AAT2556IWP-CA-T1 - AnalogicTech

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

2556.2009.08.1.3 1

www.analogictech.com

General Description

The AAT2556 is a member of AnalogicTech’s Total Power

Management IC™ (TPMIC™) product family. It is a fully

integrated 500mA battery charger plus a 250mA step-

down converter. The input voltage range is 4V to 6.5V for

the battery charger and 2.7V to 5.5V for the step-down

converter, making it ideal for single-cell lithium-ion/poly-

mer battery-powered applications.

The battery charger is a complete constant current/ con-

stant voltage linear charger. It offers an integrated pass

device, reverse blocking protection, high current accu-

racy and voltage regulation, charge status, and charge

termination. The charging current is programmable via

external resistor from 15mA to 500mA. In addition to

standard features, the device offers over-voltage, cur-

rent limit, and thermal protection.

The step-down converter is a highly integrated converter

operating at 1.5MHz of switching frequency, minimizing

the size of external components while keeping switching

losses low. It has independent input and enable pins.

The output voltage ranges from 0.6V to the input volt-

age. The feedback and control deliver excellent load

regulation and transient response with a small output

inductor and capacitor.

The AAT2556 is available in a Pb-free, thermally-

enhanced TDFN33-12 package and is rated over the

-40°C to +85°C temperature range.

Features

• Battery Charger:

▪ Input Voltage Range: 4V to 6.5V

▪ Programmable Charging Current up to 500mA

▪ Highly Integrated Battery Charger

▪ Charging Device

▪ Reverse Blocking Diode

• Step-Down Converter:

▪ Input Voltage Range: 2.7V to 5.5V

▪ Output Voltage Range: 0.6V to VIN

▪ 250mA Output Current

▪ Up to 96% Efficiency

▪ 30μA Quiescent Current

▪ 1.5MHz Switching Frequency

▪ 100μs Start-Up Time

• Short-Circuit, Over-Temperature, and Current Limit

Protection

• TDFN33-12 Package

• -40°C to +85°C Temperature Range

Applications

• Bluetooth™ Headsets

• Cellular Phones

• Handheld Instruments

• MP3 and Portable Music Players

• PDAs and Handheld Computers

• Portable Media Players

Typical Application

BATT -

ADP

ISET

GND

BAT

BATT +

Adapter / USB Input

STAT

EN_BATEnable

RSET

VIN

EN_BUCK

L= 3.3μH

RFB2

RFB1

COUT

VOUT

System

Battery Pack

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

2 2556.2009.08.1.3

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Pin Descriptions

Pin # Symbol Function

1 FB Feedback input. This pin must be connected directly to an external resistor divider. Nominal voltage is 0.6V.

2, 8, 10 GND Ground.

3 EN_BUCK Enable pin for the step-down converter. When connected to logic low, the step-down converter is disabled

and it consumes less than 1μA of current. When connected to logic high, it resumes normal operation.

4 EN_BAT Enable pin for the battery charger. When internally pulled down, the battery charger is disabled and it con-

sumes less than 1μA of current. When connected to logic high, it resumes normal operation.

5 ISET Charge current set point. Connect a resistor from this pin to ground. Refer to typical curves for resistor

selection.

6 BAT Battery charging and sensing.

7 STAT Charge status input. Open drain status input.

9 ADP Input for USB/adapter charger.

11 LX Output of the step-down converter. Connect the inductor to this pin. Internally, it is connected to the drain

of both high- and low-side MOSFETs.

12 VIN Input voltage for the step-down converter.

EP Exposed paddle (bottom): connect to ground directly beneath the package.

Pin Configuration

TDFN33-12

(Top View)

GND

EN_BUCK

EN_BAT

ISET

BAT

VIN

GND

ADP

GND

STA

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

2556.2009.08.1.3 3

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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.

Absolute Maximum Ratings1

Symbol Description Value Units

VIN Input Voltage to GND 6.0 V

VADP Adapter Voltage to GND -0.3 to 7.5 V

VLX LX to GND -0.3 to VIN + 0.3 V

VFB FB to GND -0.3 to VIN + 0.3 V

VEN EN_BAT and EN_BUCK to GND -0.3 to 6.0 V

VXBAT, ISET and STAT to GND -0.3 to VADP + 0.3 V

TJOperating Junction Temperature Range -40 to 150 °C

TLEAD Maximum Soldering Temperature (at leads, 10 sec) 300 °C

Thermal Information

Symbol Description Value Units

PDMaximum Power Dissipation 2.0 W

θJA Thermal Resistance250 °C/W

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

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1. The AAT2556 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correla-

tion with statistical process controls.

2. Output voltage tolerance is independent of feedback resistor network accuracy.

Electrical Characteristics1

VIN = 3.6V; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C.

