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REF70: REF70 need big Cout?

Brian Li
Genius 9975 points
Part Number: REF70
Other Parts Discussed in Thread: AFE2256

Hi team,

We can saw below from the datasheet:

For low noise application, the Cout need low ESR.  

And from the ESR of capacitor, we can saw that the small capacitance have high ESR.

So is that means our REF70 need big Cout?

Thanks,

Brian

  • +1
    TI__Genius 11301 points

    Hi Brian 

    Can you please explain the detail about your application  

    • ESR creates a zero and we want to push zero away to make sure loop stability. 

    Noise will be similar as the output imedance of REF70 is pretty small. You can refer Figure 7-14. 

    Can you please provide more detail about the application. We can suggest you the good cap.

    Regards

    Trailokya 

  • 0 in reply to Trailokya Rai
    TI__Genius 9975 points

    Hi Trailokya,

    Customer is using our REF7012 for AFE2256's VREF.

    In their application, there are 12*AFE2256 and 4*REF7012，each REF7012 connect to 3*AFE2256 and every REF2256 have a 47uF on VREF PIN.( Sch as below)

    And now customer want to minimize the VREF noise, so they need to choose the low ESR capacitor.

    Could you please kindly help check their sch if there's anything need to change?

    Thanks,

    Brian

  • 0 in reply to Brian Li
    TI__Genius 11301 points

    Hi Brian 

    Let's talk over mail in detail. 

    Regards

    Trailokya