LM3402 Reference Design - 1 InGaN UV LED, 420 mA

Design Specifications

Inputs	Outputs #1
VinMin=6	Vout1=3.8
VinMax=42	Iout1=0.420

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
Co	TDK	C2012X7R1C105M	1u F
D1	Central Semiconductor	CMSH1-60M	0.5 V
L1	TDK	SLF7032T-330MR75-2	33u H, 0.15 Ohms
Ron	Vishay	CRCW08058062F	80.6k Ohms
Rsns	Panasonic	ERJ6BQFR56V	0.56 Ohms
U1	National Semiconductor	LM3402

Design Description

This circuit is designed to drive a single InGaN UV LED (VF = 3.8V) at a forward current of 420 mA with a peak-to-peak ripple current of 80 mA or less. The input is 6V to 42V, with LED current and switching frequency (400 kHz) optimized at Vin = 13.8V.

This circuit is rated to withstand input voltage surges up to 42V.

Schematic

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