Symbol Description Conditions Min Typ Max Units

Step-Down Converter

VIN Input Voltage 2.7 5.5 V

VUVLO UVLO Threshold

VIN Rising 2.7 V

Hysteresis 200 mV

VIN Falling 1.8 V

VOUT Output Voltage Tolerance2IOUT = 0 to 250mA, VIN = 2.7V to 5.5V -3.0 3.0 %

VOUT Output Voltage Range 0.6 VIN V

IQQuiescent Current No Load 30 μA

ISHDN Shutdown Current EN = GND 1.0 μA

ILIM P-Channel Current Limit 600 mA

RDS(ON)H High-Side Switch On Resistance 0.59 Ω

RDS(ON)L Low-Side Switch On Resistance 0.42 Ω

ILXLEAK LX Leakage Current VIN = 5.5V, VLX = 0 to VIN 1.0 μA

ΔVLinereg/

ΔVIN

Line Regulation VIN = 2.7V to 5.5V 0.2 %/V

VFB Feedback Threshold Voltage Accuracy VIN = 3.6V 0.591 0.600 0.609 V

IFB FB Leakage Current VOUT = 1.0V 0.2 μA

FOSC Oscillator Frequency 1.5 MHz

TSStartup Time From Enable to Output Regulation 100 μs

TSD Over-Temperature Shutdown Threshold 140 °C

THYS Over-Temperature Shutdown Hysteresis 15 °C

VEN(L) Enable Threshold Low 0.6 V

VEN(H) Enable Threshold High 1.4 V

IEN Input Low Current VIN = VEN = 5.5V -1.0 1.0 μA

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

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1. The AAT2556 output charge voltage is specified over the 0° to 70°C ambient temperature range; operation over the -25°C to +85°C temperature range is guaranteed by

design.

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

Battery Charger

Operation

VADP Adapter Voltage Range 4.0 6.5 V

VUVLO Under-Voltage Lockout (UVLO) Rising Edge 3 4 V

UVLO Hysteresis 150 mV

IOP Operating Current Charge Current = 200mA 0.5 1 mA

ISHUTDOWN Shutdown Current VBAT = 4.25V, EN = GND 0.3 1 μA

ILEAKAGE Reverse Leakage Current from BAT Pin VBAT = 4V, ADP Pin Open 0.4 2 μA

Voltage Regulation

VBAT_EOC End of Charge Accuracy 4.158 4.20 4.242 V

ΔVCH/VCH Output Charge Voltage Tolerance 0.5 %

VMIN Preconditioning Voltage Threshold 2.85 3.0 3.15 V

VRCH Battery Recharge Voltage Threshold Measured from VBAT_EOC -0.1 V

Current Regulation

ICH Charge Current Programmable Range 15 500 mA

ΔICH/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 0.9 1.1 Ω

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/ICHG Pre-Charge Current ICH = 100mA 10 %

ITERM/ICHG Charge Termination Threshold Current 10 %

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

6 2556.2009.08.1.3

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Typical Characteristics – Step-Down Converter

Efficiency vs. Load

(VOUT = 1.8V; L = 3.3µH)

Output Current (mA)

Efficiency (%)

100

0.1 1 10 100 1000

VIN = 3.6V

VIN = 2.7V

VIN = 4.2V

VIN = 5.0V

VIN = 5.5V

DC Load Regulation

(VOUT = 1.8V; L = 3.3µH)

Output Current (mA)

Output Error (%)

-1.0

-0.5

0.0

0.5

1.0

0.1 1 10 100 1000

VIN = 4.2V

VIN = 3.6V

VIN = 2.7V

VIN = 5.5V

VIN = 5.0V

Efficiency vs. Load

(VOUT = 1.2V; L = 1.5µH)

Output Current (mA)

Efficiency (%)

100

0.1 1 10 100 1000

VIN = 3.6V

VIN = 2.7V

VIN = 5.5V

VIN = 4.2V

VIN = 5.0V

DC Load Regulation

(VOUT = 1.2V; L = 1.5µH)

Output Current (mA)

Output Error (%)

-1.0

-0.5

0.0

0.5

1.0

0.1 1 10 100 1000

VIN = 5.0V

VIN = 5.5V

VIN = 2.7V

VIN = 4.2V

VIN = 3.6V

Soft Start

(VIN = 3.6V; VOUT = 1.8V;

IOUT = 250mA; CFF = 100pF)

Enable and Output Voltage

(top) (V)

Inductor Current

(bottom) (A)

Time (100µs/div)

-5.0

-4.0

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

-0.2

-0.4

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

VEN

Line Regulation

(VOUT = 1.8V)

Input Voltage (V)

Accuracy (%)

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0

IOUT = 250mA

IOUT = 10mA

IOUT = 0mA

IOUT = 50mA

IOUT = 150mA

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

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Typical Characteristics – Step-Down Converter

Output Voltage Error vs. Temperature

(VIN = 3.6V; VOUT = 1.8V; IOUT = 250mA)

Temperature (°

Output Error (%)

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

-40 -20 0 20 40 60 80 100

Switching Frequency Variation

vs. Temperature

(VIN = 3.6V; VOUT = 1.8V)

Temperature (°

Variation (%)

-10.0

-8.0

-6.0

-4.0

-2.0

0.0

2.0

4.0

6.0

8.0

10.0

-40 -20 0 20 40 60 80 100

Frequency Variation vs. Input Voltage

(VOUT = 1.8V)

Input Voltage (V)

Frequency Variation (%)

-4.0

-3.0

-2.0

-1.0

0.0

1.0

2.0

2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5

No Load Quiescent Current vs. Input Voltage

Input Voltage (V)

Supply Current (µA)

2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5

85°C

25°C

-40°C

P-Channel RDS(ON) vs. Input Voltage

Input Voltage (V)

RDS(ON)H (mΩ

)

300

400

500

600

700

800

900

1000

2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0

120°C 100°C

85°C

25°C

N-Channel RDS(ON) vs. Input Voltage

Input Voltage (V)

RDS(ON)L (mΩ

)

