Analogic AAT3681AIJS-4.2-T1 500ma usb port or ac adapter lithium-ion/polymer battery charger Datasheet

AAT3681A
500mA USB Port or AC Adapter
Lithium-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.
•
The AAT3681A precisely regulates battery charge
voltage and current for 4.2V (4.375V option) lithiumion/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 500mA.
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 AAT3681A is available in a Pb-free, thermally
enhanced, space-saving 8-pin 2.0x2.1mm SC70JW
package and is specified for operation over the
-40°C to +85°C temperature range.
•
•
•
•
•
•
•
•
•
•
•
BatteryManager™
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
Automatic Current Sensing
Automatic Recharge Sequencing
Full Battery Charge Auto Turn Off/Sleep
Mode/Charge Termination
Shutdown Current <1µA
Automatic Trickle Charge for Battery PreConditioning (AAT3681A-1 is No Trickle
Charge Option)
Over-Voltage and Emergency Thermal
Protection
Power On Reset and Soft Start
LED Status Pin
8-Pin 2.0x2.1mm SC70JW Package
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+
ADP
BAT
C
AAT3681A
Enable
BATTBattery
Pack
STAT
EN
ISET
GND
RSET
3681A.2007.10.1.2
1
AAT3681A
500mA USB Port or AC Adapter
Lithium-Ion/Polymer Battery Charger
Pin Description
Pin #
Symbol
Type
1
EN
In
2
3
4
5
6, 7, 8
ISET
BAT
ADP
STAT
GND
In/Out
In/Out
Power In
Out
Power
Function
Enable pin.
AAT3681A, AAT3681A-1: Logic high enables the IC (internally pulled down).
AAT3681A-2: Logic low enables the IC (internally pulled down).
AAT3681A-3: Logic low enables the IC (no internal pull-down resistor).
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)
EN
ISET
BAT
ADP
2
1
8
2
7
3
6
4
5
GND
GND
GND
STAT
3681A.2007.10.1.2
AAT3681A
500mA USB Port or AC Adapter
Lithium-Ion/Polymer Battery Charger
AAT3681A Feature Options
Product
Trickle Charge
Enable
Charge Termination
Threshold Current
AAT3681A
AAT3681A-1
AAT3681A-2
AAT3681A-3
Yes
No
Yes
Yes
Active High
Active High
Active Low
Active Low
10%
10%
10%
0
Absolute Maximum Ratings1
Symbol
VP
VN
TJ
TLEAD
Description
Value
Units
-0.3 to 8.0
-0.3 to VP + 0.3
-40 to 150
300
V
V
°C
°C
Description
Value
Units
Maximum Power Dissipation
Maximum Thermal Resistance
0.687
160
W
°C/W
ADP Continuous
BAT, STAT, ISET, EN
Operating Junction Temperature Range
Maximum Soldering Temperature (at Leads)
Thermal Information2
Symbol
PD
θJA
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.
3681A.2007.10.1.2
3
AAT3681A
500mA USB Port or AC Adapter
Lithium-Ion/Polymer Battery Charger
Electrical Characteristics1
VADP = 5V, TA = -25°C to +85°C, unless otherwise noted. Typical values are TA = 25°C.
Symbol
Operation
VADP
VUVLO
IOP
ISHUTDOWN
Description
Adapter Voltage Range
Under-Voltage Lockout (UVLO)
UVLO Hysteresis
Operating Current
Shutdown Current
ILEAKAGE
Reverse Leakage Current from BAT Pin
Voltage Regulation
VBAT_EOC
End of Charge Accuracy
ΔVCH/VCH Output Charge Voltage Tolerance
VMIN
Preconditioning Voltage Threshold
VRCH
Battery Recharge Voltage Threshold
Current Regulation
ICH
Charge Current Programmable Range2
ΔICH/ICH
Charge Current Regulation Tolerance
VSET
ISET Pin Voltage
KI_A
Current Set Factor: ICH/ISET
Charging Devices
RDS(ON)
Charging Transistor On Resistance
Logic Control/Protection
VEN(H)
Input High Threshold
VEN(L)
Input Low Threshold
VSTAT
Output Low Voltage
ISTAT
STAT Pin Current Sink Capability
VOVP
Over-Voltage Protection Threshold
ITK/ICH
ITERM/ICH
Pre-Charge Current
Charge Termination Threshold Current
Conditions
Min
Rising Edge
4.0
3
Max Units
150
0.5
1
V
V
mV
mA
0.3
1
µA
0.4
2
µA
4.158
4.20
0.5
4.242
V
%
2.85
3.0
3.15
V
Charge Current = 200mA
VBAT = 4.25V, VEN = GND
(AAT3681A, AAT3681A-1)
VBAT = 4.25V, VEN = 5V
(AAT3681A-2, AAT3681A-3)
VBAT = 4V, ADP Pin Open
AAT3681A, AAT3681A-2,
and AAT3681A-3 Only
Measured from VBAT_EOC
AAT3681A, AAT3681A-1,
and AAT3681A-2 Only
Typ
7.5
4
-0.1
15
V
500
mA
%
V
1
Ω
0.4
0.4
8
4.4
V
V
V
mA
V
10
%
10
%
10
2
800
VADP = 5.5V
0.6
1.6
STAT Pin Sinks 4mA
ICH = 100mA; AAT3681A,
AAT3681A-2, and
AAT3681A-3 Only
AAT3681A, AAT3681A-1, and
AAT3681A-2 Only
1. The AAT3681A output charge voltage is specified over the 0° to 70°C ambient temperature range; operation over the -25°C to +85°C
temperature range is guaranteed by design.
