Panasonic EB-G450 Technical Manual

Also see for EB-G450: Operating instructions Service manual Operating instructions

Contents

Panasonic EB-G450 Technical Manual Manual pdf 32 page image

http://cxema.ru9 POWER SUPPLIES9.1 IntroductionThis section describes the Power Supply Unit (PSU) used on the G450 logic PCB and the method by which it iscontrolled.This section has detailed information on:1 An overview of the circuit functionality2 Powering-up the phone3 Powering-down the phone4 Power management9.2 OverviewThe 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 batterydischarge, and also provides an interrupt to shut down the phone if the battery is suddenly removed, primarily toprotect the SIM.The SIM power supply should be enabled and disabled as part of the SIM interface procedures and therefore fallsoutside the scope of this document.Figure 1: Block diagram 450-0901Signal CPU I/O DescriptionKBR0 I Power key. This signal is connected to the KBR0 pin on Polestar. When thepower key is held down this signal is HIGHEXT_PWR NC External power supply from AC adapter etc. When present the PSU isforced onEXT_PWR_SENSE I EXT_PWR scaled and sensed by the CPU as an analogue voltageBAT_VOLT IScaled battery voltage. This parameter is measured by the CPU and usedfor gas gauging, regulating LED brightness, charging and to decide when topower-down etc.MCUK971001G8 Section 9 Issue 1Technical Guide 9 - 1 Revision 0POWER SUPPLIESBattery VoltageDetector Logic 3.0 V Regulator3.6 V Regulator5 V SIM SupplyGeminiARM CPUEXT_PWREXTINTKBR0EXT_PWR_SENSEBAT_VOLTnIGNITIONSTAY_ALIVEnPOW_ONSIM_PWR