Nokia RM-824 Service Manual

Contents

Voltage Voltage [V] ConditionHigher extreme voltage4.2(fast charging)SW Shutdown VoltagesSw shutdown 3.3The PM8921 PMIC determines the system bootup (or shutdown) by comparing the battery voltage with theUVLO thresholds.Table 9 UVLO performance specificationsParameter Comments Min Typ Max UnitsThreshold voltage, falling Programmable value 1.500 2.700 3.050 VThreshold voltage accuracy -5 - +5 %Hysteresis 100 175 250 mVUVLO detection interval - 1.0 - μsThe hysteresis acts the following way:• For rising threshold (during power up), the threshold would be 2700 + 175 mV• For falling threshold (to determine shutdown), the threshold would be 2700 mVPower key and system power upWhen the battery is placed in the phone, the power key circuits are energized. When the power key is pressed,the system boots up (if an adequate battery voltage is present).Power down can be initiated by pressing the power key again and the system is powered down with the aidof SW. The power key is connected to EM ASIC (N2200) via the KYPD_PWR_N signal.Modes of operationMode DescriptionNO_SUPPLY (Dead) mode means that the main battery is not present or its voltage is too low (belowN2200 master reset threshold) and that the back-up battery voltage is too low.BACK_UP The main battery is not present or its voltage is too low but back-up battery is adequateand the 32 kHz oscillator is running.PWR_OFF In this mode (warm), the main battery is present and its voltage is over N2200 masterreset threshold. All regulators are disabled, PURX is on low state, the RTC is on and theoscillator is on. PWR_OFF (cold) mode is almost the same as PWR_OFF (warm), but theRTC and the oscillator are off.RESET RESET mode is a synonym for start-up sequence. RESET mode uses 32 kHz clock to countthe RESET mode delay (typically 16ms).SLEEP SLEEP mode is entered only from PWR_ON mode with the aid of SW when the system’sactivity is low.FLASHING FLASHING mode is for SW downloading.RM-824; RM-825; RM-826System ModulePage 6 – 10 NOKIA INTERNAL USE ONLY Issue 2Copyright © 2012 Nokia. All rights reserved.