LED Drivers for High-Brightness LightingSolutions Guide national.com/LED2011 Vol. 1Technology OverviewProduct...
Energy-Efficient LED Driver Designs ...
ContentsTechnology Overview .................................................................................................
High-Brightness LED LightingOverview High-Brightness LEDs: In...
When Input Voltage Exceeds When Input Voltage is Less thanLED Voltage ...
LED Drivers Selection Tables Buck (Step-Down) High-Brightness LED Drivers ...
Boost (Step-Up) High-Brightness LED Drivers VIN Range No. of ...
Key Products OverviewLM3450 – LED Driver with Power Factor Correction and Phase-Dimming DecoderFeatures• Solution accepts ...
LM3464 – LED Driver with Dynamic Headroom Control and Thermal Control InterfacesFeatures• Wide input voltage range (12V to...
Key Products OverviewLM3409 – PFET Buck Controller for High-Power LED DriversFeatures• 2.0Ω MOSFET gate drive ...
High-Brightness LED ApplicationsNational Offers a Diverse Portfolio of Constant-Current Regulators for Driving LEDsFeature...
High-Brightness LED ApplicationsTwo-Wire DimmingTwo-Wire DimmingLM3406 Two-Wire DimmingAdding an external input diode and ...
High-Brightness LED Applications ...
High-Brightness LED ApplicationsLED BulbsDesign 1: MR16 Using LM3405ADescription:• This circuit is designed to drive a 3W ...
Design 2: MR16 Using LM3407Description:• This circuit is designed to drive an array of 3 series-connected 1W LEDs from an...
High-Brightness LED ApplicationsLED BulbsDesign 3: MR16 with Two-Wire Dimming Driven by the LM3406Description:• This circu...
High-Brightness LED Applications Outdoor High-P...
High-Brightness LED ApplicationsOutdoor High-Power Wide Area High-Brightness LED ApplicationsStreet LampDesign 1: 1W LED S...
Design 2: 3W LED String Using LM3404HVDescription:• This circuit is designed to drive an array of 10 to 12 series- connec...
High-Brightness LED ApplicationsOutdoor High-Power Wide AreaDesign 3: Key Benefits of LM3464 in Street Lamp DesignDescript...
Designer’s Corner EMI Design for ...
High-Brightness LED ApplicationsPortable ProjectorsPortable Projector• The LM3433/34 is a high-power constant-current LED ...
National lighting solutions
National lighting solutions
National lighting solutions
National lighting solutions
National lighting solutions
National lighting solutions
National lighting solutions
National lighting solutions
National lighting solutions
National lighting solutions
National lighting solutions
National lighting solutions
National lighting solutions
National lighting solutions
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National lighting solutions

Published on: Mar 3, 2016
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  • 1. LED Drivers for High-Brightness LightingSolutions Guide national.com/LED2011 Vol. 1Technology OverviewProduct HighlightsApplication InformationDesign ExamplesArticles
  • 2. Energy-Efficient LED Driver Designs national.com/LEDF or 50 years, National has been known for its reliable, energy-efficient power management products. Thecompany continues to bring this knowledge, experience, and Award-Winning Design Tools National’s unique WEBENCH LED Designer online tool allowsmanufacturing capability to help customers create better for quick and easy selection andlighting designs. National’s LED drivers incorporate the simulation of a complete LEDintelligence that systems need to deliver high-performance, and LED driver solution. The toolreliable, and robust LED lighting solutions to the market. provides lighting designers a competitive advantage and faster time to market. National’s on-demand tools makeNational Semiconductor’s broad portfolio of PowerWise® it easy for designers to explore and learn, compare andenergy-efficient power management ICs provide constant select products, and then design and build their systemcurrent for driving both low-power and high-brightness online. LEDs, enabling color and brightness matching over Wide Range of Applications a wide temperature range. National has products that fit into a wide range of These LED drivers enable applications including: greater energy efficiency and • Downlighting flexibility in lighting designs. Driving numerous LEDs in one • Replacement lampsstring, they provide greater than 90 percent efficiency • Outdoor area fixtures such as street lamps and parkingand accurate current regulation with less power and garage lightsheat dissipation. • Industrial/commercial such as high bay and low baySolving Customer Design Challenges fixtures for warehouse lightingTo enable customers to build differentiated products • Portable consumer: flashlights and sports equipmentmore quickly, National’s easy-to-use solutions addressa number of lighting design challenges through features • Entertainment and projectionsuch as: • Architectural/decorative fixtures• Dynamic