The problem statement is that our 30W flyback converter has a thermal shutdown in 25°C ambient temperature.
The flyback is located in an enclosure with no air movement.
We are using the UCC28610 to charge batteries at a maximum load of 30 watts from a full-wave rectified 120VAc line voltage.
The flyback transformer has 500uH primary inductance. At full load, the peak primary current measures, at the peak input haversine voltage (170V), about 1.7Apk, fs=80kHz.
The schematic for the Primary side is virtually the same as shown in Figure 44 found in the UCC28610 Datasheet (revised 9/2015).
We use the same decoupling capacitors, gate drive resistors values, and equivalent diodes.
Vdd is connected to a 15V linear regulator that is powered from the Aux. primary winding.
** What are my options to reduce the power dissipated in the controller to relieve the thermal shutdowns?
