AAT3681AIJS-4.1-5-T1 - Skyworks Solutions, Inc.

AAT3681A

DATA SHEET

500mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger

Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

201883B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 25, 2012

General Description

The AAT3681A BatteryManager is an integrated single cell

lithium-ion/polymer battery charger IC, designed to oper-

ate 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 volt-

age and current for 4.2V (4.375V option) lithium-ion/

polymer battery cells. When charged from an AC adapt-

er 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 automati-

cally 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 2.0 × 2.1mm 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 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 <1μA

• Automatic Trickle Charge for Battery Pre-Conditioning

(AAT3681A-1/AAT3681A-4 is No Trickle Charge

Option)

• Over-Voltage and Emergency Thermal Protection

• Power On Reset and Soft Start

• LED Status Pin

• 8-Pin 2.0 × 2.1mm 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

SKY83681A-x

BATT-

Battery

Pack

ADP

GND

BAT

BATT+

RSET

dapter/USB Input

STAT

ISET

Enable

AAT3681A

DATA SHEET

500mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger

2Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

201883B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 25, 2012

Pin Description

Pin # Symbol Type Function

1ENIn

Enable pin.

AAT3681A, AAT3681A-1, AAT3681A-4, AAT3681A-5: Logic high enables the IC

(internal pull down 6MΩ resistor).

AAT3681A-2: Logic low enables the IC (internal pull down resistor).

2 ISET In/Out Connect resistor here to set the charge current.

3 BAT In/Out Battery charging and sensing.

4 ADP Power In Input from USB/adapter charger.

5 STAT Out Open drain status pin.

6, 7, 8 GND Power Ground connection.

Pin Configuration

SC70JW-8

(Top View)

ISET

BAT

ADP

GND

STAT

EN 1

AAT3681A

DATA SHEET

500mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger

Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

201883B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 25, 2012

AAT3681A Feature Options

Product Trickle Charge Enable Charge Termination

Threshold Current Constant Regulated Output

Voltage VCO(REG)

AAT3681A Yes Active High 10% 4.2 (Optional 4.1V)

AAT3681A-1 No Active High 10% 4.2

AAT3681A-2 Yes Active Low 10% 4.2

AAT3681A-4 No Active High 10% 4.2

AAT3681A-5 Yes Active High 10% 4.1

Absolute Maximum Ratings1

Symbol Description Value Units

VPADP Continuous -0.3 to 8.0 V

VNBAT, STAT, ISET, EN -0.3 to VP + 0.3

TAOperating Temperature Range -40 to 85

°CTJJunction Temperature Range -40 to 150

TLEAD Maximum Soldering Temperature (at Leads) 300

Thermal Information2

Symbol Description Value Units

PDMaximum Power Dissipation 0.687 W

JA Maximum Thermal Resistance 160 °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.

AAT3681A

DATA SHEET

500mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger

4Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

201883B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 25, 2012

Electrical Characteristics1

VADP = 5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C.

Symbol Description Conditions Min Typ Max Units

Operation

VADP Adapter Voltage Range 4.0 7.5 V

VUVLO

Under-Voltage Lockout (UVLO) Rising Edge for AAT3681A/-1/-2 3.0 V

Rising Edge for AAT3681A-4/-5 3.2

UVLO Hysteresis 150 mV

IOP Operating Current Charge Current = 200mA 0.5 1 mA

ISHUTDOWN Shutdown Current

VBAT = 4.25V, VEN = GND (AAT3681A, AAT3681A-1,

AAT3681A-4) 0.3 1 μA

VBAT = 4.25V, VEN = 5V (AAT3681A-2)

ILEAKAGE

Reverse Leakage Current from

BAT Pin VBAT = 4V, ADP Pin Open 0.4 2 μA

Voltage Regulation

VCO(REG) Constant Output Voltage Accuracy For AAT3681A/-1/-2/-4 4.158 4.20 4.242 V

AAT3681A-5 Only 4.059 4.10 4.141

VCH/VCH Output Charge Voltage Tolerance 0.5 %

VMIN Preconditioning Voltage Threshold AAT3681A, AAT3681A-2 Only 2.85 3.0 3.15 V

VRCH

Battery Recharge Voltage

Threshold

AAT3681A, AAT3681A-1, AAT3681A-2 and

AAT3681A-4 Only; Measured from VCO(REG)

