AAT3691IRN-4.2-T1 - AnalogicTech

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

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General Description

The AAT3691 BatteryManager™ is an integrated single

cell Lithium-Ion (Li-Ion) battery charger IC, designed to

operate from USB ports, AC adapter inputs, or from a

cellular phone charger adapter up to an input voltage of

typical 6.75V. For increased safety, The AAT3691 also

includes over-voltage input protection (OVP) up to 28V.

The AAT3691 precisely regulates battery charge voltage

and current for 4.2V Li-Ion battery cells. The charge

current can be programmed up to 1.6A for ADP charging

and 0.5A for USB charging by external resistors on the

ADPSET/USBSET pins. In the case of an over-voltage

condition of ADP or USB input power exceeding typical

6.75V, the internal series switch opens, blocking the

damage to the battery and charging circuitry.

The AAT3691 also includes a no-battery present input

(NOBAT). When the NOBAT indicates that no battery is

present, OVP block will prevent the input power from

passing through the OVP block and suspend the charging

function.

Battery charging status is continuously monitored for

fault conditions. In the event of a battery over voltage or

chip over thermal failure, the charger will automatically

shutdown, protecting the charging device, control system

and battery, until the fault condition is removed. The

open drain status monitor output pin (STAT) is adopted

to report battery charging activity by active low.

The AAT3691 comes in a thermally enhanced, space-

saving, Pb-free 16-pin 3x4 mm TDFN package and is

specified for operation over the -40°C to +85°C tempera-

ture range.

Features

• Dual Input USB and AC Adapter Input

 Programmable Constant Current from 100mA to

1.6A for ADP Charge

 Programmable Constant Current from 50mA to 0.5A

for USB Charge

• No Battery Present Input Detection

• 3.0V ~ 6.75V (typical) Input Voltage Range

• Over-Voltage Input Protection up to 28V

• High Level of Integration with Internal:

 Power Device

 Reverse Current Blocking

 Current Sensing

• Automatic Recharge Sequencing

• Fast Over-Voltage Protection Turn Off and Release

Turn On Time

• Full Battery Charge Auto Turn Off/Sleep Mode/Charge

Termination

• Charge Status Indicator

• Automatic Trickle Charge for Battery Preconditioning

• Thermal Shutdown Protection

• Power On Reset and Soft Start

• Active Low Enable with Internal 200k Resistor Pull-

Down to GND

• 3x4mm TDFN Package

Applications

• Digital Still Cameras

• Mobile Phones

• Personal Data Assistants (PDAs)

• Other Li-Ion Battery Powered Devices

Typical Application

AAT3691

10μF BATT-

USBIN

Battery

Pack

BATT+

ON/OFF

GND

BAT

RUSBSET

USBSET

USB

USBCH

2.2μF

ADP

ADPIN

ADPSET

RADPSET

STAT

ADPCH

2.2μF

NOBATNOBAT

Voltage

Source

1μF

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

2 3691.2009.03.1.1

www.analogictech.com

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

2 3691.2009.03.1.1

www.analogictech.com

Pin Descriptions

Pin # Name Type Function

1 USB I Input from USB port connector

2. USBCH I/O Output from USB OVP stage, input to battery charger. Decouple with 2.2F capacitor.

3 ADP I Input from adapter port connector

4 ADPCH I/O Output from ADP OVP stage, input to battery charger. Decouple with 2.2F capacitor.

5, 7, 10 IC I Internally used. Connect to GND or leave ﬂ oating.

6STAT O Charge status indication pin, open drain.

8, 9 GND Connect to power ground

11 EN I Active low enable with internal 200k resistor pull-down to GND.

12 ADPSET I ADP charge current programming input pin.

13 USBSET I USB charge current programming input pin.

14 NOBAT I No battery present input. Logic “High“ indicates no battery. Internal 1.6M pull-high resistor.

15 N/C No connection.

16 BAT O Connect to lithium-ion battery.

Pin Configuration

TDFN34-16

(Top View)

ADP

DPCH

USB

USBCH

STAT

GND

NOBAT

USBSET

ADPSET

BAT

N/C

GND

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

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AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

3691.2009.03.1.1 3

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Absolute Maximum Ratings1

Symbol Description Value Units

VADP ,VUSB ADP, USB input continuous 28 V

VADPCH,, VUSBCH Charger input continuous -0.3 to 7.5 V

VNBAT, STAT, EN, ADPSET , USBSET, NOBAT, IC -0.3 to 7.5 + 0.3 V

TJOperating Junction Temperature Range -40 to 150 °C

TLEAD Maximum Soldering Temperature (at Leads) 300 °C

Thermal Information2

Symbol Description Value Units

ΘJA Maximum Thermal Resistance (TDFN 3x4) 50 °C/W

PDMaximum Power Dissipation 2 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 a FR4 board.

