AAT3681 - Skyworks Solutions, Inc.

DATA SHEET
AAT3681
USB Port or AC Adapter Li-Ion/Polymer Battery Charger
General Description
Features
The AAT3681 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 300mA
• 4.0V ~ 7.5V Input Voltage Range
• High Level of Integration with Internal:
▪ Charging Device
▪ Reverse Blocking Diode
• Automatic Current Sensing
• Automatic Recharge Sequencing
• Full Battery Charge Auto Turn Off/Sleep Mode/Charge
Termination
• Shutdown Current <1μA
• Automatic Trickle Charge for Battery Pre-Conditioning
(AAT3681-1 is No Trickle Charge Option)
• Over-Voltage and Emergency Thermal Protection
• Power On Reset and Soft Start
• LED Status Pin
• 8-Pin 2.0 × 2.2mm SC70JW Package
The AAT3681 precisely regulates battery charge voltage
and current for 4.2V (4.375V option) lithium-ion/polymer battery cells. When charged from an AC adapter or
USB port, the battery charging current can be set by an
external resistor up to 300mA.
Battery charge state is continuously monitored for fault
conditions. In the event of an over-voltage, short-circuit, or over-temperature failure, the device will automatically shut down, thus protecting the charging device,
control system, and the battery under charge. A status
monitor output pin is provided to indicate the battery
charge status by directly driving an external LED.
The AAT3681 is available in a Pb-free, thermally
enhanced, space-saving 8-pin 2.0 × 2.2mm SC70JW
package and is specified for operation over the -40°C to
+85°C temperature range.
Applications
•
•
•
•
•
•
•
Bluetooth® Headsets
DECT Headsets
Digital Still Cameras
MP3, Portable Music, and Portable Media Players
Personal Data Assistants (PDAs)
Wrist Watches
Other Lithium-Ion/Polymer Battery-Powered Devices
Typical Application
Adapter/USB Input
BATT+
BAT
ADP
C
AAT3681
Enable
BATTBattery
Pack
STAT
EN
ISET
GND
RSET
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201882C • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • February 7, 2013
1
DATA SHEET
AAT3681
USB Port or AC Adapter Li-Ion/Polymer Battery Charger
Pin Descriptions
Pin #
Symbol
Type
1
2
3
4
5
6, 7, 8
EN
ISET
BAT
ADP
STAT
GND
In
In/Out
In/Out
Power In
Out
Power
Function
Enable pin. Logic high enables the IC (internally pulled down).
Connect resistor here to set the charge current.
Battery charging and sensing.
Input from USB/adapter charger.
Open drain status pin.
Ground connection.
Pin Configuration
SC70JW-8
(Top View)
2
EN
1
8
GND
ISET
2
7
GND
BAT
3
6
GND
ADP
4
5
STAT
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201882C • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • February 7, 2013
DATA SHEET
AAT3681
USB Port or AC Adapter Li-Ion/Polymer Battery Charger
AAT3681 Feature Options
Product
Trickle Charge
AAT3681
AAT3681-1
Yes
No
Absolute Maximum Ratings1
Symbol
VP
VN
TJ
TLEAD
Description
ADP Continuous
BAT, STAT, ISET, EN
Operating Junction Temperature Range
Maximum Soldering Temperature (at Leads)
Value
-0.3 to 8.0
-0.3 to VP + 0.3
-40 to 150
300
Units
V
°C
Thermal Information2
Symbol
PD
JA
Description
Maximum Power Dissipation
Maximum Thermal Resistance
Value
Units
0.687
160
W
°C/W
1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions
specified is not implied. Only one Absolute Maximum Rating should be applied at any one time.
2. Mounted on an FR4 board.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201882C • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • February 7, 2013
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DATA SHEET
AAT3681
USB Port or AC Adapter Li-Ion/Polymer Battery Charger
Electrical Characteristics1
VADP = 5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C.
