AAT3681

USB Port or AC Adapter

Lithium-Ion/Polymer Battery Charger

3681.2006.05.1.1

BatteryManager

General Description

The AAT3681 BatteryManager is a member of
AnalogicTech's Total Power Management ICTM
(TPMICTM) product family. This product is an inte-
grated single cell lithium-ion/polymer battery charg-
er IC, designed to operate from a DC power source
or USB port up to an input voltage of 6.5V. It requires
just one external component.

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 cur-
rent 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 bat-
tery 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 2.0x2.1mm SC70JW
package and is specified for operation over the
-40°C to +85°C temperature range.

Features

USB or AC Adapter System Power Charger
-- Programmable from 15mA to 300mA

4.0V ~ 6.5V 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

Over-Voltage and Emergency Thermal
Protection

Power On Reset and Soft Start

LED Status Pin

8-Pin 2.0x2.1mm SC70JW Package

Applications

BluetoothTM 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

AAT3681

BATT-

Battery

Pack

ADP

GND

BAT

BATT+

SET

Adapter/USB Input

STAT

ISET

Enable

Absolute Maximum Ratings

Thermal Information

Symbol

Description

Value

Units

Maximum Power Dissipation

0.687

Maximum Thermal Resistance

160

°C/W

Symbol

Description

Value

Units

ADP Continuous

-0.3 to 7.5

BAT, STAT, ISET, EN

-0.3 to V

+ 0.3

Operating Junction Temperature Range

-40 to 150

°C

LEAD

Maximum Soldering Temperature (at Leads)

300

°C

AAT3681

USB Port or AC Adapter

Lithium-Ion/Polymer Battery Charger

3681.2006.05.1.1

1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at condi-

tions 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.

Electrical Characteristics

ADP

= 5V, T

= -25°C to +85°C, unless otherwise noted. Typical values are T

= 25°C.

Symbol

Description

Conditions

Min

Typ

Max Units

Operation

ADP

Adapter Voltage Range

4.0

6.5

UVLO

Under-Voltage Lockout (UVLO)

Rising Edge

UVLO Hysteresis

150

Operating Current

Charge Current = 200mA

0.5

SHUTDOWN

Shutdown Current

BAT

= 4.25V, EN = GND

0.3

µA

LEAKAGE

Reverse Leakage Current from BAT Pin

BAT

= 4V, ADP Pin Open

0.4

µA

Voltage Regulation

BAT_EOC

End of Charge Accuracy

4.158

4.20 4.242

Output Charge Voltage Tolerance

0.5

MIN

Preconditioning Voltage Threshold

2.85

3.0

3.15

RCH

Battery Recharge Voltage Threshold

Measured from V

BAT_EOC

-0.1

Current Regulation

Charge Current Programmable Range

300

Charge Current Regulation Tolerance

SET

ISET Pin Voltage

I_A

Current Set Factor: I

SET

800

Charging Devices

DS(ON)

Charging Transistor On Resistance

ADP

= 5.5V

0.9

1.1

Logic Control/Protection

EN(H)

Input High Threshold

1.6

EN(L)

Input Low Threshold

0.4

STAT

Output Low Voltage

STAT Pin Sinks 4mA

0.4

STAT

STAT Pin Current Sink Capability

OVP

Over-Voltage Protection Threshold

4.4

CHG

Pre-Charge Current

= 100mA

TERM

CHG

Charge Termination Threshold Current

AAT3681

USB Port or AC Adapter

Lithium-Ion/Polymer Battery Charger

3681.2006.05.1.1

1. The AAT3681 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.

Typical Characteristics

Constant Charging Current vs. Temperature

SET

= 8.06k

)

Temperature (

°C)

(mA)

190

193

195

198

200

203

205

208

210

-50

-25

100

Constant Charging Current vs.

