Bringing light to life

March 2012

Najmi KamalPower Design Engineer for Lighting

TI Lighting System Solution

• NSC + TI = strong system level know-how

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Lighting Portfolio LED driver Architecture Dimming techniques

LED driverMR16 LED bulb designController, Ref design

High brightness LEDs driverOff line LED Bulb/T8 Ref design

Multi Channel LED driverSystem solutions ( Triac, DALI, 0 to 10V)

WEBENCH Architect

Lighting Summary

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Texas Instrument’s Current LED Driver Solutions

Quick Selection guide

How to drive LEDs?

• With current (high end system)– Light output is proportional to forward current– Brightness AND color can change with current

• With power(low end system)– Bulb

N or P FET

Duty Cycle Limits Max VO in Bucks

High Side N-MOSFETs (internal or external FETs)

10

Must turn off for ~200 ns each cycle to recharge CBOOT

The max number of LEDs is then:

The lower the switching frequency, fSW, the closer VO-MAX is to VIN

PFET Bucks Can Provide 100% Duty Cycle

• High Side P-MOSFETs

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Gate is driven below source to turn the PFET ON

Gate can drive to VCC indefinitely

PFET can stay on indefinitely

True 100% duty cycle capability

Buck is better than buck-boost

Better efficiency

Less parts

Faster dimming

Dimming

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Various dimming techniques

• Dimming using PWM signal

– White LEDs change Colour over Current!

– Solution:

Maintain Current and Change ON-Time = PWM

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Two different PWM dimming methods

• First method: Dim 1: Continuous inductor current (Good EMC, extra Mosfet )

• Second method: Dim 2: more efficient (2khz dim max)

D0LED0

D1LED1

D3LED2

Q2NMOS

Q1NMOS

Vout

GND

PWM dim1

PWM dim2

Output capacitor for a Buck topology

+

-

+

L

C OVIN

D

Δ I L

V FB

V F

+

-

+

-

R FB

Δ I C

I o

Vo

Vo Limited by VIN

Cout not needed

Continuous output current, low EMI

Easy to stabilize, if needed

Inherent protections against

failure

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Buck (step-down) DCM or CCM

LED Drivers

LM3409/09HV: High-Side PFET Buck Controller

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– VIN 6V to 42V (LM3409)

– VIN 6V to 75V (LM3409HV)

– External power PFET• 100% Duty Cycle Capable• Output Currents up to 4A

– Differential, high-side current sense

• Simplifies system wiring– PWM dimming and analog

dimming at 1000:1– Thermally enhanced eMSOP-10

package– No control-loop compensation

IADJ

EN

CSN

LM3409/09HV

UVLO

D1

L1

RSNS

CIN

VIN

IF up to 4A

VCC

COFF

GND Q1

CSP

CF

VIN

ROFF

PGATEVO

VO

COFF

RUV2

RUV1

DAP

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LM3401 Hysteretic PFET controller HB LED Driver

Key Features

• VIN Range: 4.5V – 35V

• Output range: 0.2V (Vfb) to VIN, adjusts to deliver constant current to up to 9 HB LEDs in series with scalable LED current > 2A

• No output cap, no compensation components

• Logic level dimming 1% to 100%, 70nS delay

• Controlled start up allows PWM at Vin for dimming

• PFET driver 100% duty cycle capable

• Adjustable Dual Side Hysteresis

– Adjustable ripple current

– Flexible inductor selection

– Fine tuning of switching frequency up to 1.5MHz

• MSOP-8 package

Applications:Automotive Lighting, General Illumination, MR16

replacement, Industrial Lighting, Gaming, High-end LCD Backlighting

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• Runs from 6V to 35V• Drives one white LED in at 800 mA• High-side PFET topology can do 100% duty cycle

Ref design: LM3401 - 20 Cent-Sized PCB

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Key Features: COT• VIN Range:

– LM340X: 6V – 42V, Buck– LM340XHV: 6V – 75V, Buck

• True average current control• Two PWM LED dimming options:

– Fast logic pin PWM dimming– LM3406: 2-wire dimming by VIN pin-

70%• Feedback Voltage = 200mV• Internal NFET for reduced parts count• Switching Frequency up to 1MHz • Exposed pad eTSSOP-14 package• Drives 1W, 3W, and higher powered LEDs

