Trickle charging
Trickle charging of the main battery, enabled through software and powered from VDD, is provided
by the PM6658 device. This mode is used to raise a severely depleted battery’s voltage to a level
sufficient to begin fast charging. If fast charging is enabled while the battery is below 2.55 V (the
UVLO threshold), the battery pulls VDD down and causes the phone to turn off. Even if the battery
voltage is between 2.55 and 3.10 V, fast charging is still not recommended because the regulators
can fail. Trickle charging avoids these two potential problems by getting the battery voltage to about
3.1 V or more before attempting fast charging.
The trickle charger is an on-chip programmable current source that supplies current from VDD to
the VBAT pin; pertinent performance specifications are given in Tabl. Software must terminate
trickle charging based upon battery voltage measurements at the MSM device’s HKADC (routed
through the PM analog multiplexer) and the battery type - there is no preset termination threshold.
LGE Internal Use Only
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
3. TECHNICAL BRIEF
- 59 -
Figure. Trickle Charging
Summary of Contents for KT610
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