AAT3158ITP-T1 - Advanced Analog Technology, Inc.

General Description

The AAT3158 is a low noise, constant frequency

charge pump DC/DC converter that uses a tri-

mode load switch (1X), fractional (1.5X), and dou-

bling (2X) conversion to maximize efficiency for

white LED applications. The AAT3158 is capable of

driving up to four LED channels at 20mA per chan-

nel from a 2.7V to 5.5V input. The current sinks

may be operated individually or in parallel for driv-

ing higher current LEDs. A low external parts count

(two 1µF flying capacitors and two small 1µF

capacitors at VIN and VOUT) make this part ideally

suited for small, battery-powered applications.

AnalogicTech's S2Cwire™ (Simple Serial

Control™) serial digital input is used to enable, dis-

able, and set current for each LED with 16 settings

down to 50µA. The low current mode supply cur-

rent can be as low as 50µA to save power.

Each output of the AAT3158 is equipped with built-

in protection for VOUT short circuit and auto disable

for load short-circuit conditions. Built-in soft-start

circuitry prevents excessive inrush current during

start-up. A low current shutdown feature discon-

nects the load from VIN and reduces quiescent cur-

rent to less than 1µA.

The AAT3158 is available in a Pb-free, space-saving

2.85x3.0mm TSOPJW-12 package.

Features

•V

IN Range: 2.7V to 5.5V

• Fully Programmable Current with Single Wire

— 16 Current Levels

— Four Low Current Settings Down to 50µA

• Low IQ(50µA) for Low Current Mode

• Tri-Mode 1X, 1.5X, and 2X Charge Pump for

Maximum Efficiency and VFCoverage

• Drives Up to Four LED Channels

• No Inductors, Low Noise Operation

• 1MHz Constant Switching Frequency

• Small Application Circuit

• Built-In Thermal Protection

• Automatic Soft-Start

•I

Q<1µA in Shutdown

• 2.85x3mm TSOPJW-12 Package

Applications

• Color (RGB) Lighting

• Programmable Current Sinks

• White LED Backlighting

• White Photo Flash for Digital Still Cameras

AAT3158

High Efficiency 1X/1.5X/2X Charge Pump

for White LED Applications

Typical Application

2.7V to 5.5V

EN/SET

VIN

EN/SET

C2+

C2-

C1+

C1-

VOUT

GND

AAT3158

CIN

1µF

COUT

1µF

D1 D2 D3 D4

3158.2006.02.1.0 1

ChargePump™

Pin Descriptions

Pin Configuration TSOPJW-12

(Top View)

EN/SET

C1+

C1-

VOUT

C2+

GND

VIN

C2-

Pin # Symbol Function

1 D4 Current sink input #4.

2 EN/SET S2Cwire serial interface control pin.

3 C1+ Flying capacitor 1 positive terminal. Connect a 1µF capacitor between C1+ and C1-.

4 C1- Flying capacitor 1 negative terminal.

5 VOUT Charge pump output to drive load circuit. Requires 1µF capacitor connected between

this pin and ground.

6 C2+ Flying capacitor 2 positive terminal. Connect a 1µF capacitor between C2+ and C2-.

7 C2- Flying capacitor 2 negative terminal.

8 VIN Input power supply. Requires 1µF capacitor connected between this pin and ground.

9 GND Ground.

10 D3 Current sink input #3.

11 D2 Current sink input #2.

12 D1 Current sink input #1.

AAT3158

High Efficiency 1X/1.5X/2X Charge Pump

for White LED Applications

23158.2006.02.1.0

Absolute Maximum Ratings1

Thermal Information3

Symbol Description Value Units

PDMaximum Power Dissipation40.625 W

θJA Maximum Thermal Resistance 160 °C/W

Symbol Description Value Units

VIN Input Voltage -0.3 to 6 V

VEN/SET EN/SET to GND Voltage -0.3 to VIN + 0.3 V

IOUT2Maximum DC Output Current 150 mA

TJOperating Junction Temperature Range -40 to 150 °C

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

AAT3158

High Efficiency 1X/1.5X/2X Charge Pump

for White LED Applications

3158.2006.02.1.0 3

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. Based on long-term current density limitation.

