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Low Noise White LED Power Supply Circuit w/ Current Control

Topics: LED Circuits

Uses an LTC3201 to provide an adjustable ultra-smooth supply current to white LEDs.

Screenshot: Low Noise White LED Power Supply Circuit w/ Current Control

The LTC 3201 is an ultralow noise, constant frequency, charge pump DC/DC converter specifically designed for powering white LEDs. The part produces a low noise boosted supply capable of supplying 100mA of output current. LED current is regulated for accurate and stable backlighting. A 3-bit DAC provides output current adjust for brightness control.

Low external parts count (one small flying capacitor and three small bypass capacitors) and small MSOP-10 package size make the LTC3201 ideally suited for space constrained applications. An input noise filter further reduces input noise,thus enabling direct connection to the battery. High switching frequency enables the use of small external capacitors.

The LTC3201 contains overtemperature protection and can survive an indefinite output short to GND. Internal soft-start circuitry also prevents excessive inrush current on start-up. A low current shutdown feature disconnects the load from VIN and reduces quiescent current to less than 1μA.

  • Input Noise Filter Minimizes Supply Noise
  • Constant Frequency Operation
  • 3-Bit LED Current Control
  • No Inductors
  • Low Shutdown Current: IIN < 1μA
  • Output Current: 100mA
  • VIN Range: 2.7V to 4.5V
  • 1.8MHz Switching Frequency
  • Soft-Start Limits Inrush Current at Turn-On
  • Short-Circuit and Overtemperature Protected
  • Available in 10-Pin MSOP Package
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