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

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AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

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Electrical Characteristics1

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

Symbol Description Conditions Min Typ Max Units

Operation

VADP_MAX,

VUSB_MAX

Input Over-Voltage Protection Range 28 V

VADP, VUSB

ADP and USB Normal Operating Input Voltage

Range 3.0 6.5 V

IADP_OP,

IUSB_OP

Operating Current VADP or VUSB = 5V, Charge current =

100mA, EN = 0V 0.5 1.5 mA

ISD(OFF) Shutdown Supply Current VADP or VUSB = 5V, EN = 5V 8 A

ISTANDBY Standby Mode Current Charge Terminated 300 A

IBAT Leakage Current from BAT Pin VBAT = 4V, USB and ADP open 1 4 A

Over-Voltage Protection

VOVPT

Over-Voltage Protection Trip Voltage Rising edge 6.5 6.75 7.0 V

Hysteresis 300 mV

Battery Charger

VUVLO_ADP,

VUVLO_USB

Under-Voltage Lockout Threshold Rising edge 3.0 V

UVLO Hysteresis 150 mV

Voltage Regulation

VBAT_EOC Output Charge Voltage Regulation 4.158 4.20 4.242 V

ΔVCH/VCH Output Charge Voltage Tolerance 0.5 %

VMIN Preconditioning Voltage Threshold 2.4 2.6 2.8 V

VRCH Battery Recharge Voltage Threshold VBAT_EOC

- 0.1 V

Battery Charging Device

RDS(ON) Charging and OVP Total ON Resistance VADP or VUSB = 5V, TA = 25°C 600 mΩ

Current Regulation

ILIM_ADP ADP Charge Current Programmable Range 100 1600 mA

ILIM_USB USB Charge Current Programmable Range 50 500 mA

ICH_CC Constant-Current Mode Charge Current VBAT = 3.6V -10 10 %

VADPSET

VUSBSET

ADPSET, USBSET Pin Voltage 2V

KIADPSET Charge Current Set Factor: ICH_CC/IADPSET Constant current mode, VBAT = 3.6V 800

KIUSBSET Charge Current Set Factor: ICH_CC/IUSBSET Constant current mode, VBAT = 3.6V 800

ICH_TRK Trickle Charge Current RADPSET = 8kΩ51015%

ICH_CC

ICH_TERM Charge Termination Threshold Current ICH_CC  800mA 8 10 12 %

1. The AAT3691 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and are assured by design, characterization and correla-

tion with statistical process controls.

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

3691.2009.03.1.1 5

www.analogictech.com

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

3691.2009.03.1.1 5

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Electrical Characteristics (continued)1

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

Symbol Description Conditions Min Typ Max Units

Logic Control / Battery Protection

VEN#(H) Input High Threshold VADP = 5V 1.2 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 48mA

VNOBAT(H) No Battery Present Input High Threshold 1.2 V

VNOBAT(L) No Battery Present Input Low Threshold 0.4 V

VBOVP Battery Over-Voltage Protection Threshold 4.4 V

TRESPOV Over-Voltage Response Time VADP

, VUSB voltage step up signal from 6V

to 8V 0.5 1.0 s

TOVPON OVP Switch OVP Release Turn-On Delay Time VADP voltage step down signal from 8V to

6V, RLOAD = 10Ω, CADPCH = 1F 5 s

TOVPSTARTON OVP Switch Start Up Turn-On Delay Time VADP voltage step up signal from 0V to

5V, RLOAD = 10Ω, CADPCH = 1F 130 s

TOVPR OVP Switch Turn-On Rise Time RLOAD = 10Ω, CADPCH = 1F 100 s

TSHDN Chip Thermal Shutdown Temperature Thermal Shutdown Threshold 140 °C

Hysteresis 15

1. The AAT3691 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and are assured by design, characterization and correla-

tion with statistical process controls.

