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Custom board with STM32f417 + native USB

Question asked by MarcZ on Nov 26, 2014
Hi everyone,

We started working on USG OTG for a project with a STM32f417.

Now, we are at the step where we want to add the USB to our design.
But our question is based on Protection circuit between the STM32 and the USB Connector.
We use the USB only for Data transfer with a PC, no power supply by USB.

On some design I see a interface component for VBUS, D+, D- and ID. And on others, only resistors. Could someone help me undestanding the principles of each solution?

Right now, for testing purposes, we just link a connector directly to the right pins of the STM32.
And during our tests, we realize that when we unplug the usb from the computer side, it just blows up our board and the STM32.  However, when we unplug on the device side, it does not implies any problems.

Thank you,
And if a protection circuit is needed, could you propose one?

Marc

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