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A. Power up sequence logic
The ADP3408 controls power on sequence.
B. Power on sequence
If a battery is inserted, the battery powers the 6 LDOs.
Then if PWRONKEY is detected, the LDOs output turn on.
REFOUT is also enabled.
Reset is generated and send to the AD6522.
C. LDO block
There are 6 LDOs in the ADP3408.
VSIM
2.86 V (is provided to SIM card)
VCORE
2.45 V (is provided to the AD6522 and AD6521's digital core)
VRTC
2.45 V (is provided to the RTC and Backup Battery)
VAN
2.45 V (is provided to the AD6521 I/O and used as microphone bias)
VTCXO
2.715 V (is provided to VCTCXO)
VMEM
2.80 V (is provided to Flash)
D. Battery charging block
It can be used to charge Lithium Ion and/or Nickel Metal Hydride batteries. LG-512W use Li-Ion and
Li-polymer battery only.
Charger initialization, trickle charging, and Li-Ion charging control are implemented in hardware.
E. Charging Process
Check charger is inserted or not.
If ADP3408 detects that Charger is inserted, the CC-CV charging starts.
Exception: When battery voltage is lower than 3.2V, the precharge (low current charge mode) starts
firstly.
And the battery voltage reach to 3.2V the CC-CV charging starts.
F. Pins used for charging
CHARGERDETECT: Interrupt to the AD6522 when charger is plugged.
CHARGEEN: Control signal from the AD6522 to charge Li+ battery .
EOC: Interrupt to the AD6522 when battery is fully charged.
GATEIN: Control signal from AD6522 to charge NiMH battery. But, not used.
MVBAT: Battery voltage divider. Divide ratio is 1:2.3 and it is sensed in AD6521 AUX_ADC.
Table 3-11. LDO Block.
Description
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3. TECHNICAL BRIEF
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