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

6 3691.2009.03.1.1

www.analogictech.com

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

6 3691.2009.03.1.1

www.analogictech.com

Typical Characteristics

Over-Voltage Protection vs. Temperature

Temperature (°C)

VADP or VUSB (V)

-40 -20 0 20 40 60 80

6.50

6.55

6.60

6.65

6.70

6.75

6.80

Power sweep low to high

Power sweep high to low

End of Charge Voltage vs. Supply Voltag

(RADPSET = 1kΩ, RUSBSET = 3.2kΩ

)

VADP or VUSB (V)

VEOC (V)

4.4 4.8 5.2 5.6 6.0 6.4 6.8

4.18

4.19

4.20

4.21

4.22

USB

ADP

ICHARGE vs. RADPSET

RADPSET (kΩ)

ICHARGE (mA)

1 10 100

100

1000

10000

ICHARGE vs. RUSBSET

RUSBSET (kΩ)

ICHARGE (mA)

1 10 100

100

1000

Battery Recharge Voltage Threshold

vs. Supply Voltag

(RADPSET = 1kΩ; RUSBSET = 3.2kΩ; CBAT = 22μF

)

VADP or VUSB (V)

VRCH (V)

4.5 4.9 5.3 5.7 6.1 6.5

3.96

3.98

4.00

4.02

4.04

4.06

4.08

4.10

USB

ADP

Battery Recharge Voltage Threshold

vs. Temperature

(VADP = VUSB = 5V; RADPSET = 1kΩ; RUSBSET = 3.2kΩ; CBAT = 22μF)

Temperature (°C)

VRCH (V)

-40 -20 0 20 40 60 80

4.00

4.02

4.04

4.06

4.08

4.10

USB

ADP

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

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AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

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Typical Characteristics

End of Charge Voltage vs. Temperature

(RADPSET = 1kΩ; RUSBSET = 3.2kΩ)

Temperature (°C)

VEOC (V)

-40 -20 0 20 40 60 80

4.18

4.19

4.20

4.21

4.22

USB

ADP

Charge Current vs. Temperature

ADP

= V

USB

= 5V; V

BAT

= 3.6V;

ADPSET

= 1kΩ; R

USBSET

= 3.2kΩ)

Temperature (°C)

ICH (mA)

-40 -20 0 20 40 60 80

200

400

600

800

1000

1200

1400

1600

1800

ADP

USB

Charging Current vs. Battery Voltage

(VADP = VUSB = 5V; RADPSET = 1kΩ; RUSBSET = 3.2kΩ)

VBAT (V)

ICH (mA)

2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5

200

400

600

800

1000

1200

1400

1600

1800

ADP

USB

USB Charging Current vs. Supply Voltage

(RUSBSET = 3.2kΩ)

VUSB (V)

ICH_USB (mA)

4.0 4.4 4.8 5.2 5.6 6.0 6.4 6.8

100

200

300

400

500

600

VBAT = 3.3V

VBAT = 3.6V

VBAT = 3.9V

ADP Charging Current vs. Supply Voltage

(RADPSET = 1kΩ)

VADP (V)

ICH_ADP (mA)

4.0 4.4 4.8 5.2 5.6 6.0 6.4 6.8

200

400

600

800

1000

1200

1400

1600

1800

VBAT = 3.3V

VBAT = 3.6V

VBAT = 3.9V

USB Charging Current vs. Supply Voltage

(RUSBSET = 3.2kΩ)

VUSB (V)

ICH_USB (mA)

4.0 4.4 4.8 5.2 5.6 6.0 6.4 6.8

100

200

300

400

500

600

-40°C

0°C

25°C

50°C

85°C

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

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AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

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Typical Characteristics

ADP Charging Current vs. Battery Voltage

(VADP = 5V)

VBAT (V)

ICH_ADP (mA)

2.5 2.9 3.3 3.7 4.1 4.5

300

600

900

1200

1500

1800

RSET = 1kΩ

RSET = 1.14kΩ

RSET = 1.33kΩ

RSET = 1.6kΩ

RSET = 2kΩ

RSET = 3.2kΩ

RSET = 5.33kΩ

RSET = 16kΩ

USB Charging Current vs. Battery Voltage

(VUSB = 5V)

VBAT (V)

ICH_USB (mA)

100

200

300

400

500

600

4.54.03.53.02.5

RSET = 3.2kΩ

RSET = 4kΩ

RSET = 5.33kΩ

RSET = 8kΩ

RSET = 16kΩ

RSET = 32kΩ

NOBAT High Input Threshold vs. Input Power

VUSB or VADP (V)

NOBAT VIH (V)

