AAT3697IWP-4.2-T1 - Advanced Analog Technology, Inc.

AAT3697

2A Lithium-Ion/Polymer Battery Charger

3697.2007.02.1.1 1

BatteryManager™

General Description

The AAT3697 BatteryManager is a highly integrat-

ed single-cell lithium-ion/polymer battery charger

IC designed to operate with AC adapter inputs. It

requires a minimum number of external compo-

nents. The AAT3697 precisely regulates battery

charge voltage and current for 4.2V lithium-

ion/polymer battery cells. Adapter charge current

rates can be programmed up to 2.0A. An active

thermal management system regulates the fast

charge constant current for all ambient tempera-

ture and input vs. output voltage conditions.

Battery 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, thus protecting

the charging device, control system, and the bat-

tery under charge. Status monitor output pins are

provided to indicate the battery charge status by

directly driving two external LEDs. A serial interface

output is available to report 12 various charging

status states to a microcontroller.

The AAT3697 is available in a Pb-free, thermally-

enhanced, space-saving 12-pin TDFN 3x3mm

package and is rated over the -40°C to +85°C tem-

perature range.

Features

• Input Voltage Range: 4.0V to 5.5V

• Up to 2.0A Charging Current

• Adapter Present Indicator (ADPP#)

• High Level of Integration with Internal:

— Charging Device

— Reverse Blocking Diode

— Current Sensing

• Active Thermal Loop Charge Reduction

• Automatic Recharge Sequencing

• Battery Temperature Monitoring

• Full Battery Charge Auto Turn-Off / Sleep Mode

• Over-Voltage, Over-Current, and Over-

Temperature Protection

• Power On Reset and Soft Start

• Serial Interface Status Report

• 12-Pin 3x3mm TDFN Package

• -40°C to +85°C Temperature Range

Applications

• Cellular Telephones

• Digital Still Cameras

• Hand Held PCs

• MP3 Players

• Personal Data Assistants (PDAs)

• Other Lithium-Ion/Polymer Battery-Powered

Devices

Typical Application

AAT3697

OUT

10μF

BATT-

TEMP

Battery

Pack

ADP

ADPSET

GND

BAT

BATT+

SET

10μF

0.1μF

dapter

STAT1

LED1

LED2

STAT2

DATA

Serial Interface

ENEnable

ADPP#

Adapter

Present

ADP

Pin Descriptions

Pin Configuration

TDFN33-12

(Top View)

BAT

ADP

GND

DPP#

ADPSE

N/C

STAT1

STAT2

DATA

Pin # Name Type Function

1 BAT Out Battery charging and sensing.

2 ADP In Adapter input.

3 GND Ground Ground connection.

4 EN In Enable pin. Logic high enables the IC..

5 ADPP# Out Adapter present indicator. This pin is open drain until ADP pin reaches

threshold.

6 TS In/Out Battery temperature sense input.

7 DATA Out Status report to microcontroller via serial interface: open drain.

8 STAT2 Out Battery charge status indicator pin to drive an LED: active low, open drain.

9 STAT1 Out Battery charge status indicator pin to drive an LED: active low, open drain.

10 CT In/Out Timing capacitor to adjust internal watchdog timer. Set maximum charge

time for adapter powered trickle, CC, and CV charge modes. If timing

function is not needed, terminate this pin to ground.

11 N/C No connection.

12 ADPSET In/Out Use resistor at this pin to set adapter charging current.

EP Exposed paddle (bottom); connect to GND directly beneath package.

