LNK306 as LED Driver

You can use the buck configuration but you will need to implement the feedback circuit as shown in Figure 6 of AN-37.

Regards,

The Traveler

A buck configuration as shown in Figure 1a  and a feedback circuit as shown in Figure 6 of AN-37? Please give me more details what you mean in Figure 6 or how its looks like.   Thank You

 LNK306 has switching of the MOSFET enabled when current flowing into the feedbackpin is less than 49uA.  Switching is disabled when feedback pin current is greater than 49uA.  It's a pretty simple on/off control scheme.  

In a typical constant voltage power supply, the output voltage is fed into the feedback pin through an isolating/levelshifting diode (Dfb in Figure 1a) and a feedback resister divider network (Rfs and Rbias).  The ripple on the feedback signal is minimized with the use of Cfb.  

In a constant current application, you're designing for a fixed output current regardless of output voltage.  In that situation, you need some way to translate the output current into a voltage that can be fed into the feedback pin.  In Figure 6 of AN-37, this is accomplished through the use of Rsense which provides a differential voltage in response to the output current of the power supply.  Csense filters the large ripple seen across Rsense.  

Changed to a buck configuration, the buck-boost configuration shown in Figure 6 of AN-37 will have L and Dfw swapped (as in a buck configuration) and the output diode polarity will be reversed.

Out of curiosity, what are your general power supply specs?  Input voltage, input frequency, etc...

Regards,

The Traveler

The Input Voltage is 85 -265 VAC, 50Hz, the Input Stage is full-wave rectification.. (Table 9, right figure). The Output Voltage is Vo=9V and Io=350mA.

Thank you for your help

The Input Voltage is 85 -265 VAC, 50Hz, the Input Stage is full-wave rectification.. (Table 9, right figure). The Output Voltage is Vo=9V and Io=350mA.

Thank you for your help

rol2 - 

I would recommend that you switch to using LinkSwitch-PL.  It is designed specificly for LED applications and as going to work much better for application.

Here is a link to the LinkSwitch-PL Product Page:

http://www.powerint.com/en/products/linkswitch-family/linkswitch-pl

Here are links to the LinkSwitch-PL datasheet and main application notes:

http://www.powerint.com/sites/default/files/product-docs/linkswitch-pl_family_datasheet.pdf

http://www.powerint.com/sites/default/files/product-docs/an50.pdf

We also have numerous reference designs that you are free to use in their entirety, modifiy, leverage, etc.  They are located here:

http://www.powerint.com/en/design-support/reference-designs/design-examples

Regards,

The Traveler

I want to use this application as non isolatet, low cost solution.

Can you send me a eMail with a Spice Model from LNK306?

Thank You

rol2 - 

Unfortunately we don't provide spice models for any of our products.

As far as your spec requirement though, I still think LinkSwitch-PL would be a good solution for you and will give you a lot of good features not provided in LinkSwitch-TN.  You'll get much better power factor, start-up will be more consistent, etc.  It's also possible to configure it several different way, some of which are non-isolated.  In fact, non-isolated applications is one of the primary areas that LinkSwitch-PL gets used.

Here are some of our reference designs using LinkSwitch-PL.  I really do think this would be the best solution for your application based on the information you've given me.

http://www.powerint.com/sites/default/files/PDFFiles/der301.pdf

http://www.powerint.com/sites/default/files/PDFFiles/rdr268.pdf

http://www.powerint.com/sites/default/files/PDFFiles/der304.pdf

Regards,

The Traveler

Hi

Please help me to design a 36V/200mA LED Driver.

I Tried DER-386, can u help me to redesign it to 36V.

Please tell me,

if R2=15ohms instead of 13.3 and D1=UF4007 what would be the output.

I'm getting 1.2V only at output.

Please help.

Thanks

gk

You can start with the attached PIXls design.