Huawei ME909 Series - USB Interface

HUAWEI ME909 Series LTE LGA Module
Hardware Guide
Description of the Application Interfaces
Issue V0.3 (2013-05-21)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
33
3.6 USB Interface
The ME909 is compliant with USB 2.0 High speed protocol. The USB interface is
powered directly from the VBAT supply. The USB signal lines are compatible with the
USB 2.0 signal specifications. Figure 3-14 shows the circuit of the USB interface.
Table 3-8 Definition of the USB interface
Pin No.
Pin Name
I/O
Description
DC Characteristics (V)
Min.
Typ.
Max.
85
USB_DM
I/O
USB data signal D-
-
-
-
86
USB_DP
I/O
USB data signal D+
-
-
-
According to USB protocol, for bus timing or electrical characteristics of ME909 USB
signal, please refer to the chapter 7.3.2 of Universal Serial Bus Specification 2.0.
Figure 3-14 Recommended circuit of USB interface

Since the USB interface of ME909 module supports USB 2.0 high speed, the resistance
“RV102 and RV103” in the Figure 3-14 must be Voltage Sensitive Resistor with small
capacitance (ALVC18S02003 manufactured by AMOTECH or B72590T7900V60
manufactured by EPCOS is recommended.). In addition, The layout design of this circuit on
the DTE board should comply with the USB 2.0 high speed protocol, with differential lining
and impedance control to 90 Ω

It is recommended that set USB_DM and USB_DP pins as test points and then place these
test points on the DTE for debugging. But layout stub should not be generated.