EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: Gizmo on November 23, 2016, 09:29:36 pm
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I'm working on a USB device based on the SAMD21 chip. Up until now I've been using the Sparkfun breakout / dev board and have the USB comms working how I want. I've since created a custom PCB for my needs, but when I connect it to the PC I am getting "power surge on hub port" reported by Windows.
I can run the device hooked up to a bench supply and it draws around 800ua according to the multimeter. I dont see any surge on startup, although that could be just down to the reaction speed of the multi-meter I guess.
However the capacitance is just over 1uf (replacing the 10uf tantalum with 1uf ceramic) on the input side with a ferrite for filtering, feeding a 3.3v regulator. It doesn't look like it should be drawing anywhere near the 50ma required to trip the power surge?
I've tried replacing the 10uf electrolytic tantalum in the schematic with a 1uf (as mentioned above) as well as using the 10uf with the same results.
When connected to the bench supply I can program and use the micro no problem and it never draws more than 1ma.
A bit confused. ::)
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Ok, it turns out I'm an idiot. Even though I double checked, I managed to get the footprint for the mini-b connector backwards so gnd and +ve were reversed, which explains the over current.
I butchered a usb cable and wired it up the right way around and all is now working as expected. :palm:
Live and learn.