Problem with LM5030

[MarkoAnte]

Hi,

I made a isolated DC/DC converter based on TIDU355 (same circuit around the chip) and I can't get the LM5030 to work. The voltages on pins are : Vcc = 12V, Rt = 2V,  Vin = around 11 V pin floating(tried tying it to 24V no difference), SS ramps up to 5V, Vfb = 0V tied to gnd, SC = 0V , COMP = 0V (Is this ok?) and  both PWM = 0V.

What I'm a missing. I tried 3 different chips and they all don't work in the exact same way. ( I have ofc measured all pins for shorts or bed solder connections). I find it strange that I measure 0V on COMP is this OK? In the data sheet shoves COMP connected to 5V via resistor - annotated at 1.4V)

Best regards,

Marko