-0.1 V

Current Regulation

ICH

Charge Current Programmable

Range215 500 mA

ICH/ICH

Charge Current Regulation

Tolerance 10 %

VSET ISET Pin Voltage 2V

KI_A Current Set Factor: ICH/ISET 800

Charging Devices

RDS(ON) Charging Transistor On Resistance VADP = 5.5V 0.6 1 

Logic Control/Protection

VEN(H) Input High Threshold 1.6 V

VEN(L) Input Low Threshold 0.4 V

VSTAT Output Low Voltage STAT Pin Sinks 4mA 0.4 V

ISTAT STAT Pin Current Sink Capability 8mA

VOVP Over-Voltage Protection Threshold 4.4 V

ITK/ICH Pre-Charge Current ICH = 100mA; AAT3681A, AAT3681A-2,

and AAT3681A-5 Only 10 %

ITERM/ICH

Charge Termination Threshold

Current

AAT3681A, AAT3681A-1, AAT3681A-2,

AAT3681A-4, and AAT3681A-5 Only 10 %

1. The AAT3681A 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.

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.

AAT3681A

DATA SHEET

500mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger

Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

201883B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 25, 2012

Typical Characteristics

RSET (kΩ

)

ICH (mA)

100

1000

1 10 100 1000

Constant Charging Current

vs. Set Resistor Values

Operating Supply Current vs. RSET

(VIN = 5V)

RSET (kΩ

)

ISUPPLY (µA)

100

1000

1 10 100

VBAT = 2.85V

VBAT = 3.6V

Constant Regulated Output Voltage

vs. Input Voltage

(AAT3681A, AAT3681A-1/-2/-4)

Input Voltage (V)

Battery Voltage (V)

4.180

4.185

4.190

4.195

4.200

4.205

4.210

4.215

4.220

4.5 5.0 5.5 6.0 6.5 7.0 7.5

Constant Regulated Output Voltage

vs. Temperature

(AAT3681A, AAT3681A-1/-2/-4; RSET = 8.06kΩ)

Temperature (°

VCO(REG) (V)

4.17

4.18

4.19

4.20

4.21

4.22

4.23

-50 -25 0 25 50 75 100

Constant Regulated Output Voltage

vs. Input Voltage

(AAT3681A-4.1, AAT3681A-5 Only)

Input Voltage (V)

End Of Charge

Voltage Regulation (V)

5.0 5.5 6.0 6.5 7.0 7.5

4.05

4.07

4.09

4.11

4.13

4.15

Constant Regulated Output Voltage

vs. Temperature

(AAT3681A-4.1 and AAT3681A-5 Only)

Temperature (°

End Of Charge

Voltage Regulation (V)

-40 -15 10 35 60 85

4.080

4.085

4.090

4.095

4.100

4.105

4.110

AAT3681A

DATA SHEET

500mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger

6Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

201883B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 25, 2012

Typical Characteristics

Charging Current vs. Battery Voltage

(AAT3681A, AAT3681A-2, and AAT3681A-5 only)

VBAT (V)

ICH (mA)

100

200

300

400

500

600

2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3

RSET = 8.06kΩ

RSET = 5.36kΩ

RSET = 3.24kΩ

RSET = 16.2kΩ

RSET = 31.6kΩ

Charging Current vs. Battery Voltage

(AAT3681A-1 and AAT3681A-4 only)

VBAT (V)

ICH (mA)

100

200

300

400

500

600

2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3

RSET = 8.06kΩ

RSET = 5.36kΩ

RSET = 3.24kΩ

RSET = 16.2kΩ

RSET = 31.6kΩ

Battery Charging Current vs. Input Voltage

(AAT3681A-4.1 and AAT3681A-5 only; VCO(REG) = 4.1V)

Input Voltage (V)

Battery Charging Current (mA)

4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5

150

160

170

180

190

200

210

220

230

VBAT = 3.3V

VBAT = 3.6V

VBAT = 3.9V

VBAT = 4.0V

Charging Current vs. Battery Voltage

(AAT3681A-4.1 and AAT3681A-5 Only)

Battery Voltage (V)

Battery Charging Current (mA)

2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2

-100

100

200

300

400

500

600

RSET = 3.24KΩ

RSET = 5.36KΩ

RSET = 8.06KΩ

RSET = 16.2KΩ

RSET = 31.6KΩ

Battery Charging Current vs. Battery Voltage

(AAT3681A-4.1 and AAT3681A-5 Only)