Symbol
Operation
VADP
VUVLO
Description
Adapter Voltage Range
Under-Voltage Lockout (UVLO)
UVLO Hysteresis
Operating Current
IOP
Shutdown Current
ISHUTDOWN
Reverse Leakage Current from BAT Pin
ILEAKAGE
Voltage Regulation
End of Charge Accuracy
VBAT_EOC
VCH/VCH
Output Charge Voltage Tolerance
Preconditioning Voltage Threshold
VMIN
VRCH
Battery Recharge Voltage Threshold
Current Regulation
Charge Current Programmable Range
ICH
ICH/ICH
Charge Current Regulation Tolerance
ISET Pin Voltage
VSET
KI_A
Current Set Factor: ICH/ISET
Charging Devices
Charging Transistor On-Resistance
RDS(ON)
Logic Control/Protection
Input High Threshold
VEN(H)
VEN(L)
Input Low Threshold
Output Low Voltage
VSTAT
STAT Pin Current Sink Capability
ISTAT
VOVP
Over-Voltage Protection Threshold
Pre-Charge Current
ITK/ICH
ITERM/ICH
Charge Termination Threshold Current
Conditions
Rising Edge
Min
4.0
3
150
0.5
0.3
0.4
Charge Current = 200mA
VBAT = 4.25V, EN = GND
VBAT = 4V, ADP Pin Open
4.158
AAT3681 Only
Measured from VBAT_EOC
Typ
2.85
4.20
0.5
3.0
-0.1
15
Max
Units
7.5
4
V
1
1
2
4.242
3.15
0.9
μA
V
%
V
300
mA
%
V
1.1

0.4
0.4
8
V
10
2
800
VADP = 5.5V
mV
mA
1.6
STAT Pin Sinks 4mA
ICH = 100mA; AAT3681 Only
4.4
10
10
mA
V
%
1. The AAT3681 output charge voltage is specified over the 0° to 70°C ambient temperature range; operation over the -40°C to +85°C temperature range is guaranteed by design.
4
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201882C • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • February 7, 2013
DATA SHEET
AAT3681
USB Port or AC Adapter Li-Ion/Polymer Battery Charger
Typical Characteristics
Charging Current vs. Battery Voltage
Constant Charging Current
vs. Set Resistor Values
(AAT3681 Only)
350
1000
RSET = 5.36kΩ
250
100
ICH (mA)
ICH (mA)
300
10
RSET = 8.06kΩ
200
150
RSET = 16.2kΩ
100
50
1
0
1
10
100
1000
RSET = 31.6kΩ
2.7
2.9
4.3
4.215
RSET = 5.36K
RSET = 8.06K
RSET = 16.2K
0
2.7
2.9
3.1
3.3
3.5
3.7
3.9
4.1
4.210
4.205
4.200
4.195
4.190
4.185
4.180
4.5
4.3
5.0
5.5
VBAT (V)
Charging Current (mA)
4.21
4.20
4.19
4.18
260
240
220
50
Temperature (°C)
75
100
VBAT = 3.3V
200
180
160
VBAT = 3.6V
140
VBAT = 4.0V
120
25
7.5
280
4.22
0
7.0
(RSET = 8.06kΩ
Ω)
4.23
-25
6.5
Constant Charging Current vs. Input Voltage
(RSET = 8.06kΩ
Ω)
-50
6.0
Input Voltage (V)
End of Charge Voltage Regulation
vs. Temperature
VBAT_EOC (V)
4.1
4.220
RSET = 3.24K
RSET = 31.6K
4.17
3.9
End of Charge Battery Voltage
vs. Input Voltage
Battery Voltage (V)
ICH (mA)
100
3.7
Charging Current vs. Battery Voltage
400
200
3.5
VBAT (V)
600
300
3.3
RSET (kΩ
Ω)
(AAT3681-1 Only)
500
3.1
4
4.5
5
5.5
6
6.5
7
7.5
Input Voltage (V)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201882C • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • February 7, 2013
5
DATA SHEET
AAT3681
USB Port or AC Adapter Li-Ion/Polymer Battery Charger
Typical Characteristics
Constant Charging Current vs. Temperature
Operating Supply Current vs. Set Resistor
(RSET = 8.06kΩ
Ω)
210
1000
208
VBAT = 3.6V
203
IOP (µA)
ICH (mA)
205
200
198
VBAT = 2.85V
100
195
193
190
-50
-25
0
25
50
75
10
100
1
10
100
RSET (kΩ
Ω)
Temperature (°C)
Operating Current vs. Temperature
Preconditioning Threshold Voltage
vs. Temperature
(RSET = 8.06kΩ
Ω)
(RSET = 8.06kΩ
Ω; AAT3681 Only)
550
3.03
3.02
450
VMIN (V)
IOP (µA)
500
400
3.01
3
2.99
350
2.98
300
-50
-25
0
25
50
75
2.97
-50
100
-25
0
Temperature (°C)
Trickle Charge Current (mA)
ITRICKLE (mA)
20.6
20.4
20.2
20.0
19.8
19.6
19.4
0
25
50
Temperature (°C)
6
100
(AAT3681 Only)
20.8
-25
75
Preconditioning Charge Current vs. Input Voltage
(RSET = 8.06kΩ
Ω; AAT3681 Only)
-50
50
