TPS54240: TPS54240 About 5 percent of the damage occurred when the power was turned on

Hi,

The waveform that you showed me looked normal.
I am thinking maybe there is transient condition at the input during startup.
You could check VIN during startup and check VIN for any spikes. Also you could try to add a schottky diode between the -15V output to GND. The anode of the diode will be on the -15V side and the cathode will be on the primary GND side.

Thanks
-Arief

hi  

  I have test Vin  VPP<30V;

HI Arief Hernadi :
Also you could try to add a schottky diode between the -15V ,What is the main function for this? and I test the Vin waveform have not peak voltage;

hi Team:

As test,the result as below:

1.  when the power is turn on,VIN=9V,Iout=100mA, when is run Some time later,The tps54240 is about 4-5% percent of the damage occurred,I test with a multimeter,pin2 and pin11 is short;

2.  I find the datasheet in 7.3.14, when the  Frequency rising,the VIN is voltage falling,so I use the WEBENCH® Designer ,the result Switching frequency<700K,then I use 600K frequency,and test the  result is about 4% percent of the damage occurred,I test with a multimeter,pin2 and pin11 is  not short,but the IC can not work!

3. how to Solve this problem?