Battery Voltage (V)

Battery Charging Current (mA)

2.6 2.8 3.02.2 2.4 3.2 3.4 3.6 3.8 4.0 4.2

120

160

200

240

VBAT = 5.0V

VBAT = 5.5V

VBAT = 6.0V

VBAT = 6.5V

VBAT = 7.0V

VBAT = 7.5V

Constant Charging Current vs. Temperature

(RSET = 8.06kΩ

)

Temperature (

ICH (mA)

190

193

195

198

200

203

205

208

210

-50 -25 0 25 50 75 100

AAT3681A

DATA SHEET

500mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger

Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

201883B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 25, 2012

Typical Characteristics

Constant Charging Current vs. Input Voltage

(RSET = 8.06kΩ

)

Input Voltage (V)

Charging Current (mA)

120

140

160

180

200

220

240

260

280

4 4.5 5 5.5 6 6.5 7 7.5

VBAT = 3.3V

VBAT = 3.6V

VBAT = 4.0V

Operating Current vs. Temperature

(RSET = 8.06kΩ

)

Temperature (

IOP (µA)

300

350

400

450

500

550

-50 -25 0 25 50 75 100

Preconditioning Threshold Voltage vs. Temperature

(RSET = 8.06kΩ

; AAT3681A, AAT3681A-2,

and AAT3681A-5 Only)

Temperature (

VMIN (V)

2.97

2.98

2.99

3.01

3.02

3.03

-50 -25 0 25 50 75 100

Preconditioning Voltage Threshold

vs. Input Voltage

(AAT3681A-4.1 and AAT3681A-5 Only)

Input Voltage (V)

Preconditioning

Threshold Voltage (V)

5.0 5.5 6.0 6.5 7.0 7.5

2.90

2.91

2.92

2.93

2.94

2.95

Preconditioning Threshold Voltage

vs. Temperature

(AAT3681AIJS-4.1-T1 Only)

Temperature (°

Preconditioning

Threshold Voltage (V)

-40 -15 10 35 60 85

2.80

2.82

2.84

2.86

2.88

2.90

2.92

2.94

2.96

2.98

3.00

Preconditioning Charge Current vs. Temperature

(RSET = 8.06kΩ

; AAT3681A, AAT3681A-2,and AAT3681A-5 Only)

Temperature (

ITRICKLE (mA)

19.2

19.4

19.6

19.8

20.0

20.2

20.4

20.6

20.8

-50 -25 0 25 50 75 100

AAT3681A

DATA SHEET

500mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger

8Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

201883B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 25, 2012

Typical Characteristics

Preconditioning Charge Current vs. Input Voltage

(AAT3681A, AAT3681A-2, and AAT3681A-5 Only)

Input Voltage (V)

Trickle Charge Current (mA)

4 4.5 5 5.5 6 6.5 7 7.5

RSET = 5.36kΩ

RSET = 8.06kΩ

RSET = 16.2kΩ

RSET = 31.6kΩ

Recharging Threshold Voltage vs. Temperature

(RSET = 8.06kΩ;

;

AAT3681A, AAT3681A-1,

AAT3681A-2, and AAT3681A-4 Only)

Temperature (

VRCH (V)

4.02

4.04

4.06

4.08

4.10

4.12

4.14

4.16

4.18

-50 -25 0 25 50 75 100

Recharging Threshold Voltage vs. Temperature

(AAT3681A-4.1 and AAT3681A-5 Only)

Temperature (°

End Of Charge Voltage

Regulation (V)

-40 -15 10 35 60 85

3.950

3.970

3.990

4.010

4.030

4.050

Shutdown Current vs. Supply Voltage

(RSET = 8.06kΩ

)

Supply Voltage (V)

Shutdown Current (nA)

200

400

600

800

1000

1200

1400

1600

1800

4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.