AAT3697

2A Lithium-Ion/Polymer Battery Charger

23697.2007.02.1.1

Absolute Maximum Ratings1

Thermal Information

Symbol Description Value Units

θJA Maximum Thermal Resistance250 °C/W

PDMaximum Power Dissipation 2.0 W

Symbol Description Value Units

VPADP Input Voltage, <30ms, Duty Cycle <10% -0.3 to 7.0 V

VPADP Input Voltage, Continuous -0.3 to 6.0 V

VNBAT, TS, ADPSET, ADPP#, DATA, CT, EN, STAT1, STAT2 -0.3 to VP+ 0.3 V

TJOperating Junction Temperature Range -40 to 150 °C

TLEAD Maximum Soldering Temperature (at leads) 300 °C

AAT3697

2A Lithium-Ion/Polymer Battery Charger

3697.2007.02.1.1 3

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 Characteristics1

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

Symbol Description Conditions Min Typ Max Units

Operation

ADP Adapter Voltage Range 4.0 5.5 V

VADPP Adapter Present Threshold Voltage 3.0 V

VUVLO

Under-Voltage Lockout (UVLO) Rising Edge 3.0 V

UVLO Hysteresis 150 mV

IOP Operating Current Charge Current = 100mA 0.3 1.5 mA

ISLEEP Sleep Mode Current VBAT = 4.25V 0.3 1.0 μA

ILeakage

Reverse Leakage Current from VBAT = 4V, ADP Pin Open 1.0 μA

BAT Pin

Voltage Regulation

VBAT_EOC1End of Charge Voltage Accuracy 4.158 4.20 4.242 V

ΔVCH/VCH Output Charge Voltage Tolerance 0.5 %

VMIN Preconditioning Voltage Threshold 2.8 3.0 3.15 V

VRCH Battery Recharge Voltage Threshold VBAT_EOC - 0.1 V

Current Regulation

ICH Charge Current 100 2000 mA

ΔICH/ICH Charge Current Regulation Tolerance 10 %

VADPSET ADPSET Pin Voltage CC Mode 2.0 V

KIA Current Set Factor: ICH/IADPSET 4000

Charging Devices

RDS(ON)

Adapter Charging Transistor VIN = 5.5V 0.2 0.25 0.35 Ω

On Resistance

AAT3697

2A Lithium-Ion/Polymer Battery Charger

43697.2007.02.1.1

1. The AAT3697 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.

Electrical Characteristics1

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

Symbol Description Conditions Min Typ Max Units

Logic Control / Protection

VEN(H) Input High Threshold 1.6 V

VEN(L) Input Low Threshold 0.4 V

VADPP# Output Low Voltage ADPP# Pin Sinks 500μA 0.4 V

Preconditioning Plus Constant CCT = 100nF, VADP = 5.5V 3.0 Hour

Current Mode Time Out

TPPreconditioning Time Out CCT = 100nF, VADP = 5.5V 25 Minute

TVConstant Voltage Mode Time Out CCT = 100nF, VADP = 5.5V 3.0 Hour

VSTAT Output Low Voltage STAT Pin Sinks 4mA 0.4 V

ISTAT STAT Pin Current Sink Capability 8.0 mA

VOVP Over-Voltage Protection Threshold 4.4 V

ITK/ICH Pre-Charge Current 10 %

ITERM/ICH Charge Termination Threshold 7.5 %

Current

VTS1 High Temperature Threshold VADP = 5.5V 29.1 30 30.9 %VADP

VTS2 Low Temperature Threshold VADP = 5.5V 58.2 60 61.8 %VADP

IDATA DATA Pin Sink Current DATA Pin is Active Low State 3 mA

IADPP# ADPP# Current Sink ADPP# Pin is Active Low State 8 mA

VDATA(H) Input High Threshold 1.6 V

VDATA(L) Input Low Threshold 0.4 V

SQPULSE Status Request Pulse Width Status Request 200 ns

tPERIOD System Clock Period 50 μs

fDATA Data Output Frequency 20 kHz

TREG Thermal Loop Regulation 90 °C

TLOOP_IN Thermal Loop Entering Threshold 110 °C

TLOOP_OUT Thermal Loop Exiting Threshold 85 °C

TOVSD

Over-Temperature Shutdown 145 °C

Threshold

AAT3697

2A Lithium-Ion/Polymer Battery Charger

3697.2007.02.1.1 5

1. The AAT3697 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.

Typical Characteristics

Charge Current vs. Temperature

(ADPSET = 8.06kΩ

)

Temperature (

(mA)

900

920

940

960

980

1000

1020

1040

1060

1080

1100

-50 -25 0 25 50 75 100

Pre-Charge Current vs. Temperature

(ADPSET = 8.06kΩ

)

Temperature (

(mA)

100

110

120

-50 -25 0 25 50 75 100

Preconditioning Threshold

Voltage vs. Temperature

Temperature (°

MIN

(V)

2.95

2.96

2.97

2.98

2.99

3.00

3.01

3.02

3.03

3.04

3.05

-50 -25 0 25 50 75 100

End of Charge Voltage Regulation

vs. Temperature

Temperature (°

BAT_EOC

(V)

