| Electronics > Beginners |
| A niche chip (LT4320) for mains powered AC -> low volt DC "linear" based psu ? |
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| digsys:
--- Quote from: Phaedrus --- What's your efficiency looking like? --- End quote --- DAMN GOOD, even at 20A! If you check the waveforms, V2 has a drop of ~100mV for 1-2 mS. Even with that small PCB, the FETs didn't get too hot, well under their rating. V1 are good to 15A with very little heat. In V3, I'll go back to 4oz and add small Cu wings, just for extra headroom. |
| Zero999:
Just thinking. Another use for this IC could be a brushless motor driver designed to maintain compatibility with a permanent magnet DC motor h-bridge. The driver circuit would always be powered from the same polarity but an input could be connected to the bridge rectifier input to reverse the motor when the input polarity is reversed. |
| BravoV:
Just want to thank the "Santa Claus" in this thread here, attached photo below the thing I found under my chimney. :-DD |
| Phaedrus:
Hm, would be nice if they had a higher-voltage version that can work directly off mains voltage (up to 264VAC). The bridge rectifier is one of the last remaining major loss zones in an ATX PSU. Being able to get rid of those diode losses is a major goal. If a high-voltage version of this chip could be implemented more cheaply than a digital controlled bridgeless PFC, then this could be a great option... |
| tszaboo:
--- Quote from: AcHmed99 on December 27, 2013, 10:35:38 pm --- --- Quote from: Phaedrus on December 27, 2013, 05:43:05 pm ---Hm, would be nice if they had a higher-voltage version that can work directly off mains voltage (up to 264VAC). The bridge rectifier is one of the last remaining major loss zones in an ATX PSU. Being able to get rid of those diode losses is a major goal. If a high-voltage version of this chip could be implemented more cheaply than a digital controlled bridgeless PFC, then this could be a great option... --- End quote --- The problem really wouldn't be the driver it's the switches. The pickings for single digit or even sub 20moHm fets (500V- 800V) are slim to non-existent, what does exist is expensive. They do make some IGBT modules but again these aren't cheap. When it gets to the point bridge losses are excessive building a small 1W isolated power-supply for driving some fets would just be a drop in the bucket. They do have some decent power rectifiers you can always parrallel them to help with the losses a bit. I know you don't get perfect current sharing but thats about it. VISHAY makes some reasonablly priced ones VS SERIES in T0247 so you can bolt them to a basic heatsink and spread the dissapation out. Even a bridgless PFC really isn't all that much better you still need at least one or two addtional switches can't recall exactly off the top of my head. --- End quote --- Not to mention, at 6V the diode drop is 10%, at 230 it is only 0,3%. Well, just close numbers. |
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