What considerations should be given to the design in order to pass the in-rush current testing?

Question: What considerations should be given to the design in order to pass the in-rush current testing?

 

Answer:

If the device is self powered (does not use power to from the USB pin 1), the device should only monitor the power by connecting it to an I/O pin. If the device is bus powered (receives it power from the bus), the device should be able to pass In-rush current by limiting the un-configured current of the device to 100 mA and limiting the load capacitance on the VBUS signal of the USB pin 1 to 6.8 uF. The design of the bus will allow up to 10 uF on the VBUS signal, but due to part tolerances the capacitance should be limited to 6.8 uF.  (An exact value of 10 uF will allow for the device to be under the 51.4 uC limit).