300

350

400

450

500

550

600

650

700

750

2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0

120°C100°C

85°C

25°C

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

8 2556.2009.08.1.3

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Typical Characteristics – Step-Down Converter

Load Transient Response

(10mA to 250mA; VIN = 3.6V; VOUT = 1.8V;

COUT = 4.7µF; CFF = 100pF)

Output Voltage

(top) (V)

Load and Inductor Current

(bottom) (200mA/div)

Time (25µs/div)

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2.0

ILX

Load Transient Response

(10mA to 250mA; VIN = 3.6V; VOUT = 1.8V; COUT = 4.7µF)

Output Voltage

(top) (V)

Load and Inductor Current

(bottom) (200mA/div)

Time (25µs/div)

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2.0

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

ILX

Line Response

(VOUT = 1.8V @ 250mA; CFF = 100pF)

Output Voltage

(top) (V)

Input Voltage

(bottom) (V)

Time (25µs/div)

1.50

1.55

1.60

1.65

1.70

1.75

1.80

1.85

1.90

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

VIN

Output Ripple

(VIN = 3.6V; VOUT = 1.8V; IOUT = 1mA)

Output Voltage

(AC Coupled) (top) (mV)

Inductor Current

(bottom) (A)

Time (2µs/div)

-120

-100

-80

-60

-40

-20

-0.01

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

Output Ripple

(VIN = 3.6V; VOUT = 1.8V; IOUT = 250mA)

Output Voltage

(AC Coupled) (top) (V)

Inductor Current

(bottom) (A)

Time (200ns/div)

-120

-100

-80

-60

-40

-20

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

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Typical Characteristics – Battery Charger

RSET (kΩ

)

ICH (mA)

Constant Charging Current

vs. Set Resistor Values

100

1000

1 10 100 1000

Charging Current vs. Battery Voltage

(VADP = 5V)

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.

RSET = 8.06kΩ

RSET = 5.36kΩ

RSET = 3.24kΩ

RSET = 16.2kΩRSET = 31.6kΩ

End of Charge Battery Voltage

vs. Supply Voltage

VADP (V)

VBAT_EOC (V)

4.194

4.196

4.198

4.200

4.202

4.204

4.206

4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5

RSET = 8.06kΩ

RSET = 31.6kΩ

End of Charge Voltage Regulation

vs. Temperature

(RSET = 8.06kΩ

)

Temperature (

VBAT_EOC (V)

4.17

4.18

4.19

4.20

4.21

4.22

4.23

-50 -25 0 25 50 75 100

Constant Charging Current vs.

Supply Voltage

(RSET = 8.06kΩ

)

VADP (V)

ICH (mA)

170

180

190

200

210

220

4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25

6.5

VBAT = 3.6V

VBAT = 4V

VBAT = 3.3V

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

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

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Typical Characteristics – Battery Charger

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

)

Temperature (

VMIN (V)

2.97

2.98

2.99

3.01

3.02

3.03

-50 -25 0 25 50 75 100

Preconditioning Charge Current

vs. Temperature

(RSET = 8.06kΩ

)

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

Preconditioning Charge Current

vs. Supply Voltage

VADP (V)

ITRICKLE (mA)

4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 6 6.2 6.4

RSET = 8.06kΩ

RSET = 5.36kΩ

RSET = 3.24kΩ

RSET = 16.2kΩRSET = 31.6kΩ

Recharging Threshold Voltage

vs. Temperature

(RSET = 8.06kΩ

)

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

Sleep Mode Current vs. Supply Voltage

(RSET = 8.06kΩ

)

VADP (V)

ISLEEP (nA)

100

200

300

400

500

600

700

800

4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5

85°C

25°C-40°C

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

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Typical Characteristics – Battery Charger

VEN(H) vs. Supply Voltage

(RSET = 8.06kΩ

)

VADP (V)

VEN(H) (V)

0.7

0.8

0.9

1.1

1.2

4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5

-40°C

25°C 85°C

VEN(L) vs. Supply Voltage

(RSET = 8.06kΩ

)

VADP (V)

VEN(L) (V)

0.6

0.7

0.8

0.9

1.1

4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5

-40°C

25°C 85°C

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

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Functional Description

The AAT2556 is a high performance power system com-

prised of a 500mA lithium-ion/polymer battery charger

and a 250mA step-down converter.

The battery charger is designed for single-cell lithium-ion/

polymer batteries using a constant current and constant

voltage algorithm. The battery charger operates from the

adapter/USB input voltage range from 4V to 6.5V. The

adapter/USB charging current level can be programmed

up to 500mA for rapid charging applications. A status

monitor output pin is provided to indicate the battery

charge state by directly driving one external LED. Internal

device temperature and charging state are fully moni-

tored for fault conditions. In the event of an over-voltage

or over-temperature failure, the device will automatically

shut down, protecting the charging device, control sys-

tem, and the battery under charge. Other features include

an integrated reverse blocking diode and sense resistor.

The step-down converter operates with an input voltage

of 2.7V to 5.5V. The switching frequency is 1.5MHz,

minimizing the size of the inductor. Under light load con-

ditions, the device enters power-saving mode; the

switching frequency is reduced, and the converter con-

sumes 30μA of current, making it ideal for battery-oper-

ated applications. The output voltage is programmable

from VIN to as low as 0.6V. Power devices are sized for

250mA current capability while maintaining over 90%

efficiency at full load. Light load efficiency is maintained

at greater than 80% down to 1mA of load current. A

high-DC gain error amplifier with internal compensation

controls the output. It provides excellent transient

response and load/line regulation.