Supply Voltage

SET

= 8.06k

)

(V)

(mA)

170

180

190

200

210

220

4.25

4.5

4.75

5.25

5.5

5.75

6.25

6.5

BAT

= 3.6V

BAT

= 4V

BAT

= 3.3V

End of Charge Voltage Regulation

vs. Temperature

SET

= 8.06k

)

Temperature (

°C)

BAT_EOC

(V)

4.17

4.18

4.19

4.20

4.21

4.22

4.23

-50

-25

100

End of Charge Battery Voltage

vs. Supply Voltage

(V)

BAT_EOC

(V)

4.194

4.196

4.198

4.200

4.202

4.204

4.206

4.5

4.75

5.25

5.5

5.75

6.25

6.5

SET

= 8.06k

SET

= 31.6k

Charging Current vs. Battery Voltage

BAT

(V)

(mA)

100

150

200

250

300

350

2.7

2.9

3.1

3.3

3.5

3.7

3.9

4.1

4.3

SET

= 8.06k

SET

= 5.36k

SET

= 16.2k

SET

= 31.6k

SET

)

(mA)

100

1000

100

1000

Constant Charging Current

vs. Set Resistor Values

AAT3681

USB Port or AC Adapter

Lithium-Ion/Polymer Battery Charger

3681.2006.05.1.1

Typical Characteristics

Recharging Threshold Voltage

vs. Temperature

SET

= 8.06k

)

Temperature (

°C)

RCH

(V)

4.02

4.04

4.06

4.08

4.10

4.12

4.14

4.16

4.18

-50

-25

100

Preconditioning Charge Current

vs. Supply Voltage

(V)

TRICKLE

(mA)

4.25

4.5

4.75

5.25

5.5

5.75

6.25

6.5

SET

= 8.06k

SET

= 5.36k

SET

= 16.2k

SET

= 31.6k

Preconditioning Charge Current

vs. Temperature

SET

= 8.06k

)

Temperature (

°C)

TRICKLE

(mA)

19.2

19.4

19.6

19.8

20.0

20.2

20.4

20.6

20.8

-50

-25

100

Preconditioning Threshold Voltage

vs. Temperature

SET

= 8.06k

)

Temperature (

°C)

MIN

(V)

2.97

2.98

2.99

3.01

3.02

3.03

-50

-25

100

Operating Current vs. Temperature

SET

= 8.06k

)

Temperature (

°C)

(µA)

300

350

400

450

500

550

-50

-25

100

Operating Supply Current vs. Set Resistor

SET

)

(µA)

100

1000

100

BAT

= 2.85V

BAT

= 3.6V

AAT3681

USB Port or AC Adapter

Lithium-Ion/Polymer Battery Charger

3681.2006.05.1.1

Typical Characteristics

IL_ENABLE

vs. Supply Voltage

SET

= 8.06k

)

(V)

IL_ENABLE

(V)

0.6

0.7

0.8

0.9

1.1

4.25

4.5

4.75

5.25

5.5

5.75

6.25

6.5

-40°C

25°C

85°C

IH_ENABLE

vs. Supply Voltage

SET

= 8.06k

)

(V)

IH_ENABLE

(V)

0.7

0.8

0.9

1.1

1.2

4.25

4.5

4.75

5.25

5.5

5.75

6.25

6.5

-40°C

25°C

85°C

Sleep Mode Current vs. Supply Voltage

SET

= 8.06k

)

(V)

SLEEP

(nA)

100

200

300

400

500

600

700

800

4.25

4.5

4.75

5.25

5.5

5.75

6.25

6.5

85°C

25°C

-40°C

AAT3681

USB Port or AC Adapter

Lithium-Ion/Polymer Battery Charger

3681.2006.05.1.1

AAT3681

USB Port or AC Adapter

Lithium-Ion/Polymer Battery Charger

3681.2006.05.1.1

Functional Block Diagram

Charge
Control

Current

Compare

Reverse Blocking

CV/

Precharge

Constant

Current

ADP

BAT

ISET

UVLO

Over-

Temperature

Protection

Charge

Status

STAT

GND

Functional Description

The AAT3681 is a high performance battery charg-
er designed to charge single cell lithium-ion/poly-
mer 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 oper-
ating 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.

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 AAT3681 has four basic modes for the battery
charge cycle: pre-conditioning/trickle charge; con-
stant current/fast charge; constant voltage; and
end of charge. (See Figure 1.)

