause the problem you're seeing
This was the issue. Thanks for the help! You are a life-saver!
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf