Power Supplies; Introduction; Overview - Panasonic EB-G450 Technical Manual
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Also See for EB-G450:
- Operating instructions manual (32 pages) ,
- Service manual (108 pages) ,
- Operating instructions manual (32 pages)
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9
POWER SUPPLIES
9.1
Introduction
This section describes the Power Supply Unit (PSU) used on the G450 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, and 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
Signal
KBR0
EXT_PWR
EXT_PWR_SENSE
BAT_VOLT
MCUK971001G8
Technical Guide
http://cxema.ru
Battery Voltage
Detector
EXT_PWR
EXTINT
KBR0
EXT_PWR_SENSE
BAT_VOLT
nIGNITION
CPU I/O
Description
Power key. This signal is connected to the KBR0 pin on Polestar. When the
I
power key is held down this signal is HIGH
External power supply from AC adapter etc. When present the PSU is
NC
forced on
I
EXT_PWR scaled and sensed by the CPU as an analogue voltage
Scaled battery voltage. This parameter is measured by the CPU and used
I
for gas gauging, regulating LED brightness, charging and to decide when to
power-down etc.
nPOW_ON
Logic
STAY_ALIVE
Gemini
ARM CPU
SIM_PWR
Section 9
9 - 1
POWER SUPPLIES
3.0 V Regulator
3.6 V Regulator
5 V SIM Supply
450-0901
Revision 0
Issue 1
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