Dimmable Driver

Hi,

We have a design example on our web site which is a 12V LED power supply with built in power factor correction. Below is a link to the engineering report for this design example.

http://www.powerint.com/sites/default/files/PDFFiles/der168.pdf

You are free to modify this design to suit your exact requirements.

We can only answer specific technical questions on the forum, for additional design support, please contact the regional office of Power Integrations in your area.

Regards

PI-Sarek

Hi sareek,

we already prototyped this board and tested this board its working nicely but we have some starting problems when the dimmer is in lower positions.We used the same feed back circuit what you are used in the der 168.Please tell me if there is any modifications we have to do .what is the most common causes of this problem or any other help?.Also i woulid like to know constuction details of transformer with EFD 25 core with 66Khz.

regards
siju

Hi,

The dimming problem is often because of the triac inside the dimmer turning off because of lack of holding current. It is typical of circuits that work well with several triac dimmers to not to work we with a particular triac dimmer. The solution often consists of addition of a dummy load at the dimmer output though this has the effect of reducing efficiency.

The design engineering report that we referred you to yesterday shows how PI-Expert can be used to design a transformer. Should you want to design around a dfferent core type, please download PI Expert from our web site and modify the design.

Regards

PI-Sarek

Hi
We achieved 100% dimming with this dimmer but only problem is not turning on at its minimum positions. I have tried some modifications in control but i am not getting any improvement and where i need to consentrate to fix this problem.
please do help..
regards
siju