Nokia NSE–3 SERIES Service Manual

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Nokia NSE–3 SERIES Service Manual Manual pdf 23 page image

PAMSTechnical DocumentationNSE–3System ModulePage 3 – 17Original 11/97Functional DescriptionPower DistributionIn normal operation the baseband is powered from the phone‘s battery.The battery consists of one Lithium–Ion cell. There is also a possibility touse batteries consisting of three Nickel Metal Hydride cells. An externalcharger can be used for recharging the battery and supplying power tothe phone. The charger can be either a standard charger that can deliveraround 400 mA or so called performance charger, which can deliver sup-ply current up to 850 mA.The baseband contains components that control power distribution towhole phone excluding those parts that use continuous battery supply.The battery feeds power directly to three parts of the system: CCONT,power amplifier, and UI (buzzer and display and keyboard lights). Figure 4shows a block diagram of the power distribution.The power management circuit CHAPS provides protection agains over-voltages, charger failures and pirate chargers etc. that would otherwisecause damage to the phone.CCONT SIM+BOTTOM CONNECTORCHAPSCOBBABATTERYPA SUPPLY RF SUPPLIESVBBBASEBANDVBATVCOBBA VSIMVBBCNTVRPWMVBATPWRONXPURXVINUIBACKUPRTCMEMORIESMADLIMVBB