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HUAWEI EM820W HSPA+ PC Embedded Module
Hardware Guide Electrical and Reliability Features
Issue 01 (2010-12-31)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
30
5.5 Power Supply Features
5.5.1 Power Supply
The EM820W receives its power supply from a 3.3 V power source, which must
satisfy all requirements of PCI Express Mini CEM specifications, such as voltage
tolerance and peak and normal current. The detailed requirements are listed in
Table
5-3.
Table 5-3 Power requirements
Power Voltage Tolerance Peak (Maximum) Normal (Maximum)
3.3 V ±9% 2750 mA 1100 mA
In burst transmit mode of GSM/GPRS/EDGE, the instantaneous current of the module will
exceed 2.75 A, which will pull down the power voltage transitorily and perhaps result in the
reset of the module or host. In order to prevent this situation, you can add a large bulk
capacitor beside the module on the host side (at least two 330uF capacitors).
5.5.2 Power Consumption
The power consumptions of the EM820W in different scenarios are listed in Table 5-4,
Table 5-5 and Table 5-6 respectively.
Table 5-4 DC power consumption (HSPA/WCDMA)
Description Band Test Value Units Power (dBm)
284 1 dBm Tx Power
336 10 dBm Tx Power
Band I
544
mA
24 dBm Tx Power
289 1 dBm Tx Power
340 10 dBm Tx Power
Band II
606
mA
24 dBm Tx Power
293 1 dBm Tx Power
317 10 dBm Tx Power
Band V
501
mA
24 dBm Tx Power
291 1 dBm Tx Power
310 10 dBm Tx Power
WCDMA
Band
VIII
517
mA
24 dBm Tx Power