USB signals need to be as short as practical with matched length and routed as a 90-ohm differential pair between the USB connector and the FTDI chip. The USB interfaces on all of our FTDI products are rated up to 2KV range for ESD sensitivity. External ESD protection is recommended. Ensure that the ESD devices are specified for USB use. Some ESD devices have a high capacitance which will adversely affect the USB signal integrity.