Nokia 9000i Service Manual page 54

RAE/RAK–1N
Baseband
If the phone is in power–off state, the PSL+ will detect the charging
voltage and turn on the phone. If the battery voltage is high enough the
reset will be released and the MCU will start controlling charging. If the
battery voltage is too low the phone stays in reset state and the charging
control circuitry will pass small charging current to the battery. When the
battery voltage has reached 5.5 V (+/– 0.2 V) the reset will be removed
and the MCU starts controlling charging.
MCU controls the charging with pulse width modulation output. Charging
voltage is limited by hardware in normal operation to 8.9 V and during a
call to 7.6 V.
Battery and charging voltages are calibrated in production; 6V is fed to the
battery and charger pin and the MCU's A/D converter values are stored to
EEPROM.
Main components
– PSL+ ASIC (N230)
– transistors BCP69–25 (V250), BCV27 (V253,V254), BCW30 (V255)
and Schottky STPS340U (V251)
– transistors BCX51 (V231) and BCP69–25 (V230, V232)
DSPU
Introduction
The DSPU performs of the low–level digital signal processing and control
tasks required in channel monitoring and speech and data calls. The
DSPU resides physically both in MCM2 (DSP and RAMs) and on CMT
motherboard (clock generator and Schottky diode AND gate). Main
interfaces of the DSPU:
– MCU via ASIC mailbox
– ASIC
– audio codec
– data bus interface (DBUS) for tracing purposes
– digital audio interface (DAI) for type approval measurements
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Generates voltages, contains power on switch, charger and
battery voltage detector and watchdog.
These components are used for implementing the charging
switch.
External output transistors for VL1/VL2 and VA3 regulators in
PSL+.
After Sales
Technical Documentation
Original, 08/96