4.158

4.179

4.200

4.221

4.242

-50 -25 0 25 50 75 100

Battery Voltage vs. Supply Voltage

Supply Voltage (V)

BAT

(V)

4.158

4.179

4.200

4.221

4.242

4.5 4.75 5.0 5.25 5.5

Charge Current vs. R

SET

(kΩ

)

(mA)

100

1000

10000

1 10 100

AAT3697

2A Lithium-Ion/Polymer Battery Charger

63697.2007.02.1.1

Typical Characteristics

Counter Timeout vs. Temperature

= 0.1µF)

Temperature (°

Counter Timeout (%)

-10

-8

-6

-4

-2

-50 -25 0 25 50 75 100

Operating Current vs. ADPSET Resistor

ADPSET Resistor (kΩ

)

(mA)

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1 10 100 1000

Pre-Conditioning

Constant Current

vs. Supply Voltage

EN Pin (Falling)

Supply Voltage (V)

(V)

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

4.2 4.4 4.6 4.8 5.0 5.2 5.4 5.6 5.8 6.0

-40°C +25°C

+85°C

vs. Supply Voltage

EN Pin (Rising)

Supply Voltage (V)

(V)

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

4.2 4.4 4.6 4.8 5.0 5.2 5.4 5.6 5.8 6.0

-40°C +25°C

+85°C

Charge Current vs. Supply Voltage

(ADPSET = 8.06kΩ

)

Supply Voltage (V)

(mA)

200

400

600

800

1000

1200

4.5 4.75 5.0 5.25 5.5 5.75 6.0

BAT

= 3.3V

BAT

= 3.5V

BAT

= 3.9V

Charge Current vs. Battery Voltage

(ADPSET = 8.06kΩ

; V

= 5.0V)

Battery Voltage (V)

(A)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

2.5 2.9 3.3 3.7 4.1 4.5

AAT3697

2A Lithium-Ion/Polymer Battery Charger

3697.2007.02.1.1 7

Typical Characteristics

High and Low Temperature

Threshold vs. Temperature

Temperature (°

(% V

ADP

)

100

-50 -25 0 25 50 75 100

TS2

TS1

CT Pin Capacitance vs. Counter Timeout

Time (hours)

Capacitance (μ

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

0246810

Precondition Timeout

Precondition + Constant Current Timeout

or Constant Voltage Timeout

AAT3697

2A Lithium-Ion/Polymer Battery Charger

83697.2007.02.1.1

AAT3697

2A Lithium-Ion/Polymer Battery Charger

3697.2007.02.1.1 9

Functional Block Diagram

Charge

Control

Reverse Blocking

CV/

Precharge

Constant

Current

Compare

ADP

BAT

DPSET

UVLO

Over-

Temperature

Protection

Charge

Status

STAT2

STAT1

4.2V

Serial

Data

DATA

Watchdog

Timer

Voltage

Sense

ADPP#

GND

IC enable

Functional Description

The AAT3697 is a highly integrated single-cell lithi-

um-ion/polymer battery charger IC designed to

operate with standard AC adapter input sources,

while requiring a minimum number of external

components. The AAT3697 precisely regulates

battery charge voltage and current for 4.2V lithium-

ion/polymer battery cells.

The adapter charge input constant current level

can be programmed up to 2.0A for rapid charging

applications. The AAT3697 is rated for operation

from -40°C to +85°C. In the event of operating

ambient temperatures exceeding the power dissi-

pation abilities of the device package for a given

constant current charge level, the charge control

will enter into thermal regulation. When the system

thermal regulation becomes active, the pro-

grammed constant current charge amplitude will

be automatically reduced to a safe level for the cur-

rent operating condition. Should the ambient oper-

ating temperature drop below the thermal loop

threshold, the system will automatically resume

charging at the full programmed constant current

level. This intelligent thermal management system

permits the AAT3697 to operate and safely charge

a battery cell over a wide range of ambient condi-

tions while maximizing the greatest possible

charge current for the given set of conditions.

Status monitor output pins are provided to indicate

the battery charge state by directly driving two

external LEDs. A serial interface output is also

available to report any one of 12 distinct charge

states to the system microcontroller.

Battery 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, thus protecting

the charging device, control system, and the bat-

tery under charge. In addition to internal charge

controller thermal protection, the AAT3697 also

provides a temperature sense feedback function

(TS pin) from the battery to shut down the device in

the event the battery exceeds its own thermal limit

during charging. All fault events are reported to the

user either by the simple status LEDs or via the

DATA pin function.

