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LT4320 based active rectifier

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#683
I don’t think the point was ever to use it with a strictly “center tapped” trafo, but to use in such a way that only one expensive LT4320 bridge and four low RDson MOSFETs are required for a dual rail PSU. That has been demonstrated to work very well, even at full Class A currents. The limitation being a maximum voltage of +/-35v should be observed in choosing transformers suitable for doing this.
 
#685
xrk971 said:
I don’t think the point was ever to use it with a strictly “center tapped” trafo, but to use in such a way that only one expensive LT4320 bridge and four low RDson MOSFETs are required for a dual rail PSU. That has been demonstrated to work very well, even at full Class A currents. The limitation being a maximum voltage of +/-35v should be observed in choosing transformers suitable for doing this.
Click to expand...

correct X, blitz had asked for an alternate/different connection scheme while using 1 lt4320 with 4 mosfets to get dual rail voltage (post # 666). you have it demonstrated comprehensively. very nice work.
 
#686
Note that using only one set of MOSFETs for the full Class A load does make them run warmer than spreading it over two sets as before. Under 2.5A continuous Class A load, I measured temps at the dual MOSFETs of 75C (smaller than the ones shown in photo above). Whereas they were barely warm before. But it is all within operating temperature range still.

2.5A is a typical load as seen by 25W Pass Class A amps (F5, M2, etc) as they typically have 1.25A bias current per channel.
 
#693
Your little bridges are a great tool to have on hand, Prasi. I am using them all over the place now.

Would be nice if they could be ENIG finish - have you ever considered that? The SMT parts would be much nicer to paste solder - especially that little VSON chip. I actually think the MSOP is the way to go. Exposed leads makes for easier soldering.

Thanks,
X
 
#699
I am working on a new design of the LT4320 with following changes
1. removal of snubbers
2. size optimization for smaller footprint (SMD could be same as Vishay PB3510 SIP rectifiers in terms of width)
3. MSOP LT4320 chip option along with earlier DIP option
4. LED indication for THT also (is it really necessary?)
5. 2.4 mm thick, 70 um copper with ENIG finish

I will post here when design is done and see the interest for such PCBs.
 
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