2. Achievable charge current may be limited by power dissipation capability of the package under certain operating conditions. See
“Thermal Considerations” section of this datasheet.
4
3681A.2007.10.1.2
AAT3681A
500mA USB Port or AC Adapter
Lithium-Ion/Polymer Battery Charger
Typical Characteristics
Charging Current vs. Battery Voltage
Constant Charging Current
vs. Set Resistor Values
(AAT3681A, AAT3681A-2 and AAT3681A-3 only)
600
1000
RSET = 3.24kΩ
100
ICH (mA)
ICH (mA)
500
10
RSET = 5.36kΩ
400
300
RSET = 8.06kΩ
200
RSET = 16.2kΩ
100
1
0
1
10
100
1000
RSET = 31.6kΩ
2.7
2.9
3.7
3.9
4.1
Charging Current vs. Battery Voltage
End of Charge Battery Voltage
vs. Input Voltage
4.3
4.220
RSET = 3.24kΩ
4.215
Battery Voltage (V)
500
400
RSET = 5.36kΩ
300
RSET = 8.06kΩ
200
RSET = 16.2kΩ
100
RSET = 31.6kΩ
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
25
50
Temperature (°C)
3681A.2007.10.1.2
75
100
VBAT = 3.3V
200
180
160
VBAT = 3.6V
140
VBAT = 4.0V
120
0
7.5
280
4.22
-25
7.0
(RSET = 8.06kΩ
Ω)
4.23
-50
6.5
Constant Charging Current vs. Input Voltage
(RSET = 8.06kΩ
Ω)
4.17
6.0
Input Voltage (V)
End of Charge Voltage Regulation
vs. Temperature
VBAT_EOC (V)
3.5
VBAT (V)
600
ICH (mA)
3.3
RSET (kΩ
Ω)
(AAT3681A-1 only)
0
3.1
4
4.5
5
5.5
6
6.5
7
7.5
Input Voltage (V)
5
AAT3681A
500mA USB Port or AC Adapter
Lithium-Ion/Polymer Battery Charger
Typical Characteristics
Constant Charging Current vs. Temperature
Operating Supply Current vs. RSET
(RSET = 8.06kΩ
Ω)
(VIN = 5V)
1000
210
VBAT = 3.6V
208
ISUPPLY (µA)
ICH (mA)
205
203
200
198
VBAT = 2.85V
100
10
195
193
190
-50
-25
0
25
50
75
1
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; AAT3681A, AAT3681A-2, and AAT3681A-3 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)
ITRICKLE (mA)
20.6
20.4
20.2
20.0
19.8
19.6
19.4
0
25
50
Temperature (°C)
6
75
100
Trickle Charge Current (mA)
20.8
-25
75
100
(AAT3681A, AAT3681A-2, and AAT3681A-3 Only)
(RSET = 8.06kΩ
Ω; AAT3681A, AAT3681A-2, and AAT3681A-3 Only)
-50
50
Preconditioning Charge Current vs. Input Voltage
Preconditioning Charge Current
vs. Temperature
19.2
25
Temperature (°C)
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
7
7.5
Input Voltage (V)
3681A.2007.10.1.2
AAT3681A
500mA USB Port or AC Adapter
Lithium-Ion/Polymer Battery Charger
Typical Characteristics
Recharging Threshold Voltage
vs. Temperature
Shutdown Current vs. Supply Voltage
(RSET = 8.06kΩ
Ω)
(RSET = 8.06kΩ;
Ω; AAT3681A, AAT3681A-1 and AAT3681A-2 only)
Shutdown Current (nA)
4.18
4.16
VRCH (V)
4.14
4.12
4.10
4.08
4.06
4.04
4.02
1800
-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)
3681A.2007.10.1.2
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)
7
AAT3681A
500mA USB Port or AC Adapter
Lithium-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 AAT3681A is a high performance battery
charger designed to charge single cell lithiumion/polymer batteries with up to 500mA of current
from an external power source. It is a stand-alone
charging solution, with just one external component required for complete functionality. The
AAT3681A 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 500mA for rapid
charging applications. The AAT3681A 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 over-voltage or over-temperature failure, the
device will automatically shut down, protecting the
charging device, control system, and the battery
under charge.