Under-Voltage Lockout

The AAT2556 has internal circuits for UVLO and power on

reset features. If the ADP supply voltage drops below the

UVLO threshold, the battery charger will suspend charg-

ing and shut down. When power is reapplied to the ADP

pin or the UVLO condition recovers, the system charge

control will automatically resume charging in the appro-

priate mode for the condition of the battery. If the input

voltage of the step-down converter drops below UVLO,

the internal circuit will shut down.

Protection Circuitry

Over-Voltage Protection

An over-voltage protection event is defined as a condition

where the voltage on the BAT pin exceeds the over-volt-

age protection threshold (VOVP). If this over-voltage condi-

tion occurs, the charger control circuitry will shut down

the device. The charger will resume normal charging

operation after the over-voltage condition is removed.

Functional Block Diagram

Charge

Control

Reverse Blocking

Constant

Current

BAT

UVLO

Over-

Temperature

Protection

STAT

GND

ISET

ADP

EN_BA

VIN

Logic

VREF

Input

EN_BUCK

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

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Current Limit, Over-Temperature Protection

For overload conditions, the peak input current is limited

at the step-down converter. As load impedance decreas-

es and the output voltage falls closer to zero, more

power is dissipated internally, which causes the internal

die temperature to rise. In this case, the thermal protec-

tion circuit completely disables switching, which protects

the device from damage.

The battery charger has a thermal protection circuit which

will shut down charging functions when the internal die

temperature exceeds the preset thermal limit threshold.

Once the internal die temperature falls below the thermal

limit, normal charging operation will resume.

Control Loop

The AAT2556 contains a compact, current mode step-

down DC/DC controller. The current through the P-channel

MOSFET (high side) is sensed for current loop control, as

well as short-circuit and overload protection. A fixed

slope compensation signal is added to the sensed cur-

rent to maintain stability for duty cycles greater than

50%. The peak current mode loop appears as a voltage-

programmed current source in parallel with the output

capacitor. The output of the voltage error amplifier pro-

grams the current mode loop for the necessary peak

switch current to force a constant output voltage for all

load and line conditions. Internal loop compensation ter-

minates the transconductance voltage error amplifier

output. The error amplifier reference is fixed at 0.6V.

Battery Charging Operation

Battery charging commences only after checking several

conditions in order to maintain a safe charging environ-

ment. The input supply (ADP) must be above the mini-

mum operating voltage (UVLO) and the enable pin must

be high (internally pulled down). When the battery is

connected to the BAT pin, the charger checks the condi-

tion of the battery and determines which charging mode

to apply. If the battery voltage is below VMIN, the charger

begins battery pre-conditioning by charging at 10% of

the programmed constant current; e.g., if the pro-

grammed current is 150mA, then the pre-conditioning

current (trickle charge) is 15mA. Pre-conditioning is

purely 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 voltage dif-

ferential is at its highest.

Pre-conditioning continues until the battery voltage

reaches VMIN. At this point, the charger begins constant-

current charging. The current level for this mode is pro-

grammed using a single resistor from the ISET pin to

ground. Programmed current can be set from a mini-

mum 15mA up to a maximum of 500mA. Constant cur-

rent charging will continue until the battery voltage

reaches the voltage regulation point, VBAT

. When the bat-

tery voltage reaches VBAT

, the battery charger begins

constant voltage mode. The regulation voltage is factory

programmed to a nominal 4.2V (±0.5%) and will con-

tinue charging until the charging current has reduced to

10% of the programmed current.

After the charge cycle is complete, the pass device turns

off and the device automatically goes into a power-sav-

ing sleep mode. During this time, the series pass device

will block current in both directions, preventing the bat-

tery from discharging through the IC.

The battery charger will remain in sleep mode, even if

the charger source is disconnected, until one of the fol-

lowing events occurs: 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

charger will monitor all parameters and resume charging

in the most appropriate mode.

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

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

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

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Battery Charging System Operation Flow Chart

Power On Reset

Power Input

Voltage

VADP > VUVLO

Fault Conditions

Monitoring

OV, OT

Preconditioning

Test

VMIN > VBAT

Current Phase Test

VADP

> VBAT

Voltage Phase Test

IBAT > ITERM

Yes

Preconditioning

(Trickle Charge)

Constant

Current Charge

Mode

Constant

Voltage Charge

Mode

Yes

Charge Completed

Charge

Control

Recharge Test

VRCH > VBAT

Yes

Shut Down Yes

Enable

Yes

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

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Application Information

Soft Start / Enable

The EN_BAT pin is internally pulled down. When pulled

to a logic high level, the battery charger is enabled.

When left open or pulled to a logic low level, the battery

charger is shut down and forced into the sleep state.

Charging will be halted regardless of the battery voltage

or charging state. When it is re-enabled, the charge con-

trol circuit will automatically reset and resume charging

functions with the appropriate charging mode based on

the battery charge state and measured cell voltage from

the BAT pin.

The step-down converter features a soft start that limits

the inrush current and eliminates output voltage over-

shoot during startup. The circuit is designed to increase

the inductor current limit in discrete steps when the

input voltage or enable input is applied. Typical start up

time is 100μs.

Pulling EN_BUCK to logic low forces the converter in a

low power, non-switching state, and it consumes less

than 1μA of quiescent current. Connecting it to logic high

enables the converter and resumes normal operation.

