AAT3693 Advanced Analogic Technologies, Inc., AAT3693 Datasheet - Page 11

• Manufacturer Part Number: AAT3693
• Description: 1.6a Lithium-ion/polymer Battery Charger In 2.2x2.2 Tdfn
• Manufacturer: Advanced Analogic Technologies, Inc.

BatteryManager
In the event of an internal over-temperature condition
caused by excessive ambient operating temperature or
excessive power dissipation condition, the AAT3693
enables a digitally controlled thermal loop system that
will reduce the charging current to prevent the device
from thermal shutdown. The digital thermal loop will
maintain the maximum possible battery charging cur-
rent for the given set of input to output power dissipa-
tion and ambient temperature conditions.
The digital thermal loop control is dynamic in the sense
that it will continue to adjust the battery charging cur-
rent as operating conditions change.
The digital thermal loop will reset and resume normal
operation when the power dissipation or over tempera-
ture conditions are removed.
Charging Operation
Figure 1 illustrates the entire battery charging profile or
operation, which consists of four phases:
1. Preconditioning (Trickle) Charge
2. Constant Current Charge
3. Constant Voltage Charge
4. Automatic Recharge
Battery Preconditioning
Battery charging commences only after the AAT3693
checks several conditions in order to maintain a safe
charging environment. The input supply must be above
the minimum operating voltage (V
pin must be high.
3693.2009.04.1.1
Charge Complete Voltage
Constant Current Mode
Termination Threshold
Regulated Current
Trickle Charge and
Voltage Threshold
I = CC / 10
Preconditioning
Trickle Charge
Phase
TM
Figure 1: Current vs. Voltage Profile During Charging Phases.
I = Max CC
UVLO
1.6A Lithium-Ion/Polymer Battery Charger in 2.2x2.2 TDFN
Constant Current
) and the enable
Charge Phase
w w w . a n a l o g i c t e c h . c o m
When the battery is connected to the BAT pin, the
AAT3693 checks the condition of the battery and deter-
mines which charging mode to apply. If the battery volt-
age is below the preconditioning voltage threshold, V
then the AAT3693 begins preconditioning the battery cell
(trickle charging) by charging at 10% of the programmed
constant current. For example, if the programmed cur-
rent is 500mA, then the preconditioning mode (trickle
charge) current is 50mA. Battery cell preconditioning
(trickle charging) is a safety precaution for deeply dis-
charged cells and will also reduce the power dissipation
in the internal series pass MOSFET when the input-out-
put voltage differential is at the greatest potential.
Constant Current Charging
Battery cell preconditioning continues until the battery
voltage reaches the preconditioning voltage threshold,
V
charging. The current level for this mode is programmed
using a single resistor from the ISET pin to ground.
Programmed current can be set from a minimum of
100mA up to a maximum of 1.6A
Constant Voltage Charging
Constant current charging will continue until the battery
voltage reaches the constant output voltage (end of
charge) voltage regulation point, V
tery voltage reaches V
to constant voltage mode. The regulation voltage is fac-
tory programmed to a nominal 4.2V and will continue
charging until the charge termination current is reached.
MIN
Constant Voltage
. At this point, the AAT3693 begins constant current
Charge Phase
PRODUCT DATASHEET
CO(REG)
Battery Discharge
Voltage Threshold
Battery Recharge
, the AAT3693 will transition
AAT3693
CO(REG)
. When the bat-
Constant Voltage
Charge Phase
MIN
11
,