headroom control to maximize system efficiency • LED backlit displays• Multiple outputs maximize LED strings per driver • Automotive headlamps and reduce system solution size, cost, and complexity • and more• Thermal foldback ensures LEDs operate reliably over varying temperature conditions for a robust solution that doesn’t require complex external temperature sensing circuitry• Patent-pending architectures enable state-of-the-art TRIAC/ phase dimming compatibility in LED retrofit lamps and new installation fixtures for a seamless transition to LED lighting technology• Analog and Pulse-Width Modulation (PWM) dimming capabilities for design flexibility• Small driver solutions for space-constrained applications• Tools such as WEBENCH® LED Designer for easier design
  • 3. ContentsTechnology Overview ................................................................................................................................................................................ 4LED Drivers Selection Tables ................................................................................................................................................................... 6Key Products Overview ............................................................................................................................................................................ 8High-Brightness LED Applications........................................................................................................................................................ 11 Two-Wire Dimming ........................................................................................................................................................................... 12 LED Bulbs ........................................................................................................................................................................................... 13 Outdoor High-Power Wide Area .................................................................................................................................................... 17 Portable Projectors .......................................................................................................................................................................... 22 Automotive ........................................................................................................................................................................................ 24 TRIAC Dimming ................................................................................................................................................................................. 28Designer’s Corner .................................................................................................................................................................................... 29WEBENCH LED Architect ....................................................................................................................................................................... 33Design Resources .................................................................................................................................................................................... 34national.com/LED 3
  • 4. High-Brightness LED LightingOverview High-Brightness LEDs: Input Voltage andRegardless of type, color, size, or power, all LEDs work best Forward Voltagewhen driven with a constant current. LED manufacturers specify Sources of input voltage for LED arrays come from batteries orthe characteristics (such as lumens, beam pattern, color) of power supplies that have a certain tolerance. An automotivetheir devices at a specified forward current (IF), not at a specific battery, for example, may supply 8V to 16V depending on the loadforward voltage (VF). and the age of the battery. The "silver box" power supply inside a desktop CPU may supply 12V ±10%.Most power supply ICs are designed to provide constant voltageoutputs over a range of currents (see below); hence, it can be High-brightness (HB) LEDs also give a range of forward voltage.difficult to ascertain which parts will work for a given application A typical HB LED might be characterized at a forward currentfrom the device datasheet alone. of 350 mA. The forward voltage of the LED when IF = 350 mA is specified with a range that includes a typical value as well asWith an array of LEDs, the main challenge is to ensure every LED over-temperature maximum and minimum values. To ensure thatin the array is driven with the same current. Placing all the LEDs a true constant current is delivered to each LED in an array, thein a series string ensures that exactly the same current flows power topology must be able to deliver an output voltage equalthrough each device. to the sum of the maximum forward voltages of every device placed in the string. Manufacturers bin their devices for color, brightness, and forward voltage. Binning for all three characteristics is expensive, and forward voltage is often the specification that is allowed to vary the most. Adding this to the shift in forward voltage as the LED die temperature changes gives rise to the need for constant-current regulators that have a wide range of output voltage. Constant Voltage Regulator Constant Current Regulator4
