Question I want to make a programmable LDO. What devices could I use? Answer For this application, I'd recommend a digital potentiometer such as the AD5141 plus one of our LDOs, in linear gain setting mode. You can select any of our LDOs, ie. ADP1708, and place the AD5141 in the feedback loop. In this case, configuring the digipot in linear gain setting mode, the error will be ratiometric, so you should expect voltage error due to resistor mismatch below 1%. http://www.analog.com/static/imported-files/application_notes/AN-1169.pdf

Operation below 2.3VDD

Question Can the part operate below 2.3V VDD? Answer The part has not been characterizing below 2.3V due to EEPROM functionality restrictions. In other words, the EEPROM cannot be programmed below this supply voltage.

Power Supply Sequence

Question What is the exact power-supply sequence? How long does it take? Answer At power-up, the part resets all the internal registers, loads half scale in the RDAC and proceeds to read the EEPROM. Once the EEPROM is correctly read back, the part loads the new RDAC value into the register. Typically the power-up sequence takes 50uS, while reset after the part is already powered up is a little faster at 30uS.