LM3402 Reference Design - 2 InGaN LEDs, 350 mA

Design Specifications

Inputs	Outputs #1
VinMin=9	Vout1=7.2
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	C3225X7R1H335M	NumCaps=1, 3.3u F
D1	Central Semiconductor	CMSH1-60M	0.5 V
L1	TDK	SLF7045T-680MR75-1PF	68u H, 0.27 Ohms
Ron	Vishay	CRCW08057682F	76.8k Ohms
Rsns	Panasonic	ERJ6BQFR62V	0.62 Ohms
U1	National Semiconductor	LM3402

Design Description

This circuit has been designed to drive a string of two InGaN white, blue or green LEDs (total Vo = 7.2V) at a forward current of 350 mA +-10% mA with a peak-to-peak ripple current of 130 mA or less. The input is 9V to 42V, with LED current and switching frequency (700 kHz) centered at Vin = 24V.

In expectation of fast PWM dimming requirements there is no output capacitor used in this design.

Schematic

The WEBENCH® Electrical Simulator requires the Adobe Flash Player minimum version of 8,0,0,0.

A new browser window has been launched (a pop-up) to install the Flash player.
Please disable the appropriate browser pop-up blockers.

It appears that your web browser does not have any Flash plugin or at least not the required version.
We recommend that you close all browser windows (except this one, of course) before continuing.

After the correct version of Flash has been installed please refresh this page and proceed to use the WEBENCH Electrical Simulator.

Refresh this page
The installation/upgrade process will probably only require that you refresh this page. However, depending on your web browser, this upgrade might require closing and re-opening your web browser. It might even require that you reboot your system.

A separate installation window has been opened for you. If for some reason it does not appear, you can click here or the latest version of the Flash plugin for your browser can be downloaded from
Get Flash.

If you are still having trouble with the upgrade you can try the following;

Bookmark this page

Uninstall Flash using uninstaller from this page.

Close all web browser windows

Restart the web browser and return to this page.

Click here to test the version of Flash that is currently running on your system.

Adobe web site.

Example Schematic Showing Connection for all Components.