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by Blaster
Fri Sep 14, 2018 12:02 pm
Forum: HATs and other add-ons
Topic: PoE HAT - USB Ports not working - over-current (FIXED - New Hardware Release)
Replies: 327
Views: 81686

Re: PoE HAT - USB Ports not working - over-current

So to sum it up a little. The only issue with PoE HAT is faulty design - inability to at least copy recommended design component values - followed with lack of final design tests. And that "different chip vendors" mumbo jumbo is only smoke screen. There must not be any significant voltage ripple on ...
by Blaster
Fri Sep 07, 2018 7:04 pm
Forum: HATs and other add-ons
Topic: PoE HAT - USB Ports not working - over-current (FIXED - New Hardware Release)
Replies: 327
Views: 81686

Re: PoE HAT - USB Ports not working - over-current

If I assume that preproduction prototypes of PoE HAT has been really thoroughly tested (together with RPi3B+) and doesn't exhibit faulty behaviour as new production boards, I would suggest to concentrate on two suspisious components at first and try to verify if they are or not possible causes of th...
by Blaster
Thu Sep 06, 2018 5:45 am
Forum: HATs and other add-ons
Topic: PoE HAT - USB Ports not working - over-current (FIXED - New Hardware Release)
Replies: 327
Views: 81686

Re: PoE HAT - USB Ports not working - over-current

@daytona: try to measure capacitance of that ceramic capacitors with 5V DC bias applied (if you are able to do). Multilayer ceramic capacitors very often drop capacitance to only fraction of nominal value when subjected to even nominal DC voltage, generally being worse with smaller size/bigger capac...
by Blaster
Tue Sep 04, 2018 12:44 pm
Forum: HATs and other add-ons
Topic: PoE HAT - USB Ports not working - over-current (FIXED - New Hardware Release)
Replies: 327
Views: 81686

Re: PoE HAT - USB Ports not working - over-current

My guess is that problem lies in converter output voltage filtering, excessive noise disturbing overcurrent supervising feature of USB controller producing false "over-current" messages. In this type of applications the current monitoring is commonly realised as voltage drop sensing, so it's usually...

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