Nokia 8208 Service Manual page 132

Voltage
Nominal voltage
Lower extreme voltage
Higher extreme voltage
(fast charging)
Vmstr+
Vmstr+
Sw shutdown
Sw shutdown
Power key and system power-up
The MSM6800A and PMIC control the power up and reset. The baseband can power up in the following ways:
Pressing the Power button, this means to pull high the KPD_PWR ("KPD_PWR" pin in 7205 schematic) pin

of the MSM6800A.
Connecting the charger/USB to the micro-USB connector.

After receiving one of the above signals, the PMIC will start to enter reset mode. The watchdog starts, and if
started by power button, the battery voltage has to greater than its threshold (2.85V) and started by
charger/USB, the battery voltage has to greater than its threshold (3V). Then, V_MSMC, V_MSME, V_MSMP, BT_2.6V
and V_MSMA regulators are enabled in sequence, and then TCXO_EN and RX_EN are sent from MSM to enable
V_TCXO_2.85 and V_RFRX0_2.85V. Less than 60ms, the PON_RST_N line be pulled-high and holds high for a
moment and sent to MSM. Resets are generated for the MSM's internal MCU and its internal DSP, and MSM sends
PS_HOLD signal to PMIC to hold regulators and then other regulators be enabled. This will keep all regulators at
on state in order to complete this power on sequence. KPD_PWR key can be released after PS_HOLD goes high.
The RESOUT2_2.6V_N from MSM6800A is used to reset flash memory during power up and to put the flash
memory in power down during sleep mode. LCD_RS from MSM6800A is used to reset LCD module during
power up. All baseband regulators are switched on when the PMIC is powered on. The MSM6800A's internal
watchdog runs and resets during normal operation. If the watchdog expires, it will generate a reset signal to
reset to MSM status. Then, MSM6800A drives RESOUT_2.6V_N and LCD_RS low to reset flash memory and LCD
module. Below figure represents the PMIC start-up sequence from reset to power-on.
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Voltage [V]
General Conditions
3.7
3.05
4.25
4.2
HW Shutdown Voltages
2.423-2.678
2.423-2.678
SW Shutdown Voltages
3.2
3.2
Table 28 Normal and extreme voltages
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System Module and User Interface
Condition
Off to on
On to off
In call
In idle
RM-384
Issue1