  • 5. When Input Voltage Exceeds When Input Voltage is Less thanLED Voltage LED VoltageIf input voltage always exceeds the sum of the maximum When the minimum forward voltage of all the LEDs in a string willforward voltages of every LED in a string, then two options are always exceed the maximum input voltage, a step-up, or boost,available: linear regulators and buck regulators. regulator is needed.A linear regulator introduces efficiency and thermal drawbacks, The inductive-boost converter is the simplest regulator that canbut is the simplest design option. In order to provide constant deliver currents above 350 mA with a varying output voltage.current, the linear regulator must be an adjustable type that As with linear and buck regulators, a boost converter with auses a pair of feedback resistors. Replacing the top feedback feedback-divider network can be modified to become a constantresistor with the LED string and placing a current-sensing current source. One important distinction between the buckresistor in the bottom position "tricks" the former constant regulator and boost regulator must be made when the powervoltage source into adjusting the output voltage until enough switch is internal to the control IC. Such monolithic systems havecurrent flows through the current sensing resistor to equal the a fixed current limit.feedback voltage of the IC. In buck regulators, the internal switch passes the same DCLinear regulators have the advantages of simplicity, low parts current as the LED. A boost converter differs in that the internalcount, and very little Electromagnetic Interference (EMI). switch sees a higher current that varies with input voltage;They can deliver constant current as long as the VF in the LED the greater the difference between VIN and VOUT, the higherstring does not exceed their dropout-limited output voltage. the internal switch current. Care must be taken to evaluate aThe disadvantage lies in efficiency and thermal dissipation. monolithic boost regulator-based LED drive to make sure that itLoss in a linear regulator LED driver is approximately equal to will not hit the fixed current limit over the range of input voltage.(VIN – n x VF) x IF , where "n" is the number of LEDs in the string.At currents of 350 mA and above, the linear solution may requirea heatsink, adding cost and size to the design. When Input Voltage Range Overlaps LEDThe more efficient option when input voltage always exceeds Voltage Rangethe LED voltage is a step-down or buck regulator. As with As HB LEDs are adopted into more and more applications,linear regulators, this must be an adjustable type, and the same situations will arise when the input voltage varies above andmethod can be used to turn almost any buck regulator into a below the forward voltage of the LED string. For these cases,constant current source for LEDs. Buck regulators enjoy high a current regulator is needed that can both buck and boost asefficiency and eliminate the need for a heatsink, at the cost of a required by the input and output conditions. Possible topologiesmore complex circuit and the addition of switching noise. Many include the buck-boost, SEPIC, Cuk, flyback, and VIN referencedrecent buck regulators switch at 1 MHz and above, making their buck-boost (also called the floating buck-boost).external components so small that at currents under 1A theymay actually use less space than a linear regulator. In all of these topologies, the power-switch current exceeds the LED current and varies with input voltage. The same attention to peak switch current must be made over the full range of input voltage, especially if a regulator with an internal power switch and fixed current limit is implemented. For more information about National’s LED products, samples, design simulation tools, and more, visit: national.com/LED.national.com/LED 5
