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LT4320 based active rectifier

Any way of building using TO-263-7 SMD format?

I'd really like to use IPB010N06N mosfet 60V, it has very low Qg and RdsOn, but Vgsth is 2.1v compared to >3V recommendation?

If not any other PCB's that wil support?

I don't think there are any other TH mosfets that come close to this level of performance?
Qg is 208 typical, which is high unless I'm missing something?
 
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Recommended MOSFET gate charge, based on practical experience, is less than 70 nC. LT4320 wouldn’t be able to drive IPB010N06N properly.

From the datasheet:
“The LT4320 gate pull-up/pull-down current strengths specified in the Electrical Characteristics section, and the MOSFET total gate charge (Qg), determine the MOSFET turn-on/off times and the maximum operating frequency in an AC application. Choosing the lowest gate capacitance while meeting RDS(ON) speeds up the response time for full enhancement, regulation, turn-off and input shorting events.”
 
It’s 208 nC, not mC
Yeah I know.
The Siliconix SUP70060E-GE3 I used (from the recommended list) has a Qg of 53.5 typical.

There is some interesting info in this thread
Someone there said 50 nC is max recommended Qg

And from the datasheet, on mosfet selection,
"Avoid oversizing theMOSFET, since an oversized MOSFET limits the maximum operating frequency, creates unintended efficiency losses, adversely increases turn-on/turn-off times, and increases the total solution cost. The LT4320 gate pull-up/pull-down current strengths specified in the Electrical Characteristics section, and the MOSFET total gate charge (Qg), determine the MOSFET turn-on/off times and the maximum operating frequency in an AC application."
 
Interesting… (commercial product name removed). It’s not my design…

E7FB1E14-7B8C-4249-AFF7-D159BADC4C54.jpeg


This is what I'd like to replicate. I presume it's 'better' than other implementations because a good indicator of MOSFET performance is FOMQoss = Rdss(on) * Qoss (source).

I have no previous experience - trying to work out what makes this so good.
 
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Could be some high current application where high switch on/off time and some cross conduction is not important. Question is, are we fine with close to 70 us rectifier “recovery time”?

Basic capacitor current/voltage equation gives 100 us to change IPB010N06N gate (15 – 18 nF Ciss) voltage from 10 V to 0, at the average LT4320 driving current of 1.5 mA. I see no advantage by using that MOSFET. IMO, nothing wrong with the available SMD version and recommended MOSFETs.
 
I was surprised to find that the LT4320 eval board uses a somewhat similar Infineon mosfet, but it does have a lower Qg of 98 typ
The eval board is out of stock until end of the year, but that would be a way to try a similar mosfet.
Great find - that board seems like a predecessor / same basis as the one I posted the picture of. Might be a good way forward for me, but really I’d need 60v.

Could be some high current application where high switch on/off time and some cross conduction is not important. Question is, are we fine with close to 70 us rectifier “recovery time”?

Basic capacitor current/voltage equation gives 100 us to change IPB010N06N gate (15 – 18 nF Ciss) voltage from 10 V to 0, at the average LT4320 driving current of 1.5 mA. I see no advantage by using that MOSFET. IMO, nothing wrong with the available SMD version and recommended MOSFETs.
@tombo56 the power supply application uses an ungodly amount of smoothing caps, some 440,000 uf. Trying to provide lowest impedance as well as nV levels of ripple.

Because it sounds so good compared to Saligny standard that came before it (same circuit otherwise) I’m trying to pin down the criteria for success.

The eval board that Randy mentions might be a good start, but so far there is little in the way of criteria for success that I’ve found for selecting mosfets for sync rectification (other than the Infineon guide and mosfet choice guidelines on Prasi’s schema). Any guidance would be welcomed.
 
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Did a quick search at infineon site
https://www.infineon.com/cms/en/product/power/mosfet/n-channel/bsc019n08ns5/

80V mosfet with low RDSon, slightly lower Qg.
If you could get the gerbers for the eval board, you could go fab it and install these.
There might be better parts, was a really quick search I did.

What is the voltage from your transformer? What DC voltage are you shooting for?
 
Did a quick search at infineon site
https://www.infineon.com/cms/en/product/power/mosfet/n-channel/bsc019n08ns5/

80V mosfet with low RDSon, slightly lower Qg.
If you could get the gerbers for the eval board, you could go fab it and install these.
There might be better parts, was a really quick search I did.

What is the voltage from your transformer? What DC voltage are you shooting for?
Thanks - great idea.

24vac out of secondaries, so about 34vdc to amplifier
 
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the power supply application uses an ungodly amount of smoothing caps, some 440,000 uf. Trying to provide lowest impedance as well as nV levels of ripple.
Because it sounds so good compared to Saligny standard that came before it (same circuit otherwise) I’m trying to pin down the criteria for success.

With such high capacitance, rectified charging pulses are short, with very high amplitude, especially if transformer is oversized as well. In such conditions, less than 1 mΩ RDS(on) of IPB010N06N is an advantage that could be responsible for a perceived better performance.
 
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The LT4320 datasheet has a short section on mosfet selection, and a table towards the end showing a few parameters where they use a BSZ110N06NS3 and a BSC031N06NS3. In both of those examples, input is 24 VAC.
On mosfet selection, it seems to be a tradeoff of RDSon versus Qg. They also provide guidance for max RDSon based on how many amps you need.
They also say a 60V mosfet is good for 24 VAC as an example.
So I think they already derated the eval board, and it would work for 24VAC secondaries. I didn't check the cap voltages, but they would be easy to change if need be.

On your high capacitance, once you charge the caps, then your current draw will drop drastically, depending on the amp wattage. I don't know if I'd design around charging the caps.
 
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once you charge the caps, then your current draw will drop drastically, depending on the amp wattage.
Inrush current after power on is a different matter. During normal operation, such large capacitors will be charged with very short current pulses (1–2 ms long) at 20-30 A peaks minimum, if average output current is 3 A. For a different output current, charging pulses would be proportionally higher or smaller (not exactly a linear proportion).
 
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Hi 'stretchneck'
Yesterday, you mentioned above "Because it sounds so good compared to Saligny standard that came before it (same circuit otherwise)"

Could you indicate what made up the "Saligny Standard" supply that didn't meet your expectations and that the nearly half Farad capacitance (at +/- 60v?) 'did the job'?

Maybe I've not understood this properly as I've not found any problems at all with the Saligny products even using "normal to large" sized power capacitors (ie 3 x 15mF per rail/ch for example)

Also, what's your application where the very low ripple at this rail voltage is so significant?
 
Saligny products are great - all I can say is that this rectifier sounds better, as if several veils have been removed. The reason for that I don't fully understand. But with the help of tombo56 and randytsuch at least I've now got a way of making something similar and experimenting, as you can't buy the rectifier I pictured anytmore. My experiment won't be happening anytime soon however as I'm going to read more about mosfets, look at some of the other mosefets suggested for use with Prasis PCB (looks like SMD, as TH can't achieve similar values as far as I'm aware) and also a bit of research on GaN.