Temperature (°C)
Preconditioning Charge Current
vs. Temperature
19.2
25
75
100
35
RSET = 5.36kΩ
30
25
RSET = 8.06kΩ
20
15
RSET = 16.2kΩ
10
5
0
RSET = 31.6kΩ
4
4.5
5
5.5
6
6.5
Input Voltage (V)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201882C • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • February 7, 2013
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7.5
DATA SHEET
AAT3681
USB Port or AC Adapter Li-Ion/Polymer Battery Charger
Typical Characteristics
Recharging Threshold Voltage
vs. Temperature
Shutdown Current vs. Supply Voltage
(RSET = 8.06kΩ
Ω)
(RSET = 8.06kΩ
Ω)
1800
Shutdown Current (nA)
4.18
4.16
VRCH (V)
4.14
4.12
4.10
4.08
4.06
4.04
4.02
-50
-25
0
25
50
75
1600
1400
1000
800
600
400
200
0
4.0
100
4.5
5.0
5.5
6.0
6.5
7.0
Supply Voltage (V)
VIH_ENABLE vs. Supply Voltage
VIL_ENABLE vs. Supply Voltage
7.5
(RSET = 8.06kΩ
Ω)
1.5
1.2
1.4
-40°C
1.1
1.3
-40°C
1.2
VIL_ENABLE (V)
VIH_ENABLE (V)
-40°C
25°C
Temperature (°C)
(RSET = 8.06kΩ
Ω)
1.1
1.0
0.9
0.8
25°C
0.7
85°C
4.0
4.5
5.0
5.5
6.0
VIN (V)
1.0
0.9
0.8
0.7
85°C
25°C
0.6
0.5
0.6
0.5
85°C
1200
6.5
7.0
7.5
0.4
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
VIN (V)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201882C • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • February 7, 2013
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DATA SHEET
AAT3681
USB Port or AC Adapter Li-Ion/Polymer Battery Charger
Functional Block Diagram
Reverse Blocking
ADP
BAT
Current
Compare
Constant
Current
ISET
STAT
Charge
Status
CV/
Precharge
Charge
Control
UVLO
OverTemperature
Protection
GND
EN
Functional Description
The AAT3681 is a high performance battery charger
designed to charge single cell lithium-ion/polymer batteries with up to 300mA of current from an external power
source. It is a stand-alone charging solution, with just one
external component required for complete functionality.
The AAT3681 precisely regulates battery charge voltage
and current for 4.2V lithium-ion/polymer battery cells.
The adapter/USB charge input constant current level can
be programmed up to 300mA for rapid charging applications. The AAT3681 is rated for operation from -40°C to
+85°C. In the event of operating ambient temperatures
exceeding the power dissipation abilities of the device
package for a given constant current charge level, the
charge control will enter into thermal limit.
8
A status monitor output pin is provided to indicate the
battery charge state by directly driving one external
LED.
Device junction temperature and charge state are fully
monitored for fault conditions. In the event of an overvoltage or over-temperature failure, the device will automatically shut down, protecting the charging device,
control system, and the battery under charge.
Charging Operation
The AAT3681 has four basic modes for the battery charge
cycle: pre-conditioning/trickle charge; constant current/
fast charge; constant voltage; and end of charge (see
Figure 1). (AAT3681-1 does not have trickle charge.)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201882C • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • February 7, 2013
DATA SHEET
AAT3681
USB Port or AC Adapter Li-Ion/Polymer Battery Charger
Preconditioning
Trickle Charge
Phase
Constant Current
Charge Phase
Constant Voltage
Charge Phase
Battery Discharge
Constant Voltage
Charge Phase
Charge Complete Voltage
I = Max CC
Regulated Current
Battery Recharge
Voltage Threshold
Constant Current Mode
Voltage Threshold
Trickle Charge and
Termination Threshold
I = CC / 10
Figure 1: Current vs. Voltage Profile During Charging Phases.