  • 6. LED Drivers Selection Tables Buck (Step-Down) High-Brightness LED Drivers No. of Internal Auto Product ID VIN Range (V) VOUT (V) ILED (A) LEDs SWITCH Topology Key Features Grade Dual-side hysteresis, very low reference voltage and LM3401 E, W 4.5 to 35 Up to 35 3 1 to 9 — Buck short propagation delay, 100% duty cycle LM3402/HV E, W 6.0 to 42/6.0 to 75 Up to 37/67 0.425 1 to 9/15 ✔ Buck 200 mV feedback voltage, fast PWM dimming LM3404/HV E, W 6.0 to 42/6.0 to 75 Up to 37/67 1 1 to 9/15 ✔ Buck 200 mV feedback voltage, fast PWM dimming 200 mV feedback voltage, fast PWM dimming, LM3405A E, W 3.0 to 22 Up to 20 1 1 to 3 ✔ Buck thin package 200 mV feedback voltage, fast PWM or two-wire LM3406/HV E, W 6.0 to 42/6.0 to 75 Up to 37/67 1.5 1 to 9/15 ✔ Buck dimming, true average current control LM3407 E, W Floating Constant frequency PWM with true average current 4.5 to 30 Up to 27 0.35 1 to 7 ✔ Buck control External high-side P-FET current source with LM3409/HV E, W 6.0 to 42/6.0 to 75 Up to 42/75 3.0+ 1 to 9/15 — Buck differential current sensing and analog current adjust, 100% duty cycle Requires no external current sensing resistor and Floating LM3414/HV E, W 4.5 to 65 Up to 60 1 1 to 15 ✔ no external compensation, LED current adjustment, Buck temperature foldback Floating 20 mV to 1.235V adjustable differential current sense LM3421 E, W 4.5 to 75 Adjustable 3.0+ 1 to 16 — Buck voltage, 50 kHz max PWM dimming 20 mV to 1.235V adjustable differential current sense Floating LM3423 E, W 4.5 to 75 Adjustable 3.0+ 1 to 16 — voltage, 50 kHz max PWM dimming, fault timer, LED Buck ready flag, high-side dimming Floating Temperature foldback, synchronizable 50 kHz max LM3424 E, W 4.5 to 75 Adjustable 3.0+ 1 to 18 — Buck PWM dimming Floating 50 mV to 1:25 adjustable high-side current-sense LM3429 E, W 4.5 to 75 Adjustable 3.0+ 1 to 20 — Buck voltage, analog and PWM dimming Negative Negative output voltage capability allows LED anode to LM3433 E, W -9.0 to -14 Up to 6 20+ 1 to 2 — SYNC Buck be tied directly to chassis for max heat sink efficacy Output current > 20A, PWM frequency capable > 30 kHz, Negative LM3434 E, W -9.0 to -30 Up to 27 20+ 1 to 6 — negative output voltage capability allows LED anode to SYNC Buck be tied directly to chassis for maximum heat sink efficacy Dynamic Headroom Control (DHC) High-Brightness LED Driver Solutions VIN Range No. of Multi- Internal Product ID (V) VOUT (V) ILED (A) LEDs Output SWITCH Topology Key Features Individual 4-channels with individual current regulation, DHC output 12 to 80/ Current interfaces with external power supply to adjust LED supply LM3464/A E, W 80 to 277 3.0+ 20 per ch 4 ch — 12 to 95 Regulator voltage for maximum efficiency, temperature foldback, + DHC analog and PWM dimming No loop compensation required, programmable LED current !NEW Adjustable from 50 mA to 200 mA, 1000:1 contrast ratio at a dimming LM3492 E, W 4.5 to 65 0.2 14 per ch 2 ch ✔ Boost to 65 frequency of more than 3 kHz, minimum LED current pulse width is 300 ns, DHC maximizes efficiency PowerWise® product E Evaluation board W WEBENCH® enabled 6
  • 7. Boost (Step-Up) High-Brightness LED Drivers VIN Range No. of Multi- Internal Auto Product ID (V) VOUT (V) ILED (A) LEDs Output SWITCH Topology Key Features Grade Ultra-low stand-by current of 80 nA, internally LM3410 E, W 2.7 to 5.5 24 2.1(1) 1 to 5 — ✔ Boost compensated 20 mV to 1.235V adjustable differential current sense LM3421 E, W 4.5 to 75 Adjustable 3.0+ 1 to 20 — — Boost voltage, 50 kHz max PWM dimming 20 mV to 1.235V adjustable differential current sense LM3423 E, W 4.5 to 75 Adjustable 3.0+ 1 to 20 — — Boost voltage, 50 kHz max PWM dimming, fault timer, LED ready flag, high-side dimming Temperature foldback, synchronizable 50 kHz max PWM LM3424 E, W 4.5 to 75 Adjustable 3.0+ 1 to 18 — — Boost dimming 50 mV to 1.25V adjustable high-side current-sense LM3429 E, W 4.5 to 75 Adjustable 3.0+ 1 to 20 — — Boost voltage, analog and PWM dimming LM3431 E, W 5.0 to 36 40 0.15 3 x 10 ✔ — Boost LED protection: short, open, and thermal Buck-Boost High-Brightness LED Drivers VIN Range No. of Multi- Internal Auto Product ID (V) VOUT (V) ILED (A) LEDs Output SWITCH Topology Key Features Grade Ultra-low stand-by current of 80 nA, internally LM3410 E, W 2.7 to 5.5 24 2.1(1) 1 to 5 — ✔ SEPIC compensated Floating Buck- 20 mV to 1.235V adjustable differential current LM3421 E, W 4.5 to 75 Adjustable 3.0+ 1 to 20 — — Boost SEPIC sense voltage, 50 kHz max PWM dimming 20 mV to 1.235V adjustable differential current Floating Buck- LM3423 E, W 4.5 to 75 Adjustable 3.0+ 1 to 20 — — sense voltage, 50 kHz max PWM dimming, fault Boost SEPIC timer, LED ready flag, high-side dimming Floating Buck- Temperature foldback, synchronizable 50 kHz max LM3424 E, W 4.5 to 75 Adjustable 3.0+ 1 to 18 — — Boost SEPIC PWM dimming Buck-Boost 50 mV to 1.25V adjustable high-side current-sense LM3429 E, W 4.5 to 75 Adjustable 3.0+ 1 to 20 — — Flyback SEPIC voltage, analog and PWM dimming Offline High-Brightness LED Driver Solutions VIN Range VOUT Max ILED No. of Multi- Internal Product ID (V) (V) (A) LEDs Output SWITCH Topology Key FeaturesNEW ! Floating Non-dimmable version of LM3445, adaptive programmable offline LM3444 E, W 80 to 277 Adjustable 1+ 1 to 14+ — — Buck allows for constant ripple current, no 120/100 Hz flicker Integrated TRIAC dim decoder circuit for LED dimming, adaptive Floating LM3445 E, W 80 to 277 Adjustable 1+ 1 to 14+ — — programmable offline allows for constant ripple current, no Buck 120/100 Hz flicker ! Active power factor correction, 70:1 PWM decoded from phaseNEW Isolated LM3450 E, W 80 to 277 Adjustable 1+ 1 to 14+ — — dimmer, analog dimming, digital angle and dimmer detection, Flyback dynamic holding current and smooth dimming transition Note (1) Specified in ISW PowerWise® product E Evaluation board W WEBENCH® enabled national.com/LED 7
