National Semiconductor LM3509 Technical data

LM3509
High Efficiency Boost for White LED's and/or OLED
Displays with Dual Current Sinks and I2C Compatible
Brightness Control

May 2007

LM3509 High Efficiency Boost for White LED's and/or OLED Displays with Dual Current Sinks

and I

2

C Compatible Brightness Control

General Description

The LM3509 current mode boost converter offers two sepa­rate outputs. The first output (MAIN) is a constant current sink
for driving series white LED’s. The second output (SUB/FB)
is configurable as a constant current sink for series white LED
bias, or as a feedback pin to set a constant output voltage for
powering OLED panels.

When configured as a dual output white LED bias supply, the
LM3509 adaptively regulates the supply voltage of the LED
strings to maximize efficiency and insure the current sinks re­main in regulation. The maximum current per output is set via
a single external low power resistor. An I2C compatible inter­face allows for independent adjustment of the LED current in
either output from 0 to max current in 32 exponential steps.
When configured as a white LED + OLED bias supply the
LM3509 can independently and simultaneously drive a string
of up to 5 white LED’s and deliver a constant output voltage
of up to 21V for OLED panels.

Output over-voltage protection shuts down the device if
V

rises above 21V allowing for the use of small sized low

OUT

voltage output capacitors. The LM3509 is offered in a small
10-pin thermally- enhanced LLP package and operates over
the -40°C to +85°C temperature range.

Typical Application Circuits

Features

Integrated OLED Display Power Supply and LED Driver

■

Drives up to 10 LED’s at 30mA

■

Drives up to 5 LED’s at 20mA and delivers up to 21V at

■

40mA
Over 90% Efficient

■

32 Exponential Dimming Steps

■

0.15% Accurate Current Matching Between Strings

■

Internal Soft-Start Limits Inrush Current

■

True Shutdown Isolation for LED’s

■

Wide 2.7V to 5.5V Input Voltage Range

■

21V Over-Voltage Protection

■

1.27MHz Fixed Frequency Operation

■

Low Profile 10-pin LLP Package (3mm x 3mm x 0.8mm)

■

General Purpose I/O

■

Active Low Hardware Reset

■

Applications

Dual Display LCD Backlighting for Portable Applications

■

Large Format LCD Backlighting

■

OLED Panel Power Supply

■

30004361

© 2007 National Semiconductor Corporation 300043 www.national.com

LM3509

30004301

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Connection Diagram

LM3509

Top View

10-Pin LLP (3mm × 3mm × 0.8mm)

30004302

Ordering Information

Order Number Package Type NSC Package Drawing Top Mark Supplied As

LM3509SD 10-Pin LLP SDA010A L3509 1000 units, Tape-and-Reel, No-Lead

LM3509SDX 10-Pin LLP SDA010A L3509 4500 units, Tape-and-Reel, No Lead

Pin Descriptions/Functions

Pin Name Function

1 MAIN Main Current Sink Input.

2 SUB/FB Secondary Current Sink Input or 1.25V Feedback Connection for Constant Voltage Output.

3 SET LED Current Setting Connection. Connect a resistor from SET to GND to set the maximum LED

current into MAIN or SUB/FB (when in LED mode), where I

4 VIO Logic Voltage Level Input

5 RESET/GPIO Active Low Hardware Reset and Programmable General Purpose I/O.

6 SW Drain Connection for Internal NMOS Switch

7 OVP Over-Voltage Protection Sense Connection. Connect OVP to the positive terminal of the output

capacitor.

8 IN Input Voltage Connection. Connect IN to the input supply, and bypass to GND with a 1µF ceramic

capacitor.

9 SDA Serial Data Input/Output

10 SCL Serial Clock Input

DAP GND Ground

LED_MAX

= 192×1.244V/R

SET

.

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Absolute Maximum Ratings (Notes 1, 2)

If Military/Aerospace specified devices are required,

LM3509

please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

V

IN

VSW, V

V

SUB/FB

V

SCL

V

SET

Continuous Power Dissipation Internally Limited
Junction Temperature (T

Storage Temperature Range -65ºC to +150º C

, V

OVP

, V

SDA

,

MAIN

, V

RESET\GPIO

, VIO ,

J-MAX

−0.3V to 25V

−0.3V to 23V

)

−0.3V to 6V

−0.3V to 6V

+150ºC

Operating Ratings (Notes 1, 2)

V

IN

VSW, V

V

SUB/FB

OVP

, V

,

MAIN

Junction Temperature Range
(TJ)(Note 4)

Ambient Temperature Range
(TA)(Note 5)

Thermal Properties

Junction to Ambient Thermal
Resistance (θJA)(Note 6)

-40ºC to +110ºC

-40ºC to +85ºC

Maximum Lead Temperature
(Soldering, 10s)(Note 3) +300°C

ESD Rating(Note 10)
Human Body Model 2.5kV

ESD Caution Notice

National Semiconductor recommends that all integrated cir­cuits be handled with appropriate ESD precautions. Failure to
observe proper ESD handling techniques can result in dam­age to the device.

