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LT4320 based active rectifier

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#601
@Prasi
Thanks! Yeah, I always use sockets for opamps but since this is responsible for AC/DC conversion, I was a little afraid something could potentially go wrong with socket and opted for direct connexion. I have a de-solder station in case I need to remove them so no worries.

@Vunce
Thanks for the nice comment earlier, sorry I was in the car (not the one driving) so I answered rapidly. These are the Mosfets I use # CSD19535KCS

All the best!
Do
 
#602
Do,

If possible can you please compare the output voltage after rectification using this power supply vs a "standard" rectifier based CRC power supply? I recall one member mentioning that he was get around ~1 Volt DC higher on a +/- 24V DC PSU after opting for an ideal rectifier one.
 
#603
Hi zman01,

The problem when comparing will be the type of diodes used in the regular PSU and their voltage drop. The only amplifiers that I have in chassis assembling process are the Mirand A1 v1.2, the SimpelStark+ and another AB class amplifier. They both use +/-40Vdc supplies. I can tell you what type of diodes I'm using in the regular PSU and the difference in voltage drop between the ideal bridge and the regular diode PSU.

I also have the Babelfish JX but this one pulls 7A per rail and I don't know if the Mosfets from the BoM will be cool enough with this load.

But what I need most right now is a chassis which I need to order... In the meantime, I'll test on direct heatsink.

Thanks
Do
 
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#605
I switched from a set of FEP30 diodes on the diyAudio PSU rectifier section to the earlier LT4320-based THT boards from this group buy thread in my M2x. Power transformer in this amp is an Antek AS-4218, and quiescent current is 1.31 Amps. The power rails went from +/– 22.2V to +/– 23.4V, which was a worthwhile improvement.
 
#611
TungstenAudio said:
I switched from a set of FEP30 diodes on the diyAudio PSU rectifier section to the earlier LT4320-based THT boards from this group buy thread in my M2x. Power transformer in this amp is an Antek AS-4218, and quiescent current is 1.31 Amps. The power rails went from +/– 22.2V to +/– 23.4V, which was a worthwhile improvement.
Click to expand...

The increase in voltage is exactly equal to two Si diode drops (2x 0.6v) normally experienced by conventional full wave bridge diode rectifier. No voltage drop essentially with low RDSon MOSFETs.
 
#612
xrk971 said:
The increase in voltage is exactly equal to two Si diode drops (2x 0.6v) normally experienced by conventional full wave bridge diode rectifier. No voltage drop essentially with low RDSon MOSFETs.
Click to expand...
That does not tell the whole story.
I have built two amplifiers with LT4320 based rectifiers, and they both exhibit a significant amount of voltage drop beyond a simple RdsOn * quiescent current. In the case of my M2x, the transformer is delivering its rated secondary voltage of 18V RMS to the input of the rectifier. Peak sinusoidal amplitude is 18 * 1.4 = 25.2 Volts. The CRC filter drops 154 mV, leaving about 1.64V as the remainder which is consumed by the LT4320 based rectifier. This is not bad, and is a worthwhile improvement over conventional diode bridges, but certainly isn't the 'ideal' either.

The SLB power supplies that I'm using in my hotrod F6 exhibit similar performance in their rectifier and CRC sections. When I was making voltage measurements using an earlier quiescent current of 1.45 Amps and Antek AS-3222 transformers which were delivering 22V to the inputs of the PSU boards, I was seeing about 28 Volts at the input of the Cap Multiplier section. Good, but still not 'ideal'. The math is very straightforward.

I have been using the IPP029N06N Mosfets in my synchronous rectifiers. These are qualified for the target application and have Rds(ON) and gate charge Qg figures of merit that suggest good performance. It is certainly possible that other Mosfets may have better performance in this particular application, yielding higher output voltage from the rectifier. It would be interesting to hear experiences from other builders who may be using different parts and getting different results.
 
#616
TungstenAudio said:
T... The CRC filter drops 154 mV, leaving about 1.64V as the remainder which is consumed by the LT4320 based rectifier. This is not bad, and is a worthwhile improvement over conventional diode bridges, but certainly isn't the 'ideal' either.

The SLB power supplies that I'm using in my hotrod F6 exhibit similar performance in their rectifier and CRC sections. When I was making voltage measurements using an earlier quiescent current of 1.45 Amps and Antek AS-3222 transformers which were delivering 22V to the inputs of the PSU boards, I was seeing about 28 Volts at the input of the Cap Multiplier section. Good, but still not 'ideal'. The math is very straightforward.

I have been using the IPP029N06N Mosfets in my synchronous rectifiers. These are qualified for the target application and have Rds(ON) and gate charge Qg figures of merit that suggest good performance. It is certainly possible that other Mosfets may have better performance in this particular application, yielding higher output voltage from the rectifier. It would be interesting to hear experiences from other builders who may be using different parts and getting different results.
Click to expand...

IPP029N06N have a Rdson of 3mohm. You say that rectifier eat 1,64V. This indicate a 0,82V per mosfet. This lead to a current of 0,82/0,003=273Amper. 😀

I think you confuse with the loss on your power transformer secondary under load, which for sure will be higher than in the Ideal bridge itself.


Regards,
Tibi
 
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#617
Hello all,
Thanks for the payments. I have updated the sheet with latest status.

Sorry , I can not confirm individually to everyone for the payments received.
Just because , no time from work... Sorry...

I am travelling to Geneva, Switzerland on saturday, anyone from there interested PCBs , I can hand carry and do local shipping.

And also, to everyone, please post your requirements / questions, etc in the thread, I will try as far as possible to fulfill all. If anyone is left out, I will sure to make another GB to fulfill.

Many different avenues of contact (PMs, Email, Site feedback form, etc) means , I cant keep track of all.

Regards
Prasi

Please ask questions you have here..
cost:
LT4320 SMD- 1.8 USD per pair
LT4320 THT rectifier: 3 USD per pair
LT4320+CRC PSU PCBs: 6.5 USD per PCB.

Shipping /handling , packing and paypal extra.
 
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#619
Thanks Zee,
I will be representing India @ the 80th session of GRPE, WP.29, under UNECE... a committee meant for world harmonization of emission regulations of vehicles. (whatever that means !😀)
Top job, but very demanding:O.
I find less and less time for
1. my own DIY activity
2. for the DIY community
A drastic drop in number of PCB designs posted for DIYA members.🙁
 
#620
Hello Prasi,
thank you for your great work and support despite your responsible main job.
Please make possible what all of our politicians cannot do, but every normal person with common sense wishes.
I know I am dreaming, but it's a nice dream. 😉
Good luck, have a good flight and come back home healthy.

André
 
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