Charger Voltage Measurement

The charger voltage is measured to determine the type of charger used. MCU A/D converter channel 1 is used for this purpose. The input circuitry to the charger measurement A/D channel implements an LP-filter. The input voltage must be scaled before it is fed to the A/D converter input. Due to the high input voltage range scaling is performed outside PSCLD, N301. The scaling factor required is 22/(22+100) = 0.18. The charger voltage measurement switch is integrated into PSCLD, N301. Charger voltage is not supplied to the A/D converter input in power off mode. This is done to protect the A/D converter input in case power is switched off and the charger remains connected to the baseband. The charger A/D converter value can be calculated using the same formula as described in above section. The resistor values are different since the scaling factor is larger.

The battery size, capacity is determined by measuring the voltage on the BSI pin on the battery pack when the battery is attached to the phone. The MCU A/D converter channel 3 is used for this purpose. The BSI signal is pulled up on the base band using a 47 kohm resistor and the resistor inside the battery pack is reflecting the capacity of the battery. There are two special cases to be detected by the MCU. The first case is the Lithium battery. The Lithium battery has reserved values in the battery size table. Lithium type batteries are all the same from charging point of view. Lithium batteries are charged to a constant voltage and charging is aborted when the predefined voltage is reached. The Lithium battery capacity is a function of the battery voltage. The battery voltage drops linearly as the battery is discharged. The other case that has to be handled is the dummy battery. This battery is used for A/D converter field calibration at service centers and together with a defined voltage on the BTEMP pin on the battery pack to put the baseband into Local mode in production. Battery sizes below 250 mAh will be treated as dummy battery. The different battery size values are shown in tthe table below . The battery size A/D converter value can be calculated using the following formula:

where RSI is the value of the resistor inside the battery pack.

DIY Battery Repair

DIY Battery Repair

You can now recondition your old batteries at home and bring them back to 100 percent of their working condition. This guide will enable you to revive All NiCd batteries regardless of brand and battery volt. It will give you the required information on how to re-energize and revive your NiCd batteries through the RVD process, charging method and charging guidelines.

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