PRODUCTION STOP! Noise issues multiple designs with LNK306

Posted by: HCCP_EVM on 03/25/2015

Hello,

About 4 years ago, we have integrated the LNK306D on one of our products (design H09108). It already created some noise, which have been investigated (changing coils, different diodes, contact with Power Int., etc.), but because non of our clients noticed it and the noised didn't decreased, we put the investigation on hold.

We recently integrated this circuit into a new design (H12001). On this one, the noise is more intensive as the earlier design, so we decided to investigate this part again.

In the mean time, our customer has noticed the noise 4 weeks ago, and checked the last batch, and disapproved the product. We now get 1 month from our customer to decrease the noise. I hope you could help us to lower the noise.

Main point at this moment is the design H09108, because this one could get a production stop in 1 month for that customer. The goal of the H12001 is to have the sound solved in the middle of June.

Attached the schematics / layouts of both designes.

Regards,
Eric van Maldegem

Files

Schematic / layout design H12001 (49.41 KB)

Schematic / layout design H09108 (89.19 KB)

Comments

Hi,
Thanks for contacting PI and sharing the design.
What is the intention to use the 22nH (L601) on the drain of the LNK TN?

Hi,

The 22nH was inserted because of a RF circuit on 868MHz. There were some emmisions which disturbed the RF circuit, the 22nH prevents this. I already shorted the 22nH, but this didn't reduce the sound issue.

Hi,

Is it possible to send complete products to Power Integrations so you could also test / solve the problem?

Hi
If you want to contact PI for supporting, you could contact local FAE team or sales team.

Thanks