Dual channel LED driver for range of lighting applications

A dual channel, 36V high efficiency, synchronous, step-down LED driver from Analog Devices has internal 40V, 1.6A power switches and an I2C interface. The LT3964 operates from an input ranging from 4V to 36V and features two independently controlled LED drivers that switch at up to 2MHz.

The LT3964 features fixed frequency, current mode control, allowing it to operate as a constant-current and constant-voltage source with accurate current regulation. This, says the company, provides optimal LED lighting in automotive, industrial and architectural lighting applications. Meanwhile, synchronous operation results in efficiencies of more than 94% with both channels at full current load.

A 400kHz I2C interface simplifies digital PWM dimming. Instead of a PWM signal being sent from an MCU to the LED driver, internal registers are programmed with the desired dimming duty cycle, which is synchronised to the internal clock. This provides dimming ratios up to 8192:1 and eliminates beat frequencies. Alternatively, with analogue dimming, an 8bit scale factor can be set via the I2C interface to control the voltage-to-LED current ratio.

With a switching frequency programmable from 200kHz to 2MHz or synchronised to an external clock, the part features open LED and short-circuit LED fault detection, and LED overcurrent and overvoltage detection, all reportable via the I2C interface. Thermal shutdown is also provided.

Supplied in a thermally enhanced 36-lead 5 x 6mm QFN, the LT3964 is available in three temperature grades, with operation from –40 to 125°C (Tj) for the extended and industrial grades and a high temperature grade of –40 to 150°C.