AAT3697

2A Lithium-Ion/Polymer Battery Charger

10 3697.2007.02.1.1

Charging Operation

The AAT3697 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).

Battery Preconditioning

Before the start of charging, the AAT3697 checks

several conditions in order to assure a safe charging

environment. The input supply must be above the

minimum operating voltage, or under-voltage lockout

threshold (VUVLO), for the charging sequence to

begin. Also, the cell temperature, as reported by a

thermistor connected to the TS pin from the battery,

must be within the proper window for safe charging.

When these conditions have been met and a battery

is connected to the BAT pin, the AAT3697 checks the

state of the battery. If the cell voltage is below the pre-

conditioning voltage threshold (VMIN), the charge

control begins preconditioning the cell.

The battery preconditioning trickle charge current is

equal to the fast charge constant current divided by

10. For example, if the programmed fast charge

current is 1.5A, then the preconditioning mode

(trickle charge) current will be 150mA. Cell precon-

ditioning is a safety precaution for deeply dis-

charged battery cells and also aids in limiting power

dissipation in the pass transistor when the voltage

across the device is at the greatest potential.

Fast Charge / Constant Current Charging

Battery cell preconditioning continues until the volt-

age on the BAT pin exceeds the preconditioning

voltage threshold (VMIN). At this point, the AAT3697

begins the constant current fast charging phase.

The fast charge constant current (ICH) amplitude is

programmed by the user via the RSET resistor. The

AAT3697 remains in the constant current charge

mode until the battery reaches the voltage regula-

tion point, VBAT_EOC.

Constant Voltage Charging

The system transitions to a constant voltage charg-

ing mode when the battery voltage reaches the

output charge regulation threshold (VBAT_EOC) dur-

ing the constant current fast charge phase. The

regulation voltage level is factory programmed to

4.2V (±1%). 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 7.5% 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 (VRCH).

When the input supply is disconnected, the charg-

er will automatically transition into a power-saving

sleep mode. Only consuming an ultra-low 0.3μAin

sleep mode, the AAT3697 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 AAT3697

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

AAT3697

2A Lithium-Ion/Polymer Battery Charger

3697.2007.02.1.1 11

System Operation Flow Chart

Yes Yes

Yes

Set

Enable

Timing

Expire

TERM

BAT_EOC

Yes

ADP

Application Information

Adapter Power Input

Constant current charge levels up to 2.0A may be

programmed by the user when powered from a suf-

ficient input power source. The AAT3697 will oper-

ate from the adapter input over a 4.0V to 5.5V

range.

The constant current fast charge current for the

adapter input is set by the RSET resistor connected

between the ADPSET pin and ground. Refer to

Table 1 for recommended RSET values for a desired

constant current charge level. The presence of volt-

age on the adapter input is indicated by the ADPP#

pin function. This indicator pin uses an internal open

drain device that will pull the ADPP# pin low when

voltage is detected on the ADP pin. The precise

AAT3697

2A Lithium-Ion/Polymer Battery Charger

12 3697.2007.02.1.1

charging function of the AAT3697 may be read from

the DATA pin and/or status LEDs. Please refer to

the Battery Charge Status Indication discussion for

further details on data reporting.

Thermal Loop Control

Due to the integrated nature of the linear charging

control pass device for the adapter input, a special

thermal loop control system has been employed to

maximize charging current under all operating con-

ditions. The thermal management system meas-

ures the internal circuit die temperature and reduces

the fast charge current when the device exceeds a

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:

Eq. 1:

The thermal loop control re-evaluates the circuit die

temperature in 330ms intervals and adjusts the fast

charge current back up in small steps to the full fast

charge current level or until an equilibrium current

is discovered and maximized for the given ambient

temperature condition. The thermal loop controls

the system charge level; therefore, the AAT3697

will always provide the highest level of constant

current in the fast charge mode possible for any

given ambient temperature condition.

Adapter Input Charge Inhibit and Resume

The AAT3697 has a UVLO and power on reset fea-

ture so that the charger will suspend charging and

shut down if the input supply to the adapter pin

drops below the UVLO threshold. When power is

re-applied to the adapter pin or the UVLO condi-

tions recovers, the system charge control will

assess the state of charge on the battery cell and

will automatically resume charging in the appropri-

ate mode for the condition of the battery.

