I have now circuit boards with 16 devices on. due to a control problem at startup, all the LMG5200s turn on and short out the power supply briefly (2mS). The Power supply is 24 volts, and has 3200uF of low ESR electrolytic capacitors. This does not seem to have hurt the circuit, or so I thought. Looking at my pulse waveforms it is apparent that there seems to be some pull up.
I isolated the outputs of the devices and measured typically 40 ohms between the output and the VIN. Some devices have subsequently failed completely in use, first the top transistor and then the lower, leaving the device a short between rails. I have replaced some devices, not one of my strong skills, and the replaced devices measure between 2k - 200k ohms between output and VIN. The devices are still working, but if I crank up the operating frequency they gradually go into thermal runaway, which is non destructive as protection circuit shuts them off before they actually fail.
1) is this the normal failure mode
2) Presumably I have damaged the ones I replaced with my hot air gun whilst soldering the devices to the board 
thanks
d
