MP6515 failed on voltage above 20V

I use MP6515 to drive a DC motor
When the voltage is above 20V the part - burns.
When I used 150uHy inductor - instead a Motor- the part works properly,
The wires to the DC motor are 4meters
Should I add any protective circuitry? (clamping diodes? Zener diodes? snubbers - values of cap+res? please elaborate)
enclosed the schematic.

The device -intrinsic diodes - are not working well.
After adding external diodes - the device works well.

Hi amichay,

Good to hear the device is now working properly with the added circuitry. Please let us know if you have additional questions.