lnk306 fails at vin > 60Vdc
I am trying to make a powersupply for some mesurement equiptment.
the input is 230Vac at 50Hz and the output has to be 6Vdc 300mA.
my design works with a input range between 12Vdc and 60Vdc but above the 60Vdc it gives no output.
Vin_120Vdc.jpg and Vin._60Vdc.jpg are mesured over R5.
Comments
if the internal mosfet fails with the buck converter then the input is directly connected to the output.
but with the buck-boost converter design the input is shortend so the load is not subjected to the full input voltage.
is it possible you run the test without L1?
with L1 shorted the waveform remains the same for 120Vdc but at 60Vdc there is a small difference (see attachment: Vin_60Vdc_L1-shorted.jpg)
I Am trying to explain myself the behavior of your waveforms by watching your paper design, I have some questions. Why do you need R5? This R will have an effect in the curve of your current because you have and RL circuit instead of an inductance. I think you should remove R5.
The ILIMT of the LNK306 is about 500 mA. But your inductor is rated 0.3 mA. You may be saturating the inductor and damaging it at high line because as you increase the line voltage, then you will increase the slope of the current in your inductor. So I suggest you use another inductance with larger current capability.
Also you need to maintain an output load to maintain regulation
Hope after these suggestions your power works properly
Hope you can see a result after
I Am trying to explain myself the behavior of your waveforms by watching your paper design, I have some questions. Why do you need R5? This R will have an effect in the curve of your current because you have and RL circuit instead of an inductance. I think you should remove R5.
The ILIMT of the LNK306 is about 500 mA. But your inductor is rated 0.3 mA. You may be saturating the inductor and damaging it at high line because as you increase the line voltage, then you will increase the slope of the current in your inductor. So I suggest you use another inductance with larger current capability.
Also you need to maintain an output load to maintain regulation
Hope after these suggestions your power works properly
Hope you can see a result after
You are trying to design a buck-boost converter. Just by curiosity, why do not implement your design with a buck converter?
The buck converter is a simpler design and isa good fit for your specs.