Nokia 2160 Technical Documentation Manual

Also see for 2160: Owner's manual User guide

Contents

Nokia 2160 Technical Documentation Manual Manual pdf 7 page image

After SalesTechnical Documentation Desktop Charger CHH–2Page – 7Original 50/96AN5/CHVOL Charger voltage detectionAN7/LIREF Lithium reference voltage input• range: 0...5 V• resolution: 19.5 mV/bitCharging the Spare BatteryCharging current for the spare battery is fed in via switching transistorV130 and Schottky diode V131. The transistor is controlled by the proces-sor (BSW line). When the transistor is on, a constant current is suppliedto the battery. This is the rapid charging mode. In the pulsed chargingmode, charging current is adjusted by pulsing this rapid charge current.Battery voltage is measured through resistor divider R143/R144 (100/121kohm). The range measured is 0 to 11 V; a voltage variation of 43 mV canbe detected. For improved resolution, i.e. rapid charge cut off, operationalamplifier N140 is added. This amplifies the battery voltage by a factor of(1 + 100 kohm/56 kΩ) and compares the result to a +5 V reference sup-ply. The A/D converter receives a battery voltage range of 7.0 to 11 V; abetter resolution of 16 mV results.Battery size is determined by reading the BSI line state. This is pulled to+5 V reference voltage by R147 (100 kΩ). In the battery pack a ”size” re-sistor is connected between BSI and GND.Temperature is measured over the BTEMP line. This line is pulled to +5 Vreference voltage by R145 (27 kΩ). In the battery pack an NTC resistor isconnected between BTEMP and GND.Because the phone and the spare battery cannot be charged at the sametime the charging current of the phone must be detected. This is done atthe A/D input AN2 (PDET). The charging current for the phone is directedthrough series diode V114. If the voltage drop across the diode is higherthan 100 mV (corresponds to A/D value of 5), charging current is flowingto the phone.The CHH–2 desktop charger has two dual–colour LEDs to indicate thecharging states of the phone and the spare battery.Discharging the Spare BatteryThe desktop charger is also provided with a discharge function. This isactivated by pressing a discharge switch on top of the charger. The sparebattery is then discharged before charging. Resistors R181–R188 deter-mines the discharge current which is fed through switching transistorV134 controlled by processor over the DISW line (pin 64). The battery isdischarged to 5 V and thereafter charged normally. The state of the dis-charge switch is read via the DBIN line (pin 63).Watchdog CircuitThe processor generates positive pulses to output PC7 (pin 18). Thesepulses are received by transistor V201 discharging capacitor C161. The