60.9 USB Interface

The USB interface consists of a differential data pair (D+/D-) and a power supply (VBUS, GND). Refer to the Electrical Characteristics section for operating voltages which will allow USB operation.

Table 60-10. USB Interface Checklist
Signal NameRecommended Pin ConnectionDescription
D+
  • The impedance of the pair must be matched on the PCB to minimize reflections.
  • USB differential tracks must be routed with the same characteristics (length, width, number of vias, etc.)
  • For a tightly coupled differential pair, the signal routing must be as parallel as possible, with a minimum number of angles and vias.
USB full speed/low speed positive data upstream pin
D-USB full speed/low speed negative data upstream pin

USB Host and Device Interface recommendations can be found in the “Basic 32-Bit MCU Design and Troubleshooting Checklist” guide, available on the Microchip web site, www.microchip.com/.