85°C

25°C-40°C

Input Enable High Voltage vs. Supply Voltage

(RSET = 8.06kΩ)

VIN (V)

VIH_ENABLE (V)

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5

-40°C

25°C85°C

Input Enable Low Voltage vs. Supply Voltage

(RSET = 8.06kΩ)

VIN (V)

VIL_ENABLE (V)

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5

-40°C

25°C

85°C

AAT3681A

DATA SHEET

500mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger

Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

201883B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 25, 2012

Functional Description

The AAT3681A is a high performance battery charger

designed for single cell lithium-ion/polymer batteries

with up to 500mA of charge current from an external

power source. It is a stand-alone charging solution, with

just one external component required for complete func-

tionality. The AAT3681A precisely regulates battery

charge voltage and current for 4.2V lithium-ion/polymer

battery cells. The AAT3681A-5 regulates battery charge

voltage for 4.1V Lithium-ion/polymer battery cells.

The adapter/USB charge input constant current level can

be programmed up to 500mA for rapid charging applica-

tions. The AAT3681A/-1/-2/-4/-5 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.

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 auto-

matically 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 charge termi-

nation (see Figure 1). (AAT3681A-1 and AAT3681A-4 do

not have trickle charge.)

Functional Block Diagram

Charge

Control

Current

Compare

Reverse Blocking

CV/

Precharge

Constant

Current

ADP BAT

ISET

UVLO

Over-

Temperature

Protection

Charge

Status

STAT

GND

AAT3681A

DATA SHEET

500mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger

10 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

201883B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 25, 2012

Battery Preconditioning

Before the start of charging, the AAT3681A checks sev-

eral conditions in order to assure a safe charging envi-

ronment. 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 bat-

tery. If the cell voltage is below the preconditioning volt-

age threshold (VMIN), the charge control begins precon-

ditioning the cell. The battery preconditioning trickle

charge current is equal to the fast charge constant cur-

rent divided by 10. For example, if the programmed fast

charge current is 300mA, then the preconditioning mode

(trickle charge) current will be 30mA. Cell precondition-

ing 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 con-

stant voltage regulation point, VCO(REG).

Constant Voltage Charging

The system transitions to a constant voltage charging

mode when the battery voltage reaches the constant

output voltage charge regulation threshold (VCO(REG)) dur-

ing the constant current fast charge phase. The regula-

tion voltage level is factory programmed to 4.2V

(±0.5%) for AAT3681A/-1/-2/-4 and 4.1 (±0.5%) for

AAT3681A-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 pro-

grammed fast charge current level in the constant volt-

age 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 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.

Constant Current

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

Battery Recharge

Voltage Threshold

Battery Discharge

Constant Voltage

Charge Phase

Constant Voltage

Charge Phase

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

AAT3681A

DATA SHEET

500mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger

Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

201883B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 25, 2012

System Operation Flow Chart

Power On Reset

Power Input

Voltage

VIN > VUVLO

Fault Conditions

Monitoring

OV, OT

Preconditioning

Test

VMIN > VBAT

Current Phase Test

VCO(REG)

> VBAT

Voltage Phase Test

IBAT > ITERM

No (AAT3681A,

AAT3681A-2,

AAT3681A-5)

Yes

Preconditioning

(Trickle Charge)

Constant

Current Charge

Mode

Constant

Voltage Charge

Mode

Yes

Charge Completed

Charge

Control

No (AAT3681A, AAT3681A-1,

AAT3681A-2, AAT3681A-4,

AAT3681A-5, AAT3681A-6)

Recharge Test

VRCH > VBAT

Yes

Shut Down Yes

Enable

Yes

No (AAT3681A-1,

AAT3681A-4)

AAT3681A

DATA SHEET

500mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger

12 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

201883B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 25, 2012

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

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, 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.

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.

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 domi-

nated by the tolerance of the set resistor used. For this

reason, a 1% tolerance metal film resistor is recom-

mended for the set resistor function. Fast charge con-

stant current levels from 15mA to 500mA may be set by

selecting the appropriate resistor value from Table 1.

Nominal

ICHARGE (mA) Set Resistor

Value (k)

500 3.24

450 3.57

400 4.12

350 4.64

300 5.36

250 6.49

200 8.06

150 10.7

100 16.2

50 31.6

40 38.3

30 53.6

20 78.7

15 105

Table 1: RSET Values.

RSET (kΩ

)

ICH (mA)

100

1000

1 10 100 1000

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 bat-

tery charge voltage and is set by the over-voltage pro-

tection threshold (VOVP). If an over-voltage condition

AAT3681A

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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.

Over-Temperature Shutdown

The AAT3681A has a thermal protection control circuit

which will shut down charging functions should the inter-

nal die temperature exceed the preset thermal limit

threshold. Once the internal die temperature falls below

the thermal limit, normal operation will resume the pre-

vious charging state.