  • 8. Key Products OverviewLM3450 – LED Driver with Power Factor Correction and Phase-Dimming DecoderFeatures• Solution accepts universal line voltages• Active power factor correction IC with phase-dimmer V REF BIAS decoder Return HOLD• Unique dynamic hold circuitry allows for high- performance, smooth dimming without flicker EMI Filter FLT2 ZCD• Compatible with both forward-phase (TRIAC) and FLT1 V CC reverse-phase dimmers LM3450 Secondary LED Driver PWM• 70:1 PWM decoded from phase dimmer DIM GATE LED Load• Up to 100W output power AC V AC CS Input Optical• Programmable dimming range COMP GND Isolation• Analog adjust pin allows for interface to sensors, thermal foldback, analog dimming, or dimmer range adjust FB ISEN Hold PWM Return• Can be used in either single- or two-stage configurations for tradeoffs between solution size, efficiency, and noise immunity• Over-voltage protection• Feedback short-circuit protection• Available in TSSOP-16 packagingApplicationsIdeal for use in phase-dimmable LED fixtures (10W to 100W output power)LM3445 – TRIAC-Dimmable LED Driver V+ D3 VBUCK C7 D9Features BR1 D8 C10 C12 VLED R2 D4 C9 - R4• Solution accepts universal line voltages TRIAC Q1• Application voltage range from 80 VAC to 277 VAC Dimmer D2 VLED- VAC• Angle detector/decoder enables wide (100:1) full range dimming D1 R5 C5 D10 Q3• Integrated 300Ω bleeder resistor to ensure proper TRIAC signal L2 decoding• Patent-pending control architecture allows for constant ripple 1 ASNS BLDR 10 current which extends the life of the LEDs R1 U1 I COLL• Scalable output current up to and greater than 1A 2 FLTR1 VCC 9 LM3445• Master/slave control for uniform dimming across multi-channel C3 3 DIM GATE 8 Q2 applications 4 COFF ISNS 7Applications C4 5 FLTR2 GND 6 R3Ideal for use in LED bulbs up to 10W to 15W output power C118
  • 9. LM3464 – LED Driver with Dynamic Headroom Control and Thermal Control InterfacesFeatures• Wide input voltage range (12V to 80V) VLED High Power LED Arrays• Dynamic headroom control ensures maximum efficiency A NTC thermistor To thermal sensor couple to terminals LED arrays• 4 output channels with individual current Voltage output R FB 1 B regulation R DHC OUTP EN VIN DR1 Voltage• High channel-to-channel accuracy Primary VLEDFB DR2 feedback pin CDHC power supply DR3 DR4 R FB 2 C DHC FAULT_CAP• Digital PWM/analog dimming control C FLT GD1 Q1 SE1 interface GD2 Q2 PGND AGND LM3464 SE2• Resistor-programmable dimming External voltage headroom control VDHC GD3 Q3 VDHC Fault acknowledgement output FAULTb SE3 FAULTb Q4 frequency and minimum duty cycle (analog PWM DIM VCC GD4 SE4 dimming input dimming mode) DIM R THM 1 THERMAL R ISNS 1 R ISNS 2 R ISNS 3 R ISNS 4• Direct interface to thermal sensor R THM 2 C VCC R DMIN 1 PGND PGND PGND PGND• Fault detection A DMIN THM_CAP SYNC R DMIN 2• Over-temperature protection To NTC thermal sensor B C THM AGND PGND• Thermal shutdown• Under-voltage lockout AGND PGND• Available in thermally-enhanced eTSSOP-28 packagingApplicationsIdeal for use in high-power white applications such as street lamps, parking garage lamps, and warehouse lightingLM3414 – 1A 60W Common-Mode-Capable Constant-Current Buck LED DriverFeatures• Wide input voltage ranges: VIN IOUT = 1A 4.5V – 42 VDC (LM3414) ˚ 4.5V to 42V (LM3414) C IN 4.5V – 65 VDC (LM3414HV) High power LED Array ˚ 4.5V to 65V (LM3414HV) D1• Supports output powers up to 60W GND• Adjustable LED current from 350 mA to 1A C VCC LM3414/14HV• Analog and PWM dimming VCC VIN L1 PGND LX• Thermal foldback IADJ DIM• Requires no external current sensing resistor GND FS PWM dimming signal• ±3% LED current accuracy GND R IADJ * DAP connect to GND• Up to 96% efficiency R FS• Integrated low-side N-channel MOSFET• Switching frequency adjustable from 250 kHz to 1 MHz GND GND• Thermal shutdown protection• Available in power-enhanced ePSOP-8 or LLP-8 (3 mm x 3 mm) packagingApplicationsIdeal for use in space-constrained general illumination applications, MR16 replacement lamps, and LED fixturesnational.com/LED 9