Enable / Disable

The AAT3697 provides an enable function to control

the charger IC on and off. The enable (EN) pin is

active high. When pulled to a logic low level, the

AAT3697 will be shut down and forced into the sleep

state. Charging will be halted regardless of the bat-

tery voltage or charging state. When the device is re-

enabled, the charge control circuit will automatically

reset and resume charging functions with the appro-

priate 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 ADPSET pin and ground. The accu-

racy of the fast charge, as well as the precondi-

tioning trickle charge current, is dominated by the

tolerance of the set resistor used. For this reason,

a 1% tolerance metal film resistor is recommended

for the set resistor function.

Fast charge constant current levels from 50mA to

2.0A can be set by selecting the appropriate resis-

tor value from Table 1.

Table 1: Recommended RSET Values.

Figure 2: ICH vs. RSET.

SET

(kΩ

)

(mA)

100

1000

10000

1 10 100

ICH (mA) RSET (kΩΩ)I

CH (mA) RSET (kΩΩ)

100 84.5 1100 7.32

200 43.2 1200 6.65

300 28.0 1300 6.04

400 21.0 1400 5.62

500 16.9 1500 5.36

600 13.3 1600 4.87

700 11.5 1700 4.53

800 10.2 1800 4.22

900 90.9 1900 3.92

1000 8.06 2000 3.65

TLOOP

= I

0.44

AAT3697

2A Lithium-Ion/Polymer Battery Charger

3697.2007.02.1.1 13

Protection Circuitry

Programmable Watchdog Timer

The AAT3697 contains a watchdog timing circuit to

shut down charging functions in the event of a defec-

tive battery cell not accepting a charge over a preset

period of time. Typically, a 0.1μF ceramic capacitor

is connected between the CT pin and ground. When

a 0.1μF ceramic capacitor is used, the device will

time out a shutdown condition if the trickle charge

mode exceeds 25 minutes and a combined trickle

charge plus fast charge mode of 3 hours. When the

device transitions to the constant voltage mode, the

timing counter is reset and will time out after an addi-

tional 3 hours if the charge current does not drop to

the charge termination level.

Table 2: Summary for a 0.1μF Ceramic

Capacitor Used for the Timing Capacitor.

The CT pin is driven by a constant current source

and will provide a linear response to increases in the

timing capacitor value. Thus, if the timing capacitor

were to be doubled from the nominal 0.1μF value,

the time-out periods would be doubled.

If the programmable watchdog timer function is not

needed, it can be disabled by terminating the CT

pin to ground. The CT pin should not be left float-

ing or un-terminated, as this will cause errors in the

internal timing control circuit.

The constant current provided to charge the timing

capacitor is very small, and this pin is susceptible

to noise and changes in capacitance value.

Therefore, the timing capacitor should be physical-

ly located on the printed circuit board layout as

close as possible to the CT pin. Since the accura-

cy of the internal timer is dominated by the capaci-

tance value, a 10% tolerance or better ceramic

capacitor is recommended. Ceramic capacitor

materials, such as X7R and X5R types, are a good

choice for this application.

Over-Voltage Protection

An over-voltage event is defined as a condition

where the voltage on the BAT pin exceeds the

maximum battery charge voltage and is set by the

over-voltage protection threshold (VOVP). If an

over-voltage condition occurs, the AAT3697 charge

control will shut down the device until the voltage

on the BAT pin drops below VOVP. The AAT3697

will resume normal charging operation after the

over-voltage condition is removed. During an over-

voltage event, the STAT LEDs will report a system

fault, and the actual fault condition can be read via

the DATA pin signal.

Over-Temperature Shutdown

The AAT3697 has a thermal protection control cir-

cuit which will shut down charging functions should

the internal die temperature exceed the preset

thermal limit threshold.

Battery Temperature Fault Monitoring

In the event of a battery over-temperature condi-

tion, the charge control will turn off the internal pass

device and report a battery temperature fault on the

DATA pin function. The STAT LEDs will also dis-

play a system fault. After the system recovers from

a temperature fault, the device will resume charg-

ing operation.

