Synchronous buck-boost LED driver achieves 98% efficiency

Linear Technology announces the LT3791, a synchronous buck-boost dc-dc LED driver and voltage controller, which can deliver more than 100 W of LED power. Its 4.7 to 60 V input voltage range makes it well suited to a variety of applications, including automotive, industrial, and architectural lighting. Output voltage can be set from 0 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, helpful in 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 unique 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 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 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.

The LT3791EFE is available in a 38-lead thermally enhanced TSSOP package. An Extended temperature high temperature, and high reliability versions are also available.

For more information, contact Linear Technology Corp., 1630 McCarthy Blvd., Milpitas, CA 95035. Phone: (408) 432-1900.