3. Mounted on an FR4 board.

4. Derate 6.25mW/°C above 25°C.

Electrical Characteristics1

CIN = COUT = C1= C2= 1.0µF; TA= -40°C to +85°C, unless otherwise noted. Typical values are TA= 25°C,

VIN = 3.6V.

Symbol Description Conditions Min Typ Max Units

Input Power Supply

VIN Operation Range 2.7 5.5 V

1X Mode, 3.0 ≤VIN ≤5.5, Active, 0.3 1

No Load Current

1.5X Mode, 3.0 ≤VIN ≤5.5, Active, 1 3 mA

ICC Operating Current No Load Current

2X Mode, 3.0 ≤VIN ≤5.5, Active, 1

No Load Current

50µA Setting, 1X Mode 50 µA

ISHDN Shutdown Current EN/SET = 0 1 µA

IDX ISINK Average Current Accuracy 18 20 22 mA

I(D-Match) Current Matching2VF:D1:D4 = 3.6V 0.5 1 %

VTH

1X to 1.5X or 1.5X to 2X Transition 150 mV

Threshold at Any ISINK Pin

Charge Pump Section

TSS Soft-Start Time 100 µs

FCLK Clock Frequency 1000 kHz

EN/SET

VEN(L) Enable Threshold Low VIN = 2.7V 0.4 V

VEN(H) Enable Threshold High VIN = 5.5V 1.4 V

TEN/SET LO EN/SET Low Time 0.3 75 µs

TEN/SET HI MIN Minimum EN/SET High Time 50 ns

TEN/SET HI MAX Maximum EN/SET High Time 75 µs

TOFF EN/SET Off Timeout 500 µs

TLAT EN/SET Latch Timeout 500 µs

IEN/SET EN/SET Input Leakage -1 1 µA

AAT3158

High Efficiency 1X/1.5X/2X Charge Pump

for White LED Applications

43158.2006.02.1.0

1. The AAT3158 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured

by design, characterization, and correlation with statistical process controls.

2. Current matching is defined as the deviation of any sink current from the average of all active channels.

Typical Characteristics

Diode Current vs. Temperature

(20mA/channel)

Temperature (°

Diode Current (mA)

18.0

18.5

19.0

19.5

20.0

20.5

21.0

21.5

22.0

-40 -25 -10 5 20 35 50 65 80 9

ID1

ID4

ID2

ID3

Turn-Off from 1.5X Mode

(VIN = 3.5V; 20mA/ch Load)

Time (100µs/div)

EN/SET

(2V/div)

(1V/div)

IIN

(100mA/div)

Turn-On to 2X Mode

(VIN = 2.8V; 20mA/ch Load)

Time (100µs/div)

EN/SET

(2V/div)

VOUT

(2V/div)

IIN

(500mA/div)

VSINK

(500mV/div)

Turn-On to 1.5X Mode

(VIN = 3.5V; 20mA/ch Load)

Time (100µs/div)

EN/SET

(2V/div)

VOUT

(2V/div)

IIN

(200mA/div)

VSINK

(1V/div)

Turn-On to 1X Mode

(VIN = 4.2V; 20mA/ch Load)

Time (100µs/div)

EN/SET

(2V/div)

VOUT

(2V/div)

IIN

(100mA/div)

VSINK

(1V/div)

Efficiency vs. Supply Voltage

Supply Voltage (V)

Efficiency (%)

100

2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5

6mA/ch

VF = 3V

500µA/ch

VF = 2.7V

20mA/ch

VF = 3.4V

AAT3158

High Efficiency 1X/1.5X/2X Charge Pump

for White LED Applications

3158.2006.02.1.0 5

Typical Characteristics

Input Ripple vs. Input Voltage

Input Voltage (V)

