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HUAWEI EM820W HSPA+ PC Embedded Module
Hardware Guide
Figure 3-1 HUAWEI EM820W power supply time sequence.
Parameter
Tpd
3.5 USB Signals
The EM820W is compliant with USB 2.0 specification. It supports full-speed (12
Mbit/s) and high-speed (480 Mbit/s) modes when acting as a peripheral and supports
low-speed, full-speed, and high-speed modes when acting as a host. The USB 2.0
specifications allow peripherals to support any one or more of these speeds. To
ensure best performance, the PC USB host controller should support high-speed
mode when using the EM820W USB high-speed mode.
Table 3-3 USB pins
Name
USB D-
USB D+
The USB interface is powered directly from the 3.3 V supply. The USB input/output
lines are compatible with the USB2.0 3.3 V signal specifications.
Table 3-4 USB signal DC characteristics
VOHmin
2.8 V
Issue 01 (2010-12-09)
Remarks
Power Valid to USB D+ high
Pin
36
38
To minimize the RF radiation through the PCI-E interface, you can add a 33 pF ceramic
capacitor in the ground on every pin of the PCI-E on the host side except USB D+/D-.
VOLmax
0.3 V
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
Description of the Application Interfaces
Time(Nominal value)
3.45
Description
USB data signal D-
USB data signal D+
VIHmin
2 V
Unit
sec
Direction to Module
Input/output
Input/output
VILmax
0.8 V
9
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