LM3402 Reference Design - 1 InGaN LED, 350 mA

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Design Specifications

Inputs	Outputs #1
VinMin=6	Vout1=3.5
VinMax=42	Iout1=0.350

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	C3216X7R1H105M	NumCaps=1, 1u F
D1	Central Semiconductor	CMSH1-60M	0.5 V
L1	TDK	SLF10145T-101M1R0	100u H, 0.2 Ohms
Ron	Vishay	CRCW08054642F	46.4k Ohms
Rsns	Panasonic	ERJ6BQFR62V	0.62 Ohms
U1	National Semiconductor	LM3402

Design Description

This LM3402 circuit and BOM have been designed to provide a constant forward current of 350 mA to a single LED with a forward voltage of approximately 3.5V. (Typical of white, blue, and green LEDs using InGaN technology.) When powered from a 24V +-5% input the circuit will maintain the average LED current to within 10% of 350 mA. The ripple current will not exceed 70 mA peak-to-peak. Switching frequency for this design is 500kHz +-10% when the input is 6V to 42V.

Schematic

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