Hi,
I'm using a TI integrated class-D audio amp in my alternator simulator, a TPA3255, but it shuts down at 17 amps peak current and I have a customer that may need more.
So I might want to make an amp out of four hunky mosfets and a controller chip. The main supply is +48 volts.
Does anyone have driver chips that they like? Ideally, the input would be baseband audio and it would drive the mosfets PWM. A controller with separate hi/lo gate drivers is an option.
The Si8275 dual isolated gate driver is a great chip, extremely fast for an isolated driver, and beefy output. As I did a few months back I've pushed several watts into a resistive load at 5 MHz just using the drivers and they had bandwidth to spare.
Very nice for $2 in quantity. Downside is the chips seem to be very moisture-sensitive, moreso than the Analog Devices isolated drivers that are also moisture sensitive. so have to be soldered straight out of the bag or else if that card starts changing color they're done for without baking.
The Si8274 is the PWM-input variant.
The nice thing about the TI chip is that it does everything, audio sine wave in to power out, including thermal and current limiting. If we just use mosfet drivers, we have to make the PWM ourselves, and make sure the bootstraps are properly fed, and probably current limit somehow. I'd rather buy all that if I can.
There must be chip for all that.
I don't see a good way to parallel two of the TI parts.
TI (in parallel with) H-brigde via gatedrivers controlled by the TI output?
Well it's actually for a bidirectional buck/boost PWM controller for moving battery power back and forth from a bus, but might be able to press this one into service as an audio frequency PWM modulator by feeding the COMP input, it includes overcurrent detect/protection circuitry. Just add driver. And most modern gate drivers like the one I mentioned have thermal limiting.
Infineon makes an analog-input driver "for 500W applications", is 1000W in a bridge configuration enough?
Here is the frequency response test signal:
HIP4081?
I know you asked for a chip not a module, but in case you haven't seen these, they have quite impressive specs due to the unusual design - especially Zout, bandwidth, distortion, noise. I haven't used them but I have no reason to doubt the specs.
Depending on your production volume and engineering costs, it might make sense. The continuous power ratings of their products are much lower than the "audio" ratings so you'd need a bigger one than the product names would suggest.
Auggh! A hideous monstrocity. As long as you only want to run at 30-40 V it actually isn't so horrible, but the specsmanship on that chip is awful, with the best circuit layout one can only get to about 60 % of the (over)rated voltage.
There must be newer stuff that works much better, that part is over 20 years old.
Jon
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