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Bringing light to life. Najmi Kamal Power Design Engineer for Lighting. March 2012. TI Lighting System Solution. NSC + TI = strong system level know-how . Lighting Summary. - PowerPoint PPT Presentation


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Bringing light to lifeMarch 2012

Najmi KamalPower Design Engineer for Lighting

1ApplicationsGeneral Illumination Retrofit Commercial Professional Back Lighting Portable Monitor Digital TVAutomotive Exterior Lighting

ExpertiseAC/DC Analog Digital DC/DC Analog DigitalLinearWireless & PLCLight Measurement

Full System SolutionsPower ManagementMulti-StringSingle-StringMulti-StageSingle-StageMonitoringCommunication

ResourcesEVMsCook BookRef. designsSample softwareApplication reportsLocal design servicesLighting training supportTI Solid State Lighting (SSL) Core Competencies

Lighting Know-HowHighPerformanceSolution

223Market Segment Focus

High Power Wide Area LM340x

Downlighting LM3464,LM3466LED Lamp LM3445,TPS92310

Automotive LM342x, LM3409 Street Lights Parking Lights Ext. Building Energy Saving intelligent Lights Public Buildings Commercial Energy SavingCost drivenHigh Light quality Cost driven Fast growth

TI Lighting System SolutionNSC + TI = strong system level know-how

44Lighting Portfolio LED driver Architecture Dimming techniques LED driverMR16 LED bulb designController, Ref designHigh brightness LEDs driverOff line LED Bulb/T8 Ref designMulti Channel LED driverSystem solutions ( Triac, DALI, 0 to 10V)WEBENCH Architect

Lighting Summary6Texas Instruments Current LED Driver Solutions

Quick Selection guide DC/DC Buck Converters for LED Lighting2A1.5A1A0.5A0.35A102030405060708090TPS92510 (RTM:10/2011) MAX LED CurrentInput Voltage (V)LM3402HVLM3402LM3404HVLM3404LM3406HVLM3406 ALM3405LM3407LM3414HVLM3414TPS92501 (RTM:12/2011) How to drive LEDs?With current (high end system)Light output is proportional to forward currentBrightness AND color can change with current

With power(low end system)Bulb

8N or P FETDuty Cycle Limits Max VO in BucksHigh 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 VINThis section of a block diagram is from the LM3404, but it applies to the LM3402 and LM3406 as well.Do you have an idea why we didnt use in the past P mosfet but N mosfte driver?PFET Bucks Can Provide 100% Duty CycleHigh Side P-MOSFETs11

Gate is driven below source to turn the PFET ONGate can drive to VCC indefinitelyPFET can stay on indefinitelyTrue 100% duty cycle capabilityBuck is better than buck-boostBetter efficiencyLess partsFaster dimmingThe LM3401 and LM3409/09HV are all PFET bucksDimming13Various dimming techniques Dimming using PWM signal

White LEDs change Colour over Current! Solution:Maintain Current and Change ON-Time = PWM

4/4/20121314Two different PWM dimming methods First method: Dim 1: Continuous inductor current (Good EMC, extra Mosfet ) Second method: Dim 2: more efficient (2khz dim max)

4/4/201214Output capacitor for a Buck topology+-+LCOVINDILVFBVF+-+-RFBICIoVoVo Limited by VIN

Cout not needed

Continuous output current, low EMI

Easy to stabilize, if needed

Inherent protections against failure

16Buck (step-down) DCM or CCMDo we need an output cap for driving LEDs ?Since we need a current source and not voltage source.In CCM mode you can leave without cap but big inductor and EMI PBIn DCM mode small inductor and big cap.The best is in between.

17BUCK - To Cap or Not to CapNo Output CapacitorNo output cap provides high output impedanceSaves a componentLeads to higher LED ripple currentMay generate more electromagnetic interference (EMI)With Output CapacitorAdding an output cap reduces ripple currentSmall cap + small inductor is smaller than one large inductorSlows pulse-width modulation (PWM) dimmingMust be rated to VIN in case of output open circuit18BUCK - To Cap or Not to CapNo Output CapWith Output Cap

Note inductor height as well

4.5mm1.4mmThree Pieces of the Puzzle

Thermal Critical. Good designs integrate heat sinking into the design of the lamp

Optical Just as critical, must be integrated into the mechanical design of the lamp

LED Driver Critical.Must be good designs.(Efficient, small size,EMI/Safety proved) 19LED DriversLM3409/09HV: High-Side PFET Buck Controller21VIN 6V to 42V (LM3409)VIN 6V to 75V (LM3409HV)External power PFET100% Duty Cycle CapableOutput Currents up to 4A Differential, high-side current senseSimplifies system wiringPWM dimming and analog dimming at 1000:1Thermally enhanced eMSOP-10 packageNo control-loop compensation