Input Ripple (mV)

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

2.5 3.0 3.5 4.0 4.5 5.0 5.5

20mA/ch

14mA/ch

10mA/ch

Load Characteristics

(VIN = 2.9V; 2X Mode; 14mA/ch Load)

Time (500ns/div)

VIN

(20mV/div)

VSINK

(40mV/div)

VCP

(40mV/div)

Load Characteristics

(VIN = 2.9V; 2X Mode; 20mA/ch Load)

Time (500ns/div)

VIN

(20mV/div)

VSINK

(40mV/div)

VCP

(40mV/div)

Load Characteristics

(VIN = 3.5V; 1.5X Mode; 14mA/ch Load)

Time (500ns/div)

VIN

(20mV/div)

VSINK

(20mV/div)

VCP

(40mV/div)

Load Characteristics

(VIN = 3.7V; 1.5X Mode; 20mA/ch Load)

Time (500ns/div)

VIN

(20mV/div)

VSINK

(20mV/div)

VCP

(40mV/div)

AAT3158

High Efficiency 1X/1.5X/2X Charge Pump

for White LED Applications

63158.2006.02.1.0

Typical Characteristics

Enable Threshold Low vs. Input Voltage

Input Voltage (V)

Enable Threshold Low (V)

0.4

0.6

0.8

1.0

1.2

1.4

2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5

-40°C

25°C85°C

Enable Threshold High vs. Input Voltage

Input Voltage (V)

Enable Threshold High (V)

0.4

0.6

0.8

1.0

1.2

1.4

2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5

-40°C

25°C85°C

EN/SET Off Timeout vs. Input Voltage

Input Voltage (V)

EN/SET Off Timeout (µs)

100

150

200

250

300

350

2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5

-40°C

25°C85°C

EN/SET Latch Timeout vs. Input Voltage

Input Voltage (V)

EN/SET Latch Timeout (µs)

100

150

200

250

300

350

2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5

-40°C

25°C85°C

AAT3158

High Efficiency 1X/1.5X/2X Charge Pump

for White LED Applications

3158.2006.02.1.0 7

AAT3158

High Efficiency 1X/1.5X/2X Charge Pump

for White LED Applications

83158.2006.02.1.0

Functional Block Diagram

1X, 1.5X, 2X

Charge Pump

D/A

6 x 16 bit

ROM

S2Cwire

Interface

Soft-Start

Control

1MHz

Oscillator

Voltage

Reference

VIN

EN/SET

D/A D4

GND

VOUT

C1+ C1- C2+ C2-

Functional Description

The AAT3158 is a tri-mode load switch (1X) and

high efficiency (1.5X or 2X) charge pump device

intended for white LED backlight applications. To

maximize power conversion efficiency, an internal

sensing circuit monitors the voltage required on

each constant current sink input and sets the load

switch and charge pump modes based on the input

battery voltage and the current sink input voltage.

As the battery discharges over time, the AAT3158

charge pump is enabled when any of the four cur-

rent sink inputs nears dropout. The charge pump

initially starts in 1.5X mode. If the charge pump

output droops enough for any current source out-

put to become close to dropout, the charge pump

will automatically transition to 2X mode. The

AAT3158 requires only four external components:

two 1µF ceramic capacitors for the charge pump

flying capacitors (C1and C2), one 1µF ceramic

input capacitor (CIN), and one 0.33µF to 1µF

ceramic charge pump output capacitor (COUT).

The four constant current sink inputs (D1 to D4)

can drive four individual LEDs with a maximum cur-

rent of 20mA each. The unused sink inputs must be

connected to VOUT; otherwise, the part will operate

only in 2X charge pump mode. The S2Cwire serial

interface enables the AAT3158 and sets the cur-

rent sink magnitudes.