3.0 3.6 4.2 4.8 5.4 6.0 6.6

0.80

0.85

0.90

0.95

1.00

1.05

1.10

1.15

1.20

-40°C

25°C

85°C

NOBAT Low Input Threshold vs. Input Power

VUSB or VADP (V)

NOBAT VIL (V)

3.0 3.6 4.2 4.8 5.4 6.0 6.6

0.40

0.45

0.50

0.55

0.60

0.65

0.70

-40°C

25°C

85°C

Enable Input High Threshold vs. Input Power

VUSB or VADP (V)

EN VIH (V)

4.0 4.4 4.8 5.2 5.6 6.0 6.4

0.80

0.85

0.90

0.95

1.00

1.05

1.10

1.15

1.20

-40°C

25°C

85°C

Enable Input Low Threshold vs. Input Power

VUSB or VADP (V)

EN VIL (V)

4.0 4.4 4.8 5.2 5.6 6.0 6.4

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75

0.80

-40°C

25°C

85°C

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

3691.2009.03.1.1 9

www.analogictech.com

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

3691.2009.03.1.1 9

www.analogictech.com

Functional Description

The AAT3691 is a high performance battery charger

designed to charge single cell Lithium Ion or Polymer

batteries with up to 1600mA charging current from an

adaptor (ADP) power source, or with up to 500mA

charging current from an USB power source. The

AAT3691 is a stand-alone charging solution, with just a

few external component required for complete function-

ality. Both input paths include a fast turn-off over-volt-

age protection (OVP) circuit with voltage up to +28V and

an under-voltage lockout level of 3.0V.

The AAT3691 automatically selects the charging source

from USB or ADP according to ADP and USB voltage. The

ADP path is always the high priority charging path when

ADP voltage is higher than 4.5V. The charging current is

determined by the selected charging path and its exter-

nal set resistor (RSET).

USB charging uses an automatic charge reduction loop

control allow battery charging with limited available cur-

rent from a USB port while maintaining the regulated

port voltage. This system assures that the battery

charge function will not overload a USB port while charg-

ing if other system demands also share power with the

respective port supply.

During adapter charging, high set charging current or

high ambient operating temperature may cause the

AAT3691 junction temperature to rise up to 110°C. A

special digital thermal loop control system is employed

to maximize charging current by dynamically decreasing

the battery charging current.

Thermal protection shuts down the AAT3691's charging

function when internal dissipation becomes excessive,

while OVP function still works. The junction over-temper-

ature threshold is 140°C with 15°C of hysteresis. Once

an over-temperature condition is removed, the charging

function automatically recovers.

The status monitor output pin (STAT) is designed to indi-

cate the battery charge status with open-drain structure

by directly driving one external LED.

Battery Charging Operation

Regardless of which charge input function is selected

(adapter input or USB input), the AAT3691 has three

basic modes for the battery charge cycle: precondition-

ing (trickle) charge, constant current/fast charge, and

constant voltage charge. When no automatic charge

reduction mode or digital thermal loop is triggered, the

charge profile is controlled as shown in Figure 1.

Functional Block Diagram

Charge

Control

Current

Compare

Current

Compare

Reverse Blocking

BAT

UVLO

Over-Temp.

Protect

GND

STAT

USB

CV/Precharge

USBCH

USBSET

Charge

Status

DPSET

NOBAT

Reverse Blocking

OVP Sense

and Control

OVP Sense

and Control

ADPCH

ADP

OVP Switch

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

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Regulated Current

Constant Current Mode

Voltage Threshold

Trickle Charge and

Termination Threshold

I = CC/10

I = Max CC

Preconditioning

Trickle Charge

Phase

Constant Current

Charge Phase

Constant Voltage

Charge Phase

Charge Current

Battery Voltage

Time

Battery Charge Current Battery Voltage

Charge Complete Voltage

Figure 1: Charge Current vs. Battery Voltage Profile during Charging Phases.

Battery charging commences only after the AAT3691

checks several conditions in order to maintain a safe

charging environment. The input supply must be above

the minimum operating voltage and the enable pin must

be low. When the battery is connected to the BAT pin and

the NOBAT pin indicates there is a battery connected,

the AAT3691 checks the condition of the battery and

determines which charging mode to apply. If the battery

voltage is below VMIN, then the device begins trickle

charging by charging at 10% of the programmed con-

stant current. For example, if the programmed current is

500mA, then the trickle charge current is 50mA. Trickle

charging is a safety precaution for a deeply discharged

cell and will also reduce the power dissipation in the

internal series pass MOSFET when the input-output volt-

age differential is at its highest. Trickle charging contin-

ues until the battery voltage reaches VMIN. At this point,

the AAT3691 begins constant current charging. The cur-

rent value for this mode is programmed by the external

resistors from the ADPSET and USBSET pin to ground.

