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9
POWER SUPPLIES
9.1
Introduction
This section describes the Power Supply Unit (PSU) used on the G600 logic PCB and the method by which it is
controlled.
This section has detailed information on:
1. An overview of the circuit functionality
2. Powering-up the phone
3. Powering-down the phone
4. Power management
9.2
Overview
The circuit contains two linear regulators; 3.6V for the LCD and 3.0V for everything else, analogue and digital.
There is a low current step-up converter to provide 5.0V for the SIM interface. The battery voltage detector,
nominally set to 3.6V prevents the phone from powering up if the battery voltage is very low (to avoid deep battery
discharge), The detector also provides an interrupt to shut down the phone if the battery is suddenly removed
−
primarily to protect the SIM.
The SIM power supply should be enabled and disabled as part of the SIM interface procedures and therefore falls
outside the scope of this document.
Figure 1:
Block diagram
600-1001
Signal
CPU I/O
Description
KBR0
I
Power key. This signal is connected to the KBR0 pin on GEMINI. When the
power key is held down this signal is HIGH
EXT_PWR
NC
External power supply from AC adapter etc. When present, the PSU is
forced on
EXT_PWR_SENSE
I
EXT_PWR scaled and sensed by the CPU as an analogue voltage
BAT_VOLT
I
Scaled battery voltage. This parameter is measured by the CPU and used
for gas gauging, regulating LED brightness, charging and to decide when to
power-down etc.
MCUK980101G8
Section 9
Issue 1
Technical Guide
9 - 1
Revision 0
POWER SUPPLIES
Battery Voltage
Detector
Logic
3.0 V Regulator
3.4 V Regulator
5 V SIM Supply
Gemini
ARM CPU
EXT_PWR
LUA
KBR0
EXT_PWR_SENSE
BAT_VOLT
nIGNITION
LOGIC_PWR
DC_OUT
SIM_PWR_CNT