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I designed a SEPIC using the LT3467 with coupled inductors. It supply 17V starting from a 12V input. On the simulator (LTSPICE) everything works, but on the test board there is a problem. With 70mA output current there is a ripple of 1V (see pic attached) caused by the wrong regulation of the chip.

Output node ripple

It seems that the regulator is working on burst mode, and that is the the cause of all my problems. Here it is a pic of the switching node. Switching node

Do you have any idea on how can i make the switching node switch regularly? Maybe there is a problem on the feedback loop. I cannot post the pic of the schematic because i don't have enough reputation points, so if you need it you can tell me another way to post it.

Here is the schematic: enter image description here

In the link below you can find the schematic and the output node and the switching node with 200mA at the output.

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  • \$\begingroup\$ What happens with load currents larger than 70mA? \$\endgroup\$
    – next-hack
    Sep 19, 2017 at 11:34
  • \$\begingroup\$ I haven't test it yet, but as soon as I can I will \$\endgroup\$
    – Alecoglia
    Sep 19, 2017 at 11:39
  • \$\begingroup\$ For proper answers without guessing, include the schematic! Draw a schematic using the tool or make it available somewhere (like google drive) and include the link then someone can add it in. \$\endgroup\$ Sep 19, 2017 at 12:31
  • \$\begingroup\$ drive.google.com/drive/folders/… In the link you can find the schematic and the output node and the switching node with 200mA at the output. \$\endgroup\$
    – Alecoglia
    Sep 19, 2017 at 12:48
  • \$\begingroup\$ I added the schematic to your post for you \$\endgroup\$
    – DerStrom8
    Sep 19, 2017 at 12:59

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