AAT3783_12 Datasheet, PDF (14/20 Pages) Skyworks Solutions Inc. – 1-A Linear Li-Ion/Polymer Battery Charger with 28V Over-Voltage Protection

DATA SHEET
AAT3783
1-A Linear Li-Ion/Polymer Battery Charger with 28V Over-Voltage Protection
Application Information
Programming the Over-Voltage
Protection Trip Point
The default over-voltage protection trip point of the
AAT3783 is set to 6.5V by the factory. However, the
over-voltage protection trip point can be programmed
from 3.8V to 7.5V by the user with one external resistor,
either R5 or R6. The placement of R5 is between IN and
OVP. The placement of R6 is between OVP and GND.
Table 2 summarizes resistor values for various over-
voltage protection trip points. Use 1% tolerance metal
film resistors for programming the desired OVP trip
point.
R6 (KΩ)
short
0.499
1.3
3.01
open
open
open
open
open
R5 (KΩ)
open
open
open
open
open
4.99
2.49
1.0
short
V_{OVP_TRIP POINT} (V)
7.5
7.25
7.0
6.75
6.5
5.5
5.0
4.5
3.87
Table 2: Programming OVP Trip Point for
AAT3783 with One Resistor.
Battery Connection
and Battery Voltage Sensing
Battery Connection (BAT)
A single cell Li-Ion/Polymer battery should be connected
between the BAT pin and ground.
Battery Voltage Sensing (BATS)
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 AAT3783
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.
Constant 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 3.
Constant Charging
Current (mA)
10
20
50
100
200
300
400
500
600
700
800
900
1000
Set Resistor Value (kΩ)
162
80.6
32.4
16
8.06
5.36
4.02
3.24
2.67
2.26
2
1.78
1.62
Table 3: R_SET Values.
10000
1000
100
10
1
1
10
100
1000
R_SET (kΩ)
Figure 2: Constant Charging Current
vs. Set Resistor Values.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
14
201903B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 27, 2012