I'm using the LM317 and LM337 for regulation of positive and negative high voltage rails. I noticed in the datasheets (LM317, LM337) that they have a thermal cutoff, but I wonder if this could actually lead to device failure.
I use the regulators floating, so they regulate 220V down to 200V using a voltage divider on the output. The output is therefore 200V with respect to ground, and the input is 220V with respect to ground. Let's also say that I connect the output to an op-amp's power rails. If the thermal cutoff operated, would it not lead to the situation where the input was 220V, and the output 0V? The op-amp could in theory drag the power rail to 0V if one of its signal inputs were grounded, leading to 220V potential across the LM317, which far exceeds its 37V rating.
Would this still be ok for the regulator, or lead to some smoke?