LM3402/4/6 and LM3402HV/4HV/6HV 0.5A/1.0A/1.5A HB LED Driver

GND

DIM

BOOT SW

VOUT

RON

LM3406/06HV

VIN

D1

L1CB

RSNS

CF

RONCIN

VIN

IF

VCC

CS

COMP

CC

GND

BOOT SW

VOUT

RON

VIN

D2

L1CB

RSNS

CF

RONCIN

VIN

IF

VCC

CS

COMP

CC

VINS

D1

LM3406/06HV

Fast PWM Dim

2-Wire Dim

Applications:Automotive Lighting, General Illumination, Industrial

Lighting, Arcitectual

• Support LED power up to 60W*: 18x 3W HBLEDs • Patented True Average Current Control Provides ±3% Accuracy to Average LED Current• Requires NO external current sensing resistor • Up to 96% efficiency ,1 active component• High contrast ratio

– (Minimum dimming current pulse width <10 µS)

• Adjustable Constant LED current from 350mA to 1000mA

– ±3% LED current accuracy

• Support PWM /analog dimming and thermal fold-back

• Wide input voltage range:– 4.5V to 42V (LM3414)– 4.5V to 65V (LM3414HV)

• Constant Switching Frequency – adjustable from 250 kHz to 1000 kHz

• Thermal shutdown protection• ePSOP-8 or LLP-8 package

LM3414/14HV Low Side Converter for High Power LED Drives

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VIN

LX

DIM

FS

PGND

IADJ

GND

VCC

* DAP connect to GND

D1

LED

x 4

L1

GND

Iout = 500mA (nom.)

LM3414

RFS

RIADJ

Vin

GND

24VDCnom

CIN

CVCC

GND

GND

40V3A

68uH

X7R 50V4.7uF

X7R16V 1uF

5.76k40.2k

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TPS92550 (LML416504)LED Driver Module

• Wide Input Voltage Range : 4.5V - 65V • Can drive up to 18 LEDs in series with 65V input • LED current accurately trimmed to +/-3% • 450mA LED current + fine tuning by external resistor (=

analog dimming!)• Integrated shielded inductor and power components • Efficiency up to 95% • Input Under-Voltage Lock-Out (UVLO) • Stable with ceramic and low ESR capacitors • Low radiated and conducted emissions • LED open and short circuit protection • Thermal Shutdown • Only 3 external passive components needed• Simple PCB layout and high Power Density • RoHS Compliant

Actual LML416504 Module

Retrofit MR16

AC Transformer for MR16 Reference Designs

Issue:•Resistive load = PF•Doesn’t switch off at 0v input•Small form factor

PHASE DIMMERAC

MAINS

12VACRMS

TRANSFORMER

MR16 MR16 MR16

LED MR16 Replacement Solutions

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LM3407 0.35A HB LED Driver

Key Features: floating buck

• VIN Range: 4.5V to 30V

• Less than ±10% load current variation• Adjustable switching frequency from

150 kHz to 1 MHz• Internal low side NFET for reduced parts

count• Feedback Voltage = 200mV• Fast PWM dimming enabled• Exposed pad eMSOP-8 package• Drives 1W LEDs

Applications:Automotive Lighting, General Illumination, Industrial

Lighting

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• Runs from low voltage: 11VAC to 20VAC or 14V to 30VDC

– Magnetic transformers only– Nominal 12VAC or 24VDC inputs

• Drive three white LEDs in series at 350 mA ±10%

• 1 MHz switching frequency for minimum inductor size

• Low-side buck topology uses small, efficient N-MOSFET

• Complete solution including a diode bridge and holdup capacitor fits in standard MR-16 bulb housing

LM3407 - MR-16 Retrofit

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Halogen MR16 vs. SSL MR16 waveforms

Final schematic of the MR16

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• Vin: 12VAC• Vout: 6.2V (2 series LEDs)• Iout: 1A • Pout: 6.2W• Efficiency: 81%• PF: 0.85• Dimmable with electronic low

voltage dimmers/electronic transformers

• LED Agnostic • Demo board, reference design,

CAD design files available online (RD-188)

LM3401 MR16 Reference Design

http://www.national.com/rd/RDhtml/RD-188.html

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TPS40211 Sepic Reference Design

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LM3444 Boost Reference Design

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LM3444 BUCK BOOST Reference Design

Controller/ Regulator/ Ref design

Why Not More Internal FET Boosts?

