After reading a bunch of interesting discussions in this forum I thougt I might share some of my own experiences concerning class D amps.
I've build a class D amp based on the Zetex ZXCD1000 controller.
Output stage incorporates both n-ch and p-ch FET's (IRF540 + IRF5210) in a full bridge topology with capacitivly coupled gate drive. No NFB.
Efficiency is approx. 91% @ 140W/4 ohm (45V supply voltage, 2Vpp, 1kHz sinewave input).
I have not meassured THD performance yet but at first glance it works pretty well. I think the prototype will do as a reasonable counterpoise for further improvements (I'm currently working on a up-grade aiming for 500W/4ohm).
Attached is a picture of the prototype board.
Regards,
Soeren
I've build a class D amp based on the Zetex ZXCD1000 controller.
Output stage incorporates both n-ch and p-ch FET's (IRF540 + IRF5210) in a full bridge topology with capacitivly coupled gate drive. No NFB.
Efficiency is approx. 91% @ 140W/4 ohm (45V supply voltage, 2Vpp, 1kHz sinewave input).
I have not meassured THD performance yet but at first glance it works pretty well. I think the prototype will do as a reasonable counterpoise for further improvements (I'm currently working on a up-grade aiming for 500W/4ohm).
Attached is a picture of the prototype board.
Regards,
Soeren
Attachments
Here is a picture of the bottom side of the PCB. As one might see a few modifications were necessary in order to get things to work propperly.
Board dimensions are: 70mm x 80mm (height 30 mm)
Anybody else who has experiences with the ZXCD1000 controller?
The fact that the Zetex controller provides an integrated solution (internal triangle generator and pwm comparator) solves a lot of PCB layout issues otherwise encountered with a more "discrete" design. Well, at least that is my experience after have tried a few other approaches with disappointing results! An other point of interest is the use of a solid ground plane (70u) and seperation of power ground and signal ground (must be connected at one point only!). And of course, propper decoupling not to forget
Regards,
Soeren
Board dimensions are: 70mm x 80mm (height 30 mm)
Anybody else who has experiences with the ZXCD1000 controller?
The fact that the Zetex controller provides an integrated solution (internal triangle generator and pwm comparator) solves a lot of PCB layout issues otherwise encountered with a more "discrete" design. Well, at least that is my experience after have tried a few other approaches with disappointing results! An other point of interest is the use of a solid ground plane (70u) and seperation of power ground and signal ground (must be connected at one point only!). And of course, propper decoupling not to forget
Regards,
Soeren
Attachments
Regarding the sound quallity of the amplifier....well I have only build one prototype and tested it on a loudspeaker in a laboratory environment! I don't think it would be fair to make a final conclusion based on those harsh conditions but on the face of it the sound quality seems reasonable. I might mention that this amp is intended for a subwoofer.
Regards,
Soeren
Regards,
Soeren
I forgot to answer the second question - sorry Mark.
I'll try to go as far as possible with the present design - or at least as far as the 100V FET's will get me. However, I have a hunch that tells me that the P-channel FET's will give me some trouble so I might go for a pure N-channel solution using a couple of LM51xx high side drivers.
Regards,
Soeren
I'll try to go as far as possible with the present design - or at least as far as the 100V FET's will get me. However, I have a hunch that tells me that the P-channel FET's will give me some trouble so I might go for a pure N-channel solution using a couple of LM51xx high side drivers.
Regards,
Soeren
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