Electronic Products & Technology

Synchronous step-down LED driver delivers over 20A of continuous LED current


Electronics CEL

Linear Technology announces the LT3743, a synchronous step-down DC/DC converter designed to deliver constant current to drive high current LEDs.

The device’s 5.5V to 36V input voltage range makes it ideal for a wide variety of applications, including industrial, DLP projection and architectural lighting. The LT3743 provides up to 20A of continuous LED current from a nominal 12V input, delivering in excess of 80 Watts. In pulsed LED applications, it can deliver up to 40A of LED current or 160 Watts from a 12V input. Efficiencies as high as 95% eliminate any need for external heat sinking and significantly simplify the thermal design. A frequency adjust pin enables the user to program the frequency between 100kHz and 1MHz so designers can optimize efficiency while minimizing external component size. Combined with a 4mm x 5mm QFN or thermally enhanced TSSOP-28 package, the LT3743 offers a very compact high-power LED driver solution.

The LT3743 offers both PWM and CTRL_SELECT dimming, offering 3,000:1 dimming capability at three LED current levels, making it ideal for color mixing applications such as those required in DLP projectors. Similarly, the LT3743’s unique topology enables it to transition between two regulated LED current levels in less than 2µsec, enabling more accurate color mixing in RGB applications. LED current accuracy of ±6% is maintained in order to ensure the most accurate luminosity of light from the LED. Additional features include output voltage regulation, open-LED protection, overcurrent protection and a thermal derating circuit.

Summary of Features: LT3743


– PWM Dimming Provides Up to 3000:1 Dimming Ratio
– CTRL_SEL Dimming Provides Up to 3000:1 Dimming Ratio Between Any Current
– Three-State Current Control for Color Mixing
– ±6% Current Regulation Accuracy
– 5.5V to 36V Input Voltage Range
– Average Current Mode Control
– 2µs Maximum Recovery Time Between Any Current Regulation State
– 1µA Shutdown Current
– Output Voltage Regulation & Open-LED Protection
– Thermally Enhanced 4mm × 5mm QFN & 28-Pin FE Package



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