Battery Preconditioning
Constant Voltage Charging
Before the start of charging, the AAT3681 checks several conditions in order to assure a safe charging environment. The input supply must be above the minimum
operating voltage, or under-voltage lockout threshold
(VUVLO), for the charging sequence to begin. When these
conditions have been met and a battery is connected to
the BAT pin, the AAT3681 checks the state of the battery. If the cell voltage is below the preconditioning voltage threshold (VMIN), the charge control begins preconditioning the cell. The battery preconditioning trickle
charge current is equal to the fast charge constant current divided by 10. For example, if the programmed fast
charge current is 300mA, then the preconditioning mode
(trickle charge) current will be 30mA. Cell preconditioning is a safety precaution for deeply discharged battery
cells and also aids in limiting power dissipation in the
pass transistor when the voltage across the device is at
the greatest potential.
The system transitions to a constant voltage charging
mode when the battery voltage reaches the output
charge regulation threshold (VBAT_EOC) during the constant current fast charge phase. The regulation voltage
level is factory programmed to 4.2V (±0.5%). Charge
current in the constant voltage mode drops as the battery cell under charge reaches its maximum capacity.
Constant Current Charging
Battery cell preconditioning continues until the voltage
on the BAT pin exceeds the preconditioning voltage
threshold (VMIN). At this point, the AAT3681 begins the
constant current charging phase. The charge constant
current (ICH) amplitude is programmed by the user via
the RSET resistor. The AAT3681 remains in the constant
current charge mode until the battery reaches the voltage regulation point, VBAT_EOC.
End of Charge Cycle Termination
and Recharge Sequence
When the charge current drops to 10% of the programmed fast charge current level in the constant voltage mode, the device terminates charging and goes into
a sleep state. The charger will remain in a sleep state
until the battery voltage decreases to a level below the
battery recharge voltage threshold (VRCH).
Consuming very low current in sleep state, the AAT3681
minimizes battery drain when it is not charging. This
feature is particularly useful in applications where the
input supply level may fall below the battery charge or
under-voltage lockout level. In such cases where the
AAT3681 input voltage drops, the device will enter sleep
state and automatically resume charging once the input
supply has recovered from the fault condition.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201882C • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • February 7, 2013
9
DATA SHEET
AAT3681
USB Port or AC Adapter Li-Ion/Polymer Battery Charger
System Operation Flow Chart
Enable
No
Power On Reset
Yes
Power Input
Voltage
VIN > VUVLO
Yes
Shut Down
Yes
Fault Conditions
Monitoring
OV, OT
Charge
Control
No (AAT3681)
No (AAT3681-1)
Preconditioning
Test
V MIN > VBAT
Yes
Preconditioning
(Trickle Charge)
Yes
Constant
Current Charge
Mode
Yes
Constant
Voltage Charge
Mode
No
No
Recharge Test
V RCH > VBAT
Yes
Current Phase Test
VBAT_EOC > VBAT
No
Voltage Phase Test
IBAT > ITERM
No
Charge Completed
10
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201882C • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • February 7, 2013
DATA SHEET
AAT3681
USB Port or AC Adapter Li-Ion/Polymer Battery Charger
Application Information
Nominal
ICHARGE (mA)
Set Resistor
Value (k)
300
250
200
150
100
50
40
30
20
15
5.36
6.49
8.06
10.7
16.2
31.6
38.3
53.6
78.7
105
Adapter or USB Power Input
Constant current charge levels up to 300mA may be
programmed by the user when powered from a sufficient
input power source. The AAT3681 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.
Table 1: RSET Values.
Adapter Input Charge Inhibit and Resume
Enable / Disable
The AAT3681 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, AAT3681
is enabled. When left open or pulled to a logic low level,
the AAT3681 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.
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 300mA may be set by
selecting the appropriate resistor value from Table 1.
1000
ICH (mA)
The AAT3681 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.
