Based on the functional block diagram in the TPS7A4701 datasheet and the location of Cnr, I would expect to get optimal noise performance in adjustable mode by using the ANYOUT pins to set the internal reference voltage as high as possible, and then use an external resistor divider connected to the SENSE/FB pin for any additional gain.
For example, if I were targeting an output voltage of 30V and left the ANYOUT pins disconnected, my external resistor ratio would have to be (30/1.4 - 1) = 20.4:1, and I would expect the noise to be about 21.4 x 4.17uV = 89 uV RMS. If, on the other hand, I connected the appropriate ANYOUT pins to ground such that the internal reference is at 15V, then my external resistor ratio would have to be 1:1, and I would expect the noise to be about 2 x 12.28uV = 24 uV RMS.
Is using the ANYOUT pins in combination with the ADJ pin in this fashion permitted, and does it result in improved output noise as I suspect?
Thanks,
-Greg
