Synchronous rectifier driver for Power Integrations

Another synch rectifier driver chip that power integrations would surely sell in great numbers is as attached. Are there plans to make something like this?....
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The attached is a Two Transistor forward , done with a Full bridge controller which has a synch rect driver output which can be used to drive the “freewheel” synch fet via a small Pulse transformer as in the attached LTspice sim and pdf schem. A “freewheel” synch fet is all that’s needed as the duty cycle can be made low such that the “power” synch fet can be avoided and so just a diode is OK here.
I am sure (?) many would agree that this is a perfectly satisfactory way to reduce secondary rectifier losses. Also, it avoids the dreadful problem of shoot through which can happen with those secondary side synch rect control chips which are afflicted by noise as they “look” at the noisy switching node. Also, the shown method here means you can slap in TO220 synch rects in parallel and not worry about lead or bonding wire stray inductance effects. No messing about trying to heatsink those “low stray inductance” SMD FET packages…..they are lousy as they need heatsinking through the FR4 PCB. (albeit with thermal vias but thermal vias are pretty lousy compared to a good solid metal TO220 tab screwed to a metal heatsink with just a little 100um thick insulating spacer)
The LTC3723 assures that the synch rect drive is delayed and “clipped” such that there is no shoot through. This means less field failures and so the extra cost of the LTC3723 is worth while.
This is also in the name of "design for maintenance" where SMPS's are designed by experts but have to be maintained by engineers who do not have a decade of experience of SMPS design.
(By the way, the other reason to use a full bridge controller is that it has the “spare” output which could be used for pri side bootstrap high-side drive capacitor refresh, ..good in light load.)
I am wondering why no semi-co’s are making chips like this? The LTC3723 can be “hacked” to do it as shown here but its expensive at approx $4.5 per 1000 pces. I am sure this could be done cheaper than the LTC3723 chip?

PI does have synchronous rectifier drivers - they are integrated into products like Inno Switch.
I doubt that there would be much interest in marketing a stand-alone synchronous rectifier controller, as this doesn't mesh with our operating strategy of providing integrated solutions.

Thanks, but i dont necessarily agree with your sentiments....what about the Capzero?...that isnt integrated with HiperTFS etc etc.

Synchronous rectifier capability would be a massive seller for  going with power integrations chips.

The point is, and i ask if you agree, that synchronous rectification is down right dangerous and risky if not done properly. The SMPS can be blown up by malfunctioning sync rects.

For example, any instability or sub-harmonic oscillation at startup etc can really mess up sync rects..not to mention the effect of lead inductance etc in the sync rect leads.

Synchronous rectifiers need massive care.......they should be disabled during startup...and really should only be used at power levels greater then 30%...because otherwise the otuput inductor current can massively reverse if the SMPS goes into discontinuous mode....this can destroy the SMPS.

Do you agree, this is the real reason that power integrations dont do synchronous rectifiers?......because the customers could mess it up.

Synchronous rectifiers would be the icing on the cake for eg HiperTFS and Hiper LCS.

There are thousands of offtheshelf synchronous rectifier controlelrs which "Live" on the secondary side.....why has power integrations never recomended to use any of these, in all the hundreds of design examples that power integrations provides?.......do you agree...it is because synchronous rectification is just too risky to be entrusted into many of Power Integrations' customers?

The innoswitch is brilliant, and does the sync rect control from the primary side, which is how is is best done (less risky)...but innoswitch cannot really do above 250W...Innoswitch shoudlnt really be used above 150W.....

Power integrations only have one design note where a sync rect driver is used...and that is SRK2000 in DER385........once!...thats not enough.....above 250W and sync rects are really really needed!......and BTW, reactive type sync rect controllers like SRK2000 can be extremely risky to use, woudl you agree?

PI's sole rationale is providing integrated solutions for our customers to enable them to drastically reduce external component count in their designs. This push started all the way back in 1994 with the introduction of the original TOPSwitch, which offered a drastic reduction in parts count compared to conventional controller/mosfet flyback solutions in vogue at the time of its introduction. 

It has never been PI's practice to market stand-alone "jelly bean" parts like controllers, drivers, mosfets, or other functionality. Our GaN-based solutions have the GaN fet integrated inside the part with a special driver to optimize performance and to ensure that GaN fet and driver are in close proximity. 

Our new PFS-5 PFC solution uses an internal GaN fet with special driver to enable DCM operation with valley switching to reduce switching loss, enabling 250W power handling. with PCB board trace heat sinking. The part also incorporates an internal CapZero to further reduce external package count. However, this part at 250W capability is short of your power requirement.

If you are looking for a solution for your requirements that will supply the required output power with a PFC front end, I can suggest our new Hiper LCS2 chip set that incorporates internal synchronous rectifier drivers, flux link communication to eliminate optocouplers and TL431, and current-mode operation. This solution will have no problem with your proposed load profile. The Hiper LCS2 could be paired with a PFS-4 PFC front end. 

Another possibility would be a PFS-4 front end paired with a HiperLCS DC-DC converter. With a ~2% minimum load and 37V output, this solution would probably achieve overall efficiency of around 90%, even with standard Schottky rectifiers at the output. The down side would be the increased parts count due to inclusion of TL431/optocoupler regulation circuitry.