Boost converter: Voltage limit on RDCM pin of LT3750 controller?

[treez]

Hello,
We are doing a Boundary conduction mode boost converter to charge up an output capacitor to 300V within 5ms.
We are using the LT3750 controller, but what is the voltage limit on its RDCM pin?
The datasheet does not say. The RDCM pin gets 300V on its RDCM pin in our application. Is this overvoltage on that pin? The datasheet does not say.

Schematic and LTspice simulation attached.

LT3750 datasheet:
http://cds.linear.com/docs/en/datasheet/3750fa.pdf

 

[FvM]

The datasheet gives a +/- 1 mA specification, so you can be quite sure that the pin has internal clamp diodes. It also says the 42 k resistor is for 300V with 1:10 transformer, so it will be hardly suited to receive 300 V directly through a 42 k resistor.