AAT3690 Datasheet, PDF (10/20 Pages) Advanced Analogic Technologies – 1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger

AAT3690
1.0A USB Port/Adapter
Lithium-Ion/Polymer Battery Charger
Charging Operation
Regardless of which charge input function is selected (i.e., either the adapter input or USB input), the AAT3690
has three basic modes for the battery charge cycle: constant current/fast charge; constant voltage; and end of
charge (see Figure 1).
Charge Complete Voltage
Regulated Current
Constant Current
Charge Phase
I = Max CC
Constant Voltage
Charge Phase
I = CC/10
Figure 1: Current vs. Voltage Profile During Charging Phases.
Fast Charge / Constant Current Charging
When enabled, the AAT3690 begins constant-cur-
rent fast charging. The fast charge Constant
Current (I_CC) amplitude is determined by the
charge mode, ADP or USB, and is programmed by
the user via the R_SETADP and R_SETUSB resistors. The
AAT3690 remains in constant current charge mode
until the battery reaches the voltage regulation
point, V_BAT.
Constant Voltage Charging
The system transitions to a constant voltage charg-
ing mode when the battery voltage reaches output
charge regulation threshold (V_BAT) during the con-
stant current fast charge phase. The regulation
voltage level is factory programmed to 4.2V (±1%).
The charge current in the constant voltage mode
drops as the battery cell under charge reaches its
maximum capacity.
End of Charge Cycle Termination and
Recharge Sequence
When the charge current drops to 7.5% of the pro-
grammed fast charge current level in the constant
voltage mode, the device terminates charging and
goes into a standby state. The charger will remain
in a standby state until the battery voltage decreas-
es to a level below the battery recharge voltage
threshold (V_RCH).
When the input supply is disconnected or drops
below UVLO or EN = 0, the charger will automati-
cally enter power-saving sleep mode. Consuming
an ultra-low 2μA in sleep mode, the AAT3690 min-
imizes battery drain when it is not charging. This
feature is particularly useful in applications where
the input supply level may fall below the battery
charge or under-voltage lockout level. In such
cases where the AAT3690 input voltage drops, the
device will enter the sleep mode and automatically
resume charging once the input supply has recov-
ered from its fault condition.
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3690.2007.01.1.2