Programmed current can be set from a minimum of

100mA up to a maximum of 1.6A for an ADP power

source, and from a minimum of 50mA up to a maximum

of 500mA for a USB power source. Constant current

charging continues until the battery voltage reaches the

voltage regulation point, VBAT_EOC. When the battery volt-

age reaches VBAT_EOC (typical 4.2V), the AAT3691 will

switch to constant voltage mode. Constant current

charge will continue until the charging current is reduced

to 10% of the programmed current. After the charge

cycle is complete, the AAT3691 turns off the series pass

device and automatically goes into standby mode.

During this time, the series pass device will block current

in both directions, therefore preventing the battery from

discharging through the IC.

The AAT3691 remains in standby mode until either the

battery terminal voltage drops below the VRCH threshold,

the charger EN pin is recycled, or the charging source is

reconnected. In all cases, the AAT3691 will monitor all

parameters and resume charging in the most appropri-

ate mode.

Over-Voltage Protection

In normal operation an OVP switch acts as a slew-rate

controlled load switch, connecting and disconnecting the

power supply from ADP to ADPCH and USB to USBCH. A

low-resistance MOSFET is used to minimize the voltage

drop between the voltage source and the charger and to

reduce the power dissipation. When the voltage on the

input exceeds the 6.75V (typical) voltage limit, the

device immediately turns off the internal OVP switch,

disconnecting the load from the abnormal voltage and

preventing damage to any downstream components.

On initial power-up with low and battery present, if

VUSB/ADP < VUVLO (3V maximum), the OVP switch is held

off; if VUVLO < VUSB/ADP < 6.75V (typical), the OVP switch

will turn on after a 130s typical internal delay; if VUSB/ADP

rises above 6.75V (typical), the OVP switch is turned off

after a 0.5s typical internal delay.

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

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System Operation Flowchart

Power On Reset

OVP (6.75V) ≥

VUSB or VADP ≥

VUVLO_ADP or VUVLO_USB

(3V)

Preconditioning

Test

VMIN > VBAT

Current Phase Test

VIN > VBAT_EOC

Voltage Phase Test

IBAT > ITERM

Yes

Preconditioning

(Trickle Charge)

Constant

Current Charge

Mode

Constant

Voltage Charge

Mode

Yes

Charge Completed

Recharge Test

VRCH > VBAT

Yes

NOBAT Indicates No

Battery

Yes

VUSBCH < 4.5V

Auto Charge

Reduction

Loop

Control

OVP Switch Off

USBCH =

ADPCH = 0V

Enable

Yes

USBCH = USB,

ADPCH = ADP

VADPCH > VUVLO_ADPCH

(3.5V)

No VUSBCH > VUVLO_USBCH

(3.5V)

Preconditioning

Test

VMIN > VBAT

Current Phase Test

VIN > VBAT_EOC

Voltage Phase Test

IBAT > ITERM

Yes

Preconditioning

(Trickle Charge)

Constant

Current Charge

Mode

Constant

Voltage Charge

Mode

Yes

Charge Completed

Recharge Test

VRCH > VBAT

Yes

Device Thermal

Loop Monitor

TJ> 115°C

Thermal Loop

Current

Reduction in

C.C. Mode

Yes

Adapter Charge

USB Charge

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

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Application Information

Charge Sources

The AAT3691 operates from sources of an adapter or

USB interface. The internal system control will always

select the adapter input to charge the battery rather

than the USB input if the adapter voltage is above 4.5V.

The normal charging input voltage range is up to typical

6.75V. The device can withstand up to 28V on the adapt-

er or USB inputs without damage to the IC. If VADP or VUSB

is greater than 6.75V, the internal over-voltage protec-

tion circuitry disables charging until the input falls below

typical 6.55V

AC Adapter/USB System Power Charging

Adapter Mode

In the adapter mode, constant current charge levels up

to 1.6A can be programmed by the user. The fast charge

current for the adapter input mode is set by the RADPSET

resistor connected between ADPSET and ground. It is

programmed by the following equations:

ADPSET

ADP_CC

= · KI

ADPSET

ADP_CC

ADPSET

= · KI

ADPSET

with KIADPSET = 800. Table 1 gives the recommended 1%

tolerance metal film resistance values for a desired con-

stant current charge level.

