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TPS6507x DCDCx : Internal resistor divider values

Alexander
Prodigy 10 points
Other Parts Discussed in Thread: TPS65073

Hi,

I need the DCDC1 of TPS65073 at 3.3V at startup (default: 1.8V). If I use an external resistor divider (e.g. 1k5:1k8), the 1k8 resistor is in parallel to the internal resistor divider (which I can not disable, due to my microcontroller needs the 3.3V initially to be able to set the DEFDCDC1.DCDC1extadj bit.To calculate the correct 1k8 resistor value, I have to know the series resistance values of the internal resistors.

Thank you!

 

  • 0
    TI__Genius 17240 points

    You could apply a voltage to the output VDCDC1and measure the ground current to get an idea of the size of the internal resistor divider. This will not be exact since there will be other current paths but the feedback divider should dominate.
    I would expect the total resistance to be in the 1M Ohm range.

    If this is the case, you should keep your external resistor divider in the 100k Ohm range.