Hi;
I am using USB Port 0 to write to a flash drive. Do these pins have ESD protecton?
On which product?
A quick scan of the products with USB ports show that none of them have ESD protection on the USB lines. Only the 22R resistors.
ALF2X-SC-512
No there is not but I believe the chip has some internal protection and there are resistors in series to help. Should be good in most uses but not sure if enough to pass CE.
Are you using the IC itself on your own board or one of the evaluation boards with that IC? For evaluation it will be fine but for production, use protection on the lines.
AN4879 here shows that EMC/EMI protection is NEEDED on the USB lines so if you are designing your own board, use them. The USBLC6 is cheap protection for your boards.
http://www.st.com/resource/en/application_note/dm00296349.pdf
This datasheet also explains how to route the tracks and that you can do away with the 22R resistors. Not needed.
The full speed USB driver impedance on STM32 MCUs is guaranteed by design to be between 28 ohms and 44 ohms. The result is that these products do not need an external resistor on the board for the output driver impedance.
As an aside, it’s always good to check the manufacturers datasheets on the device. GHI actually indicates this on the products datasheet.
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