LT3478 and LT3478-1, two 40V, 4.5A dc-dc converters designed to drive high-current LEDs at constant current. Their 2.8V to 36V input range suits them for a variety of applications, including automotive, industrial, and architectural lighting. In boost mode, the LT3478/-1 can drive up to six 700mA LEDs in series from a 12V input, targeting the device for automotive display backlighting.
The LT3478-1 uses an internal current sense resistor, limiting output current to 1A, whereas the LT3478 uses an external sense resistor to extend the maximum LED current up to 4.5A. Both parts can deliver efficiencies up to 90% in boost mode from a thermally enhanced TSSOP-16E package.
The devices use True Colour PWM dimming, which delivers constant LED colour with dimming ranges up to 3000:1. A fixed-frequency, current-mode architecture offers stable operation over a wide range of supply and output voltages. Also, a frequency-adjust pin lets users program the frequency between 200kHz and 2.25MHz.