LT4363-2 Current Limit Protection( DC Power Supply)

Hello,

FET  Switch (U21)  is burned below conditions.

DC POWER  SUPPLY 12V: CURRENT LIMIT  2A,

LOAD: 2A,

WHEN  POWER ON,

FET(U21):  TPW4R50ANHQ

         surface  mount,  

Q)  How  can  I   prevent  FET  burning?

(Change   large size  FET?)

(DC POWER SUPPLY  Current Limit: 2A  to 15A)

(LOAD: 0  to 15A)

(Customer  may use DC  POWER SUPPLY  with  CURRENT LIMIT)

Thank you for your help.

I am  waiting your answer.

Regards,

Circuit Diagram (Pls  do not  open  to  a WEB)

Waveform1    U21  FET Switch is burned(or  High temp.)

 DC  SUPPLY Current  limit  :  2.5A

LOAD:2.5A

Waveform2  U21 FET  (NO PLOBLEM)

DC  SUPLLY Current limt:  2.5A

LOAD:0.5A