DATA SHEET
AAT3681A
500mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger
General Description
Features
The AAT3681A BatteryManager is an integrated single cell
lithium-ion/polymer battery charger IC, designed to operate from a DC power source or USB port up to an input
voltage of 7.5V. It requires just one external component.
• USB or AC Adapter System Power Charger
▪ Programmable from 15mA to 500mA
• 4.0V ~ 7.5V Input Voltage Range
• High Level of Integration with Internal:
▪ Charging Device
▪ Reverse Blocking Diode
Constant Regulated Output Voltage:
▪ 4.1 in AAT3681A-5
▪ 4.2 in AAT3681A-1/-2/-4
• Automatic Current Sensing
• Automatic Recharge Sequencing
• Full Battery Charge Auto Turn Off/Sleep Mode/Charge
Termination
• Shutdown Current VUVLO
Yes
Shut Down
Yes
Fault Conditions
Monitoring
OV, OT
Charge
Control
No (AAT3681A,
AAT3681A-2,
AAT3681A-5)
No (AAT3681A-1,
AAT3681A-4)
Preconditioning
Test
V MIN > VBAT
Yes
Preconditioning
(Trickle Charge)
Yes
Constant
Current Charge
Mode
No
No
Recharge Test
V RCH > VBAT
Yes
Current Phase Test
V CO(REG) > VBAT
No
Voltage Phase Test
IBAT > ITERM
Yes
No
Constant
Voltage Charge
Mode
No (AAT3681A, AAT3681A-1,
AAT3681A-2, AAT3681A-4,
AAT3681A-5, AAT3681A-6)
Charge Completed
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DATA SHEET
AAT3681A
500mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger
Application Information
Adapter or USB Power Input
Constant current charge levels up to 500mA may be
programmed by the user when powered from a sufficient
input power source. The AAT3681A will operate from the
adapter input over a 4.0V to 7.5V range. The constant
current fast charge current for the adapter input is set
by the RSET resistor connected between ISET and ground.
Refer to Table 1 for recommended RSET values for a
desired constant current charge level.
Adapter Input Charge Inhibit and Resume
Programming Charge Current
The fast charge constant current charge level is user
programmed with a set resistor placed between the ISET
pin and ground. The accuracy of the fast charge, as well
as the preconditioning trickle charge current, 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. Fast charge constant current levels from 15mA to 500mA may be set by
selecting the appropriate resistor value from Table 1.
Nominal
ICHARGE (mA)
Set Resistor
Value (kW)
500
450
400
350
300
250
200
150
100
50
40
30
20
15
3.24
3.57
4.12
4.64
5.36
6.49
8.06
10.7
16.2
31.6
38.3
53.6
78.7
105
The AAT3681A 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 ADP 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.
Enable / Disable
The AAT3681A provides an enable function to control the
charger IC on and off. The EN pin functions as follows on
the various AAT3681A options:
AAT3681A-2: The enable (EN) pin is internally pulled
down. When left open or pulled to a logic low level, the
AAT3681A-2 is enabled. When pulled to a logic high
level, the AAT3681A-2 will be shut down and forced into
the sleep state.
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.
Constant
Current
Table 1:Charging
RSET Values.
vs. Set Resistor Values
1000
ICH (mA)
AAT3681A, AAT3681A-1, AAT3681A-4, and
AAT3681A-5: The enable (EN) pin is internally pulled
down through a 6MΩ resistor. When pulled to a logic high
level, the AAT3681A is enabled. When left open or pulled
to a logic low level, the AAT3681A will be shut down and
forced into the sleep state.
100
10
1
1
10
100
1000
RSET (kΩ)
Figure 2: Constant Charging Current
vs. Set Resistor Values.
Protection Circuitry
Over-Voltage Protection
An over-voltage event is defined as a condition where
the voltage on the BAT pin exceeds the maximum battery charge voltage and is set by the over-voltage protection threshold (VOVP). If an over-voltage condition
12
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201883C • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • November 19, 2012
DATA SHEET
AAT3681A
500mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger
Over-Temperature Shutdown
The AAT3681A has a thermal protection control circuit
which will shut down charging functions should the internal die temperature exceed the preset thermal limit
threshold. Once the internal die temperature falls below
the thermal limit, normal operation will resume the previous charging state.