Electrical Characteristics

Specifications in standard type face are for TA = 25°C and those in boldface type apply over the Operating Temperature Range
of TA = −40°C to +85°C. Unless otherwise specified VIN = 3.6V, VIO = 1.8V, V

RESET/GPIO

12.0kΩ, OLED = ‘0’, ENM = ENS = ‘1’, BSUB = BMAIN = Full Scale.(Notes 2, 7)

Symbol Parameter Conditions Min Typ Max Units

I

LED

I

LED-MATCH

Output Current Regulation
MAIN or SUB/FB Enabled

Maximum Current Per
Current Sink

I

MAIN

to I

SUB/FB

Current

UNI = ‘0’, or ‘1’

R

= 8.0kΩ

SET

UNI = ‘1’ (Note 11)

Matching

V

SET

I

LED/ISET

SET Pin Voltage 3.0V < VIN < 5V

I

Current to I

LED

SET

Current

Ratio

V

REG_CS

Regulated Current Sink
Headroom Voltage

V

REG_OLED

V

Regulation Voltage

SUB/FB

3.0V < VIN < 5.5V, OLED = ‘1’

in OLED Mode

V

HR

Current Sink Minimum

I

= 95% of nominal

LED

Headroom Voltage

R

DSON

NMOS Switch On

ISW = 100mA

Resistance

I

CL

V

OVP

f

SW

D

MAX

D

MIN

I

Q

NMOS Switch Current Limit VIN = 3.0V

Output Over-Voltage
Protection

ON Threshold 21.2 22 22.9

OFF Threshold 19.7 20.6 21.2

Switching Frequency

Maximum Duty Cycle

Minimum Duty Cycle

Quiescent Current, Device
Not Switching

V

MAIN

V

REG_CS

and V

, BSUB = BMAIN =

SUB/FB

>

0x00

V

SUB/FB

> V

REG_OLED

,

OLED=’1’, ENM=ENS=’0’

I

SHDN

Shutdown Current ENM = ENS = OLED = '0'

= VIN, V

18.6

= V

SUB/FB

= 0.5V, R

MAIN

20 21.8

30

0.15 1 %

1.244 V

192

500 mV

1.172 1.21 1.239 V

300 mV

0.58

650 770 875 A

1.0 1.27 1.4 MHz

90 %

10 %

400 440

250 305

3.6 5 µA

2.7V to 5.5V

0V to 23V

0V to 21V

54°C/W

=

SET

mA

Ω

V

µA

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Symbol Parameter Conditions Min Typ Max Units

RESET/GPIO Pin Voltage Specifications

V

IL

V

IH

V

OL

Input Logic Low 2.7V < VIN <5.5V, MODE bit

= 0

Input Logic High 2.7V < VIN < 5.5V, MODE bit

= 0

Output Logic Low I

=3mA, MODE bit = 1

LOAD

0.5 V

1.1 V

400 mV

I2C Compatible Voltage Specifications (SCL, SDA, VIO)

V

IO

V

IL

V

IH

V

OL

Serial Bus Voltage Level 2.7V < VIN < 5.5V (Note 9)

Input Logic Low 2.7V < VIN < 5.5V

Input Logic High 2.7V < VIN < 5.5V

Output Logic Low I

LOAD

= 3mA

1.4

0.7×V

IO

V

IN

0.36×V

V

IO

IO

400 mV

I2C Compatible Timing Specifications (SCL, SDA, VIO, see Figure 1) (Notes 8, 9)

t

1

t

2

t

3

t

4

t

5

SCL Clock Period

Data In Setup Time to SCL
High

Data Out Stable After SCL
Low

SDA Low Setup Time to
SCL Low (Start)

SDA High Hold Time After
SCL High (Stop)

2.5 µs

100 ns

0 ns

100 ns

100 ns

LM3509

V

V

V

Note 1: Absolute maximum ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions for which the device is intended
to be functional, but device parameter specifications may not be guaranteed. For guaranteed specifications and test conditions, see the Electrical Characteristics.

