LM3402 Reference Design - 2 InGaN or 3 AlInGaP LEDs, 470 - 500 mA

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  Design Specifications
Inputs Outputs #1
VinMin=10 Vout1=6.8
VinMax=30 Iout1=0.5
   Design Resources
LM3402 Reference Design

  Additional Resources

•LM3402 Product Folder
•LM3402EVAL Evaluation Board
    Bill Of Materials
Part Manufacturer Part# Attributes
Cb Vishay VJ0805Y103KXXAT 10n F
Cf Vishay VJ0805Y104KXXAT 100n F
Cin TDK C3225X7R1H225M NumCaps=1, 2.2u F
D1 Central Semiconductor CMSH1-40M 0.5 V
L1 TDK SLF10145T-150 150u H, 0.47 Ohms
Ron Vishay CRCW0805F xxxk Ohms
Rsns Panasonic ERJ6BQFR43V 0.43 Ohms
U1 National Semiconductor LM3402

  Design Description
These circuits are designed to drive a string of 2 InGaN LEDs or 3 AlInGaP LEDs in series (Vf total 6.6V) at a forward current of 470 mA to 500 mA with a peak-to-peak ripple current of 100 mA or less. The input is 10V to 30 and the switching frequency is 400 kHz +-10%.

This circuit is rated to withstand input voltage transients up to 40V.



  Schematic
Example Schematic Showing Connection for all Components.