EMI Filter for USB interface of STM32

Central SUPPORT · ‎2019-03-27

We are using USBUF01W6 as EMI filter for STM32F207VCT6 in USB D+ and D- lines in Full speed mode and we have connected VBUS (5V) at pin 3.3V pin of USBUF01W6.

Does this make sense to you?

NOTE: This question and answer originated from a customer support case which was handled by us. We regularly review support cases and add any helpful ones here for all to benefit from.

Central SUPPORT · ‎2019-03-27

As STM32 used already includes series resistors for USB D+ and D-, the right part to protect against ESD on D+ and D- is USBLC6-2SC6, instead of USBUF.

In addition, you should consider to protect 5V_USB against ESD and EOS transients (8/20µs). We recommend to use ESDA7P60-1U1M or ESDA7P120-1U1M. In this case, VBUS of USBLC6-2SC6 is connected to a 100nF capacitor or left open.

For best protection these parts should be placed as close as possible to the connector.

View solution in original post

Central SUPPORT · ‎2019-03-27

As STM32 used already includes series resistors for USB D+ and D-, the right part to protect against ESD on D+ and D- is USBLC6-2SC6, instead of USBUF.

In addition, you should consider to protect 5V_USB against ESD and EOS transients (8/20µs). We recommend to use ESDA7P60-1U1M or ESDA7P120-1U1M. In this case, VBUS of USBLC6-2SC6 is connected to a 100nF capacitor or left open.

For best protection these parts should be placed as close as possible to the connector.