AAT3683_08 Datasheet, PDF (13/23 Pages) Advanced Analogic Technologies – 1A Linear Li-Ion Battery Charger

BatteryManager^TM
Application Information
Adapter or USB Power Input
Constant current charge levels up to 1A may be pro-
grammed by the user when powered from a sufficient
input power source. The AAT3683 will operate from the
adapter input over a 4.0V to 7.5V range. The constant
current mode fast charge current for the adapter input
is set by the R_SET resistor connected between ISET and
ground. Refer to Table 4 for recommended R_SET values
for a desired constant current charge level.
Adapter Input Charge Inhibit and Resume
The AAT3683 has a UVLO and power on reset feature so
that if the input supply to the ADP pin drops below the
UVLO threshold, the charger will suspend charging and
shut down. When power is re-applied to the IN pin or the
UVLO condition recovers, the system charge control will
assess the state of charge on the battery cell and will
automatically resume charging in the appropriate mode
for the condition of the battery.
Digital Thermal Loop Control
Due to the integrated nature of the linear charging con-
trol pass device for the adapter mode, a special thermal
loop control system has been employed to maximize
charging current under all operation conditions. The
thermal management system measures the internal cir-
cuit die temperature and reduces the fast charge current
when the device exceeds a preset internal temperature
control threshold. Once the thermal loop control becomes
active, the fast charge current is initially reduced by a
factor of 0.44.
The initial thermal loop current can be estimated by the
following equation:
I_TLOOP = I_{CH_CC} · 0.44
The thermal loop control re-evaluates the circuit die tem-
perature every three seconds and adjusts the fast charge
current back up in small steps to the full fast charge cur-
rent level or until an equilibrium current is discovered
PRODUCT DATASHEET
AAT3683
1A Linear Li-Ion Battery Charger
and maximized for the given ambient temperature condi-
tion. The thermal loop controls the system charge level;
therefore, the AAT3683 will always provide the highest
level of constant current in the fast charge mode possible
for any given ambient temperature condition.
Enable / Disable
The AAT3683 provides an enable function to control the
charger IC on and off. The enable (EN) pin is internally
pulled down. When pulled to a logic high level, AAT3683
is enabled. When left open or pulled to a logic low level,
the AAT3683 will be shut down. Charging will be halted
regardless of the battery voltage or charging state.
When the device is re-enabled, the charge control circuit
will automatically reset and resume charging functions
with the appropriate charging mode based on the battery
charge state and measured cell voltage on the BAT pin.
Programming Charge Current
The constant current mode charge level is user pro-
grammed with a set resistor placed between the ISET pin
and ground. The accuracy of the constant charge cur-
rent, as well as the preconditioning trickle charge cur-
rent, is dominated by the tolerance of the set resistor
used. For this reason, a 1% tolerance metal film resistor
is recommended for the set resistor function. The con-
stant charge current levels from 100mA to 1A may be set
by selecting the appropriate resistor value from Table 1.
Constant Charging
Current (mA)
100
200
300
400
500
600
700
800
900
1000
Set Resistor
Value (kΩ)
16.2
8.06
5.36
4.02
3.24
2.67
2.26
2
1.78
1.58
Table 1: R_SET Values.
3683.2007.11.1.2
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