Const ant Current Output Level Settings

The constant current sink levels for D1 to D4 are

set via the serial interface according to a logarith-

mic scale for the first 12 codes, and a separate low

current scale for the last 4 codes. For the first 12

codes, each code is approximately 1.5dB lower

than the previous code. In this manner, LED

brightness appears linear with each increasing

code count. Because the inputs D1 to D4 are true

independent constant current sinks, the voltage

observed on any single given input will be deter-

mined by the actual forward voltage (VF) for the

LED being driven.

Since the input current sinks of the AAT3158 are

programmable, no PWM (pulse width modulation) or

additional control circuitry is needed to control LED

brightness. This feature greatly reduces the burden

on a microcontroller or system IC to manage LED or

display brightness, allowing the user to "set it and

forget it." With its high-speed serial interface (1MHz

data rate), the input sink current of the AAT3158 can

be changed successively to brighten or dim LEDs in

smooth transitions (e.g., to fade-out) or in abrupt

steps, giving the user complete programmability and

real-time control of LED brightness.

S2Cwire Serial Interface

The current level magnitude is controlled by

AnalogicTech's Simple Serial Control (S2Cwire)

serial interface. The interface records rising edges

of the EN/SET pin and decodes them into 16 differ-

ent states. The 16 current level settings available

are indicated in Table 1.

The S2Cwire serial interface has flexible timing.

Data can be clocked-in at speeds greater than

1MHz, or much slower, such as 15kHz. After data

is submitted, EN/SET is held high to latch the data.

Once EN/SET has been held in the logic high state

for time TLAT, the programmed current becomes

active and the internal data register is reset to zero.

For subsequent current level programming, the

number of rising edges corresponding to the

desired code must be entered on the EN/SET pin.

When EN/SET is held low for an amount of time

greater than TOFF, the AAT3158 enters into shutdown

mode and draws less than 1µA from VIN. The internal

data register is reset to zero during shutdown.

Auto-Disable Feature

The AAT3158 is equipped with an auto-disable fea-

ture for each LED channel. After the IC is enabled

and started up, a test current of 100µA (typical) is

forced through each sink channel. The channel will

be disabled if the voltage of that particular SINK pin

does not drop to certain threshold. This feature is

very convenient for disabling an unused channel or

during an LED fail short event.

Thermal Protection

The AAT3158 has built-in thermal protection circuit

that will shut down the charge pump if the die tem-

perature rises above the thermal limit, as is the

case during a short circuit of the VOUT pin.

Output Output

Data (mA/Ch) Data (mA/Ch)

120 9 6

218 10 4

316 11 3

414 12 2

5 12.5 13 1

6 11 14 0.5

7 9.5 15 0.1

8 8 16 0.05

AAT3158

High Efficiency 1X/1.5X/2X Charge Pump

for White LED Applications

3158.2006.02.1.0 9

S2Cwire Serial Interface Timing

EN/SET

2 n n <= 16

Data Reg 1n

THI

TLO TLAT TOFF

AAT3158

High Efficiency 1X/1.5X/2X Charge Pump

for White LED Applications

10 3158.2006.02.1.0

Applications Information

LED Selection

Although AAT3158 is specifically intended for driv-

ing white LEDs, the device can also be used to

drive most types of LEDs with forward voltage

specifications ranging from 2.0V to 4.7V. LED

applications may include main and sub-LCD dis-

play backlighting, camera photo-flash applications,

color (RGB) LEDs, infrared (IR) diodes for remotes,

and other loads benefiting from a controlled output

current generated from a varying input voltage.

Since the D1 to D4 input current sinks are matched

with negligible voltage dependence, the LED

brightness will be matched regardless of the spe-

cific LED forward voltage (VF) levels. In some

instances (e.g., in high-luminous-output applica-

tions such as photo flash), it may be necessary to

drive high-VFtype LEDs. The low dropout current

sinks in the AAT3158 make it capable of driving

LEDs with forward voltages as high as 4.7V at full

current from an input supply as low as 3.0V.