Charge Status Output
The AAT3681A provides battery charge status via a status pin. This pin is internally connected to an N-channel
open drain MOSFET, which can be used to drive an external LED. The status pin can indicate the following conditions:
Event Description
Status
No battery charging activity
Battery charging via adapter or USB port
Charging completed
OFF
ON
OFF
Table 2: LED Status Indicator.
The LED should be biased with as little current as necessary to create reasonable illumination; therefore, 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. A 2mA should be sufficient to drive most lowcost green or red LEDs. It is not recommended to exceed
8mA for driving an individual status LED.
The required ballast resistor values can be estimated
using the following formulas:
R1 =
(VADP - VF(LED))
ILED
Thermal Considerations
The AAT3681A is offered in a SC70JW-8 package which
can provide up to 687mW of power dissipation when it
is properly bonded to a printed circuit board and has a
maximum thermal resistance of 160°C/W. Many considerations should be taken into account when designing
the printed circuit board layout, as well as the placement
of the charger IC package in proximity to other heat
generating devices in a given application design. The
ambient temperature around the charger IC will also
have an effect on the thermal limits of a battery charging application. The maximum limits that can be expected for a given ambient condition can be estimated by the
following discussion.
First, the maximum power dissipation for a given situation should be calculated:
PD(MAX) =
(TJ(MAX) - TA)
θJA
Where:
PD(MAX) = Maximum Power Dissipation (W)
qJA = Package Thermal Resistance (°C/W)
TJ(MAX) = Maximum Device Junction Temperature (°C)
[135°C]
TA = Ambient Temperature (°C)
Figure 3 shows the relationship of maximum power dissipation and ambient temperature of AAT3681A.
1000
800
PD(MAX) (mW)
occurs, the AAT3681A charge control will shut down the
device until the voltage on the BAT pin drops below VOVP.
The AAT3681A will resume normal charging operation
after the over-voltage condition is removed.
600
400
200
0
0
20
40
60
80
100
TA (°C)
Example:
R1 =
(5.5V - 2.0V)
= 1.75kΩ
2mA
Figure 3: Maximum Power Dissipation.
Note: Red LED forward voltage (VF) is typically 2.0V @
2mA.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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DATA SHEET
AAT3681A
500mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger
Next, the power dissipation can be calculated by the following equation:
PD = [(VIN - VBAT) · ICH + (VIN · IOP)]
Where:
PD =
VIN =
VBAT =
ICH =
IOP
Total Power Dissipation by the Device
Input Voltage
Battery Voltage as Seen at the BAT Pin
Constant Charge Current Programmed for the
Application
= Quiescent Current Consumed by the Charger IC
for Normal Operation [0.5mA]
By substitution, we can derive the maximum charge current before reaching the thermal limit condition (thermal
cycling). The maximum charge current is the key factor
when designing battery charger applications.
ICH(MAX) =
(PD(MAX) - VIN · IOP)
VIN - VBAT
(TJ(MAX) - TA) - V · I
IN
OP
θJA
ICH(MAX) =
VIN - VBAT
In general, the worst condition is the greatest voltage
drop across the charger IC, when battery voltage is
charged up to the preconditioning voltage threshold.
Figure 4 shows the maximum charge current in different
ambient temperatures without PCB thermal enhancements.
500
450
ICH(MAX) (mA)
400
TA = 25°C
350
Capacitor Selection
Input Capacitor
In general, it is good design practice to place a decoupling capacitor between the ADP pin and GND. An input
capacitor in the range of 1µF to 22µF is recommended.
If the source supply is unregulated, it may be necessary
to increase the capacitance to keep the input voltage
above the under-voltage lockout threshold during device
enable and when battery charging is initiated. If the
AAT3681A adapter input is to be used in a system with
an external power supply source, such as a typical
AC-to-DC wall adapter, then a CIN capacitor in the range
of 10µF should be used. A larger input capacitor in this
application will minimize switching or power transient
effects when the power supply is “hot plugged” in.
