Normal And Extreme Voltages; Power Key And System Power-Up - Nokia RM-721 Service Manual

RM-721; RM-722
System Module
Battery connector
The battery connector is a spring connector. It has three springs;
• BSI (Battery size indicator)
• GND (Ground)
• VBAT (Battery voltage)
The BSI line is used to recognize the battery capacity by a battery internal pull down resistor.
Charging
This phone is charged through a separate charger connector.
Charging is controlled by energy management, and external components are needed to protect the baseband
module against EMC, reverse polarity and transient frequency deviation.
Complementary USB charging is supported as well, in case the phone is connected to a PC or to a dedicated
USB charger.

Normal and extreme voltages

Energy management is mainly carried out in the ASIC PEARL_J. These circuits contain a number of regulators.
In the table below normal and extreme voltages are shown when a BL-5C 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 (the system is powered down with the aid of
SW). The power key is connected to EM ASIC N2200 (PEARL_J) via PWRONX signal.
Issue 1
Table 11 Nominal voltages
Voltage [V]
General Conditions
4.0
3.145
4.23
HW Shutdown Voltages
2.1 ± 0.1
1.9 ± 0.1
SW Shutdown Voltages
3.106
3.2
Min Operating Voltage
2.9 ± 0.1
2.6 ± 0.1
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Condition
Off to on
On to off
In call
In idle
Off to on
On to off
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