Charging Operation
The AAT3681A 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.) (AAT3681A-1 does
not have trickle charge.)
3681A.2007.10.1.2
AAT3681A
500mA USB Port or AC Adapter
Lithium-Ion/Polymer Battery Charger
Preconditioning
Trickle Charge
Phase
Constant Current
Charge Phase
Constant Voltage
Charge Phase
Charge Complete Voltage
I = Max CC
Regulated Current
Constant Current Mode
Voltage Threshold
Trickle Charge and
Termination Threshold
I = CC / 10
Figure 1: Current vs. Voltage Profile During Charging Phases.
Battery Preconditioning
Before the start of charging, the AAT3681A 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 AAT3681A
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.
Constant Current Charging
Battery cell preconditioning continues until the voltage on the BAT pin exceeds the preconditioning
voltage threshold (VMIN). At this point, the
AAT3681A begins the constant current charging
phase. The charge constant current (ICH) amplitude
is programmed by the user via the RSET resistor.
The AAT3681A remains in the constant current
charge mode until the battery reaches the voltage
regulation point, VBAT_EOC.
3681A.2007.10.1.2
Constant Voltage Charging
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.
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). (AAT3681A-3 does not terminate
charging and thus does not go into the sleep state.
AAT3681A-3 continues to source current to the
battery and allows the charge current to asymptotically approach zero while in constant voltage
charging mode.)
Consuming very low current in sleep state, the
AAT3681A 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 AAT3681A input voltage
drops, the device will enter sleep state and automatically resume charging once the input supply
has recovered from the fault condition.
9
AAT3681A
500mA USB Port or AC Adapter
Lithium-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 (AAT3681A,
AAT3681A-2,
AAT3681A-3)
No (AAT3681A-1)
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 BAT_EOC > VBAT
No
Yes
Voltage Phase Test
IBAT > ITERM
No
(AAT3681A-3)
Constant
Voltage Charge
Mode
No (AAT3681A,
AAT3681A-1,
AAT3681A-2)
Charge Completed
10
3681A.2007.10.1.2
AAT3681A
500mA USB Port or AC Adapter
Lithium-Ion/Polymer Battery Charger
Application Information
charge state and measured cell voltage on the
BAT pin.
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
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.
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 (kΩ)
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
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 and AAT3681A-1: The enable (EN) pin
is internally pulled down. 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.
Table 1: RSET Values.
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 reenabled, the charge control circuit will automatically reset and resume charging functions with the
appropriate charging mode based on the battery
3681A.2007.10.1.2
ICH (mA)
AAT3681A-3: The enable (EN) pin is not internally
pulled down. When pulled to a logic low level, the
AAT3681A-3 is enabled. When pulled to a logic
high level, the AAT3681A-3 will be shut down and
forced into the sleep state.
1000
100
10
1
1
10
100
1000
RSET (kΩ
Ω)
Figure 2: Constant Charging Current
vs. Set Resistor Values.
11
AAT3681A
500mA USB Port or AC Adapter
Lithium-Ion/Polymer Battery Charger
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 overvoltage condition occurs, the AAT3681A charge
control will shut down the device until voltage on
the BAT pin drops below VOVP. The AAT3681A will
resume normal charging operation after the overvoltage condition is removed.
