Innoswitch Postfilter and Feedback Network

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PI-Expert places feedback resistors behind post filter. AN-72 figure 19 points out that feedback resistors must be connected before post filter. What is correct?

Hi adWe,

I checked designs of InnoSwitch3-CE and InnoSwitch3-CP in PI Expert, and it places feedback resistors before the post filter, just like in AN-72.

For which particular product or design are you seeing feedback resistors after the post filter?

Hi,

Innoswitch 3EP.

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Example Post Filter1.37 MB

Hi,

thank you for uploading your design. I loaded it into PI Expert (https://piexpertonline.power.com) and it shows that the feedback resistors are connected before the post filter.

In particular, the inductors L2 and L3 are to the right of the feedback resistors. So, the behavior is in agreement with AN-72.

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Example_design_postfilter.PNG17.86 KB

Hi,

sorry don't want to bother you, but I have a different result.

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Example Feedback Resistors56.17 KB

Hi,

what I found out so far. Using the online version of PI Expert leads to a different result than the local PI Expert Suite.

It may have been an issue that was found and fixed in the online version, but the change didn't yet make it to the stand-alone PI Expert.

Which version of the downloadable PI Expert suite are you using? Is it the latest 10.3?

Edit: It looks like the issue was fixed in patch 2.3.5 of the online version, around September of this year. The standalone 10.3 was released in February and doesn't have the fix in it.

The next version of downloadable PI Expert will have this fix. Unfortunately, I can't provide any hard dates on when it will be available.

Hi,

I'm using PI Expert Suite 10.3.2.9 x64.

In summary, this is an issue in version 10.3. AN-72 is correct.

It will be fixed in the next downloadable version. It has already been fixed in the Online version.