How to use the buck switching regulator ST1S03PUR, and dimension the components value for an out 3v3 and 500mA?

LUruc.1 · ‎2021-12-01

Hi, latelly I am trying to use the buck switching regulator ST1S03PUR and I have some problems with it. It should be something easy to do but seems like not.

I have a DC Vin 12V and i want as out 3V3 and 500mA.

For the Vout I am using the formula from datasheet VO = VFB [1 + R1 / R2].

Vfb=0,8V.

I'm a litle confused because I am following the datasheet and it is easy to put out 3v3 but once I put a load ST1S03PUR can not hold it and breaks puting in S.C Vin and GND.

Vin 12V from an lnk3206 ac/dc switching 300mA out.

For sure I'am doing something wrong and one of them is the layout of the pcb but for sure even the layout isn't the best I could do , I should not have this kind of problem.

No temperature problems detected.

Could you help me to understand what's wrong in my case?

Thank you

Leonard

Muhammed Güler · ‎2021-12-01

I have worked with ST1S14PHR before. could not start directly on load. It was working if I connect the load with 1-2 second delay.

LUruc.1 · ‎2021-12-01

Hi, yes I tried also this way but no change, anyway if this is valid also for ST1S03PUR than maybe it is the case to find diferent solution for my applacation.

Thank you

Peter BENSCH · ‎2021-12-03

You can do so much wrong with the layout of a buck regulator that the circuit does not work at all.

Are you able to share the layout of your design?

Regards

/Peter

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LUruc.1 · ‎2021-12-15

Hi Peter,

I don't have it now anyway I already order the evaluation board and and make some test.

Thank you

Leonard