We are seeing an interesting problem with the LM46002. Vin = 12V nom, Vout = 4.5V.
When the input voltage increases to close to 20V and load current around 1A, the output slowly drops by about 1V over several minutes. If the LM46002 is sprayed with cold spray, the output instantly returns to the correct voltage. Spraying the inductor had no affect. We found that an epoxy used to secure the inductor was covering pins 1-6 of the LM46002. If the epoxy is removed, then the circuit works correctly. Then the epoxy was replaced with an Electronics Grade epoxy (original was not), then the circuit works correctly, even if the LM46002 is completely covered with the epoxy.
Any ideas as to what the not-electronics grade epoxy was doing to the LM46002? Originally I thought it was a thermal issue, but I would expect to see this with the new epoxy as well. We are checking some pin voltages to see if we can tell how the control loop was impacted.