The AAT3697 checks battery temperature before

starting the charge cycle, as well as during all

stages of charging. This is accomplished by mon-

itoring the voltage at the TS pin. Either a negative

temperature coefficient thermistor (NTC) or posi-

tive temperature coefficient thermistor (PTC) can

be used because the AAT3697 checks to see that

the voltage at TS is within a voltage window bound-

ed by VTS1 and VTS2. Please see the equations

below for specifying resistors:

RT1 and RT2 for use with NTC Thermistor

Eq. 2:

5 ⋅ R

⋅ R

3 ⋅ (R

- R

)

5 ⋅ R

⋅ R

(2 ⋅ R

) - (7 ⋅ R

)

Mode Time

Trickle Charge (TC) Time Out 25 minutes

Trickle Charge (TC) + 3 hours

Fast Charge (CC) Time Out

Constant Voltage (VC) Mode 3 hours

Time Out

AAT3697

2A Lithium-Ion/Polymer Battery Charger

14 3697.2007.02.1.1

RT1 and RT2 for use with PTC Thermistor

Eq. 3:

Where RTC is the thermistor's cold temperature

resistance and RTH is the thermistor's hot tempera-

ture resistance. See thermistor specifications for

information. To ensure there is no dependence on

the input supply changes, connect the divider

between VADP and GND. Disabling the tempera-

ture-monitoring function is achieved by applying a

voltage between VTS1 and VTS2 on the TS pin.

Battery Charge Status Indication

The AAT3697 indicates the status of the battery

under charge with two different systems. First, the

device has two status LED driver outputs. These

two LEDs can indicate simple functions such as no

battery charge activity, battery charging, charge

complete, and charge fault. The AAT3697 also

provides a bi-directional data reporting function so

that a system microcontroller can interrogate the

DATA pin and read any one of 12 system states.

Status Indicator Display

Simple system charging status states can be dis-

played using one or two LEDs in conjunction with

the STAT1 and STAT2 pins on the AAT3697.

These two pins are simple open drain switches

used to connect the LED cathodes to ground. It is

not necessary to use both display LEDs if a user

simply wants to have a single lamp to show "charg-

ing" or "not charging."

This can be accomplished by using the STAT1 pin

and a single LED. Using two LEDs and both STAT

pins simply gives the user more information to the

charging states. Refer to Table 3 for LED display

definitions. The LED anodes should be connected

to VADP.

The LEDs should be biased with as little current as

necessary to create reasonable illumination; there-

fore, a ballast resistor should be placed between

the LED cathodes and the STAT1/2 pins. LED cur-

rent consumption will add to the overall thermal

power budget for the device package, hence it is

good to keep the LED drive current to a minimum.

2mA should be sufficient to drive most low-cost

green or red LEDs. It is not recommended to

exceed 8mA for driving an individual status LED.

The required ballast resistor values can be esti-

mated using the following formulas:

Eq. 4:

Example:

Eq. 5:

Note: Red LED forward voltage (VF) is typically

2.0V @ 2mA

(5.5V

- 2.0

B(STAT1)

= = 1.75kΩ

2mA

ADP

F(LED)

)

B(STAT1/2)

= I

LED(STAT1/2)

5 ⋅ R

⋅ R

3 ⋅ (R

- R

)

5 ⋅ R

⋅ R

(2 ⋅ R

) - (7 ⋅ R

)

Table 3: LED Status Indicator.

Event Description STAT1 STAT2

Charge Disabled or Low Supply Off Off

Charge Enabled Without Battery Flash1Flash1

Battery Charging On Off

Charge Completed Off On

Fault On On

1. Flashing rate depends on output capacitance.

AAT3697

2A Lithium-Ion/Polymer Battery Charger

3697.2007.02.1.1 15

Data Timing

The system microcontroller should assert an active

low data request pulse for minimum duration of

200ns; this is specified by TLO(DATA). Upon sensing

the rising edge of the end of the data request pulse,

the AAT3697 status data control will reply the data

word back to the system microcontroller after a

delay specified by the data report time specification

TDATA(RPT). The period of the following group of

data pulses will be specified by TD ATA.

Digital Charge Status Reporting

The AAT3697 has a comprehensive digital data

reporting system by use of the DATA pin feature.

This function can provide detailed information

regarding the status of the charging system. The

DATA pin is a bi-directional port which will read

back a series of data pulses when the system

microcontroller asserts a request pulse. This sin-

gle strobe request protocol will invoke one of 12

possible return pulse counts that the system micro-

controller can look up based on the serial report

data listed in Table 4.

