lnk304,306_3.3v/220mA power supply

Posted by: SaJra on 05/19/2020

i'm trying to desing ACDC, 220VAC to 3.3VDC, I want to know if my desings are correct,and if there is some samples to 3.3v, read the 12V sample but i didn't find any 3.3v sample.
I have 2 desings, with lnk304 3.3v/220mA and lnk306 3.3v/250-300mA. i want to know if there is some example, the smallest one vecause the space in the pcb.
Thank you.

Comments

Hi,

For 3.3V design, you can refer to DER-574 3V3 500mA output.
https://ac-dc.power.com/design-support/reference-designs/design-examples/der-574-165-w-non-isolated-tapped-buck-power/

Hi, thank you for your answer, I'm looking for a transformerless 3.3v power supply, I see DER-574 example and schematics and this use transformer.

Hi,
What are your efficiency and ripple requirements? Most LNK-TN2 designs utilize the output voltage to supply the internal shunt regulator thru the BP pin(4.95V minimum, 5.2V typical as per datasheet) to get the best efficiency. Without this, the IC is powered thru the Drain pin and a linear regulaton and efficiency drops significantly.

Consider designing for a 5V output, then a 3.3V post regulator. You can refer to a 5V design here (note that this uses LNK-TN2 size 2):
https://ac-dc.power.com/sites/default/files/PDFFiles/der507.pdf