The LM3409 and LM3409HV are buck PFET controllers that extend the input voltage range of the LM3401 and provide several new features at the same time. These controllers use a constant off-time control scheme which naturally combines the safety current limit with peak current control. Like the LM3401 the LM3409 is capable of a true 100% duty cycle, but it adds two important features. First, the current sensing is done on the high side. Within National, high-side current sensing means that the current sense resistor is placed before the anode of the first LED. The principal advantage of this is the simplification of the wiring. LED current returns through system ground, and this eases the design of systems with wiring harnesses, especially those where the LEDs are placed on a separate PCB or are physically distant from the drive electronics. The second addition to the LM3409 is the IADJ pin, which is designed for linear adjustment of the LED current. A 5 A current source flows from IADJ, allowing the user to set the current sense voltage by placing a resistor from IADJ to ground. The user can also apply a control voltage to IADJ, which then directly sets the current sense voltage. Both methods allow the user to make the tradeoff between power dissipation in the current sense resistor and the accuracy of the LED current. Linear dimming also opens the door to simple temperature or ambient light feedback loops.22LM3401 Hysteretic PFET controller HB LED DriverKey Features

VIN Range: 4.5V 35VOutput range: 0.2V (Vfb) to VIN, adjusts to deliver constant current to up to 9 HB LEDs in series with scalable LED current > 2ANo output cap, no compensation componentsLogic level dimming 1% to 100%, 70nS delayControlled start up allows PWM at Vin for dimmingPFET driver 100% duty cycle capableAdjustable Dual Side HysteresisAdjustable ripple currentFlexible inductor selectionFine tuning of switching frequency up to 1.5MHzMSOP-8 package

Applications:Automotive Lighting, General Illumination, MR16 replacement, Industrial Lighting, Gaming, High-end LCD Backlighting

VIN can also be used for PWM dimming when a logic signal is not available. In this mode of operation DIM should be connected to VIN through a 10 k resistor. There is typically 10 us of startup delay time when using VIN for dimming. Depending on the application, this de-lay limits the maximum dimming frequency to typically several hundred Hz.

When 100% duty, Vo=Vin, I_LED is fixed to I_LED_MAX (L is a short).

HYST control Vo goes between Vref HYS and Vref + HYSRsns ADJUST THE OUTPUT CURRENTHyst adjust the hysterisys

CS detect the max peak current and switch off the mosfetI lim adjust the peak current23Hysteretic Control (LM3401)Fast load Transient / no compensation requiredFsw changes with VIN and VOUTILED Ripple constant


4/4/20122324Runs from 6V to 35VDrives one white LED in at 800 mAHigh-side PFET topology can do 100% duty cycleRef design: LM3401 - 20 Cent-Sized PCB

25Key Features: COT

VIN Range:LM340X: 6V 42V, BuckLM340XHV: 6V 75V, Buck True average current controlTwo PWM LED dimming options:Fast logic pin PWM dimmingLM3406: 2-wire dimming by VIN pin-70%Feedback Voltage = 200mVInternal NFET for reduced parts countSwitching Frequency up to 1MHz Exposed pad eTSSOP-14 packageDrives 1W, 3W, and higher powered LEDsLM3402/4/6 and LM3402HV/4HV/6HV 0.5A/1.0A/1.5A HB LED Driver

Fast PWM Dim2-Wire Dim Applications:Automotive Lighting, General Illumination, Industrial Lighting, ArcitectualLM3402 COT: in CCM, fsw costant enough with the Vin - ton inv. Proportionally to Vin - 1W LM3404 COT: in CCM, fsw costant enough with the Vin - ton inv. Proportionally to Vin -3.5WLM3406 COT: in CCM, fsw costant enough with the Vin - ton inv. Proportionally to Vin -5W

Adding an external input diode and using the internal VINS comparator allows the LM3406/06HV to sense and respondto dimming that is done by PWM of the input voltage. If the VINS pin voltage falls 70% below the VIN pin voltage, the LM3406/06HV disables the internal power FET and shuts off the current to the LED array. The support circuitry (driver, bandgap, VCC) remains active in order to minimize the time needed to the turn the LED back on when the VINS pin voltage rises and exceeds 70% of VIN. This minimizes the response time needed to turn the LeD array back on.he LM3402, 04 and 06 all feature internal power MOSFETs, giving them the advantage of reduced component count, smaller solution footprint, and built in safety features such as current limit and thermal shutdown. Because power LED currents have coalesced around several discrete points, each member of the LM340x family specifies a minimum current limit over the full temperature range that takes into account both the average current and gives headroom for a wide LED ripple current. These minimum current limit thresholds have been set to allow the ripple currents to be 30% or more peak to peak. All the members of the LM340x family operate over Nationals industrial temperature range of minus 40 to plus 125 degrees celsius, which means that the lighting designer can count on getting the full drive current plus ripple even in har