Power Up - Nokia 1265 Description And Troubleshooting

1265 (RH-103)
Baseband Description and Troubleshooting

Power Up

The mobile terminal can use the power key or a charger to power up.
Power Key
When the power key is pressed, the PM enters the power-up sequence. Pressing the
power key causes the KPD_PWR_N (PHONE_ON_N pin in 1265 schematic) pin to
GND. The KPD_PWR_N signal is not part of the keypad matrix. The power key is
only connected to the PM. This means that when the power key is pressed, an
interrupt will be generated to the MSM in order to power on the MCU. The MCU
reads the QSC6010's interrupt register and notifies that it is a KPD_PWR_N interrupt.
The MCU reads the status of the KPD_PWR_N signal using the control bus. If the
KPD_PWR_N signal stays low for a certain time, the MCU accepts this as a valid
power-on state and continues with the software baseband initialization. If the power
key does not indicate a valid power-on situation, the MCU powers off the baseband.
Charger
Charging is controlled by start-up charging circuitry in order to detect and start
charging in cases the main battery is empty and the PM has no supply.
External Supply Source is Detected
If a valid source is applied to VCHG (pin V15 of QSC6010) and the battery voltage of
VPH_PWR exceeds PM's valid UVLO (2.5V) threshold, the power-on sequence of
PM is initiated and enables its internal regulators. UVLO is the minimum voltage
required for QSC6010 operation. If the entire power-on sequence is successful, the
appropriate interrupt from PM will be sent to the MSM. Once the battery voltage rises
Page 6 © 2007 Nokia Corporation
Figure 3: Power-on & off sequence and timing
Company Confidential Issue 1 04/2007