Note 2: All voltages are with respect to the potential at the GND pin.

Note 3: For detailed soldering specifications and information, please refer to National Semiconductor Application Note 1187: Leadless Lead frame Package

(AN-1187).

Note 4: Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at TJ=150ºC (typ.) and disengages at
TJ=140ºC (typ.).

Note 5: In applications where high power dissipation and/or poor package thermal resistance is present, the maximum ambient temperature may have to be
derated. Maximum ambient temperature (T
dissipation of the device in the application (P
following equation: T

Note 6: Junction-to-ambient thermal resistance (θJA) is taken from a thermal modeling result, performed under the conditions and guidelines set forth in the
JEDEC standard JESD51-7. The test board is a 4-layer FR-4 board measuring 114mm x 76mm x 1.6mm with a 2x1 array of thermal vias. The ground plane on
the board is 113mm x 75mm. Thickness of copper layers are 71.5µm/35µm/35µm/71.5µm (2oz/1oz/1oz/2oz). Ambient temperature in simulation is 22°C, still air.
Power dissipation is 1W. The value of θJA of this product in the LLP package could fall in a range as wide as 50ºC/W to 150ºC/W (if not wider), depending on
board material, layout, and environmental conditions. In applications where high maximum power dissipation exists special care must be paid to thermal dissipation
issues. For more information on these topics, please refer to Application Note 1187: Leadless Leadframe Package (LLP) and the Power Efficiency and Power
Dissipation section of this datasheet.

Note 7: Min and Max limits are guaranteed by design, test, or statistical analysis. Typical (Typ) numbers are not guaranteed, but represent the most likely norm.

Note 8: SCL and SDA must be glitch-free in order for proper brightness control to be realized.

Note 9: SCL and SDA signals are referenced to VIO and GND for minimum VIO voltage testing.

Note 10: The human body model is a 100pF capacitor discharged through 1.5kΩ resistor into each pin. (MIL-STD-883 3015.7).

Note 11: The matching specification between MAIN and SUB is calculated as 100 × ((I

100 × (I

MAIN

- I

SUB

)/(I

A-MAX

MAIN

+ I

= T

J-MAX-OP

SUB

– (θJA × P

).

) is dependent on the maximum operating junction temperature (TJ-MAX-OP = +105ºC), the maximum power

A-MAX

), and the junction-to ambient thermal resistance of the part/package in the application (θJA), as given by the

D-MAX

).

D-MAX

or I

) - I

) / I

MAIN

SUB

. This simplifies out to be

AVE

AVE

FIGURE 1. I2C Timing

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30004303

Typical Performance Characteristics V

Mode), C

LM3509

I

SUB

+ I

= 2.2µF (OLED Mode), CIN = 1µF, L = TDK VLF4012AT-100MR79, (RL = 0.3Ω), R

OUT

, TA = +25°C unless otherwise specified.

MAIN

= 3.6V, LEDs are OSRAM (LW M67C), C

IN

= 8.06kΩ, UNI = '1', I

SET

= 1µF (LED

OUT

LED

=

10 LED Efficiency vs I

(2 Strings of 5LEDs)

6 LED Efficiency vs I

(2 Strings of 3LEDs)

LED

LED

30004308

8 LED Efficiency vs I

(2 Strings of 4LEDs)

4 LED Efficiency vs I

(2 Strings of 2LEDs)

LED

30004309

LED

30004310

LED Efficiency vs V

(L = TDK VLF3012AT-100MR49, RL = 0.36Ω, I

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IN

LED

30004357

= 40mA)

LED Efficiency vs V

IN

(L = TDK VLF5014AT-100MR92, RL = 0.2Ω, I

30004311

LED

30004358

= 60mA)

LM3509

18V OLED Efficiency vs I

LED Line Regulation

(UNI = '0')

OUT

30004304

12V OLED Efficiency vs I

OLED Line Regulation

I

= 60mA

OLED

OUT

30004305

OLED Line Regulation

I

= 60mA

OLED

30004359

30004306

OLED Load Regulation

V

= 18V

OLED

30004307

30004313

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LM3509

OLED Load Regulation

V

= 12V

OLED

Peak Current Limit vs. V

IN

Over Voltage Limit vs. V

Switching Frequency vs. V

IN

30004312

30004315

IN

Switch On-Resistance vs. V

Maximum Duty Cycle vs. V

30004314

IN

30004317

IN

30004318

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30004319