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AFE7071: Selecting decoupling capacitors for use with AFE7071

JMT82
Prodigy 70 points
Part Number: AFE7071
Other Parts Discussed in Thread: LMX2572LP

Is there any documentation available to assist selecting decoupling capacitors for use with the AFE7071?

Thank you

  • 0
    TI__Guru* 91947 points

    JMT82,

    I would suggesting following the attached schematic.

    Regards,

    Jim

    AFE707XEVM-SCH_D.pdf 

  • 0 in reply to jim s
    Prodigy 70 points

    Thank you for your reply.

    The schematic you linked to is from the AFE707x development PCB.  On the development PCB, there are typically 3 decoupling capacitors per power supply pin.  This is more decoupling capacitors on the power supply pins than I expected to see.  For example, the LMX2572LP is the IC recommended to generate the LO signal for the AFE7071.  The data sheet for the LMX2572LP recommends 1 capacitor per power supply pin.  Why, then, does the AFE7071 need so many more?

  • 0 in reply to JMT82
    TI__Guru* 91947 points

    JMT82,

    Sorry, but I did not work on this board. After looking at the schematic in more detail, I would suggest the following:

    Only use one 0.1uF cap for each DVDD, CLKVDD, DACVDD, IOVDD, MODVDD, and FUSEVDD pin. Try to place these as close as possible to the pin.

    Use at least one bulk 10uF and 1uF cap for each regulator output along with an EMI filter such as a Murata NFM31PC276B0J3. 

    Regards,

    Jim