The DATA pin function logic is active low and

should normally be pulled high to VADP. This data

line can also be pulled high to the same level as the

high state for the logic I/O port on the system

microcontroller. In order for the DATA pin control

circuit to generate clean, sharp edges for the data

output, and to maintain the integrity of the data tim-

ing for the system, the pull-up resistor on the data

line should be low enough in value so that the

DATA signal returns to the high state without delay.

If the pull-up resistor is too high, the strobe pulse

from the system microcontroller could exceed the

maximum pulse time and the DATA output control

could issue false status reports. A 1.5kΩresistor is

recommended when pulling the DATA pin high to

5.0V on the VADP input. If the data line is pulled

high to a voltage level less than 5.0V, the pull-up

resistor can be calculated based on a recommend-

ed minimum pull-up current of 3mA. Use the fol-

lowing formula:

Eq. 6:

PULL-UP

≤3mA

Figure 3: Data Pin Application Circuit.

AAT3697

Status

Control

1.8V to 5.0V

DATA Pin

PULL_UP

μP GPIO

Port

GPIO

OUT

AAT3697

2A Lithium-Ion/Polymer Battery Charger

16 3697.2007.02.1.1

Timing Diagram

Table 4: Serial Data Report Table.

N DATA Report Status

1 Chip Over-Temperature Shutdown.

2 Battery Temperature Fault.

3 Over-Voltage Turn Off.

4 Not Used.

5 ADP Watchdog Time-Out in Battery Condition Mode.

6 ADP Battery Condition Mode.

7 ADP Watchdog Time-Out in Constant Current Mode.

8 ADP Thermal Loop Regulation in Constant Current Mode.

9 ADP Constant Current Mode.

10 ADP Watchdog Time-Out in Constant Voltage Mode.

11 ADP Constant Voltage Mode.

12 ADP End of Charging.

23 Data Report Error.

PULSE

Data

System Reset

System Start

SYNC

LAT

N=1 N=2 N=3

OFF

DATA(RPT)

= T

SYNC

+ T

LAT

< 2.5 P

DATA

OFF

> 2 P

DATA

AAT3697

2A Lithium-Ion/Polymer Battery Charger

3697.2007.02.1.1 17

Thermal Considerations

The AAT3697 is offered in a 3x3mm TDFN pack-

age which can provide up to 2.0W of power dissi-

pation when it is properly bonded to a printed cir-

cuit board and has a maximum thermal resistance

of 50°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:

Eq. 7:

Where:

PD= Total Power Dissipation by the Device

VIN = Input Voltage Amplitude, VADP

VBAT = Battery Voltage as Seen at the BAT Pin

ICC = Maximum Constant Fast Charge Current

Programmed for the Application

IOP = Quiescent Current Consumed by the

Charger IC for Normal Operation

Next, the maximum operating ambient temperature

for a given application can be estimated based on

the thermal resistance of the 3x3mm TDFN pack-

age when sufficiently mounted to a PCB layout and

the internal thermal loop temperature threshold.

Eq. 8:

Where:

TA= Ambient Temperature in °C

TJ= Maximum Device Junction Temperature

Below the Thermal Loop Threshold

PD= Total Power Dissipation by the Device

θJA = 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

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

ent temperature at which the thermal loop will

become active?

Given:

VADP = 5.0V

VBAT = 3.6V

ICC = 1A

IOP = 0.75mA

TJ= 110°C

θJA = 50°C/W

Using Equation 7, calculate the device power dissi-

pation for the stated condition:

Eq. 9:

The maximum ambient temperature before the

AAT3697 thermal loop becomes active can now be

calculated using Equation 8:

Eq. 10:

Therefore, under the stated conditions for this

worst case power dissipation example, the

AAT3697 will enter the thermal loop and lower the

fast charge constant current when the ambient

operating temperature rises above 39.8°C.

