Mosaic
Well-Known Member
Hi all:
I built the suggested buck v-reg for a PFM package 5V regulator as per figure 16 in this:
**broken link removed**
Note that C1 is actually 0.68uf, I replaced with a 1.0 uF 50V X7R ceramic.
The FB is connected directly to the 5V out as I have the 5.0V version of the part.
My D1 is a 3A 40V Schottky and C4 is a 470uf Elec. Cap.
I have a 20K IADJ resistor to limit max current to 2A.
What may be significant is I am using a 22uH inductor rated as per this:
https://www.newark.com/multicomp/mc...shielded-22uh-4-7a-smd/dp/82R4330?ost=82r4330
In testing all seems fine with a 12V supply, including a 1A load (resistive). Temp rise is a max 12°C delta.
With 30VDC applied....all seems fine with around a 50mA draw, I see a 8°C delta.
BUT when I apply the 1A load...the Buck Vreg burns up within about 1 second in a puff of smoke and a new hole in the case! This happened twice.
I need some advice on this....I don't see what is wrong.
I built the suggested buck v-reg for a PFM package 5V regulator as per figure 16 in this:
**broken link removed**
Note that C1 is actually 0.68uf, I replaced with a 1.0 uF 50V X7R ceramic.
The FB is connected directly to the 5V out as I have the 5.0V version of the part.
My D1 is a 3A 40V Schottky and C4 is a 470uf Elec. Cap.
I have a 20K IADJ resistor to limit max current to 2A.
What may be significant is I am using a 22uH inductor rated as per this:
https://www.newark.com/multicomp/mc...shielded-22uh-4-7a-smd/dp/82R4330?ost=82r4330
In testing all seems fine with a 12V supply, including a 1A load (resistive). Temp rise is a max 12°C delta.
With 30VDC applied....all seems fine with around a 50mA draw, I see a 8°C delta.
BUT when I apply the 1A load...the Buck Vreg burns up within about 1 second in a puff of smoke and a new hole in the case! This happened twice.
I need some advice on this....I don't see what is wrong.
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