LM3414MRX

LM3414/LM3414HV 1A 60W* Common Anode Capable Constant Current Buck LED Driver Requires No External Current Sensing Resistor August 9, 2010 LM3414/LM3414HV 1A 60W* Common Anode Capable Constant Current Buck LED Driver Requires No External Current Sensing Resistor General Description The LM3414 and LM3414HV are 1A 60W* common anode capable constant current buck LED drivers. They are exceptionally suitable to drive single string of 3W HBLED with up to 96% efficiency. They accept input voltages from 4.5VDC to 65VDC and deliver up to 1A average LED current with ±3% accuracy. The integrated low-side N-channel power MOSFET and current sensing element realize simple and low component count circuitry as no bootstrapping capacitor and external current sensing resistor are required. An external smallsignal resistor to ground provides very fine LED current adjustment, analog dimming as well as thermal fold-back functions. Constant switching frequency operation eases EMI. No external loop compensation network is needed. The proprietary Pulse-Level-Modulation (PLM) control method benefits in high conversion efficiency and true average LED current regulation. Fast response time realizes fine LED current pulse fulfilling the 240 Hz 256-step dimming resolution requirement for general lighting. The LM3414 and LM3414HV are available in ePSOP-8 and 3mm x 3mm LLP-8 packages. *Thermal de-rating applies according to actual operation conditions Features ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Support LED power up to 60W*: 18x 3W HBLEDs Requires NO external current sensing resistor ±3% LED current accuracy Up to 96% efficiency High contrast ratio (Minimum dimming current pulse width 0. DESIGN CONSIDERATIONS The overall performance of the LED driver is highly depends on the PCB layout and component selection. To minimize connection losses and parasitic inductance of the traces, the best practice is to keep the copper traces connecting the inductor, power switch and rectifier short and thick . Long traces on critical power paths will introduce voltage and current spikes to the LM3414/LM3414HV. If the voltage spike level exceeds the absolute maximum pin voltage of the LM3414, it could damage the device and LEDs. To avoid physical damage of the circuit, a Transient Voltage Suppressor (TVS) can be added across VIN and GND pins to suppress the spike voltage. This also helps in absorbing the input voltage spike when the circuit is powered through physical switch upon power up. 17 www.national.com LM3414/LM3414HV Additional Application Circuit 30124828 FIGURE 8. LM3414/14HV Design Example (IOUT = 500 mA) Bill of Materials Designation U1 L1 D1 CIN CVCC RIADJ RFS Description LED Driver IC LM3414 / LM3414HV Inductor 47 µH Schottky Diode 100V 2.0A Cap MLCC 100V 2.2 µF X7R Cap MLCC 16V 1.0 µF X5R Chip Resistor 3.24 kΩ 1% Chip Resistor 40.2 kΩ 1% Package ePSOP-8 8 x 8 x 4.9 (mm) SMP 1210 603 603 603 Manufacture Part # LM3414 / LM3414HV MMD-08EZ-470M-SI SS2PH10-M3 GRM32ER72A225KA35L GRM39X5R105K16D52K CRCW06033241F CRCW06034022F Vendor NSC Mag.Layers Vishay Murata Murata Vishay Vishay 30124829 FIGURE 9. Application Circuit of LM3414/14HV with Temperature Fold-Back Circuitry and PWM Dimming www.national.com 18 LM3414/LM3414HV Physical Dimensions inches (millimeters) unless otherwise noted 8-Lead LLP Package NS Package Number SDA08A 8-Lead ePSOP Package NS Package Number MRA08B 19 www.national.com LM3414/LM3414HV 1A 60W* Common Anode Capable Constant Current Buck LED Driver Requires No External Current Sensing Resistor Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: www.national.com Products Amplifiers Audio Clock and Timing Data Converters Interface LVDS Power Management Switching Regulators LDOs LED Lighting Voltage References PowerWise® Solutions Temperature Sensors PLL/VCO www.national.com/amplifiers www.national.com/audio www.national.com/timing www.national.com/adc www.national.com/interface www.national.com/lvds www.national.com/power www.national.com/switchers www.national.com/ldo www.national.com/led www.national.com/vref www.national.com/powerwise WEBENCH® Tools App Notes Reference Designs Samples Eval Boards Packaging Green Compliance Distributors Quality and Reliability Feedback/Support Design Made Easy Design Support www.national.com/webench www.national.com/appnotes www.national.com/refdesigns www.national.com/samples www.national.com/evalboards www.national.com/packaging www.national.com/quality/green www.national.com/contacts www.national.com/quality www.national.com/feedback www.national.com/easy www.national.com/solutions www.national.com/milaero www.national.com/solarmagic www.national.com/training Applications & Markets Mil/Aero PowerWise® Design University Serial Digital Interface (SDI) www.national.com/sdi www.national.com/wireless www.national.com/tempsensors SolarMagic™ THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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