Thermal Loop Control

To protect the linear charging IC from thermal problems,

a special thermal loop control system is used to maxi-

mize charging current under adapter charge mode. The

thermal management system measures the internal cir-

cuit die temperature and reduces the fast charge current

when the die exceeds the preset internal temperature

control threshold. Once the thermal loop control becomes

active, the fast charge current is initially reduced by a

factor of 0.44.

The initial thermal loop current can be estimated by the

following equation:

ITLOOP = ICC · 0.44

ICH_CC (mA) RADPSET (kΩ)R

USBSET (kΩ)

50 32.4

75 21.5

100 16 16

200 8.06 8.06

300 5.36 5.36

400 4.02 4.02

500 3.24 3.24

600 2.67

700 2.32

800 2

900 1.78

1000 1.60

1100 1.47

1200 1.33

1300 1.24

1400 1.15

1500 1.07

1600 1

Table 1: Standard 1% Metal Film Resistor Values

for Constant Current Setting.

The thermal loop control re-evaluates the circuit die

temperature every three seconds and raises the fast

charge current in small steps to the full fast charge cur-

rent level. Figure 2 illustrates the thermal loop function

at 1A fast charge current as the ambient temperature

increases and recovers. In this manner the thermal loop

controls the system charge level, and the AAT3691 pro-

vides the highest level of constant current in the fast

charge mode for any possible valid ambient temperature

condition.

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

Time (10s/div)

Charge Current (0.2A/div)

mbient Temperature decreases

Ambient Temperature increases

Figure 2: Digital Thermal Loop Function

at 1A Fast Charge Current with Ambient

Temperature Increasing and Recovering.

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

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Adapter Input Charge Inhabit and Resume

The AAT3691 has an under-voltage lockout feature so

that if the charger input supply ADP pin drops below the

UVLO threshold, the charger will suspend charging.

When the UVLO condition is removed and VADPCH > VBAT

the system charge control assesses the state of charge

of the battery cell and automatically resumes charging in

the appropriate phase (pre-conditioning trickle charge,

constant current charge, constant voltage charge or end

of charge) according to the condition of the battery.

USB Mode

The AAT3691 also provides an input for intelligent USB

charging. When no voltage is present on the adapter

input pin or adapter input is below 4.5V, the charge con-

troller will automatically switch to accepting power from

the USB input. The USB charge may be user programmed

to any level between 50mA and 500mA by selecting the

appropriate resistor values for RUSBSET

USBSET

USB_CC

= · KI

USBSET

USB_CC

USBSET

= · KI

USBSET

Among them, KIUSBSET is 800. Refer to Table 1 for recom-

mended RUSBSET values for the desired USB input constant

current charge levels.

USB Charge Reduction

In many instances, product system designers do not

know the real properties of a potential USB port used to

supply power to the battery charger. Typically, powered

USB ports found on desktop and notebook PCs should

supply up to 500mA. If a USB port being used to supply

the charger is unable to provide the programmed fast

charge current or if the system under charge must share

supply current with other functions, the AAT3691 auto-

matically reduces USB fast charge current to maintain

port integrity and protect the host system.

The USB charge reduction system becomes active when

the voltage on the USBCH input falls below the USB

charge reduction threshold, typically 4.5V. The charge

reduction system reduces the fast charge current level in

a linear fashion until the voltage sensed on the USB input

recovers above the charge reduction threshold voltage.

USB Input Charge Inhibit and Resume

The AAT3691 UVLO and power on reset feature functions

when the USB input pin voltage level drops below the

UVLO threshold. At this point, the charger suspends

charging and shuts down. When power is re-applied to

the USB pin or the UVLO condition recovers, the system

charge control will assess the state of charge on the bat-

tery cell and automatically resume charging in the

appropriate mode for the condition of the battery.

Enable / Disable

The AAT3691 provides an enable function to allow the

normal operating input voltage to pass through and con-

trol the IC charging. The Enable (EN) pin is active low

and is pulled down to ground by an internal 200k resis-

tor

. When pulled to a logic high level, the AAT3691 is

shut down and forced into the sleep state during which

input voltage up to 28V will be blocked and charging be

halted regardless of the battery voltage or charging

state. When the device is re-enabled, the OVP block will

automatically reassess the input voltage and allow the

normal operating voltage to pass through. If a battery is

also present (NOBAT is low), the charge control circuit

will automatically reset and resume charging with the

appropriate charging mode based on the battery charge

state and measured cell voltage.