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 battery charger will operate

from the adapter input over a 4.0V to 6.5V range. The

constant current fast charge current for the adapter

input is set by the RSET resistor connected between ISET

and ground. Refer to Table 1 for recommended RSET val-

ues for a desired constant current charge level.

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.

Normal

ICHARGE (mA)

Set Resistor

Value R2 (kΩ)

500 3.24

400 4.12

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.

Charge Status Output

The AAT2556 provides battery charge status via a status

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

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

nal LED. The status pin can indicate several conditions,

as shown in Table 2.

Event Description Status

No battery charging activity OFF

Battery charging via adapter or USB port ON

Charging completed OFF

Table 2: LED Status Indicator.

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

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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. 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)

)

LED

Example:

(5.5V

- 2.0

= = 1.75kΩ

2mA

Note: Red LED forward voltage (VF) is typically 2.0V @

2mA.

Thermal Considerations

The AAT2556 is offered in a TDFN33-12 package which

can provide up to 2W of power dissipation when it is

properly bonded 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 gener-

ating devices in a given application design. The ambient

temperature around the IC will also have an effect on the

thermal limits of a battery charging application. The

maximum limits that can be expected for a given ambient

condition can be estimated by the following discussion.

First, the maximum power dissipation for a given situa-

tion should be calculated:

J(MAX) -

)

D(MAX)

= θ

Where:

PD(MAX) = Maximum Power Dissipation (W)

θJA = Package Thermal Resistance (°C/W)

TJ(MAX) = Maximum Device Junction Temperature (°C)

[135°C]

TA = Ambient Temperature (°C)

Figure 3 shows the relationship of maximum power dis-

sipation and ambient temperature of the AAT2556.

TA (°

PD(MAX) (mW)

500

1000

1500

2000

2500

3000

0 20 40 60 80 100 120

Figure 3: Maximum Power Dissipation.

Next, the power dissipation of the battery charger can be

calculated by the following equation:

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

Where:

PD = Total Power Dissipation by the Device

VADP = ADP/USB 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 IC, when battery voltage is charged up

to the preconditioning voltage threshold. Figure 4 shows

the maximum charge current in different ambient tem-

peratures.

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

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VIN (V)

ICC(MAX) (mA)

100

200

300

400

500

4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 6.75

TA = 85°C

TA = 60°C

Figure 4: Maximum Charging Current Before

Thermal Cycling Becomes Active.

There are three types of losses associated with the step-

down converter: switching losses, conduction losses, and

quiescent current losses. Conduction losses are associ-

ated with the RDS(ON) characteristics of the power output

switching devices. Switching losses are dominated by the

gate charge of the power output switching devices. At full

load, assuming continuous conduction mode (CCM), a

simplified form of the losses is given by:

PTOTAL

2 · (RDSON(H) · VO + RDSON(L) · [VIN - VO])

VIN

+ (tsw · FS · IO + IQ) · VIN

IQ is the step-down converter quiescent current. The

term tsw is used to estimate the full load step-down con-

verter switching losses.

For the condition where the step-down converter is in

dropout at 100% duty cycle, the total device dissipation

reduces to:

PTOTAL = IO

2 · RDSON(H) + IQ · VIN

Since RDS(ON), quiescent current, and switching losses all

vary with input voltage, the total losses should be inves-

tigated over the complete input voltage range.

Given the total losses, the maximum junction tempera-

ture can be derived from the θJA for the TDFN33-12 pack-

age which is 50°C/W.

TJ(MAX) = PTOTAL · ΘJA + TAMB

Capacitor Selection

Battery Charger Input Capacitor (C1)

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

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.

Step-Down Converter Input Capacitor (C3)

Select a 4.7μF to 10μF X7R or X5R ceramic capacitor for

the input. To estimate the required input capacitor size,

determine the acceptable input ripple level (VPP) and solve

for CIN. The calculated value varies with input voltage and

is a maximum when VIN is double the output voltage.

⎛⎞

· 1 -

⎝⎠

VIN

CIN =

VIN

⎛⎞

- ESR · FS

⎝⎠

VPP

⎛⎞

· 1 - = for VIN = 2 · V

⎝⎠

VIN

CIN(MIN) = 1

⎛⎞

- ESR · 4 · FS

⎝⎠

VPP

Always examine the ceramic capacitor DC voltage coef-

ficient characteristics when selecting the proper value.

For example, the capacitance of a 10μF, 6.3V, X5R ceram-

ic capacitor with 5.0V DC applied is actually about 6μF.

The maximum input capacitor RMS current is:

⎛⎞

· 1 - = D · (1 - D) = 0.52 =

⎝⎠

VIN

The input capacitor RMS ripple current varies with the

input and output voltage and will always be less than or

equal to half of the total DC load current.

⎛⎞

IRMS = IO · · 1 -

⎝⎠

VIN

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

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for VIN = 2 · VO

RMS(MAX)

The term

⎛⎞

· 1 -

⎝⎠

VIN

VIN appears in both the input voltage

ripple and input capacitor RMS current equations and is

a maximum when VO is twice VIN. This is why the input

voltage ripple and the input capacitor RMS current ripple

are a maximum at 50% duty cycle.

The input capacitor provides a low impedance loop for the

edges of pulsed current drawn by the step-down con-

verter. Low ESR/ESL X7R and X5R ceramic capacitors are

ideal for this function. To minimize stray inductance, the

capacitor should be placed as closely as possible to the IC.

