Quote:
Originally Posted by GriffinRU
Nice caps, what ESR value they present and why your inductor is not as compact as caps? Ceramics should have zero, but this high capacity once must have some, more care about power ratings for them and cooling.
What do you mean by "Fets are snubbed" i.e. on-die or with the caps network?
By the way which component is failing, or it is too much to ask?
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The ceramics show about .005 ohm or so. The inductor isn't as compact as the capacitors because there isn't any inductors as compact as the capacitors -- not really sure what you mean. The smallest 22uh 4 amp inductors are at least 10mm square.
The FETs are snubbed using an RC snubber -- to prevent ringing.
The component that is failing is the switcher controller -- a National LM3485. National is looking into it with us -- seems the overcurrent circuit is failing internal to the LM3485, and leaving the chip in constant overcurrent state. That's why the output voltage drops to 1.08V - -it's in hiccup overcurrent mode. Replace the LM3485, and all works well again.
Patrick