LT3954 uses an internal 5A, 40V N-channel MOSFET and can drive up to eight 650mA white LEDs from a nominal 12V input, delivering in excess of 20 watts. It incorporates a high-side current sense, enabling use in boost mode, buck mode, buck-boost mode or SEPIC topologies. The LT3954 can deliver efficiencies of over 95% in the boost topology, eliminating the need for external heat sinking.
A frequency adjust pin permits the user to program the frequency between 100kHz and 1MHz, optimizing efficiency while minimizing external component size and cost. Combined with a 5mm x 6mm QFN package, the LT3954 offers a highly compact high power LED driver solution.
The LT3954 has an internal PWM generator that delivers dimming ratios as high as 25:1 or it can utilize an external PWM signal, delivering dimming ratios of up to 3,000:1. For less demanding dimming requirements, the CTRL pin can be used to provide a 10:1 analog dimming range. Its fixed frequency, current-mode architecture offers stable operation over a wide range of supply and output voltages. Output short-circuit protection and open LED protection enhance system reliability. The LT3954’s ground-referenced voltage FB pin serves as the input for several LED protection features and makes it possible for the converter to operate as a constant-voltage source for charging applications.
The LT3954EUHE is available in a 36-lead 5mm x 6mm QFN package. Pricing starts at $3.60 each. An extended temperature version, or I grade, the LT3954IUHE, is also available, priced starting at $3.96 each. All pricing is based on 1,000-piece quantities and both versions are available from stock.
Summary of Features: LT3954
• 3000:1 True Color PWM™ Dimming for LEDs
• Wide VIN Range: 4.5V to 40V
• Rail-to-Rail Current Sense Range: 0V to 40V
• Internal 40V/5A Switch
• Programmable PWM Dimming Signal Generator
• Constant Current (±3%) & Constant-Voltage (±2%) Regulation
• Accurate Analog Dimming
• Drives LEDs in Boost, SEPIC, CUK, Buck Mode, Buck-Boost Mode, or Flyback Configuration
• Output Short-Circuit Protected Boost
• Open LED Protection & Reporting
• Adjustable Switching Frequency: 100kHz to 1MHz
• Programmable VIN UVLO with Hysteresis
• C/10 Indication for Battery Chargers
• Low Shutdown Current: <1µA
• Thermally Enhanced 5mm × 6mm QFN-36 Package