Table 4-12 Definitions Of Signals Of The Charging Circuit - Huawei MediaPad 10 fhd Maintenance Manual

MediaPad10 FHD Maintenance Manual
switch the system power supply form the battery to external power supply to make full use of
the finite power supply capability of the USB peripheral or the AC adapter, so that the battery
is charged at the same time when the power supply of the system is guaranteed.
The DC input voltage range of the converter is 4.1 V to 16 V. A USB peripheral, AC adapter,
or car charger can be directly used to charge the battery. If a dedicated USB peripheral is used,
its input voltage can range from 4.1 V to 6.6 V. The DC input current is restricted and can
reach a maximum of 2 A. Both the DC power and the USB power support three input modes:
100 mA, 500 mA, and USB suspension. The maximum charging current can be adjusted to 2
A to support a wide range of battery capacity.
The MAX8903A also provides other functions, such as thermal adjustment, over-voltage
protection, power output in charging or faulty state, power-good detection, battery thermistor
detection, and a charging timer.
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Table 4-12 lists the signals of the charging circuit.

Table 4-12 Definitions of signals of the charging circuit

Signal Name
VCHG
GPIO74_CHARGER_EN
VPH_PWR
GPIO20_DCOK_N
GPIO24_CHARGER_FLT
GPIO5_VCHG_INT
VBATT
GPIO22_ISET_CTRL0/1
Working Principles of the Sensor Circuits
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Figure 4-21 shows the working principles of the sensor circuits.
2012-10-09
Fault analysis and location
Symptom: Charging fails, and no power is supplied to the system.
Solution: Check whether the MAX8903 is working properly.
Circuit signals
Working principles
Huawei Confidential
Function
Total power input
Charging enabling pin
Power output by the charging
chip to succeeding systems
DC insertion indication
Charging status indication
Charging interruption indication
Battery power
Charging current control
INTERNAL
Test Reference Value
or Oscillogram
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