2008-2019 Microchip Technology Inc. DS00002959A-page  1
INTRODUCTION
For customers who want to integrate the USB3320 and are looking to the USB3340/USB83340 for future products, this 
document  describes the hardware  and software considerations required to  accomplish that migration with  the least 
impact to customer design resources. By following the design guidelines outlined in this document, a designer can use 
a common PCB and software platform that can be used for both the USB3320 and USB3340/USB83340 with nothing 
more than a change to the Bill of Materials (BOM) being required.
REFERENCES
Microchip USB Transceiver Data Sheets:
• USB3320
• USB334x
• USB83340
DESIGNING A COMMON PCB FOR THE USB3320 AND USB3340/USB83340
A  common  PCB  design  can  be  engineered  to  support  both  the  USB3320  and  USB3340/USB83340  transceivers. 
Observing  a  few  simple  design  considerations  will  provide  a  seamless  transition  from  USB3320  to  USB3340/
USB83340.  Unless  otherwise  specified  within  this  document,  all  PCB  layout  design  guidelines  that  apply  to  the 
USB3320 shall apply to the USB3340/USB83340.
To design a common hardware platform for both USB transceivers, there are three design changes that must be made:
• Depopulate or disable the 1.8V regulator input.
• Change the capacitor on the VDD18 pin from a 0.1 
F to a 1.0 
F low-ESR capacitor.
• VBAT min voltage raised from 3.1V to 4.0V for the USB83340 only. (USB3340 VBAT min voltage lowered to 3.0V).
Other optional changes that can be made:
• Change the capacitor on the VDD33 pin from a 2.2 
F low-ESR to a 1.0 
F low-ESR Capacitor.
• Change the resister on the RVBUS pin from a 10k to 20k resistor.
Integrating the 1.8V Regulator
The  USB3340/USB83340  integrates  the  1.8V  regulator  that  was  external  to  the  USB3320.  The  VDD18  pin  of  the 
USB3320 is an input and requires an external voltage source to be applied to the pin. Conversely, the VDD18 pin of the 
USB3340/USB83340 is an output that must never be presented with an externally sourced voltage.
AN 19.0
Migrating USB Designs from the USB3320 to the 
USB3340/USB83340