  • 10. Key Products OverviewLM3409 – PFET Buck Controller for High-Power LED DriversFeatures• 2.0Ω MOSFET gate drive R UV2• VIN range 6V to 42V (LM3409)• VIN range 6V to 75V (LM3409HV) R UV1 1 10 UVLO VIN VIN• Differential, high-side current sensing CF C IN 2 9• No control-loop compensation required IADJ VCC• Cycle-by-cycle current limit 3 8 EN LM3409/HV CSP• 10,000:1 PWM dimming range R SNS R OFF• 250:1 analog dimming range 4 COFF CSN 7• Low power shutdown C OFF 5 DAP 6 GND PGATE Q1• Supports all-ceramic output capacitors and L1 capacitor-less outputs VOUT• Thermal shutdown protection D1 I LED• Available in thermally-enhanced eMSOP-10 packagingApplicationsIdeal for use in LED drivers, constant-current sources, automotive lighting, general illumination, and industrial lightingLM3492 – Two-Channel Individual Dimmable LED Driver withBoost Converter and Fast Current RegulatorFeatures• 4.5V to 65V input voltage range L1• Two individual dimmable LED strings up to 65V V IN D1 V OUT VIN SW• Programmable LED current from 50 mA to 200 mA R RT CDHC RT• Dynamic headroom control maximizes efficiency C FB R FB 1 C IN VCC• 1000:1 contrast ratio at a dimming frequency of more C CDHC R COMM VOUT COUT than 3 kHz C VCC EN FB LM3492 R IREF• Programmable soft-start PGND IREF R FB 2• No loop compensation required GND ILIM• Stable with ceramic and other low-ESR capacitors COMM LGND with no audible noise DIM1/CLK IOUT1• Switching frequency programmable from 200 kHz to 1 MHz DIM2 IOUT2• Over-power protection• ±3% current accuracy• Precision enable• COMM I/O pin for diagnostic and commands• Thermal shutdown protection• AEC-Q100 grade 1 qualified• Available in thermally-enhanced eTSSOP-20 packagingApplicationsIdeal for use in ultra-high contrast ratio 6.5” to 10” LCD display backlight up to 28 LEDs and automotive or marine GPS displays10
  • 11. High-Brightness LED ApplicationsNational Offers a Diverse Portfolio of Constant-Current Regulators for Driving LEDsFeatures• PowerWise® energy-efficient solutions ˚ Providing the best power-to-performance ratios ˚ Enabling reliable and robust solutions• Cutting-edge features including dimming, thermal management, fault protection, and more• Low external component count and small solution sizes• Easy-to-use tools and resources: ˚ WEBENCH LED Designer ® ˚ Reference designs ˚ Application notesApplications Outdoor High-Power Display Portable Portable LED Driver LED Bulbs Wide Area Down Lights Automotive Backlighting Medical Entertainment Consumer Projectors LM3401 ✔ ✔ ✔ ✔ ✔ LM3402/HV ✔ ✔ ✔ ✔ LM3404/HV ✔ ✔ ✔ ✔ LM3405/A ✔ ✔ ✔ ✔ LM3406/HV ✔ ✔ ✔ ✔ LM3407 ✔ ✔ ✔ ✔ LM3409/HV ✔ ✔ ✔ ✔ ✔ ✔ LM3410 ✔ ✔ ✔ ✔ ✔ LM3414/HV ✔ ✔ ✔ ✔ ✔ LM3421/23 ✔ ✔ ✔ ✔ ✔ ✔ LM3424 ✔ ✔ ✔ ✔ ✔ ✔ ✔ LM3429 ✔ ✔ ✔ ✔ ✔ ✔ LM3430/32 ✔ LM3431 ✔ ✔ ✔ LM3433 ✔ ✔ ✔ LM3434 ✔ ✔ ✔ LM3444 ✔ ✔ ✔ LM3445 ✔ ✔ LM3450 ✔ ✔ LM3464 ✔ LM3492 ✔ ✔ ✔national.com/LED 11
  • 12. High-Brightness LED ApplicationsTwo-Wire DimmingTwo-Wire DimmingLM3406 Two-Wire DimmingAdding an external input diode and using the internal VINS If the VINS pin voltage falls 70% below the VIN pin voltage, thecomparator allows the LM3406/06HV to sense and provide LM3406/06HV disables the internal power FET and shuts off thePWM dimming of the LED by chopping of the input voltage. This current to the LED array. The support circuitry (driver, bandgap,method is also referred to as "two-wire dimming," and a typical VCC) remains active in order to minimize the time needed to turnapplication circuit is shown below. the LED back on when the VINS pin voltage rises and exceeds 70% of VIN. This minimizes the response time for turning the LED array back on. The benefit of two-wire dimming: One wire less than traditional PWM dimming, further reducing the wiring cost12
  • 13. High-Brightness LED Applications LED BulbsMR16 MR16 Basic Architecture MR16 LED Circuit 12 VAC DC-DC LED Driver 12/24 VDC Input from AC-DC Adaptor 1W LED x 3/ 3W LED x1MR16 Driver SolutionsVIN No. of LEDs LED Type (W) ILED (mA) Recommended Part No. Key Features12 to 24 VAC-VDC 1 to 3 1 to 5 >1 LM3421/29 Buck-boost architecture12 to 24 VAC-VDC 1 to 3 1 to 5 >1 LM3424 Buck-boost architecture, thermal foldback12 to 48 VDC 1 5 350 LM3406 Two-wire dimming, high efficiency12 to 24 VDC 3 1 350 LM3401 100% duty cycle12 to 48V 3 5 350 LM3409 100% duty cycle, analog dimming12 VAC 3 1 350 LM3414 100% duty cycle, analog dimming12 VDC/12 VAC 3 1 350 LM3405A XMK Small size, tiny SOT23-6 packaging12 to 24 VDC 3 1 350 LM3407 High efficiency, high precision of LED current12 VDC/12 VAC 1 3 600 LM3405A XMK Small size, tiny SOT23-6 packaging12 VDC/12 VAC 1 3 750 LM3405A XMY Thermally-enhanced package, eMSOP-8national.com/LED 13
  • 14. High-Brightness LED ApplicationsLED BulbsDesign 1: MR16 Using LM3405ADescription:• This circuit is designed to drive a 3W high-brightness LED from an input of 12 VDC/12 VAC for halogen MR16 lamp replacement applications.VIN VIN VOUTTest Data:1: Output Voltage and Current Parameter Reading VIN (VDC) Load VOUT (V) ILED (A) 12 1 LED 3.8 0.702: Efficiency Reading Input Voltage (V) VIN (V) IIN (A) VOUT (V) ILED (A) Efficiency 12 12 0.274 3.80 0.70 80.9%BOM (Main Components) Item Designation Description Part No. Vendor 1 U1 LED driver IC LM3405A (eMSOP-8) National 2 C1 16V, 220 μF, 8 x 7 mm SG or YK, 220 μF, 16V Lelon or Rubycon 3 L1 Inductor 6.8 μH, 0.095 Ω, 2.6A LPS6225-682MLB Coilcraft 4 Co CAP0805, 0.47 μF GRM188R71C474KA88 Murata14
