Hi,
We are using the TPS62143 in an RFID product of ours and the DC/DC converter seems to die for no apparent reason.
We are in contact with Mike Farley at TI and so far no root cause was identified. Only a few units so far were affected by the issue.
So far we were not able to see any issues with the supply to the board (12V) and the unit itself was succesfully UL certified. For protection we have transorbs but the issue doies not seem to come from external spikes. The circuit connected to the converter consumes 900mA max. Any more than that is only possible by external shorts of the provided RS485 interface as well as other gross issues in combination.
Based on that the circuit should not be able to overload the TPS62143. We sent a damaged IC for analysis to an external lab and it showed some blistering on the output (at least we assume it is the output FET).
Monitoring the output voltage of the TPS62143 it seems stable at 5.25V (we use the DEF pin for higher output voltage). However, we managed to get a single unit to die in our lab by stressing it - LED blinking and sound playing whilst reading an RFID card.
Based on that I wanted to ask if a voltage spike on the output of the TPS62143 could kill the IC and what sort of amplitude such a spike would need to have (so far we did not see any).
In addition I wanted to ask if the inductance of the speaker could cause a problem with the loop stability of the regulator. The supply circuit as well as the speaker driver and LED driver schematics are attached.
As some of the units died at a customer installation this is a quite urgent issue for us so your help is most appreciated.
kind regards
Hans