500W SMPS topology question

Jan 29, 2005 1 Replies

Hi:



I need a little advice on switching power supplies. I'm looking to build a 500W power supply for an audio amplifier. I'm not too experienced in switching supplies, so I'm doing this as a learning experience.



What is the best topology for this, considering the power and application? From reading general books on power supplies, it seems that, at this power, a full bridge is recommended. From what I've read, the primary currents and voltages at this power level are difficult to deal with in other topologies, like the fly-back, forward/ double-ended forward etc..



I've seen designs on the internet using push-pull for this power level (for audio applications) , but none that use a bridge. From what I've read, dealing with the possible flux imbalance in a push pull can be a big problem, so I'm leaning towards the bridge (via LTC3722) ,however the only bridge circuits I see online are for really high power (in the kWs). I haven't see much else using this topology. Is this a rare topology? What is standard in the audio industry ? (if there is a standard)



What topology do people generally use for this power level? Thanks in advance for any info on this.


Full or half bridge is the normal solution.

You may find some schematics of interest at QSC's website - see the PowerLight range

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. Their drive circuitry is somewhat 'overdesigned' but it's a useful reference.

You won't need anything as esoteric as an LT device btw.

It's normal *not* to use feedback from the load side since the feedback loop won't cope with the rapid load changes. Just use the controller chip as a nice source of the right waveforms.

Graham

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