Electronics > Beginners
A niche chip (LT4320) for mains powered AC -> low volt DC "linear" based psu ?
Phaedrus:
--- Quote from: NANDBlog on December 29, 2013, 10:19:14 pm ---
--- Quote from: Phaedrus on December 29, 2013, 12:25:20 am ---...
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It looks like it has more features than I anticipated. Probably they did not take fully apart because of the SMD on the bottom.
May I ask why was DrMOS unreliable? I'm recently looking into the possibility use them in industrial applications. The only downside I see right now, that the internal MOSFET sizes are not optimal for my output voltage (I need about 2-3-4 volt output, not 1.2-1.5V they are designed). Can you share some background information?
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We haven't used them in our PSU designs, but I worked for a company that used them in motherboard VRMs. The problem is that DrMOS seems to be very sensitive to reverse voltage; just a little bit and it'll let the magic smoke out. You have to be very picky with your inductors, and don't trust the peak current ratings. The motherboards using them had higher than average DOA rates, and very high returns with blown VRMs 6-18 months down the road. Correlating with higher CPU wattage of course, but the combined current of the DrMOS should have been more than adequate.
They also aren't good voltage for ATX PSUs.
megajocke:
--- Quote from: digsys on December 28, 2013, 10:23:03 pm ---Why do we need this? O/Temp, O/Current, O/Anything SHUTDOWN ! The perfect oN/oFF control of up to 20-30A with a 10uA 3V signal !!!
woohooo heaven.
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But, you still have the body diodes of the MOSFETs, don't forget those! :) Removing the gate drive from the FETs would just turn your nice low-loss bridge rectifier into an ordinary high-loss one, and the magic smoke would be released soon if the cooling is designed for the low-loss mode of operation.
To get shutdown functionality you need more switches anyways so the functionality could be made completely separate, using just a single FET on the DC side for example.
digsys:
--- Quote from: megajocke --- But, you still have the body diodes of the MOSFETs, don't forget those! :)
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DOH !! :-) I wish we could "edit" or "delete" posts :-) ..... lol
necessaryevil:
@NANDblog, Pheadrus,
Any recommended docs/books about ac-dc topology for the novice? I'm quite interested.
ResR:
I made the PCB design for that chip also with all through hole components, the pcb is 74x69mm in size.
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