Charge Status Output

The AAT3681A provides battery charge status via a sta-

tus pin. This pin is internally connected to an N-channel

open drain MOSFET, which can be used to drive an exter-

nal LED. The status pin can indicate the following condi-

tions:

Event Description Status

No battery charging activity OFF

Battery charging via adapter or USB port ON

Charging completed OFF

Table 2: LED Status Indicator.

The LED should be biased with as little current as neces-

sary to create reasonable illumination; therefore, a bal-

last 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 pack-

age, hence it is good to keep the LED drive current to a

minimum. A 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.

The required ballast resistor values can be estimated

using the following formulas:

ADP -

F(LED)

)

= I

LED

Example:

(5.5V

- 2.0

= = 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 consid-

erations 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 charg-

ing application. The maximum limits that can be expect-

ed for a given ambient condition can be estimated by the

following discussion.

First, the maximum power dissipation for a given situa-

tion should be calculated:

J(MAX) -

)

D(MAX)

= θ

Where:

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 dis-

sipation and ambient temperature of AAT3681A.

TA (°

PD(MAX) (mW)

200

400

600

800

1000

0 20 40 60 80 100

Figure 3: Maximum Power Dissipation.

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Next, the power dissipation can be calculated by the fol-

lowing equation:

PD = [(VIN - VBAT) · ICH + (VIN · IOP)]

Where:

PD = 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 cur-

rent before reaching the thermal limit condition (thermal

cycling). The maximum charge current is the key factor

when designing battery charger applications.

D(MAX) -

)

- V

BAT

CH(MAX)

J(MAX) -

)

- V

BAT

CH(MAX)

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 enhance-

ments.

VIN (V)

ICH(MAX) (mA)

100

150

200

250

300

350

400

450

500

4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 6.75 7

TA = 85°CTA = 60°C

TA = 25°C

TA = 45°C

Figure 4: Maximum Charging Current Before

Thermal Cycling Becomes Active.

Capacitor Selection

Input Capacitor

In general, it is good design practice to place a decou-

pling 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).

AAT3681A

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Figure 5: AAT3681A Evaluation Board Figure 6: AAT3681A Evaluation Board

Top Side Layout. Bottom Side Layout.

RED LED

D1 R1

10μF

C1 2.2μF

VIN(ADP)

VBAT

8.06K

JP2

JP1

0Ω

ISET

BAT

ADP

4STAT 5

GND 6

GND 7

GND 8

AAT3681A-x

U1 (SC70JW-8)

Figure 7: AAT3681A Evaluation Board Schematic Diagram.

Component Part Number Description Manufacturer

U1 AAT3681AIJS-T1 USB/ADP Battery Charger; SC70JW-8 Package Skyworks

R1 Chip Resistor 1k, 5%, 1/4W; 0603

VishayR8 Chip Resistor 8.06k, 1%, 1/4W; 0805

JP1 Chip Resistor 0, 5%, 1/4W; 0603

C1 GRM21BR61A106KE19L Ceramic 10μF 10V 10% X5R 0805 Murata

C2 GRM21BR71A225KA01L Ceramic 2.2μF 10V 10% X7R 0805

JP2 PRPN401PAEN Connecting Header, 2mm Zip Sullins Electronics

LED1 CMD15-21SRC/TR8 Red LED; 1206 Chicago Miniature Lamp

Table 3: AAT3681A Evaluation Board Bill of Materials.

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Ordering Information

Trickle Charge Enable Package Marking1Part Number (Tape and Reel)2

Yes Active High SC70JW-8 E4XYY AAT3681AIJS-4.1-T1

Yes Active High SC70JW-8 UTXYY AAT3681AIJS-4.2-T1

No Active High SC70JW-8 UEXYY AAT3681AIJS-4.2-1-T1

Yes Active Low SC70JW-8 VSXYY AAT3681AIJS-4.2-2-T1

No Active High SC70JW-8 A9XYY AAT3681AIJS-4.2-4-T1

Yes Active High SC70JW-8 F2XYY 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

0.225

0.075

0.45

0.10

0.05

2.10

0.30

2.00

0.20

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 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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service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. Sky-

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Customers are responsible for their products and applications using Skyworks products, which may deviate from published speciﬁ cations as a result of design defects, errors, or operation of products outside of pub-

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