Power Up And Reset - Nokia 1265 Description And Troubleshooting

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Power Up and Reset

The QSC6010 controls the power up and reset. The baseband can power up in the
following ways:
Pressing the Power button, which means to ground the KPD_PWR_N
("PHONE_ON_N" pin in 1265 schematic) pin of the QSC6010
Connecting the charger to the charger input.
After receiving one of the above signals, the PM will start to enter reset mode. The
watchdog starts, and if the battery voltage is greater than its threshold (3V), a 6ms
delay starts to allow MSM to settle. After this delay elapses, the VERG_MSMC
regulator enables. Then, VERG_MSMP, VERG_MSMA & VERG_TCXO regulators
are enabled in sequence after MSMC. There is a 120us (4 Sleep_Clocks) delays
between each regulator's turn on. The PON_RESET_N ("RESIN_N" pin in 1265
schematic) line holds low for another 20ms and is sent to MSM. Resets are
generated for the MSM's internal MCU and its internal DSP, and MSM sends
TCXO_ON ("TCXO_EN" pin in 1265 schematic) signal to PM to enable TCXO. After
PON_RESET_N goes high, MSM holds PS_HOLD at low state for 200ms and then
drives PS_HOLD to high state. This will keep all regulators at on state in order to
complete this power on sequence. KPD_PWR_N key can be released after
PS_HOLD goes high.
The RESOUT_N from QSC6010 is used to reset flash memory during power up and
to put the flash memory in power down during sleep mode. LCD_RS from QSC6010
is used to reset LCD module during power up. All baseband regulators are switched
on when the PM is powered on. The QSC6010'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, QSC6010 drives RESOUT_N and LCD_RS low to reset
flash memory and LCD module.
Figure 3 represents the PM start-up sequence from reset to power-on.
Issue 1 04/2007 © 2007 Nokia Corporation
Baseband Description and Troubleshooting
Company Confidential
1265 (RH-103)
Page 5