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LMR43620-Q1: Maximum Parallel FB Resistance

Antonio Fadhel
Genius 9410 points
Part Number: LMR43620-Q1

Hi,

The LMR43620-Q1 datasheet lists a range of allowed parallel FB resistance of 5k-10k (I assume to ensure loop stability). However, Webench seems to assign larger values - similar to what you would expect based on the datasheet of the catalog version of the device (100k Rfbt):

1) Can the Webench model be updated to meet the max parallel resistance requirement?

2) Can you please confirm that the catalog version of the device will not have this requirement? Or is it that the datasheet has not been updated to reflect it?

Thanks,

Antonio

  • +1
    TI__Genius 10720 points

    Hi Antonio,

    Thank you for bringing this to out attention, I'll work with the Webench team to have the model updated so that it aligns with what is shown in the automotive datasheet. 

    The catalog version of the device will also have the same FB resistor requirements as the automotive device. The catalog datasheet will be updated to reflect the max parallel Fb resistance once we RTM the catalog device(s). For the time being, please refer to the automotive device FB resistor section when setting an adjustable output voltage. 

    Regards,

    Harrison Overturf 

  • 0 in reply to Harrison Overturf
    TI__Genius 9410 points

    Thanks Harrison! I will recommend Rfbt of 17.8k and Rfbb of 22.1k for 1.8V. You might also want to add a datasheet formula to calculate Rfbb since it is not obvious to everyone. 

    Regards,

    Antonio