AAT3681

USB Port or AC Adapter

Lithium-Ion/Polymer Battery Charger

3681.2006.05.1.1

Battery Preconditioning
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 lock-
out threshold (V

UVLO

), 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 (V

MIN

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 cur-
rent is 300mA, then the preconditioning mode (trick-
le 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 volt-
age on the BAT pin exceeds the preconditioning
voltage threshold (V

MIN

). At this point, the AAT3681

begins the constant current charging phase. The
charge constant current (I

) amplitude is pro-

grammed by the user via the R

SET

resistor. The

AAT3681 remains in the constant current charge
mode until the battery reaches the voltage regula-
tion point, V

BAT

Constant Voltage Charging
The system transitions to a constant voltage charg-
ing mode when the battery voltage reaches the
output charge regulation threshold (V

BAT

) during

the constant current fast charge phase. The regu-
lation voltage level is factory programmed to 4.2V
(±0.5%). Charge current in the constant voltage
mode drops as the battery cell under charge reach-
es its maximum capacity.

End of Charge Cycle Termination and Recharge
Sequence
When the charge current drops to 10% of the pro-
grammed 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 thresh-
old (V

RCH

When the input supply is disconnected, the charg-
er will automatically transition into a power-saving
sleep mode. Only consuming an ultra-low 0.3µA in
sleep mode, 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
mode and automatically resume charging once the
input supply has recovered from the fault condition.

Figure 1: Current vs. Voltage Profile During Charging Phases.

Constant Current

Charge Phase

Constant Voltage

Charge Phase

Preconditioning

Trickle Charge

Phase

Charge Complete Voltage

Constant Current Mode

Voltage Threshold

Regulated Current

Trickle Charge and

Termination Threshold

I = CC / 10

I = Max CC

Application Information

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 6.5V
range. The constant current fast charge current for
the adapter input is set by the R

SET

resistor con-

nected between ISET and ground. Refer to Table 1
for recommended R

SET

values for a desired con-

stant current charge level.

Adapter Input Charge Inhibit and Resume
The AAT3681 has a UVLO and power on reset fea-
ture so that if the input supply to the ADP pin drops
below the UVLO threshold, the charger will sus-
pend 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 auto-
matically resume charging in the appropriate mode
for the condition of the battery.

Enable / Disable

The AAT3681 provides an enable function to con-
trol 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 trick-
le charge current, is dominated by the tolerance of
the set resistor used. For this reason, a 1% toler-
ance metal film resistor is recommended for the set
resistor function. Fast charge constant current lev-
els from 15mA to 300mA may be set by selecting
the appropriate resistor value from Table 1.

Table 1: R

SET

Values.

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 (V

OVP

). If an over-

voltage condition occurs, the AAT3681 charge con-
trol will shut down the device until voltage on the
BAT pin drops below V

OVP

. 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.

SET

)

(mA)

100

1000

100

1000

Nominal

Set Resistor

CHARGE

(mA)

Value (k

)

300

5.36

250

6.49

200

8.06

150

10.7

100

16.2

31.6

38.3

53.6

78.7

105

AAT3681

USB Port or AC Adapter

Lithium-Ion/Polymer Battery Charger

3681.2006.05.1.1

AAT3681

USB Port or AC Adapter

Lithium-Ion/Polymer Battery Charger

3681.2006.05.1.1

Charge Status Output

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:

Table 2: LED Status Indicator.

The LED should be biased with as little current as
necessary to create reasonable illumination; there-
fore, 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 LED. It is not recommended to exceed 8mA for
driving an individual status LED.

The required ballast resistor values can be esti-
mated using the following formulas:

Example:

Note: Red LED forward voltage (V

) is typically

2.0V @ 2mA.

Thermal Considerations

The AAT3681 is offered in a SC70JW-8 package
which can provide up to 687mW of power dissipa-
tion 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 gen-
erating devices in a given application design. The
ambient temperature around the charger IC will
also have an effect on the thermal limits of a bat-
tery 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:

Where:

D(MAX)

= Maximum Power Dissipation (W)

= Package Thermal Resistance (°C/W)

J(MAX)

= Maximum Device Junction Temperature

(°C) [135°C]

= Ambient Temperature (°C)

Figure 3 shows the relationship of maximum power
dissipation and ambient temperature of AAT3681.