100
10
1
1
10
100
1000
RSET (kΩ
Ω)
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
occurs, the AAT3681 charge control will shut down the
device until voltage on the BAT pin drops below VOVP. The
AAT3681 will resume normal charging operation after
the over-voltage condition is removed.
Over-Temperature Shutdown
The AAT3681 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.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201882C • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • February 7, 2013
11
DATA SHEET
AAT3681
USB Port or AC Adapter Li-Ion/Polymer Battery Charger
The AAT3681 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
No battery charging activity
Battery charging via adapter or USB port
Charging completed
Status
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. 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.
ed 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) =
PD(MAX) = Maximum Power Dissipation (W)
JA
= 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 AAT3681.
1000
800
The required ballast resistor values can be estimated
using the following formulas:
600
400
200
0
(VADP - VF(LED))
R 1=
ILED
0
20
40
60
80
100
TA (°°C)
Figure 3: Maximum Power Dissipation.
Example:
R1 =
(5.5V - 2.0V)
= 1.75kΩ
2mA
Next, the power dissipation can be calculated by the following equation:
Note: Red LED forward voltage (VF) is typically 2.0V @
2mA.
Thermal Considerations
The AAT3681 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 expect-
12
(TJ(MAX) - TA)
θJA
Where:
PD(MAX) (mW)
Charge Status Output
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.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201882C • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • February 7, 2013
DATA SHEET
AAT3681
USB Port or AC Adapter Li-Ion/Polymer Battery Charger
ICH(MAX) =
Capacitor Selection
(PD(MAX) - VIN · IOP)
VIN - VBAT
Input Capacitor
(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.
300
TA = 25°C
ICH(MAX) (mA)
250
TA = 45°C
200
Output Capacitor
150
100
TA = 85°C
TA = 60°C
50
0
4.25
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
AAT3681 adapter input is to be used in a system with an
external power supply source, such as a typical AC-toDC 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.
4.5
4.75
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.
The AAT3681 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
AAT3681 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
AAT3681 BAT pin. To minimize voltage drops on the PCB,
keep the high current carrying traces adequately wide.
Refer to the AAT3681 evaluation board for a good layout
example (see Figures 5 and 6).
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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13
DATA SHEET
AAT3681
USB Port or AC Adapter Li-Ion/Polymer Battery Charger
Figure 5: AAT3681 Evaluation Board
Top Layer.
Figure 6: AAT3681 Evaluation Board
Bottom Layer.
VBAT
VIN(ADP)
JP2
AAT3681
C1
10μF
1
2
3
4
R8
8.06K
EN
ISET
BAT
ADP
GND
GND
GND
STAT
8
7
6
5
C2
2.2μF
U1 (SC70JW-8)
JP1
D1
R1
0Ω
RED LED
1K
Figure 7: AAT3681 Evaluation Board Schematic Diagram.
Component
Part Number
U1
R1
R8
JP1
C1
C2
JP2
LED1
AAT3681IJS-T1
Chip Resistor
Chip Resistor
Chip Resistor
GRM21BR61A106KE19L
GRM21BR71A225KA01L
PRPN401PAEN
CMD15-21SRC/TR8
Description
USB/ADP Battery Charger; SC70JW-8 Package
1k, 5%, 1/4W; 0603
8.06k, 1%, 1/4W; 0805
0, 5%, 1/4W; 0603
CER 10μF 10V 10% X5R 0805
CER 2.2μF 10V 10% X7R 0805
Connecting Header, 2mm Zip
Red LED; 1206
Manufacturer
Skyworks
Vishay
Murata
Sullins Electronics
Chicago Miniature Lamp
Table 3: AAT3681 Evaluation Board Bill of Materials.
14
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201882C • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • February 7, 2013
DATA SHEET
AAT3681
USB Port or AC Adapter Li-Ion/Polymer Battery Charger
Ordering Information
Trickle Charge
Package
Marking1
Part Number (Tape and Reel)2
Yes
No
SC70JW-8
SC70JW-8
REXYY
STXYY
AAT3681IJS-4.2-T1
AAT3681IJS-4.2-1-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
7° ± 3°
0.45 ± 0.10
4° ± 4°
0.05 ± 0.05
0.15 ± 0.05
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.
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Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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