I built a design from the attached image. I removed R2 and R3 and shorted V-pin to Source in order to disable UV protection. However, the IC turns too late - at 170-180VDC. I am trying to find out what is the internal threshold of the TOP264 IC when no UV resistors are added.
I installed UV resistors (R2 and R3). Now I observe that the IC doesn't try to turn on before specified value (100VDC or so). After this point, it enters auto-restart mode. Control pin discharges to 4.8V, then charges to above 5V every cycle. This remains until 170-180VDC.
Any advice as to where to look to make the converter turn on successfully at low voltage?