LTC4367 fault output stays low even when gate drive is available

Hi,

We use the part LTC4367IMS8#PBF in a design to protect an input of 50V DC. Desired Vuv = 47V and Vov = 53V. Values of resistors used are R1 = 88.7K, R2 = 11.3K, R3 = 9.31M.

At an input of 50V, we find that the output appears correctly (the MOSFET gate is driven at 59V), but the Fault output is stuck at low.

We need to understand if any changes are required in our resistor selection to have a foolproof design. Complete circuit is as shown below.

Regards

Sarvesh