Outputs can be paralleled to drive high-current

LEDs without complication.

Device Switching Noise Performance

The AAT3158 operates at a fixed frequency of

approximately 1MHz to control noise and limit har-

monics that can interfere with the RF operation of

cellular telephone handsets or other communica-

tion devices. Back-injected noise appearing on the

input pin of the charge pump is 20mV peak-to-

peak, typically ten times less than inductor-based

DC/DC boost converter white LED backlight solu-

tions. The AAT3158 soft-start feature prevents

noise transient effects associated with inrush cur-

rents during start-up of the charge pump circuit.

Capacitor Selection

Careful selection of the four external capacitors

(CIN, C1, C2, COUT) is important because they will

affect turn-on time, output ripple, and transient per-

formance. Optimum performance will be obtained

when low equivalent series resistance (ESR)

ceramic capacitors are used; in general, low ESR

may be defined as less than 100mΩ. A value of

1µF for all four capacitors is a good starting point

when choosing capacitors. If the LED current

sources are only programmed for light current lev-

els, then the capacitor size may be decreased.

Capacitor Characteristics

Ceramic composition capacitors are highly recom-

mended over all other types of capacitors for use

with the AAT3158. Ceramic capacitors offer many

advantages over their tantalum and aluminum elec-

trolytic counterparts. A ceramic capacitor typically

has very low ESR, is lowest cost, has a smaller

PCB footprint, and is non-polarized. Low ESR

ceramic capacitors help maximize charge pump

transient response. Since ceramic capacitors are

non-polarized, they are not prone to incorrect con-

nection damage.

Equivalent Series Resistance

ESR is an important characteristic to consider

when selecting a capacitor. ESR is a resistance

internal to a capacitor that is caused by the leads,

internal connections, size or area, material compo-

sition, and ambient temperature. Capacitor ESR is

typically measured in milliohms for ceramic capac-

itors and can range to more than several ohms for

tantalum or aluminum electrolytic capacitors.

Ceramic Capacitor Materials

Ceramic capacitors less than 0.1µF are typically

made from NPO or C0G materials. NPO and C0G

materials typically have tight tolerance and are sta-

ble over temperature. Larger capacitor values are

typically composed of X7R, X5R, Z5U, or Y5V

dielectric materials. Large ceramic capacitors, typ-

ically greater than 2.2µF, are often available in low-

cost Y5V and Z5U dielectrics, but capacitors

greater than 1µF are typically not required for

AAT3158 applications. Capacitor area is another

contributor to ESR. Capacitors that are physically

large will have a lower ESR when compared to an

equivalent material smaller capacitor. These larg-

er devices can improve circuit transient response

when compared to an equal value capacitor in a

smaller package size.

AAT3158

High Efficiency 1X/1.5X/2X Charge Pump

for White LED Applications

3158.2006.02.1.0 11

Ordering Information

Package Information TSOPJW-12

All dimensions in millimeters.

0.20 + 0.10

- 0.05

0.055 ± 0.045 0.45 ± 0.15

7° NOM

4° ± 4°

3.00 ± 0.10

2.40 ± 0.10

2.85 ± 0.20

0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC

0.15 ± 0.05

0.9625

0.0375

1.00 + 0.10

- 0.065

0.04 REF

0.010

2.75 ± 0.25

All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means

semiconductor products that are in compliance with current RoHS standards, including

the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more

information, please visit our website at http://www.analogictech.com/pbfree.

Package Marking1Part Number (Tape and Reel)2

TSOPJW-12 RHXYY AAT3158ITP-T1

Advanced Analogic Technologies, Inc.

830 E. Arques Avenue, Sunnyvale, CA 94085

Phone (408) 737-4600

Fax (408) 737-4611

1. XYY = assembly and date code.

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

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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.