Figure 3: Maximum Power Dissipation.

Next, the power dissipation can be calculated by
the following equation:

= [(V

- V

BAT

)

· I

+ (V

· I

)]

(

°
°C)

D(MAX)

(mW)

200

400

600

800

1000

100

J(MAX)

)

D(MAX)

(5.5V - 2.0V)

= 1.75k

2mA

ADP

F(LED)

)

LED

Event Description

Status

No battery charging activity

OFF

Battery charging via adapter

or USB port

Charging completed

OFF

Where:

= Total Power Dissipation by the Device

= Input Voltage

BAT

= 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.

In general, the worst condition is the greatest volt-
age drop across the charger IC, when battery volt-
age is charged up to the preconditioning voltage
threshold. Figure 4 shows the maximum charge
current in different ambient temperatures.

Figure 4: Maximum Charging Current Before

Thermal Cycling Becomes Active.

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
AAT3681 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 C

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 AAT3681 only requires a 1µF ceramic capaci-
tor 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 ade-
quately wide. Refer to the AAT3681 evaluation board
for a good layout example (see Figures 5 and 6).

(V)

CH(MAX)

(mA)

100

150

200

250

300

4.25

4.5

4.75

5.25

5.5

5.75

6.25

6.5

6.75

= 25°C

= 60°C

= 85°C

= 45°C

J(MAX)

)

- V

BAT

CH(MAX)

· I

D(MAX)

· I

)

- V

BAT

CH(MAX)

AAT3681

USB Port or AC Adapter

Lithium-Ion/Polymer Battery Charger

3681.2006.05.1.1

AAT3681

USB Port or AC Adapter

Lithium-Ion/Polymer Battery Charger

3681.2006.05.1.1

Figure 5: AAT3681 Evaluation Board

Figure 6: AAT3681 Evaluation Board

Top Layer.

Bottom Layer.

Figure 7: AAT3681 Evaluation Board Schematic Diagram.

Table 3: AAT3681 Evaluation Board Bill of Materials.

Component

Part Number

Description

Manufacturer

AAT3681IJS-T1

USB/ADP Battery Charger;

AnalogicTech

SC70JW-8 Package

Chip Resistor

, 5%, 1/4W; 0603

Vishay

Chip Resistor

8.06k

, 1%, 1/4W; 0805

Vishay

JP1

Chip Resistor

, 5%, 1/4W; 0603

Vishay

GRM21BR61A106KE19L

CER 10µF 10V 10% X5R 0805

Murata

GRM21BR71A225KA01L

CER 2.2µF 10V 10% X7R 0805

Murata

JP2

PRPN401PAEN

Connecting Header, 2mm Zip

Sullins Electronics

LED1

CMD15-21SRC/TR8

Red LED; 1206

Chicago Miniature Lamp

RED LED

10µF

2.2µF

IN(ADP)

BAT

8.06K

JP2

JP1

ISET

BAT

ADP

STAT

GND

AAT3681

U1 (SC70JW-8)

AAT3681

USB Port or AC Adapter

Lithium-Ion/Polymer Battery Charger

3681.2006.05.1.1

Advanced Analogic Technologies, Inc.

830 E. Arques Avenue, Sunnyvale, CA 94085

Phone (408) 737-4600

Fax (408) 737-4611

Ordering Information

Package Information

SC70JW-8

All dimensions in millimeters.

0.225

± 0.075

0.45

± 0.10

0.05

2.10

± 0.30

2.00

± 0.20

° ± 3°

° ± 4°

1.75

0.10

0.85

0.15

0.05

1.10 MAX

0.100

2.20

0.20

0.048REF

0.50 BSC 0.50 BSC 0.50 BSC

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.

Package

Marking

Part Number (Tape and Reel)

SC70JW-8

REXYY

AAT3681IJS-4.2-T1

1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.

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.
Customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold sub-
ject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. AnalogicTech
warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with AnalogicTech's standard warranty. Testing and other quality con-
trol 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 regis-
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