Hi Bob,
as I said before, I have removed all ferrites and to increase the ramp time I removed some capacitors on the supply line. But it seems that the ramp time is limited by the LDO, so it will not be much better than 2ms. I could eventually replace the LDO, but then it should be a pin compatible type.
For the start pin, this is something I have tried already. I am using the following sequence: all pins low -> enable power supply -> after supply settle, set start pin high (and keep it high) -> when first conversion is done (data ready signal) read data and initiate a self-calibration -> then let it run free, by keeping the start pin high.
I will play a bit with the input buffer and try the internal temperature sensor, to see if the data is valid.
Best regards,
Tobias