Charger Is Connected - Nokia RM-11 Series Troubleshooting Manual

CC Technical Documentation

Charger is Connected

In order to be able to detect and start charging in the case 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.
Whenever the VBAT level is detected to be below the master reset threshold (VMSTR-),
charging starts and is controlled by the start-up charge circuitry. Connecting a charger
forces the VCHAR input to rise above the charger detection threshold (VCHDET+) and by
detection charging is started. The UEM generates a 100mA constant output current from
the connected charger's output voltage. As the battery charges, its voltage rises and
when VBAT voltage level is detected to be higher than the master reset threshold limit
(VMSTR+), the start-up charge is terminated.
Monitoring the VBAT voltage level is done by the charge control block (CHACON).
MSTRX='1' output reset signal (internal to the UEM) is given to the UEM's RESET block
when VBAT>VMSTR+ and UEM enters into reset sequence.
If VBAT is detected to fall below VMSTR- during start-up charging, charging is cancelled.
It restarts if a new rising edge on VCHAR input is detected (VCHAR rising above
VCHDET+).
Issue 2 09/2005
©2005 Nokia Corporation
Troubleshooting - Baseband
Confidential
RM-11
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