Hello all
I designed two transistor flyback around UCC2804. Works fine except UCC2804 gets damaged sometimes, I suspect during start-up or shut-down - never observed it during normal work under load.
UCC2804 malfunction is also strange- it consumes around 670uA before it starts. Its over 6 times more than it should (100uA)
When I power UCC2804 from external source it starts and works, but still consumes more current than not-damaged part.
PSU has around 15W and 3phase input. (up to 650Vdc on bulk caps) startup resistor is 530k and I do not want to decrease it. Vcc is 11.5V when its operating. Vcc is generated in auxiliary winding of main transformer.
Vcc capacitor is 22uF + 100nF ceramic. They do not leak.
I would be grateful if anybody have idea what may be wrong.