RM-994/ RM-995/ RM-996
System Module
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The PM8038 PMIC determines the system boot up (or shutdown) by comparing the battery voltage with the
UVLO thresholds.
Table 9 UVLO performance specifications
Threshold voltage, falling
Threshold voltage accuracy
The hysteresis acts the following way:
â—Ź For rising threshold (during power up), the threshold would be 2700 + 175 mV
â—Ź For falling threshold (to determine shutdown), the threshold would be 2700 mV
Power key and system power up
When 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 aid
of SW. The power key is connected to EM ASIC (U1100) via the PON_RESET_N signal.
Modes of operation
(Dead) mode means that the main battery is not present or its voltage is too low
(below U1100 master reset threshold) and that the back-up battery voltage is too low.
The main battery is not present or its voltage is too low but back-up battery is
adequate and the 32 kHz oscillator is running.
In this mode (warm), the main battery is present and its voltage is over U1100 master
reset threshold. All regulators are disabled, PON_RESET_N is on low state, the RTC
is on and the oscillator is on. PWR_OFF (cold) mode is almost the same as
PWR_OFF (warm), but the RTC and the oscillator are off.
RESET mode is a synonym for start-up sequence. RESET mode uses 32 kHz clock to
count the RESET mode delay (typically 16ms).
SLEEP mode is entered only from PWR_ON mode with the aid of SW when the
system’s activity is low.
FLASHING mode is for SW downloading.
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