Class D Amps

[Nysan]

Does anyone have any expirience in building digitally controlled class D powerAmps?
What is your oppinion on the matter?

/David

[mwh-eng]

By digitally controlled, are you talking about using a DSP or microcomputer with built in PWMs? How would you convert the audio analog into digital? A/D Converter? If so, I don't think it will buy you much compared to the simple comparator and triangular waveform approach to produce PWM from the audio analog.

[Rog]

Im building an analogue and a digital controller for my uni project at the moment. I havent implemented the digital one yet but I have been going through different designs. The easist is counting up and down to produce the triangle wave and comparing it to your AtoD converted input.
The most prominent problem is the fact that if you want high resolution such as 16 bit you need to count up and down 16bits to produce a triangle wave. This is a huge amount of clock steps (2^16) and requires a lot of processing speed to achieve a reasonabl switching frequency. I have had to reduce AtoD resolution to get realisable clock frequencies.
I think my analogue control made of op amps is going to work much better. Viva analogue!!

Rog

[mwh-eng]

Originally posted by Rog

I think my analogue control made of op amps is going to work much better. Viva analogue!!

I vote for analog, also!

The digital methods may be good for the learning exercise, but I prefer the simple analog methods. Using an IC such as the UC3637 makes it easy to add some dead time, eliminating cross current conduction, if the topology requires it. Need level shift drive, if desired power output is limited by opamp/comparator supply voltages.