Nokia 3105 Servicehandbuch
CCS Technical Documentation
Troubleshooting — BB
RH-48
Issue 1 11/2003
© 2003 Nokia Corporation Confidential
Page 7
Figure 3: Measured power on sequence and timing
Power up with PWR key
When the Power on key is pressed, the UEM enters the power-up sequence. Pressing the
power key causes the PWRONX pin on the UEM to be grounded. The UEM PWRONX sig-
nal is not part of the keypad matrix. The power key is only connected to the UEM. This
means that when pressing the power key an interrupt is generated to the UPP that starts
the MCU. The MCU then reads the UEM interrupt register and notice that it is a PWRONX
interrupt. The MCU now reads the status of the PWRONX signal using the UEM control
bus, CBUS. If the PWRONX signal stays low for a certain time the MCU accepts this as a
valid power on state and continues with the SW initialization of the baseband. If the
power on key does not indicate a valid power-on situation, the MCU powers off the
baseband.
power key causes the PWRONX pin on the UEM to be grounded. The UEM PWRONX sig-
nal is not part of the keypad matrix. The power key is only connected to the UEM. This
means that when pressing the power key an interrupt is generated to the UPP that starts
the MCU. The MCU then reads the UEM interrupt register and notice that it is a PWRONX
interrupt. The MCU now reads the status of the PWRONX signal using the UEM control
bus, CBUS. If the PWRONX signal stays low for a certain time the MCU accepts this as a
valid power on state and continues with the SW initialization of the baseband. If the
power on key does not indicate a valid power-on situation, the MCU powers off the
baseband.
Power up when charger is connected
In order to be able to detect and start charging in cases where the main battery is fully
discharged (empty) and hence UEM has no supply (NO_SUPPLY or BACKUP mode of
UEM), charging is controlled by START-UP CHARGING circuitry.
discharged (empty) and hence UEM has no supply (NO_SUPPLY or BACKUP mode of
UEM), charging is controlled by START-UP CHARGING circuitry.
Whenever VBAT level is detected to be below master reset threshold (V
MSTR-
), charging is
controlled by START_UP charge circuitry. Connecting a charger forces VCHAR input to
rise above charger detection threshold, VCH
rise above charger detection threshold, VCH
DET+
. By detection start-up charging is
started. UEM generates 100mA constant output current from the connected charger’s
output voltage. As battery charges its voltage rises, and when VBAT voltage level higher
than master reset threshold limit (V
output voltage. As battery charges its voltage rises, and when VBAT voltage level higher
than master reset threshold limit (V
MSTR+
) is detected START_UP charge is terminated.
Monitoring the VBAT voltage level is done by charge control block (CHACON). MSTRX=‘1’
output reset signal (internal to UEM) is given to UEM’s RESET block when VBAT>V
output reset signal (internal to UEM) is given to UEM’s RESET block when VBAT>V
MSTR+