Hello,
I have more or less the same problem.
I purchased the LM5175EVM evaluation board and changed some of the componentes to adequate to my requirements:
Vin=9,6-15V. Vout=48V. Iout=1A.
Q3,Q4: CSD19533Q5A 100V-13A
D1: substitute by D2 and none in the D2.
L=47uH.
Cout: 2*68uF +3.3uF.
R2=0.05Ohms
And some other changes in FB, COMP and SLOPE components.
After one of many start-ups, the LM5175 broke. It did not have Vcc voltage and the resistance between SW1-BOOT1 and SW-BOOT2 is very different (2MegaOhms to 140Ohms). Also the resistance between Vcc to ground was almost infinite.
The D4 and D5 diodes are not broken, also, the resistor divider for the EN/UVLO is OK and the voltage in VIN is OK.