Mapping Innoswitch INN3692C PIXLS design into power expert.

Hi JK,

Thank you for your continued support to Power Integrations.

You are currently using the InnoSwitch3‑EP with a 900 V MOSFET. At the moment, PI Expert is only available for InnoSwitch3-EP family with 750 V PowiGaN and 725 V MOSFET options.
For guidance, you may check our reference design that uses 900 V MOSFETs: 

• DER-745 - 10 W Dual Output Power Supply Using InnoSwitch3-EP (900 V Si Switch) | Power Integrations
• DER-982 - 60 W Isolated Flyback Adapter Using InnoSwitch3-EP (900 V PowiGaN Switch) | Power Integrations

Also, the file you shared was not the correct format of a PI Xls design. To properly share a PI Xls design file, please follow the steps below:

1. Open Design in PI Expert or Go to File Manager 
2. Click on Action (three dots) on the right most part 
3. Select Share Design
4. Copy the generated link

I hope this helps. Let me know if you have any further questions or clarification.

Regards,

Hello Mochi,

Thanks for your inputs, I shall go through the details & let you know for any queries. Meanwhile, could you please try downloading the file again & opening in offline PI suite. I used offline PIExpert suite 10.3 to make PIXLS file. I just tried downloading the file & it gets open in offline version.

Regards,

JK

Hi JK, 

This is to inform you that the attached file in your previous post was not available for download. Please find attached screenshot. 

Regards,

Hello Mochi,

Yes, if you left click the file it will show junk. I tried right clicking & "save link as " & then it shows the PIXLS file download option to location on your PC as per attached image. For your convenience I am again attaching the offline .PIXLS file. If you are able to download, please review the excel & let me know your comments. 

Since PIExpert has no Innoswitch-EP900 option, so I used offline tool for manual excel sheet design.

Regards,

JK

Hi JK,

Thank you for the instructions. I was able to download your PI Xls design file successfully.

PI Expert Online provides an option for InnoSwitch3‑EP 900 V. I uploaded your design into the tool, and it flagged a warning related to the transformer size. Have you also encountered this warning when using the offline PI Expert tool?

You can review the file here:
https://piexpertonline.power.com/fileManager/index?shared=55a61ee2d13d609096a168bdc9cc6d09341baf1bd9d3dbf7148a4fa0aad038e8

Regards,

Hello Mochi,

Yes, I viewed the file & it looks it is only opening in online PIXLS. For offline PIExpert I can't find the device & hence unable to proceed for schematics. Even confirmed using online PIExpert which shows disabled PIEXpert button when InnoSwitch3‑EP 900 V was selected. Please see attached image.

Apart from this, I had the chance to look into DER-745, there is no detailed explanation about selection of components with equations. 

1. It would be good to get some appnotes for InnoSwitch3‑EP 900 V which can help me design clamp circuit, bias winding components, primary side overvoltage/ undervoltage protections, secondary side snubbers, feedback components, etc. Atleast I can complete the schematic part.

      2.  Also are there any design guidelines to improve regulation for isolated winding. I need to design 5V/0.85A & 24V/0.05A. Here 24V/0.05A is isolated from main 5V. 

Regards,

JK

Hi JK,

As mentioned, PI Expert is not yet available for InnoSwitch3‑EP 900 V. For now, designs using this device can only be created with PI Xls.

1. We have a general application note for the InnoSwitch3 family that you may use as a design reference. One key difference compared to 750 V devices is in the input filter: you will need to connect bulk capacitors in series and add balancing resistors across them to ensure proper voltage sharing. Please see the link below for details.

   AN-72 - InnoSwitch3 Family Design Guide | Power Integrations

2. Unfortunately, we do not have a dedicated design guide on improving regulation for isolated outputs. However, here are some practical options you can consider:
   1. Add a pre‑load resistor on the regulated output to help sustain the isolated output under no‑load conditions.
   2. Use a Zener diode or LDO regulator on the isolated output for tighter regulation, keeping in mind the potential thermal concerns

I hope this helps. Please let me know if you have further question. 

Regards,

Hello Mochi,

Thanks for your response, got it.

Regards,

jagdish