Dear support,
I have a use case similar to the application note from TI here: https://www.ti.com/lit/an/slyt689/slyt689.pdf
I want to apply external 5V which is on the output side of a step-down converter like the ADP2302. But the IC itself is not powered on the input side (normal operation with 12V here)
Here are my questions:
1. Is it safe to operate the IC like this? There is absolutely no information on such corner cases in the datasheet.
2. Is there any mechanism (e.g. flyback diode) that leads to the 5V appearing on the buck converter input side? This would be potentially harmful because there is way more load on the 12V line. The TI blog also recommends a diode at the input side to avoid affecting other rails.
3. Is it better to have the IC disabled or enabled in such a case? Intuition says disabled but some converters pull the output side to ground then.
4. Or is it possible to protect the output side only versus reverse voltage? With a diode between the coil but before the feedback node? Then the 5V would only be applied to the feedback input of an otherwise unpowered IC - is this better? Or worse?
I also opened up a case (SR-207221-K6C2D7) on this but got no reply so far. But replying in the Q&A would be even better so this information is available for everyone.
