User's Manual

LTE Module Series

BG96-NA Hardware Design

BG96-NA_Hardware_Design Confidential / Released 35 / 64

figure shows a reference circuit of USB interface.

USB_DP

USB_DM

GND

USB_DP

USB_DM

GND

Close to Module

Test Points

ESD Array

NM_0R

Minimize these stubs

Module

MCU

USB_VBUS

VDD

Figure 17: Reference Circuit of USB Application

In order to meet ensure the integrity of USB data line signal, components R1, R2, R3 and R4 must be

placed close to the module, and also these resistors should be placed close to each other. The extra

stubs of trace must be as short as possible.

In order to ensure the USB interface design corresponding with the USB 2.0 specification, please comply

with the following principles.

 It is important to route the USB signal traces as differential pairs with total grounding. The impedance

of USB differential trace is 90 ohm.

 Do not route signal traces under crystals, oscillators, magnetic devices and RF signal traces. It is

important to route the USB differential traces in inner-layer with ground shielding on not only upper

and lower layers but also right and left sides.

 Pay attention to the influence of junction capacitance of ESD protection components on USB data

lines. Typically, the capacitance value should be less than 2pF.

 Keep the ESD protection components to the USB connector as close as possible.

BG96-NA module can only be used as a slave device.

NOTE