Nokia 9000i Service Manual page 151

After Sales
Technical Documentation
PDAPWRU
Technical Description
The power block creates supply voltages for the PROCU and LCDM,
generates reset signal for CPU and contains LCD contrast control and
enable circuits. Input filter is required to reduce input noise of switching
regulators. Back–up battery keeps RTC alive when main battery is not
connected. System voltage is present allways until battery voltage drops
below 5.0V.
VBATT
LCDVCCON
5VPDX
LCDVEEON
LCDPWM
Table 23. External Signals and Connections, Inputs
Signal Name
LCDVCCON LCD Vcc on/off
LCDVEEON LCD Vee on/off
LCDPWM PWM signal for LCD voltage control
5VPDX 5V regulator powerdown
VB Battery voltage
Note 1. B2B = Board to board connector between PDA and CMT modules
Original, 08/96
3.3V 500mA current mode buck
regulator, internal switch transistor
LCD Vcc switch circuit
5V 50mA low drop–out linear regulator
21V 6mA SMPS including output voltage
adjustment by LCDPWM signal and tem-
perature compensation
Reset circuit
Undervoltage lockout
3V backup battery
Figure 9. PDAPWRU block diagram
Signal description
RAE/RAK–1N
PDA Hardware
VSYS
LCDVCC
VCC5
LCDVEE
PWRGOOD
VBACK
From (1)
PROCU
PROCU
PROCU
PROCU
B2B / VB
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