Are there models of ADP1074 and ADP1071-2 for LTSPICE available?

These models are not presently available on the web. The main criteria for deciding b/w active clamp forward and flyback is cost and efficiency assuming space is not too much of a concern. High current applications >=5A are generally better with forward converters. Take a look at 2 design examples:

http://www.analog.com/media/en/technical-documentation/user-guides/adp1074-5.5v-ebz-ug-1254.pdf

http://www.analog.com/media/en/technical-documentation/user-guides/adp1074-evalz-ug-1115.pdf

For 20-40W you can get away with a flyback converter but it really depends on all the parameters of the application. Can you please let me know the input range, output voltage, and output power. I'll be able to guide you better that way. Thanks.

Lt Comm Data.

This design is not too high power – max would be 24W.  I think the ADP1071-2 might be the better solution for this application.  Are there full datasheets available?

Thanks,

Dan Baldor

The ADP1071-2 will indeed be a good fit for this. The ADP1071-2 is in pre-release status so the full datasheet is not yet available. However, it is exactly similar to ADP1074 (active clamp forward converter) with fewer pins. I suggest you contact the local FAE/Sales to get samples. In the meantime I have attached the some data for a design that is rated at 36-60Vin, 12Vout, 3A nominal (5A peak).

Lt Comm Data

Thanks.  Do you know if there is any reason you can’t achieve the same power efficiencies with the ADP1071-2 as you do with the LT4295?  Specifically I am thinking of basing my design on the 40W PoE 12V 3A flyback design on page 18 of the datasheet.   I looked at the reference design for the ADP1071-2 and it seems to be hitting worse efficiencies and also needing a lot more snubber circuitry around the fets.  Not really sure why that is – maybe the design is targeting a smaller transformer.

Thanks

Dan

Hi,

The main difference between the two designs are the transformer and FETs (primary and secondary). If you use the same power stage you should get the same efficiencies.

Regarding the snubbers, the snubber in the UG from the previous post uses and RCD snubber as opposed to only an RC snubber on this link http://www.analog.com/media/en/technical-documentation/eval-board-schematic/DC2539A-2-A-SCH.PDF The snubber for the secondary FET is also less aggressive in my opinion but that is a designers choice. If all things remain equal you should definitely get the same efficiencies.

One other thing is that the switching frequency is 300k vs 250k in the two designs so that also explains as to why the efficiency is slightly lower. 

Your decision should be on how many external components are required in the total BOM.

Lt Comm Data.