This keeps the high frequency content of the input current

localized, minimizing EMI and input voltage ripple.

The proper placement of the input capacitor (C3) can be

seen in the evaluation board layout in Figure 6.

A laboratory test set-up typically consists of two long

wires running from the bench power supply to the evalu-

ation board input voltage pins. The inductance of these

wires, along with the low-ESR ceramic input capacitor,

can create a high Q network that may affect converter

performance. This problem often becomes apparent in

the form of excessive ringing in the output voltage dur-

ing load transients. Errors in the loop phase and gain

measurements can also result.

Since the inductance of a short PCB trace feeding the

input voltage is significantly lower than the power leads

from the bench power supply, most applications do not

exhibit this problem.

In applications where the input power source lead induc-

tance cannot be reduced to a level that does not affect

the converter performance, a high ESR tantalum or alu-

minum electrolytic capacitor should be placed in parallel

with the low ESR, ESL bypass ceramic capacitor. This

dampens the high Q network and stabilizes the system.

Battery Charger Output Capacitor (C2)

The AAT2556 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

AAT2556 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.

Step-Down Converter Output Capacitor (C4)

The output capacitor limits the output ripple and pro-

vides holdup during large load transitions. A 4.7μF to

10μF X5R or X7R ceramic capacitor typically provides

sufficient bulk capacitance to stabilize the output during

large load transitions and has the ESR and ESL charac-

teristics necessary for low output ripple. For enhanced

transient response and low temperature operation appli-

cations, a 10μF (X5R, X7R) ceramic capacitor is recom-

mended to stabilize extreme pulsed load conditions.

The output voltage droop due to a load transient is dom-

inated by the capacitance of the ceramic output capacitor.

During a step increase in load current, the ceramic output

capacitor alone supplies the load current until the loop

responds. Within two or three switching cycles, the loop

responds and the inductor current increases to match the

load current demand. The relationship of the output volt-

age droop during the three switching cycles to the output

capacitance can be estimated by:

COUT =

3 · ΔILOAD

VDROOP · FS

Once the average inductor current increases to the DC

load level, the output voltage recovers. The above equa-

tion establishes a limit on the minimum value for the

output capacitor with respect to load transients.

The internal voltage loop compensation also limits the

minimum output capacitor value to 4.7μF. This is due to

its effect on the loop crossover frequency (bandwidth),

phase margin, and gain margin. Increased output capac-

itance will reduce the crossover frequency with greater

phase margin.

The maximum output capacitor RMS ripple current is

given by:

VOUT · (VIN(MAX) - VOUT)

RMS(MAX)

IL · FS · VIN(MAX)

=·

AAT2556

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PRODUCT DATASHEET

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Dissipation due to the RMS current in the ceramic output

capacitor ESR is typically minimal, resulting in less than

a few degrees rise in hot-spot temperature.

Inductor Selection

The step-down converter uses peak current mode con-

trol with slope compensation to maintain stability for

duty cycles greater than 50%. The output inductor value

must be selected so the inductor current down slope

meets the internal slope compensation requirements.

The internal slope compensation for the AAT2556 is

0.45A/μsec. This equates to a slope compensation that

is 75% of the inductor current down slope for a 1.8V

output and 3.0μH inductor.

0.75 ⋅ V

m = = = 0.45

0.75 ⋅ 1.8V

3.0µH

µsec

0.75 ⋅ V

L = =

≈

1.67

⋅ V

= 1.67 ⋅ 3.0V = 5.0µH

0.75

⋅

0.45A

µsec

For most designs, the step-down converter operates with

an inductor value of 1μH to 4.7μH. Table 3 displays

inductor values for the AAT2556 with different output

voltage options.

Manufacturer’s specifications list both the inductor DC

current rating, which is a thermal limitation, and the

peak current rating, which is determined by the satura-

tion characteristics. The inductor should not show any

appreciable saturation under normal load conditions.

Some inductors may meet the peak and average current

ratings yet result in excessive losses due to a high DCR.

Always consider the losses associated with the DCR and

its effect on the total converter efficiency when selecting

an inductor.

The 3.0μH CDRH2D09 series inductor selected from

Sumida has a 150mΩ DCR and a 470mA DC current rat-

ing. At full load, the inductor DC loss is 9.375mW which

gives a 2.08% loss in efficiency for a 250mA, 1.8V out-

put.

Output Voltage (V) L1 (μH)

1.0 1.5

1.2 2.2

1.5 2.7

1.8 3.0/3.3

2.5 3.9/4.2

3.0 4.7

3.3 5.6

Table 3: Inductor Values.

Adjustable Output Resistor Selection

Resistors R3 and R4 of Figure 5 program the output to

regulate at a voltage higher than 0.6V. To limit the bias

current required for the external feedback resistor string

while maintaining good noise immunity, the suggested

value for R4 is 59kΩ. Decreased resistor values are nec-

essary to maintain noise immunity on the FB pin, result-

ing in increased quiescent current. Table 4 summarizes

the resistor values for various output voltages.

⎛⎞

⎝⎠

R3 = -1 · R4 = - 1 · 59kΩ = 267kΩ

VOUT

VREF

⎛⎞

⎝⎠

3.3V

0.6V

With enhanced transient response for extreme pulsed

load application, an external feed-forward capacitor (C5

in Figure 5) can be added.

