Hello,
On one of my prototype boards, I experienced failure of one of the DDC316 components. It pulls an additional ~100mA at the 12V benchtop supply (which is stepped down to 3.3V and 5V through isolated power supplies), and gets very hot to touch. The excess load is likely on the analog side of the part, as the 5V supply is also slightly warmer than normal, while there is no perceptible difference on the 3.3V supply. When trying to control and communicate to the part, I never get a pulse on nDVALID. It did work correctly when the board was first being used, though the exact time of failure can't be easily determined since we were mostly using another DDC316 on the board and the supply current was not being constantly monitored. I can't rule out thermal stress, because we have reworked the photodiode on that channel multiple times for unrelated reasons. The anode side of the diode only has the pad and a thin (4 mil) copper trace going - of course kept as short as possible - going into into the DDC316 input. While the iron was not kept on the pad for very long, the DDC316 is still the closest large heat sink.
One thing I did want to make sure was correct is that I am driving the CONV pin for an acceptable duration. I have been extending the integration time out to 40,000 us while lowering CLK to 1 MHz. The specification calls out a maximum integration time as 1,000 us - while CLK is at 40 MHz. It also calls out on another line that the integration time can be a maximum of 40,000 CLK periods. On yet another line, it states that the maximum allowed CLK period is 1000 ns. This suggests that 40,000 us integration time when CLK is at 1 MHz should be acceptable. Was my interpretation of the integration time limitations of the component incorrect and putting the component at risk?
Do you have any other insight into what sort of improper handling or use could cause this? This is a board that went through software development, and any number of erroneous control signal states could have occurred during interim stages of software development. If there are specific scenarios we should add safety features into our software to avoid, that would be good information to have.