AAT3683 Datasheet, PDF (14/24 Pages) Advanced Analogic Technologies – 1A Linear Li-Ion Battery Charger

10000
1000
100
10
1
10
100
R_SET (kΩ)
Figure 2: Constant Charging Current
vs. Set Resistor Values.
Programmable Charge Termination
Current
The charge termination current I_{CH_TERM} can be
programmed by connecting a resistor from TERM
to GND:
I_{CH_TERM}
=
15µA · R_TERM
2V
·
I_{CH_CC}
If the TERM pin is left open, the termination current
will set to 10% of the constant charging current as
the default value.
When the charge current drops to the defaulted 10%
of the programmed charge current level or pro-
grammed terminated current in the constant voltage
mode, the device terminates charging and goes into
a sleep state. The charger will remain in this sleep
state until the battery voltage decreases to a level
below the battery recharge voltage threshold (V_RCH).
Consuming very low current in sleep state, the
AAT3683 minimizes battery drain when it is not
charging. This feature is particularly useful in appli-
cations where the input supply level may fall below
the battery charge or under-voltage lockout level.
In such cases where the AAT3683 input voltage
drops, the device will enter sleep state and auto-
matically resume charging once the input supply
has recovered from the fault condition.
AAT3683
1A Linear Li-Ion Battery Charger
Charge Status Output
The AAT3683 provides battery charge status via a
status pin (AAT3683-4 provides battery charge sta-
tus via two status pins). This pin is internally con-
nected to an N-channel open-drain MOSFET,
which can be used drive an external LED. The sta-
tus pin can indicate the following conditions
(AAT3683-2, AAT3683-3):
Event Description
No battery charging activity
Battery charging via adapter or
USB port
Charging completed
STATUS
OFF
ON
OFF
Table 2: LED Status Indicator
(AAT3683-2/AAT3683-3).
The status pins can indicate the following conditions
(AAT3683-4):
Event Description
STAT1 STAT2
Charge enabled without battery
Battery charging
Charge completed
Fault
FLASH¹
ON
OFF
OFF
FLASH¹
OFF
ON
OFF
Table 3: LEDs Status Indicator.
(AAT3683-4).
The LED should be biased with as little current as
necessary to create reasonable illumination; there-
fore, a ballast resistor should be placed between
the LED cathode and the STAT pin. LED current
consumption will add to the overall thermal power
budget for the device package, hence it is good to
keep the LED drive current to a minimum. 2mA
should be sufficient to drive most low-cost green or
red LEDs. It is not recommended to exceed 8mA
for driving an individual status LED.
1. Flashing rate depends on output capacitance.
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