60-V synchronous buck-boost LED driver delivers more than 100-W of LED power

March 12, 2012 // By Paul Buckley
Linear Technology has introduced a synchronous buck-boost DC/DC LED driver and voltage controller, which can deliver over 100 W of LED power. The device’s 4.7 V to 60 V input voltage range makes it ideal for a wide variety of applications, including automotive, industrial and architectural lighting.

Similarly, its output voltage can be set from 0 V to 60 V, enabling the LT3791 to drive a wide range of LEDs in a single string. Its internal 4-switch buck-boost controller operates from input voltages above, below or equal to the output voltage, ideal for applications such as automotive, where the input voltage can vary dramatically during stop/start, cold crank and load dump scenarios. Transitions between buck, pass-through and boost operating modes are seamless, offering a well-regulated output even with wide variations of supply voltage. The LT3791’s design utilizes three control loops to monitor input current, LED current and output voltage to deliver optimal performance and reliability.

The LT3791 uses four external switching MOSFETs and delivers from 5 W to over 100 W of continuous LED power with efficiencies up to 98.5%. LED current accuracy of ±6% ensures constant lighting while ±2% output voltage accuracy enables the converter to operate as a constant voltage source. The LT3791 utilizes either analog or PWM dimming as required by the application. Furthermore, its switching frequency can be programmed between 200 kHz and 700 kHz or synchronized to an external clock. Additional features include output disconnect, input and output current monitors, open and shorted LED detection and integrated fault protection.

Availability and Pricing

The LT3791EFE is available in 38-lead thermally enhanced TSSOP package, priced starting at $4.75 each in 1,000-piece quantities. An extended temperature version, or I grade, the LT3791IFE, is also available, priced starting at $5.25 each in 1,000-piece quantities. A high temperature version, or H grade, the LT3791HFE, is also available, priced starting at $5.50 each in 1,000-piece quantities. There is also a high reliability MP grade version, LT3791MPFE, available starting at $14.75 each in 1,000-piece quantities.

All versions are available from stock.

For more information about the LT3791 synchronous buck-boost DC/DC LED driver and voltage controller www.linear.com/product/LT3791