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Linear Technology Corporation. LT3743 Presentation September 2009 Tony Armstrong Director of Product Marketing, Power Products. LT3743: What Is It?. Synchronous Step-Down LED Driver Can Drive up to 20A of Continuous LED Current Can Drive up to 40A of Pulsed LED Current
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Linear Technology Corporation LT3743 Presentation September 2009 Tony ArmstrongDirector of Product Marketing, Power Products
LT3743: What Is It? • Synchronous Step-Down LED Driver • Can Drive up to 20A of Continuous LED Current • Can Drive up to 40A of Pulsed LED Current • VIN Range of 5.5V to 36V • PWM Dimming Provides up to 3,000:1 Dimming Ratio • CNTRL_SEL Dimming Provides up to 3,000:1 Dimming Between CNTL_L and CNTRL_H Current Levels • Three-State Current Control for Color Mixing • 2usec Maximum Recover Time Between any Current Regulation State
LT3743 : Key Features • PWM Dimming Provides Up to 3000:1 Dimming Ratio • CTRL_SEL Dimming Provides Up to 3000:1 Dimming Ratio Between Any Current Levels (CTRL_H and CTRL_L) • Up to 95% Efficiency (20A LED from 12V) • Three-State Current Control for Color Mixing • 4% Current Regulation Accuracy • 5.5V to 36V Input Voltage Range • Average Current Mode Control • 2μsec Maximum Recovery Time Between Any Current Regulation State • 0μA Shutdown Current • Output Voltage Regulation and Open-LED Protection • Thermally Enhanced 4mm × 5mm QFN and 28-Pin FE Package
LT3743 – Typical Application 95% Efficient 10VIN to 30VIN, 20A LED Driver
LT3743 – Typical Application 0A to 2A to 20A LED Current Steps
LT3743 – Two Loops for Fast LED Currents Fast PWM Dimming Achieved with two switched capacitors and separate compensation
Typical Interleaved RGB Systems High Current level LED “off” Only 2 LED current levels: “ON” or “OFF”
High-Performance Interleaved RGB Systems High Current level Low Level Current for Optimizing Color Sometimes LED is “OFF” For Optimal Color Control, Fast Rise and Fall times are required
LT3743 – DLP Projector LED Driver 24VIN, 20A LED Driver Used Only to Measure Fast Current Waveforms; Not Needed in Real Circuit Using a wire loop with a DC Current Probe introduces enough inductance to slow down the LED current rise/fall times.
LT3743 PWM Dimming2A to 20A LED Current Transitions using CTRL_SEL <2msec rise time! <2msec fall time! 20A 2A ~1.0inch2 PCB Area
LT3743 Three-state Dimming3-State LED Current Dimming using PWM and CTRL_SEL <2msec rise time! <2msec fall time! 20A 2A 0A
LT3743 – Applications We Have Built Single LED drivers optimized for LED currents 1) up to 10A (95% efficiency from 12Vin) 2) 10A – 20A (95% efficiency from 12Vin) 3) pulsed 40A (89% efficiency from 12Vin) 4) pulsed 80A using two of the 40A circuits in parallel Multi-LED driver (for Luminus CBM-360 part: 4x 3.5A LEDs in series) 5) 3.5A (96% efficiency from 24Vin) 6) pulsed 9A with the same circuit as 5) For 1) 2) and 5) the circuits can operate at 100% duty cycle. For 3) 4) and 6) the circuits have more heat to dissipate, and are designed for pulsed loads only
LT3743 – DemoBoard ~25x25mm2 PCB Area 4mm x 5mm QFN
Typical Market Applications • DLP Projectors • Laser Diode Applications • High Power Architectural Lighting • High Power Industrial Lighting