Output Capacitor
The AAT3681A only requires a 1µF ceramic capacitor on
the BAT pin to maintain circuit stability. This value should
be increased to 10µF or more if the battery connection is
made any distance from the charger output. If the
AAT3681A is to be used in applications where the battery
can be removed from the charger, such as with desktop
charging cradles, an output capacitor greater than 10µF
may be required to prevent the device from cycling on
and off when no battery is present.
Printed Circuit Board
Layout Considerations
For the best results, it is recommended to physically
place the battery pack as close as possible to the
AAT3681A BAT pin. To minimize voltage drops on the
PCB, keep the high current carrying traces adequately
wide. Refer to the AAT3681A evaluation board for a good
layout example (see Figures 5 and 6).
TA = 45°C
300
250
200
150
100
50
TA = 85°C
0
4.25
4.5
4.75
TA = 60°C
5
5.25
5.5
5.75
6
6.25
6.5
6.75
7
VIN (V)
Figure 4: Maximum Charging Current Before
Thermal Cycling Becomes Active.
14
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201883C • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • November 19, 2012
DATA SHEET
AAT3681A
500mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger
Figure 5: AAT3681A Evaluation Board
Figure 6: AAT3681A Evaluation Board
Top Side Layout. Bottom Side Layout.
VBAT
VIN(ADP)
JP2
C1
10µF
1
2
3
4
R8
8.06K
AAT3681A
EN
ISET
BAT
ADP
GND
GND
GND
STAT
8
7
6
5
C2
2.2µF
U1 (SC70JW-8)
JP1
0Ω
D1
R1
RED LED
1K
Figure 7: AAT3681A Evaluation Board Schematic Diagram.
Component
Part Number
Description
Manufacturer
U1
R1
R8
JP1
C1
C2
JP2
LED1
AAT3681AIJS-T1
Chip Resistor
Chip Resistor
Chip Resistor
GRM21BR61A106KE19L
GRM21BR71A225KA01L
PRPN401PAEN
CMD15-21SRC/TR8
USB/ADP Battery Charger; SC70JW-8 Package
1kW, 5%, 1/4W; 0603
8.06kW, 1%, 1/4W; 0805
0W, 5%, 1/4W; 0603
Ceramic 10µF 10V 10% X5R 0805
Ceramic 2.2µF 10V 10% X7R 0805
Connecting Header, 2mm Zip
Red LED; 1206
Skyworks
Vishay
Murata
Sullins Electronics
Chicago Miniature Lamp
Table 3: AAT3681A Evaluation Board Bill of Materials.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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DATA SHEET
AAT3681A
500mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger
Ordering Information
Trickle Charge
Enable
Package
Marking1
Part Number (Tape and Reel)2
Yes
Yes
No
Yes
No
Yes
Active High
Active High
Active High
Active Low
Active High
Active High
SC70JW-8
SC70JW-8
SC70JW-8
SC70JW-8
SC70JW-8
SC70JW-8
E4XYY
UTXYY
UEXYY
VSXYY
A9XYY
F2XYY
AAT3681AIJS-4.1-T1
AAT3681AIJS-4.2-T1
AAT3681AIJS-4.2-1-T1
AAT3681AIJS-4.2-2-T1
AAT3681AIJS-4.2-4-T1
AAT3681AIJS-4.1-5-T1
Skyworks Green™ products are compliant with
all applicable legislation and are halogen-free.
For additional information, refer to Skyworks
Definition of Green™, document number
SQ04-0074.
Package Information
SC70JW-8
2.20 ± 0.20
1.75 ± 0.10
0.50 BSC 0.50 BSC 0.50 BSC
0.225 ± 0.075
2.00 ± 0.20
0.100
0.15 ± 0.05
0.45 ± 0.10
4° ± 4°
0.05 ± 0.05
7° ± 3°
1.10 MAX
0.85 ± 0.15
0.048REF
2.10 ± 0.30
All dimensions in millimeters.
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
16
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201883C • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • November 19, 2012
DATA SHEET
AAT3681A
500mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger
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Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201883C • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • November 19, 2012
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