= 110°C -

(

50°C/W

1.40375W)

= 39.8125°C

= (5.0V - 3.6V)

(1A)

+ (5.0V

0.75mA)

= 1.40375W

= T

- (θ

)

= [(V

- V

BAT

)

+ (V

)]

AAT3697

2A Lithium-Ion/Polymer Battery Charger

18 3697.2007.02.1.1

Capacitor Selection

Input Capacitor

In general, it is good design practice to place a

decoupling capacitor between the ADP pin and

ground. 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 AAT3697 adapter input is to be used in a sys-

tem with an external power supply source, such as

a typical AC-to-DC wall adapter, then a CIN capac-

itor 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 AAT3697 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 AAT3697 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 physi-

cally place the battery pack as close as possible to

the AAT3697 BAT pin. To minimize voltage drops

on the PCB, keep the high current carrying traces

adequately wide. For maximum power dissipation

of the AAT3697 3x3mm TDFN package, the metal

substrate should be solder bonded to the board. It

is also recommended to maximize the substrate

contact to the PCB ground plane layer to further

increase local heat dissipation. Refer to the

AAT3697 evaluation board for a good layout exam-

ple (see Figures 4 and 5).

AAT3697 Evaluation Board Layout

Figure 4: AAT3697 Evaluation Board Figure 5: AAT3697 Evaluation Board

Component Side Layout. Solder Side Layout.

AAT3697

2A Lithium-Ion/Polymer Battery Charger

3697.2007.02.1.1 19

AAT3697 Evaluation Board Schematic Diagram

D2 D1D3

8.06K

1.5K

10μF

0.1μF

SW1

DAT

123

ON/OFF

ADP

BAT

GND

(TDFN33-12)

BAT

ADP

GND

ADPP#

DATA

STAT2

STAT1

ADPSET

10k

AAT3697

RED

LED

RED

LED

GRN

LED

AAT3697

2A Lithium-Ion/Polymer Battery Charger

20 3697.2007.02.1.1

AAT3697 Evaluation Board Bill of Materials (BOM)

Quantity Description Desig. Footprint Manufacturer Part Number

1 Test Pin DATA PAD Mill-Max 6821-0-0001-00-00-08-0

1 Connecting Terminal Block, ADP, GND TBLOK2 Phoenix Contact 277-1274-ND

2.54mm, 2 Position

1 Connecting Terminal Block, BAT, TBLOK3 Phoenix Contact 277-1273-ND

2.54mm, 3 Position GND, TS

2 Capacitor, Ceramic, 10μF C1, C2 0805 Murata GRM219R60J106KE19

6.3V 10% X5R 0805

1 Capacitor, Ceramic, 0.1μF C3 0603 Murata GRM188R71C104KA01D

10% 16V X7R 0603

2 Typical Red LED, Ultra-Bright D1, D3 1206LED Chicago Miniature CMD15-21SRC/TR8

Lamp

1 Typical Green LED D2 1206LED Chicago Miniature CMD15-21VGC/TR8

Lamp

1 Header, 3-Pin J1 HEADER2MM-3 Sullins 6821-0-0001-00-00-08-0

1 Resistor, 10kΩ, 1/16W R1, R2 0603 Panasonic/ECG P10KCFCT-ND

1% 0603 SMD

1 Resistor, 8.06kΩ, 1/16W R6 0603 Panasonic/ECG P8.06KHCT-ND

1% 0603 SMD

4 Resistor, 1.5kΩ, 1/16W R3, R4, 0603 Panasonic/ECG P1.5KCGCT-ND

5% 0603 SMD R5, R7

1 Switch Tact 6mm SPST SW1 Switch ITT Industries/ CKN9012-ND

H = 5.0mm C&K Div

1 AAT3697 2A Lithium-Ion/ U1 TDFN33-12 AnalogicTech AAT3697IWP-4.2

Polymer Battery Charger

AAT3697

2A Lithium-Ion/Polymer Battery Charger

3697.2007.02.1.1 21

Ordering Information

Package Information3

TDFN33-12

All dimensions in millimeters.

Top View Bottom View

Detail "A"

Side View

3.00

0.05

Index Area Detail "A"

1.70

0.05

3.00

0.05

0.23

0.05

0.75

0.05

2.40

0.05

0.43

0.05

0.45

0.050.23

0.05

0.1 REF

Pin 1 Indicator

(optional)

C0.3

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.

Trickle Charge Package Marking1Part Number (Tape and Reel)2

Yes TDFN33-12 VCXYY AAT3697IWP-4.2-T1

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.

AAT3697

2A Lithium-Ion/Polymer Battery Charger

22 3697.2007.02.1.1

Advanced Analogic Technologies, Inc.

830 E. Arques Avenue, Sunnyvale, CA 94085

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 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-

tered trademarks or trademarks of their respective holders.