Over-Temperature Shutdown

Thermal protection completely disables charging when

internal dissipation exceeds the junction over-tempera-

ture threshold, which is 140°C with 15°C of hysteresis.

Once the over-temperature fault condition is removed,

the charge function automatically recovers.

Battery Charge Status Indication

The AAT3691 has one status LED driver output. The LED

can indicate simple functions such as battery charging,

charge complete, and charge disabled.

Description EN LED Status

Battery charging low on

Charge complete low off

Charge disabled high off

Table 2. LED Status Conditions.

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

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The LED anodes should be connected to either VUSBCH or

VADPCH, depending upon the system design requirements.

The LEDs should be biased with as little current as nec-

essary to create reasonable illumination; therefore, a

ballast resistor should be adopted to limit the current

flowing through the LED by connecting it with the LED in

series between STAT and VUSBCH or VADPCH. LED current

consumption will add to the overall thermal power bud-

get for the device package, so LED drive current should

be kept 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. The

required ballast resistor value can be estimated using

the following formulas:

To connect to ADPCH:

ADPCH

- V

FLED

LED

R =

To connect to USBCH:

USBCH

- V

FLED

LED

R =

For example, using a red LED with 2.0V VF @ 2mA, cal-

culate R under 5.5V VADPCH:

5.5V - 2.0V

2mA

R = = 1.75kΩ

Capacitor Selection

Input Capacitor

An input capacitor is used to filter the input voltage by

placing a decoupling capacitor between the ADP, ADPCH,

USB and USBCH pins and ground. An input capacitor in

the range of 1F to 10F 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. This input capac-

itor range is also suitable for a system with an external

power supply source, such as a typical AC-to-DC wall

adapter. It will minimize switching or power bounce

effects when the power supply is “hot plugged”. Likewise,

a 2.2F or greater input capacitor is recommended for

the USB input to help buffer the effects of USB source

power switching, noise, and input cable impedance.

Output Capacitor

The AAT3691 requires a 1F ceramic capacitor on the

BAT pin to maintain circuit stability. This value should be

increased to 10F or more if the battery connection is

made any distance from the charger output. In a fast

charge application with current above 1A, a 22F output

capacitor is required to obtain an accurate recharge volt-

age threshold. If the AAT3691 is used in applications

where the battery can be removed from the charger,

such as in the case of desktop charging cradles, an out-

put capacitor value greater than 10F may be required

to prevent the device from cycling on and off when no

battery is present.

Thermal Considerations

The actual maximum charging current is a function of

the charge input voltage (USBCH and ADPCH), the bat-

tery voltage at the BAT pin, the ambient temperature,

the rising temperature when charge current passing

through the RDS(ON) of the charging pass, and the thermal

impedance of the package. The maximum programma-

ble current may not be achievable under all operating

parameters.

The AAT3691 is offered in a 3x4mm TDFN package

which can provide up to 2.0W of power dissipation when

properly soldered to a printed circuit board and has a

maximum thermal resistance of 50°C/W. Many consider-

ations 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 ambi-

ent temperature around the charger IC will also have an

effect on the thermal limits of a battery charging appli-

cation. The maximum limits that can be expected for a

given ambient condition can be estimated by the follow-

ing discussion:

First, the maximum power dissipation for a given situa-

tion should be calculated:

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

Where:

PD = Total power dissipation of the AAT3691

VIN = VADP or VUSB, depending on which mode is selected

VBAT = Battery voltage at the BAT pin

ICC = Maximum constant fast charge current pro-

grammed for the application

IOP = Quiescent current consumed by the charger IC

for normal operation.

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

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Next, the maximum operating ambient temperature for

a given application can be estimated based on the ther-

mal resistance of the 3x4 TDFN package when suffi-

ciently mounted to a PCB layout and the internal thermal

loop temperature threshold.

TA = TJ - (θJA · PD)

Where:

TA = Ambient temperature in °C

TJ = Maximum device junction temperature below the

thermal loop threshold

PD = Total power dissipation by the device

JA = Package thermal resistance in °C/W.

Example:

For an application where the fast charge current for the

adapter mode is set to 1A, VADP = 5.0V, and the worst

case battery voltage is 3.6V, what is the maximum ambi-

ent temperature at which the digital thermal loop limit-

ing will become active?

