SMPS design for a car amp....not sure which topology to go with

[hardwareguy]

So I've got this crazy idea to build a car amp using 2x TDA8950 and 2x TDA8920 or simply 4x TDA8950 on connexelectronics boards.

2 of the TDA 8950s run the midbasses, the other two amps would run the mid/tweeters, so their power outputs would be modest, maybe 20-25W/ch at most in practice. 6dB or so of headroom on the mids and tweeters is a bit overkill but I like it!

So with that in mind, total system power would not be 800W RMS in practice, but probably more like 500W.

I was thinking a push pull topology driving a center tapped transformer but my friend wants a SEPIC converter for the V+ rail and a Ćuk converter (basically an inverting SEPIC) converter for the V- rail.

I like the transformer idea because I get both rails from one SMPS and I have a good concept of how it works. My friend says his way gives greater efficiency with the benefit that only inductors are needed, which are easier to get preassembled.

So which way is preferred? It seems like everyone uses the push pull converter....is there some reason for this or is my friend on to something with his dual converter design?

[richie00boy]

Push-pull for the simple reason that it gives you galvanic isolation from ground. In a car if you use your friends method you are likely to run into ground loops - alternator whine, pops and clicks etc.

[Cristi]

Well, if you will have just little patience, and wait for about one week, you might use one of these, along with the TDA89x0 amplifier modules. here is a picture of a first version, made last year, for an OEM Customer, it is capable to deliver 300W continuous and up to 500W peak with output voltages of +-2x Vin, +-3xVin and +-4xVin. it has high efficiency and very low size. undervoltage, overvoltage, overcurrent, overtemperature protections as well. the first version was 150mm long, 50mm wide and 13mm tall, at the capacitors side 22mm tall. the next version will be commercial, and is 120mm long, 50mm wide, and just 13mm tall. i will post some pictures in the following days.

[hardwareguy]

That SMPS looks amazing!