about LNK306

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I made a design using LNK306 having output specs. 140v/65mA led drive design with Constant Current Circuit Configuration (LED Driver)Figure 6. High-Side Buck-Boost Constant Current Output Configuration. On AN37

The problem is when the power to the circuit is switched of the led light flickers two to three times.

Hi,
As you remove the source to the driver what happened to the Bulk volage? What are the values in your EMI filter?

I think it would be good if you can share schematic some waveforms so that we can analyze it clearly. What type of load you are using, is it only pure LED load?

Regards,
PI-Jono

i have followed the pixls desigener buck boost. my design is attached. i have used with input pi filter of 22mfd+ 1200mH(in positive rack) + 10mfd. circuit configured and made by following the fig 6 on the application note- AN37. checked with & without soft start capacitor 10mfd. out put capacitor 10mfd used.LED used is 3.5v/60mA x 40 nos in series (140v/60mA). designed with 85-265v ac, but it is checked using 230v ac.

Hi,
This IC does not have any under-voltage detection feature that is why you may go to auto-restart mode during turn-off.

You can add a bleeder resistor across your load, try to decay your output enough to avoid any glitch during turn off.

It would be great if you can share some of your waveforms so that we can directly pin point the problem.

On page 30 of the seminar slide you can see this problem for any controllers which does not have UV feature.
http://www.powerint.com/sites/default/files/PDFFiles/seminars/2007Seminars_Pt2_TOPSwitch-HXProductIntro.pdf

Regards,
PI-Jono