creation the gap space at your core .
and keep your core with wire ( my mean is that your core will shaking and its is due to the HF fluxes ) . and you should be ensure that your core can not be shaker! *and you can use a big varnish *for keeping your core
Core saturation, current limiting, closed loop instability are all possible explanations.
by the way , if your circuit has hiccup current limiter , that can provide oscillation at low frequencies .
Well that's not surprising if the supply is in an audio amp. Like I said, if the load (or line, or really any part of the converter) is being modulated in the audible range, then you'll likely get some noise. So of course that will be the case in an audio amp (though you would hope the magnetic noise is completely dwarfed by the speaker output).Dear mtwieg
Hi
When i built a class D audio amplifier at 900W power , my carrier frequency was 300KHZ .and my inductors ( of LPF) was noisy and i optimized that with things that i said at top.
Yes, and it's also possible to get noise at light load if the controller has burst mode operation, or some other type of hysteresis in the feedback loop.[/COLOR]by the way , if your circuit has hiccup current limiter , that can provide oscillation at low frequencies .
By leading edge blanking, do you mean that the controller has a set minimum on time? You should be careful of such methods, especially if your converter ever has to operate at light loads, or has a wide line voltage range. In practice I've seen that a proper combination of lowpass filtering on the current sense, and some slope compensation, prevents pulse skipping. The slope compensation in particular is useful because it increases the amplitude of the current sense ramp, while not increasing the switching interference which causes pulse skipping.In reply to both of your comments about current limit I have also observed the audio noise phenomena. In current mode control it happens due to noisy current sense resistor and incorrect RC filter connected across it. In vero board designs we can not avoid it easily. Also I think in chips with leading edge blanking functionality this problem is addressed automatically.
The audio noise problem that I have observed practically in designs is common with ICs like UC384x series and SG352x series. However new chips like NCP1200 have addressed this audio noise problem with some genius internal design.What controller IC are you using?
The audio noise problem that I have observed practically in designs is common with ICs like UC384x series and SG352x series. However new chips like NCP1200 have addressed this audio noise problem with some genius internal design.
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