VOUT (V)

R4 = 59kΩR4 = 221kΩ

R3 (kΩ) R3 (kΩ)

0.8 19.6 75

0.9 29.4 113

1.0 39.2 150

1.1 49.9 187

1.2 59.0 221

1.3 68.1 261

1.4 78.7 301

1.5 88.7 332

1.8 118 442

1.85 124 464

2.0 137 523

2.5 187 715

3.3 267 1000

Table 4: Adjustable Resistor Values For

Step-Down Converter.

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

20 2556.2009.08.1.3

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Printed Circuit Board

Layout Considerations

For the best results, it is recommended to physically

place the battery pack as close as possible to the

AAT2556 BAT pin. To minimize voltage drops on the PCB,

keep the high current carrying traces adequately wide.

Refer to the AAT2556 evaluation board for a good layout

example (see Figures 6 and 7). The following guidelines

should be used to help ensure a proper layout.

1. The input capacitors (C1, C3) should connect as

closely as possible to ADP (Pin 9) and VIN (Pin 12).

2. C4 and L1 should be connected as closely as possi-

ble. The connection of L1 to the LX pin should be as

short as possible. Do not make the node small by

using narrow trace. The trace should be kept wide,

direct, and short.

3. The feedback pin (Pin 1) should be separate from

any power trace and connect as closely as possible

to the load point. Sensing along a high-current load

trace will degrade DC load regulation. Feedback

resistors should be placed as closely as possible to

the FB pin (Pin 1) to minimize the length of the high

impedance feedback trace. If possible, they should

also be placed away from the LX (switching node)

and inductor to improve noise immunity.

4. The resistance of the trace from the load return to

PGND (Pin 10) and GND (Pin 2) should be kept to a

minimum. This will help to minimize any error in DC

regulation due to differences in the potential of the

internal signal ground and the power ground.

5. A high density, small footprint layout can be achieved

using an inexpensive, miniature, non-shielded, high

DCR inductor.

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

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RED LED

10μF

2.2μF

ADP

8.06K

JP1

0Ω

BAT

123

Enable_BuckJP3

3μH

100pF

4.7μF

VOUT

118k

59k

1 2 3 Buck Input

JP4

Enable_BatJP2

4.7uF

VIN

ISET

BAT

6GND 8

GND

EN_BUCK

STAT 7

EN_BAT

4ADP 9

GND 10

LX 11

VIN 12

AAT2556U1

VOUT

Figure 5: AAT2556 Evaluation Board Schematic.

Figure 6: AAT2556 Evaluation Board Figure 7: AAT2556 Evaluation Board

Top Side Layout. Bottom Side Layout.

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

22 2556.2009.08.1.3

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Component Part Number Description Manufacturer

U1 AAT2556IWP-T1 Battery Charger and Step-Down Converter for Portable

Applications; TDFN33-12 Package AnalogicTech

C1 ECJ-1VB0J106M Cer 10μF 10V 20% X5R 0603 Panasonic - ECG

C2 GRM185B30J225KE25D Cer 2.2μF 6.3V 10% X7R 0603 Murata

C3, C4 GRM188R60J475KE19B Cer 4.7μF 6.3V 10% X7R 0603 Murata

C5 GRM1886R1H101JZ01J Cer 100pF 50V 5% R2H 0603 Murata

L1 CDRH2D09-3R0 Shielded SMD, 3.0μH, 150mΩ, 3x3x1mm Sumida

R1 Chip Resistor 1KΩ, 5%, 1/4W; 0603 Vishay

R2 Chip Resistor 8.06KΩ, 1%, 1/4W; 0603 Vishay

R3 Chip Resistor 118KΩ, 1%, 1/4W; 0603 Vishay

R4 Chip Resistor 59KΩ, 1%, 1/4W; 0603 Vishay

JP1 Chip Resistor 0Ω, 5%, 1/4W; 0603 Vishay

JP2, JP3, JP4 PRPN401PAEN Connecting Header, 2mm Zip Sullins Electronics

D1 CMD15-21SRC/TR8 Red LED; 1206 Chicago Miniature Lamp

Table 5: AAT2556 Evaluation Board Component Listing.

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

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Step-Down Converter Design Example

Specifications

VO = 1.8V @ 250mA, Pulsed Load ΔILOAD = 200mA

VIN = 2.7V to 4.2V (3.6V nominal)

FS = 1.5MHz

TAMB = 85°C

1.8V Output Inductor

L1 = 1.67 ⋅ V

= 1.67 ⋅ 1.8V = 3µH

µsec

(use 3.0μH; see Table 3)

For Sumida inductor CDRH2D09-3R0, 3.0μH, DCR = 150mΩ.

1.8

1.8V

ΔI

⋅ 1 - = ⋅ 1 - = 228m

L1 ⋅ F

3.0µH ⋅ 1.5MHz

4.2V

PKL1

= I

+ ΔI

= 250mA + 114mA = 364mA

= I

⋅ DCR = 250mA

⋅ 150mΩ = 9.375mW

⎛

⎝⎞

⎠

⎛

⎝⎞

⎠

1.8V Output Capacitor

VDROOP = 0.1V

1 1.8V · (4.2V - 1.8V)

3.0µH · 1.5MHz · 4.2V

RMS

IL1 · FS · VIN(MAX)

