Usb Interface - Quectel BC66-NA Manual

3.7. USB Interface

The USB interface of BC66-NA module conforms to USB 1.1 specifications and supports full speed
(12Mbps) mode. The interface can be used for software debugging and software upgrading, and supports
USB serial driver under Windows/Linux operating systems.
The following table is the pin definition of USB interface:
Table 11: Pin Definition of USB Interface
Pin Name Pin No.
USB_MODE 47
VUSB_3V3 49
USB_DP 50
USB_DM 51
The following is a reference design of USB interface:
Module
VUSB_3V3
USB_DM
USB_DP
GND
In the circuit design of USB interface, in order to ensure the performance of USB, the following principles
are suggested in the circuit design:

It is important to route the USB signal traces as differential pairs with total grounding. The impedance
of USB differential trace is 90Ω.
BC66-NA_Hardware_Design
I/O Description
Pull down the pin to achieve USB
DI
download function
PI USB power supply
IO USB differential data (+)
IO USB differential data (-)
3.3V
Figure 14: USB Interface Reference Design
NB-IoT Module Series
BC66-NA Hardware Design
Note
Vnorm=3.3V
Conform to USB 1.1
specifications.
Require 90Ω differential
impedance.
ESD Array
USB_DM
USB_DP
GND
PC
26 / 58