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TPS7A3001-EP: Feedback pin resistor calculation

Part Number: TPS7A3001-EP

Hi team, 

Good day.

If we have to consider the feedback pin current to have a greater voltage accuracy, is equation 1 still applicable? if not, what is the proper equation that will include the current in feedback pin for calculation?

Regards,
Carlo

  • Hi Carlo,

    I have a tool for this if you need a monte carlo simulation, just let me know your requirements (Vout value and desired tolerance, and resistor tolerances).

    To answer your question the feedback pin current is positive according to the datasheet, and there is a note which says that this current flows into the device (note 3).  If you run through the math, the feedback pin current will multiply by the setpoint resistance which is between Vout and the FB pin.  Let's call this resistor Rtop.  Then Rtop*I_FB will add to the typical output voltage.  So:

    Vout = -Vref [ (Vbottom + Vtop) / Vbottom ] + Rtop*I_FB

    Thanks,

    - Stephen