WEBENCH® Tools/LMZM33606: This design is not stable due phase margin either smaller than 35 or greater than 120

Prodigy 40 points

Replies: 7

Views: 147

Part Number: LMZM33606

Tool/software: WEBENCH® Design Tools

Dear All,

I'm using the LMZM33606 to generate 12 V - 5A from a battery.

The battery voltage range is: 14 - 20 V.

Using WEBENCH software it says: "Design update failed. This design is not stable due phase margin either smaller than 35 or greater than 120"

On datasheet, the allowed voltage droput is 1.1xVout. 

Why? Can you help me?

Thanks

Damiano

7 Replies

  • Hi Damiano,

    We are able to replicate this issue and we are looking into the loop model of this device. We will get back to you on this.

    Thanks & Regards,
    Praveen 

  • In reply to Praveen Badiger:

    Hi Praveen,

    Thanks for your work!

    I look forward to hearing from you.

     

    Best regards

    Damiano

  • In reply to Damiano Balzani:

    Hi Praveen,

    Do you have news?

    Thanks

    Best regards

  • I had the exact same issue in Webench for LMZM33606.
    Unfortunately on the datasheet there is no mention of phase margins whatsoever, therefore I am not sure whether I should trust this simulation warning or not.

    I hope this is cleared asap. Thank you.

  • In reply to ARM:

    Hi Domiano,

    The effective value of the total output capacitor is coming out to be very low and hence it is causing a low phase margin. We are working on the component selection of the output capacitor (Cout). We will keep you updated on this.

    Thanks & Regards,

    Praveen  

  • In reply to Praveen Badiger:

    Hi Domiano,

    We are working on it. We will keep you updated on this.

    Thanks & Regards,

    Praveen 

  • In reply to Praveen Badiger:

    Hi Praveen,

    Thanks for your work!

    I hope for good news.

    Best Regards

    Damiano