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 Nchannel 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 completed1
OFF
ON
OFF
The required ballast resistor values can be estimated using the following formulas:
R 1=
(VADP - VF(LED))
ILED
Example:
R1 =
(5.5V - 2.0V)
= 1.75kΩ
2mA
Note: Red LED forward voltage (VF) is typically
2.0V @ 2mA.
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:
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 low-cost green or
red LEDs. It is not recommended to exceed 8mA
for driving an individual status LED.
PD(MAX) =
(TJ(MAX) - TA)
θJA
Where:
PD(MAX) = Maximum Power Dissipation (W)
θJA
= Package Thermal Resistance (°C/W)
TJ(MAX) = Maximum Device Junction Temperature
(°C) [135°C]
TA
= Ambient Temperature (°C)
1. AAT3681A-3 does not terminate charging. However, the status pin turns off when IBAT ≤ ITERM and turns back on when VBAT ≤
VBAT_EOC - 0.1V.
12
3681A.2007.10.1.2
AAT3681A
500mA USB Port or AC Adapter
Lithium-Ion/Polymer Battery Charger
Figure 3 shows the relationship of maximum power
dissipation and ambient temperature of AAT3681A.
1000
600
500
450
400
400
200
0
0
20
40
60
80
100
TA (°°C)
ICH(MAX) (mA)
PD(MAX) (mW)
800
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.
Next, the power dissipation can be calculated by
the following equation:
PD = [(VIN - VBAT) · ICH + (VIN · IOP)]
250
200
150
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.
Capacitor Selection
Where:
PD
TA = 45°C
300
100
Figure 3: Maximum Power Dissipation.
TA = 25°C
350
= Total Power Dissipation by the Device
VIN = Input Voltage
VBAT = Battery Voltage as Seen at the BAT Pin
ICH
= Constant Charge Current Programmed for
the Application
IOP
= 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
3681A.2007.10.1.2
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.
13
AAT3681A
500mA USB Port or AC Adapter
Lithium-Ion/Polymer Battery Charger
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).
Printed Circuit Board Layout
Considerations
For the best results, it is recommended to physically place the battery pack as close as possible
Figure 5: AAT3681A Evaluation Board
Top Layer.
Figure 6: AAT3681A Evaluation Board
Bottom Layer.
VBAT
VIN(ADP)
JP2
AAT3681A
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: AAT3681A Evaluation Board Schematic Diagram.
14
3681A.2007.10.1.2
AAT3681A
500mA USB Port or AC Adapter
Lithium-Ion/Polymer Battery Charger
Component
U1
R1
R8
JP1
C1
C2
JP2
LED1
Part Number
AAT3681AIJS-T1
Chip Resistor
Chip Resistor
Chip Resistor
GRM21BR61A106KE19L
GRM21BR71A225KA01L
PRPN401PAEN
CMD15-21SRC/TR8
Description
USB/ADP Battery Charger;
SC70JW-8 Package
1kΩ, 5%, 1/4W; 0603
8.06kΩ, 1%, 1/4W; 0805
0Ω, 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
AnalogicTech
Vishay
Vishay
Vishay
Murata
Murata
Sullins Electronics
Chicago Miniature Lamp
Table 3: AAT3681A Evaluation Board Bill of Materials.
3681A.2007.10.1.2
15
AAT3681A
500mA USB Port or AC Adapter
Lithium-Ion/Polymer Battery Charger
Ordering Information
Trickle Charge
Enable
Package
Marking1
Part Number (Tape and Reel)2
Yes
No
Yes
Yes
Active High
Active High
Active Low
Active Low
SC70JW-8
SC70JW-8
SC70JW-8
SC70JW-8
UTXYY
UEXYY
VSXYY
XBXYY
AAT3681AIJS-4.2-T1
AAT3681AIJS-4.2-1-T1
AAT3681AIJS-4.2-2-T1
AAT3681AIJS-4.2-3-T1
All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means
semiconductor products that are in compliance with current RoHS standards, including
the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more
information, please visit our website at http://www.analogictech.com/pbfree.
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
16
3681A.2007.10.1.2
AAT3681A
500mA USB Port or AC Adapter
Lithium-Ion/Polymer Battery Charger
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.
© Advanced Analogic Technologies, Inc.
AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work
rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice. Except as provided in AnalogicTech’s terms and conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent,
copyright or other intellectual property right. In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the
customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty.
Specific testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated.
All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.
Advanced Analogic Technologies, Inc.
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Phone (408) 737-4600
Fax (408) 737-4611
3681A.2007.10.1.2
17
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