Figure 19: Reference Circuit Of Usb Application - Quectel EC25-V User Manual

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Table Of Contents

Table of Contents

Module

USB_VBUS

USB_DM

USB_DP

GND

In order to meet USB data line signal integrity, components R1, R2, R3 and R4 must be placed close to

the module, and then 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 90ohm.

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 component on USB data lines. Typically,



the capacitance value should be less than 2pF.

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



NOTE

EC25 module can only be used as a slave device.

EC25-V_User_Manual

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