Normal And Extreme Voltages; Power Key And System Power Up; Modes Of Operation - Nokia 500 Service Manual

RM-750
System Module

Normal and extreme voltages

Energy management is mainly carried out in the EM ASIC (N2200), which contains a number of regulators. In
addition, there are also some external regulators.
In the table below normal and extreme voltages are shown when a BL-4U battery is used.
Voltage
Nominal voltage
Lower extreme voltage
Higher extreme voltage
(fast charging)
Vmstr+
Vmstr-
Sw shutdown
Sw shutdown
Vcoff+
Vcoff-

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 (N2200) via the PWRONX signal.
The PWRONX line cannot be detected when SW hangs. For that reason, the user has to remove the battery.

Modes of operation

Mode
NO_SUPPLY (Dead) mode means that the main battery is not present or its voltage is too low (below
N2200 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 adequate
and the 32 kHz oscillator is running.
PWR_OFF In this mode (warm), the main battery is present and its voltage is over N2200 master
reset threshold. All regulators are disabled, PURX 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.
Issue 1
Table 9 Nominal voltages
Voltage [V]
General conditions
3.7
3.5
4.1
HW shutdown voltages
2.1 ± 0.1
1.9 ± 0.1
SW shutdown voltages
3.1
3.25
Min operating voltages
2.9 ± 0.1
2.7 ± 0.1
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Condition
Off to on
On to off
In call
In idle
Off to on
On to off
Description
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