Hi,
We are using the TPS7A49 to regulate 20V to 18V for a low noise supply. However, when testing the circuit on the PCB, the output voltage is too high (measured 19.3V). After reading other threads, we determined the cause to be from leakage current into the NR/SS pin. Our layout has the 20V input routed very close to the noise reduction capacitor. In this revision of our board, it's not possible to add guard traces to prevent the leakage current.
The datasheet mentions in the "Do's and Don'ts", to not resistively or inductively load the NR/SS pin. However, through experimentation, we noticed that adding a 10M resistor in parallel across the noise reduction capacitor brought the voltage on the output back to the expected amount.
I would like to know more details about what is meant by "Do not resistively or inductively load the NR/SS pin", and if our solution will work reliably.
Thanks,
Judd