  • 15. Design 2: MR16 Using LM3407Description:• This circuit is designed to drive an array of 3 series-connected 1W LEDs from an input of 12 VDC/12 VAC for MR16 lamp replacement applications. 3 LEDs COUT L1 IOUT D1 ISNS LX DIM GND LM3407 CVCC EN VCC FS VIN VIN RISNS RFS CINTest Data:1: Output Voltage and Current Parameter Reading VIN (VDC) Load VOUT (V) ILED (A) 12 3 LEDs 9.71 0.352: Efficiency Reading Input Voltage (V) VIN (V) IIN (A) VOUT (V) ILED (A) Efficiency 12 12.01 0.30 9.71 0.35 94.06%BOM (Main Components) Item Designation Description Part No. Vendor 1 U1 LED driver IC LM3407 (eMSOP-8) National 2 L1 Inductor 33 μH, 0.58A LPS-4018-333ML Coilcraft 3 CIN Cap MLCC 50V, 4.7 μF, X7R GRM32ER71H475K88L Murata 4 COUT Cap MLCC 25V, 2.2 μF, X7R GRM31MR71E225MA93 Muratanational.com/LED 15
  • 16. High-Brightness LED ApplicationsLED BulbsDesign 3: MR16 with Two-Wire Dimming Driven by the LM3406Description:• This circuit is designed to drive a 1.5A high-brightness LED from an input of 12 VDC for MR16 lamp replacement applications.• The two-wire dimming feature of LM3406 enables PWM dimming over the power input line. Dimming Control U1 L1 VIN VIN SW LED+ D22 VIN SW D1 C21 Cin1 Cin2 RCC CB (optional) CO Duty Cycle RON BOOT GND Control LM3406 ROUT VINS VOUT DIM1 DIM CS LED- R23 COMP VCC CC R35 GND NC CFTest Data:1: Output Voltage and Current Parameter Reading VIN (VDC) Load VOUT (V) ILED (A) 12 2 LEDs 4.20 1.502: Efficiency Reading Input Voltage (V) VIN (V) IIN (A) VOUT (V) ILED (A) Efficiency 12 12 0.62 4.20 1.50 84.68%BOM (Main Components) Item Designation Description Part No. Vendor 1 U1 LED driver IC LM3406 (eTSSOP-14) National 2 L1 15 μH, 2.2A, 47 mΩ SLF10145T-150M2R2-P TDK 3 Cin1 3.3 μF, 50V C3225X7R1H335M TDK 4 Co 0.15 μF, 50V C3216X7R1H105M TDK16
  • 17. High-Brightness LED Applications Outdoor High-Power Wide Area48V Bus Street LampKey Benefits of LM3402/04/06HV in 48V(or higher) Bus LED Street Lamp System• Wide input voltage range (6V to 42V) or (6V to 75V) ° Maximizes the number of LEDs per string (~10 to 12 LEDs in series for 1 LED driver) ° Lower system solution cost Temp Sensor LM94022 PWM Dimming• Ultra-high-efficiency LED driving solution LM95071 Signal MCU ° 96%+ efficiency with 10 LEDs connected in series LM73 ° Enhanced thermal performance in the harsh street lamp 3.3V working environment 48V• No compensation required LED Driver LED Driver LED Driver ° Easy to use AC/DC LM3402HV LM3402HV LM3402HV LM3404HV LM3404HV LM3404HVLM3424 with Integrated Temperature Management• Temperature foldback LED Street Lamp Architecture ° Eliminates the need for external thermal management circuitry ° Increases LED lifetime, allowing for a more robust and reliable system solution ° WEBENCH® LED Designer online tool with thermal management feature available to implement temperature foldback - Ease of design on a system levelThe Concept:The thermal foldback feature lowers regulated current as thetemperature increases to optimize the LED lifetime. The feature INOMincludes two parameters: A temperature corner (Tcorner)after which the nominal operating current is reduced and theslope corresponding to the amount of LED current decreasesper temperature. The LM3424 allows the user to program both LED Currentthe breakpoint and slope of the thermal foldback profile usingexternal resistors. TCORNER Temperaturenational.com/LED 17
  • 18. High-Brightness LED ApplicationsOutdoor High-Power Wide Area High-Brightness LED ApplicationsStreet LampDesign 1: 1W LED String Using LM3402HVDescription:• This circuit is designed to drive an array of 10 to 12 series- connected 1W LEDs from a 48 VDC source.• Multiple LM3402HV LED drivers can be used in the system, depending on the street lamp’s output wattage.• Each LM3402HV LED driver provides constant current for a single LED string. This enables consistent brightness of each LED in the LED street lamp.Test Data:1: Output Voltage and Current Parameter ReadingVIN (VDC) Load VOUT (V) ILED (A)48 12 LEDs 38.20 0.332: Efficiency ReadingInput Voltage (V) VIN (V) IIN (A) VOUT (V) ILED (A) Efficiency48 47.91 0.27 38.20 0.33 98.04%BOM (Main Components) Item Designation Description Part No. Vendor 1 U1 75V, 0.5A LED driver IC LM3402HV (SOIC-8 or PSOP-8) National 2 L1 18.5 x 15.4 x 7.1 mm 330 μH, 1.9A, 0.56Ω DO5022P-334 Coilcraft 3 Cin 2.2 μF/100V/1812 C4532X7R2A225M TDK 4 Co 0.15 μF, 100V, 1206 C3216X7R2A154M TDK18
