TPS54302: Output is abnormal cause Tantalum capacitor burned

Hi Sam

Please let me check about this later.

Thanks and best regards.

抓到出问题时候的ch2:input ch3:output ch1: FB

Dear 

 Why TPS54302 FB pin oscillating while CAT1 module is working

Is there any problem with Feedback Loop

Cff is now 47PF,can it be DNM?

The schematic of the power part 

Hi Sam and Xiaodong

The schematic and the components look ok to me. Some comments for layout: The Cin should be place close to the IC Vin and GND pin. especially C87. The voltage sense resistor R265 should be placed close to IC FB and GND pins and avoid any noisy nodes like SW.

Can you identify under what condition will the issue happen? Is there any interruption from other circuits? 

47pF Cff should be ok under normal condition. In case there is noise coupling, can you try making Cff DNM, and add a ~47pF between FB and GND?

Thanks and best regards.

I don't think the problem is caused by Layout ,we change TPS54302 to ohter P2P device, there is no problem. 

The Load is 4G CAT1 module ,it is abviously the FB pin Oscillating first then the output voltage raising .

Remove the CFF is valid 

But how to use TPS54302 we got confused ,and why the oscillating happening ,what test should we do to avoid this problem.

Hi Xiaodong

Did you try removing Cff and add a small ceramic cap between FB and GND?

Thanks.

Removing CFF  verified  effective .

We design circuit according to datasheet  recommended ,the test result in our LAB  is ok,but in certain condition  the DCDC works abnormal ,and the result is tens thousands of our products need to be rework or  repair .that is the point .

We concern why the DCDC enter the oscillation. what test should do to avoid this thing happen again.

Hi Xiaodong

what is the CAT1 module and can this bring some noise/interrupt?

Recommend place FB resistors close to FB pin and GND pin, and vo sample trace far away from noisy node.

What value of the capacitor should be used ? FB to GND