STKNX Buck converter don't get 12V output

[mcastilla]

I am trying to get 12V at the output of STKNX buck converter, but I am not getting it and the STKNX dead.

The RFB1 that I am using is 33K Ohm and the RFB2 is 3k Ohm, with these resistors the Vout would be 1 + 33k/3k = 12V. The maximum value of this voltage, that I got, was 9.46V while I was using RFB2 as 3.9k Ohm and if I use 3.24K (Vout = 1 + 33k/3.24k = 11.18V) the STKNX dead.

Does anyone know where the problem would be? I saw in the datasheet that the STKNX buck output could be up to 12V. Do the resistors have any limit value?

[mcastilla · Accepted solution]

I found the solution. The problem was in the configuration of STKNX, if you use the configuration of buck converter enable and linear regulator disabled, the pin VCCCORE is not good for 12V at the output of buck regulator. For this reason, you need to use the configuration of buck converter enabled and linear regulator supplied by buck converter (see datasheet).