  • 19. Design 2: 3W LED String Using LM3404HVDescription:• This circuit is designed to drive an array of 10 to 12 series- connected 3W LEDs from a 48 VDC source.• Multiple LM3404HV LED drivers are used in the LED street lamp system, depending on the street lamp’s output wattage.• Each LM3404HV LED driver provides constant current for a single LED string. This guarantees consistent brightness of each LED in the LED street lamp.Test Data:1: Output Voltage and Current Parameter Reading VIN (VDC) Load VOUT (V) ILED (A) 52 12 LEDs 41.975 1.0712: Efficiency Reading Input Voltage (V) VIN (V) IIN (A) VOUT (V) ILED (A) Efficiency 52 51.97 0.847 41.975 1.017 96.97%BOM (Main Components) Item Designation Description Part No. Vendor 1 U1 75V, 1.2A LED driver LM3404HV (SOIC-8 or PSOP-8) National 2 L1 Inductor 220 μH, 0.229Ω, 2.2A MSS1278-184KL Coilcraft 3 Cin 2.2 μF/100V/1812 C4532X7R2A225M TDK 4 Co 0.15 μF, 100V, 1206 C3216X7R2A154M TDKnational.com/LED 19
  • 20. High-Brightness LED ApplicationsOutdoor High-Power Wide AreaDesign 3: Key Benefits of LM3464 in Street Lamp DesignDescription:• Wide input voltage range • Integrated failure protection and handling circuit ° 12V to 95V (LM3464A) ° Four individual output failure-detection circuits ° 12V to 80V (LM3464) ° Prevents substantial damage due to LED failures• Dynamic Headroom Control (DHC) • Simple interface to common AC/DC converter circuits ° Automatic efficiency optimization (over 98%)• Thermal foldback control Electrical Characteristics: ° Output power reduction under high-operation temperature • Input voltage: 110 VAC/60 Hz ° Accepts analog-dimming control signal • Output rail voltage (max.): 39 VDC• Four individually-regulated current outputs • Output current (per ch.): 350 mA ° High-accuracy LED current regulation • No. of LEDs (per ch.): 12 ° External resistor-programmable output current • LED power: 53.3W• Requires no magnetic component (inductor) • AC/DC converter efficiency: 83.8% ° No cross interference among output channels • System efficiency with LM3464: 82.2% ° Eases EMC filter design • LM3464 driver stage efficiency: 98.1% Conventional Off-Line AC/DC Converter LM3464 LED Driving Stage Temperature Sensor (Optional) High-Power LED Arrays DOUT Bridge Rectifier COUT CVCC2 CIN AC Input Voltage CVCC1 (110 VAC) VIN MOSFET Ropto VIN SW RFB1 ISNS Opto1 RSENSE LM3464 GD1 Q1 AC/DC Fly-Back Ccomp SE1 Controller GD2 Q2 RDHC SE2 VFB OUTP Q3 GD3 LM431 SE3 RFB2 GD4 Q4 SE4 GND GND RISNS1 RISNS2 RISNS3 RISNS4 AGND General Structure of the LM3464 Illumination System20
  • 21. Designer’s Corner EMI Design for Outdoor High-Power Wide AreaEMI Design for LED Street Lamp ApplicationThe LM3402HV circuitry shown in Figure 1 is based on a street The modifications are:lamp application. The input is 48 VDC and the output is 12 series- 1: One resistor Rz (50 Ω) is added between the SW pin and Cbconnected 1W LEDs. To address the EMI concerns, the schematic pin. This changes the SW node waveform from Figure 3 toand PCB layout were modified. As a result of the modifications, as Figure 4. The criterion of Rz selection is dependent on the SWshown in Figure 2 below, better EMI performance was achieved turn-on slew rate and its ringing. The smaller the ringing,and the design passed the EN55022 standard. the better. 2: 1 μF output cap is added across LED connection port. 3: Input loop area should be kept as small as possible, which is shown in the blue-dashed area of Figure 5. CIN should be connected with the anode of catch diode directly. 4: The SW node should be kept as short as possible. CB L1 Radiated Emission Measurement 10 nF RZ 220 μH LED+ 2 CIN U1 50R VIN 2.2 μF/63V 8 1 D1 BOOT VIN SW COUT SS110 Ron 2M LM3402HVMR 1 μf 6 RON 5 CS LED- DIM1 GND 3 7 DIM VCC RSNS CF 0.68R 100 nF 4 Figure 1 Figure 2 Pulsating Current ST High dv/dt node ESRIN LF SW CHF VIN CIN + - I PGND Figure 3 Figure 4 Figure 5national.com/LED 21
  • 22. High-Brightness LED ApplicationsPortable ProjectorsPortable Projector• The LM3433/34 is a high-power constant-current LED driver controller which employs a negative synchronous buck topology, making it ideal for applications where a common- anode LED system is used for high current output.• An example power architecture of a portable projector using the LM3433 is shown below. The -12 VDC isolated AC/DC SMPS is used for powering LM3433 LED drivers while the LM3481 floating buck-boost is used to generate positive outputs for other logic and interface. Common Anode Window LM3433 Heat Sink TJ Die Junction Negative Buck LED Driver TB Window Frame LM3433 Negative Buck Thermistor HB LED Driver THS -12 VDC Output TREF LM3433 HB LED Driver Copper core-board Negative Buck Isolated AC/DC Chassis SMPS Heat Sink LM3481 Floating +12V/4A for other Buck-boost Converter electronics 85-264 VAC r 44.2k 0.1 LED ANODE μF Q3 Q1 CSN DMO DIMR CSP BST2 270 pF HO -12V LED TON HS ADJ ADJ 0.47μF EN EN LM3433 BST 6 μH 0.01 LED CATHODE DIM DIM VCC +3.3V VIN Q2 COMP LO CGND VEE 22 μF SS LS 4.7 μF 2.2 μF GND 0.01 μF -12V22

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