Given:

VADP = 5.0V

VBAT = 3.6V

ICC = 1A

IOP = 0.25mA

TJ = 110°C

JA = 50°C/W

The device power dissipation for the stated condition can

be calculated as below:

PD = (5.0 – 3.6V) · 1A + (5.0V · 0.25mA) ≈ 1.4W

The maximum ambient temperature is

TA = 110°C - (50°C/W · 1.4W) = 40°C

Therefore, under the stated conditions for this worst

case power dissipation example, the AAT3691 will enter

the digital thermal loop and lower the fast charge con-

stant current when the ambient operating temperature

rises above 40°C.

Printed Circuit Board

Layout Considerations

For the best results, it is recommended to physically place

the battery pack as close to the AAT3691 BAT pin as pos-

sible. To minimize voltage drops on the PCB, keep the

high current carrying traces adequately wide. For maxi-

mum power dissipation of the AAT3691 TDFN package,

the exposed pad should be soldered to the board ground

plane to further increase local heat dissipation. A ground

pad below the exposed pad is strongly recommended.

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

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C11

1μF/50V

C12

2.2μF/10V

C22

2.2μF/10V

10μF

C21

1μF/50V

USB

USBCH

ADP

ADPCH

DPCH

1.74k

LED1

Red

ADPCH

USBCH

Disable

USB

ADP

USBCH BAT

BAT

AAT3691

USBCH

USB

ADP

USBSET 13

NOBAT 14

ADPCH

EN 11

ADPSET 12

IC 10

STAT

N/C 15

BAT 16

GND

8GND 9

Figure 3: AAT3691 Evaluation Board Schematic.

Figure 4: AAT3691 Evaluation Board Figure 5: AAT3691 Evaluation Board

Top Side Layout. Bottom Side Layout.

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

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AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

3691.2009.03.1.1 17

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Component Part Number Description Manufacturer

U1 AAT3691IRN-T1 0.5A USB Port /1.6A Adapter Lithium-lon; 16-Pin 3x4 TDFN Package AnalogicTech

R1 RC0603FR-071K74L Res 1.74K 1/10W 1% 0603 SMD Yageo

R2 RC0603FR-073K24L Res 3.24K 1/10W 1% 0603 SMD Yageo

R3 RC0603FR-072KL Res 1.6K 1/10W 1% 0603 SMD Yageo

C3 GRM188R60J106M Cap Ceramic 10F 0603 X5R 6.3V 20% Murata

C11, C21 GRM21BR71H105K Cap Ceramic 1F 0805 X7R 50V 10% Murata

C12, C22 GRM188R61A225K Cap Ceramic 2.2F 0603 X5R 10V 10% Murata

J1 TMM-103-03-T-S Conn. 3-pin header, 2.54mm Pitch Samtec

J2, Disable TMM-102-03-T-S Conn. 2-pin header, 2.54mm Pitch Samtec

LED1 0805KRCT Red LED; 0805 HB

ADP, USB, BAT DG308-2.54-02-14 Multi-position micro PCB terminal blocks, 2.54mm, 2 pin, Green Degson

ADPCH, USBCH 5010K-ND Red Test point Keystone

G1, G2 5011K-ND Black Test point Keystone

Table 3: AAT3691 Evaluation Board Bill of Materials.

AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

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AAT3691

Dual Input 1.6A Linear Charger with 28V OVP in 3x4 TDFNBatteryManagerTM

PRODUCT DATASHEET

18 3691.2009.03.1.1

www.analogictech.com

Advanced Analogic Technologies, Inc.

3230 Scott Boulevard, Santa Clara, CA 95054

Phone (408) 737-4600

Fax (408) 737-4611

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 speciﬁ cations 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 ﬁ tness 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. Speciﬁ c 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.

Ordering Information

Package NOBAT Input EOC Voltage Marking1Part Number (Tape and Reel)2

TDFN34-16 Active high 4.2 4TXYY AAT3691IRN-4.2-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/about/quality.aspx.

Package Information

TDFN34-163

3.000

0.050 1.600

0.050

0.000

0.100

-0.000 0.203 REF

0.750

0.050

4.000

0.050

3.300

0.050

Index Area

Detail "A"

Top View Bottom View

Side View

0.450

0.050

0.230

0.0500.450

0.050

Detail "A"

All dimensions in millimeters.

1. XYY = assembly and date code.

2. Sample stock is generally held on part numbers listed in BOLD.

3. The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing

process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder connection.