VIPER06 degradation in continuous self-biased mode
Good day to everyone!
Could anyone consult us about the issue with using VIPER06 in flyback converter just in self-biased mode for all the operating time, as it shown in Figure 19 of datasheet DocID022794 Rev 2 and described in Chapter 8 of datasheet DocID022794 Rev 2.
After using VIPER06 in this mode (input is 220VAC, output is 5VDC, load is 0,5W) for about from half of year to one year, the lot of ICs starts to consume itself much much more current and therefore overheat until its overheat protection circuit shut down the output, although the output is 0,5W all the time. We have measured the resistance of DRAIN to GND pins and it was very small – from 50 to 400 kOhm, as where as on the ICs before its installation the resistance is INFINITY. Our conclusion – if VIPER06 works in self-biased mode as shown on Figure 19 of datasheet, and input voltage is 220-230VAC – it ALWAYS causes the degradation and DAMAGE of the IC!!! So the diagram of Figure 19 is actually NOT WORKABLE!!!
Please, explain the situation – it may cause the HUGE problems for implementation of the IC. In our opinion – the internal circuit of high-voltage current generator gets locally overheated due to pulse mode high current and more then 300VDC on its circuit through the DRAIN pin and locally degraded, gets kind of short-circuited maybe for some lines and starts to consume more and more and heats the whole IC even almost with no load.
Thanks for any help or suggestions