= ·

3 · ΔILOAD

VDROOP · FS

3 · 0.2A

0.1V · 1.5MHz

COUT = = = 4µF; use 4.7µF

· = 66mArms

(VO) · (VIN(MAX) - VO)=

Pesr = esr · IRMS2 = 5mΩ · (66mA)2 = 21.8µW

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

24 2556.2009.08.1.3

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Input Capacitor

Input Ripple VPP = 25mV

CIN = = = 1.38µF (use 4.7µF

)

⎛⎞

- ESR · 4 · FS

⎝⎠

VPP

⎛⎞

- 5mΩ · 4 · 1.5MHz

⎝⎠

25mV

0.2A

RMS

P = esr · IRMS

2 = 5mΩ · (0.1A)2 = 0.05mW

= = 0.1Arms

AAT2556 Losses

PTOTAL

+ (tsw · FS · IO + IQ) · VIN

2 · (RDSON(H) · VO + RDSON(L) · [VIN -VO])

VIN

(

5ns · 1.5MHz · 0.2A + 30µA

)

· 4.2V = 26.14mW

0.22 · (0.59Ω · 1.8V + 0.42Ω · [4.2V - 1.8V])

4.2V

MAX

)

= TAMB + Θ

A · PL

OSS

= 85°C +

(

50°C/W

)

· 26.14mW = 86.3°C

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

2556.2009.08.1.3 25

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1. For reduced quiescent current, R4 = 221kW.

2. R4 is opened, R3 is shorted.

Output Voltage

VOUT (V)

R4 = 59kΩ

R3 (kΩ)

R4 = 221kΩ1

R3 (kΩ)

L1 (μH)

0.62— — 1.5

0.8 19.6 75 1.5

0.9 29.4 113 1.5

1.0 39.2 150 1.5

1.1 49.9 187 1.5

1.2 59.0 221 1.5

1.3 68.1 261 1.5

1.4 78.7 301 2.2

1.5 88.7 332 2.7

1.8 118 442 3.0/3.3

1.85 124 464 3.0/3.3

2.0 137 523 3.0/3.3

2.5 187 715 3.9/4.2

3.3 267 1000 5.6

Table 6: Step-Down Converter Component Values.

Manufacturer Part Number

Inductance

(μH)

Max DC

Current (mA)

DCR

(mΩ)

Size (mm)

LxWxH Type

Sumida CDRH2D09-1R5 1.5 730 88 3.0x3.0x1.0 Shielded

Sumida CDRH2D09-2R2 2.2 600 115 3.0x3.0x1.0 Shielded

Sumida CDRH2D09-2R5 2.5 530 135 3.0x3.0x1.0 Shielded

Sumida CDRH2D09-3R0 3 470 150 3.0x3.0x1.0 Shielded

Sumida CDRH2D09-3R9 3.9 450 180 3.0x3.0x1.0 Shielded

Sumida CDRH2D09-4R7 4.7 410 230 3.0x3.0x1.0 Shielded

Sumida CDRH2D09-5R6 5.6 370 260 3.0x3.0x1.0 Shielded

Sumida CDRH2D11-1R5 1.5 900 54 3.2x3.2x1.2 Shielded

Sumida CDRH2D11-2R2 2.2 780 78 3.2x3.2x1.2 Shielded

Sumida CDRH2D11-3R3 3.3 600 98 3.2x3.2x1.2 Shielded

Sumida CDRH2D11-4R7 4.7 500 135 3.2x3.2x1.2 Shielded

Taiyo Yuden NR3010 1.5 1200 80 3.0x3.0x1.0 Shielded

Taiyo Yuden NR3010 2.2 1100 95 3.0x3.0x1.0 Shielded

Taiyo Yuden NR3010 3.3 870 140 3.0x3.0x1.0 Shielded

Taiyo Yuden NR3010 4.7 750 190 3.0x3.0x1.0 Shielded

FDK MIPWT3226D-1R5 1.5 1200 90 3.2x2.6x0.8 Chip shielded

FDK MIPWT3226D-2R2 2.2 1100 100 3.2x2.6x0.8 Chip shielded

FDK MIPWT3226D-3R0 3 1000 120 3.2x2.6x0.8 Chip shielded

FDK MIPWT3226D-4R2 4.2 900 140 3.2x2.6x0.8 Chip shielded

Table 7: Suggested Inductors and Suppliers.

Manufacturer Part Number Value (μF) Voltage Rating Temp. Co. Case Size

Murata GRM118R60J475KE19B 4.7 6.3 X5R 0603

Murata GRM188R60J106ME47D 10 6.3 X5R 0603

Table 8: Surface Mount Capacitors.

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

26 2556.2009.08.1.3

www.analogictech.com

1. XYY = assembly and date code.

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

3. Available exclusively outside of the United States and its territories.

Ordering Information

Package Marking1Part Number (Tape and Reel)2, 3

TDFN33-12 SPXYY AAT2556IWP-CA-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/aboutus/quality.php.

Legend

Voltage Code

Adjustable

(0.6V) A

0.9 B

1.2 E

1.5 G

1.8 I

1.9 Y

2.5 N

2.6 O

2.7 P

2.8 Q

2.85 R

2.9 S

3.0 T

3.3 W

4.2 C

AAT2556

Battery Charger and Step-Down Converter for Portable ApplicationsSystemPowerTM

PRODUCT DATASHEET

2556.2009.08.1.3 27

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.

1. 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.

Package Information

TDFN33-121

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

Pin 1 Indicator

(optional)

0.43

0.05

0.45

0.050.23

0.05

0.1 REF

C0.3

All dimensions in millimeters