AAT3663_08 Datasheet, PDF (15/23 Pages) Advanced Analogic Technologies – 1A Linear Li-Ion Battery Charger for Single and Dual Cell Applications

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PRODUCT DATASHEET
AAT3663
1A Linear Li-Ion Battery Charger for Single and Dual Cell Applications
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 AAT3663 will operate over an
input voltage range from 4.0V to 13.2V. The low input
voltage capability of the AAT3663 permits charging sin-
gle cell Li-Ion/Poly batteries from USB ports and lower
voltage input power sources. The high 13.2V input rating
of this device allows for the use of a wide range of input
power sources for both single and dual cell Li-Ion/Poly
applications.
Adapter Input Charge
Inhibit and Resume
The AAT3663 has an under-voltage lockout (UVLO) and
power on reset feature so that if the input supply to the
IN pin drops below the UVLO threshold, the charger will
suspend charging and shut down. When power is reap-
plied 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.
Battery Connection and
Battery Voltage Sensing
Battery Connection
A single or dual cell Li-Ion/Polymer battery should be
connected between the BAT pin and ground.
Battery Voltage Sensing
The BATS pin is provided to employ an accurate voltage
sensing capability to measure the positive terminal volt-
age at the battery cell being charged. This function
reduces measured battery cell voltage error between the
battery terminal and the charge control IC. The AAT3663
charge control circuit will base charging mode states
upon the voltage sensed at the BATS pin. The BATS pin
must be connected to the battery terminal for correct
operation. If the battery voltage sense function is not
needed, the BATS pin should be terminated directly to
the BAT pin. If there is concern of the battery sense
function inadvertently becoming an open circuit, the
BATS pin may be terminated to the BAT pin using a 10kΩ
resistor. Under normal operation, the connection to the
battery terminal will be close to 0Ω; if the BATS connec-
tion becomes an open circuit, the 10kΩ resistor will pro-
vide feedback to the BATS pin from the BAT connection
with a voltage sensing accuracy loss of 1mV or less.
Enable (EN)
EN is a logic input (active high) to enable the charger,
this function is internally pulled down to ground. When
the device is initially enabled or if the EN pin is cycled low
and then re-enabled, the charge control circuit will auto-
matically reset and resume charging functions with the
appropriate charging mode based on the battery charge
state and measured battery voltage on the BATS pin.
Programming Charge Current
The constant current mode charge level is user pro-
grammed with a set resistor (R_SET) connected between the
ISET pin and ground. The accuracy of the constant charge
current, 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)
17.8
8.87
5.9
4.42
3.57
2.94
2.55
2.21
1.96
1.78
Table 1: R_SET Values.
If the desired charge current level is not listed in Table
1, the R_SET resistor value can be found in Figure 2 and
calculated by the following equation:
R_SET
=
K
·
⎛V_ISET⎞
⎝ I_CC ⎠
Where:
K = K_{I_SET} = 900
V_ISET = 2V
I_CC = Fast charge constant current
3663.2008.01.1.2
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