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Innoswitch Postfilter and Feedback Network

Posted by: adWe_73249 on

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?

Comments

Submitted by PI-Cylon on 10/30/2020

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?

Submitted by adWe_73249 on 11/03/2020

Hi,

Innoswitch 3EP.

Attachment Size
Example Post Filter 1.37 MB
Submitted by PI-Cylon on 11/04/2020

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.

Attachment Size
Example_design_postfilter.PNG 17.86 KB
Submitted by adWe_73249 on 11/05/2020

Hi,

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

Attachment Size
Example Feedback Resistors 56.17 KB
Submitted by adWe_73249 on 11/05/2020

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.

Submitted by PI-Cylon on 11/06/2020

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.

Submitted by adWe_73249 on 11/08/2020

Hi,

I'm using PI Expert Suite 10.3.2.9 x64.

Submitted by PI-Cylon on 11/12/2020

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.