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Output Current with Ripple (ΔiF)

Inductor Current with Ripple (ΔiL)

O

INOLIMITMAXF V

VVII 1

OIN

OLIMITMAXF VV

VII 1

Boost and Buck-boost

SEPIC and Flyback

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LM3410 Boost and SEPIC LED Driver

FB

Vin SW

2

1

3

5

4DIM

Vin

1R

1C

1D1L

2CDIMM

GND

Key Features

– Input voltage range of 2.75 to 5.5V– Output voltage range of 3 to 24V– Switch current up to 2.1A

guaranteed over temperature– Low, 190mV feedback voltage– Option of 520 or 1600 kHz switching

frequency– PWM Dim pin– 160mΩ switch resistance– Current Mode control with internal

compensation Applications:

Portable Illumination/Flashlight, Personal Navigation Device, Portable Measurement Equipment, Automotive

Control/Entertainment Console, Portable DVD Player

eMSOP-8 SOT23-5LLP-6

TPS615003A, Boost High Brightness LED DriverFeatures Benefits• Operating Voltage Ranges:

• VIN: 2.9-18V• VOUT: VIN to 38V

• Suitable for Use in Battery,12V, or 15V Systems

• 3A Peak Switch Current • Can be Used to Drive High Current LEDs• Adjustable Switching Frequency: 200k-2.2MHz with up

to 93% Efficiency• Allows Designed to be Optimized for Efficiency or Size

• Dimming: PWM or PWM-to-Analog • Use PWM for No LED Color Shift. Use Analog to Eliminate Audible Noise from Pulsed Currents.

• UVLO, Over-Voltage, Current Limit and Thermal Shutdown

• Protects Against Abnormal and Fault Conditions

Applications• LED General Illumination• LED Flashlights• LED Backlighting

TOOLS

•TPS61500EVM-369

LM3429: Low Side N-MOSFET Controller for Constant Current LED Drivers

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LM342x Controls the Floating Buck-Boost

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VIN

VCC

RCT

EN

NDIM

CSH

COMP

AGND RPD

OVP

IS

GATE

PGND

HSP

HSN

DDRV

PWM DIMSIGNAL

VO

VO

VIN = 4.5V to 75V

LM3421

IF

RSNSCO

D1

Q1

L1

CIN

VO controlled with respect to VIN

Linear IF control

Adjustable, precision threshold protection for LEDs that fail open-circuit

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LM3423: Adds Fault Flag, Powergood Flag, and Input Disconnect

– FLT pin is for error signaling or for input disconnect via PFET

– TIMR sets the delay between when LED current is out of spec and when FLT flag goes logic HIGH

– DPOL selects the polarity of the nDIM pin when PWM dimming

– LRDY is a powergood pin for signaling a system microprocessor

VIN

RCT

VCC

EN

NDIM

CSH

COMP

AGND RPD

OVP

IS

GATE

PGND

HSP

HSN

DDRV

VO

VO

VIN = 4.5V to 75V

LM3423 IF

RSENSE

COD1

QSW

L1

CIN

ON/OFF

CBYP

RCSH

CCOMP

RHSP

RHSN

RT

CT

ROV2ROV1

+VSENSE

_

RUV2

RUV1

+VLEDS

-

QDIM

FLT

DPOL

LRDY

5V

To system microcontroller

TIMRCTIMR

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- DC Input Voltage 12V to 30V- SEPIC circuit bucks or boosts as needed• ILED up to 1.5A

• 6 White and one yellow LED for CCT adjustment

– All LEDs in series– Yellow LED has separate shunt NFET

dimming– 250Hz PWM dimming

• LM26675 supplies 5V for Nuventix SynJet active cooling

• 1500 lumens at 50 lm/W

Ref design: LM3429 PAR-38 Spotlight

5757

PAR-38 Spot Light – Block Diagram

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- DC Input Voltage 9V to 36V- Buck-boost circuit runs from 12VDC or

24VDC rails• ILED up to 1A

• Powers 1 to 12 LEDs in series• Accepts standard 0-10V linear dimming

signals and adjusts LED current down to zero

• LM2842 supplies 5V for Nuventix SynJet active cooling

Ref Design:LM3429 MR-16 retrofit with active cooling

LM3429 MR-16 Buck-boost Schematic

LED Offline products

•Retrofit E27

•T8 tube non retrofit

•High power bay (multi string)