LT3478-1 Datasheet

• True Color PWM^™ Dimming Delivers Constant LED Color with Up to 3000:1 Range
• Wide Input Voltage Range: 2.8V to 36V
• 4.5A, 60mΩ, 42V Internal Switch
• Drives LEDs in Boost, Buck-Boost or Buck Modes
• Integrated Resistors for Inductor and LED Current Sensing
• Program LED Current:
  • 100mA to 1050mA (LT3478-1)
• Program LED Current De-Rating vs Temperature
• Separate Inductor Supply Input
• Inrush Current Protection
• Programmable Soft-Start
• Fixed Frequency Operation from 200kHz to 2.25MHz
• Open LED Protection (Programmable OVP)
• Accurate Shutdown/UVLO Threshold with Programmable Hysteresis
• 16-Pin Thermally Enhanced TSSOP Package

• High Power LED Driver
• Automotive Lighting

The LT3478-1 are 4.5A step-up DC/DC converters designed to drive LEDs with a constant current over a wide programmable range. Series connection of the LEDs provides identical LED currents for uniform brightness without the need for ballast resistors and expensive factory calibration.

The LT3478-1 reduces external component count and cost by integrating the LED current sense resistor. Operating frequency can be set with an external resistor from 200kHz up to 2.25MHz. Unique circuitry allows a PWM dimming range up to 3000:1 while maintaining constant LED color. The LT3478-1 are ideal for high power LED driver applications such as automotive TFT LCD backlights, courtesy lighting and heads-up displays. One of two CTRL pins can be used to program maximum LED current. The other CTRL pin can be used to program a reduction in maximum LED current vs temperature to maximize LED usage and improve reliability.

Additional features include inrush current protection, programmable open LED protection and programmable soft-start. Each part is available in a 16-pin thermally enhanced TSSOP Package.