Hi,
We have been using the LM5072 in a standard PoE application (isolated flyback) with RAUX option for about 10 years (approx. 100,000 units) without any problems during this time.
Now we have received a lot of devices, of which some parts (approx. 10%) show a funny behaviour:
The devices work without any problems up to an input voltage of 15...16V. If the voltage is further increased, the devices start to reduce the clock frequency until no more gate pulses are generated when the supply voltage exceeds 18V. If the supply voltage is reduced to a lower value again, the circuit works as usual.
The design of the board is completely unchanged. The behaviour is reproducible and not temperature-dependent.
A lot of thanks for helpful ideas
Klaus
