Triple LED Driver in 4mm × 5mm QFN Supports LCD Backlights in Buck, Boost or Buck-Boost Modes and Delivers 3000:1 PWM Dimming Ratio
by Hua (Walker) Bai, Linear Technology, Vendor website, Sep 01 2008
Focus:
Designs based on the LT3496 three-channel LED driver IC power up to three strings of high-power LEDs, while operating at a 2.1-MHz switching frequency to achieve a small design size and allowing a 3000:1 PWM dimming ratio. These designs operate from dc sources using buck, boost, or buck-boost topologies. A buck design drives 3 strings of 8 to 12 LEDs at 500 mA and fits in a 16-mm x 16-mm footprint. A boost design drives 3 strings of up to 7 LEDs at 200 mA while operating from a regulated 12 V. For automotive applications, a buck-boost design drives 3 strings of four LEDs at 200 mA per channel while operating from an 8-V to 16-V source and withstanding load-dump transients up to 40 V.
What you’ll learn:
- How to build a compact buck converter that drives 3 strings of 8 to 12 LEDs at 500 mA
- How to build a compact boost converter that drives 3 strings of up to 7 LEDs from a 12-V source
- How to build a compact buck-boost converter that drives 3 strings of 4 LEDs at 200 mA while withstanding automotive load-dump transients
Notes:
Linear Technology Design Note 449
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