Your favourite self oscillating topology

[Tekko]

As the title sez, which do you prefer of these three self oscillating topologies:

UcD (Universal Class D)

Delta Sigma

Hysteresis

 

[ChocoHolic]

none of the listed

 

[JonSnell Electronic]

I prefer and find this works;- A standard 29kHZ xtal controlled triangular oscillator. 29kHZ because it doesn't give adverse issues with usual audio frequencies.

 

[gmarsh]

High order delta-sigma with post-filter feedback.

 

[twentyfourbit]

Hypex NCore is family of UcD

 

[Osvaldo de Banfield]

Non self oscillating, fixed frequency using HCF4047 is my prefered.

 

[Tekko]

Lemme guess, a HCF4047 and an integrator to generate the triangular wave.

 

[Osvaldo de Banfield]

Yeah! TLS272 is my integrator.

 

[Tekko]

I see that you dont mind a low switching frequency.

How do i see that ? The high value output filter inductors is a dead giveaway that FS is 250kHz or lower.

 

[Osvaldo de Banfield]

4047 is oscillating at 560KHz, and then main frequency switching is 280KHz. Tho anti phase outputs of 4047 are added at the integrator's output. It work pretty, in this moment I'm listen internet radio using this device powered from the yellow (+12) and blue (-12) of this ATX PS of this computer.

 

[ChocoHolic]

...being some more specific on my comment above.
The hysteresis oscillator is usually seen with fixed hysteresis.
That's why I said none of them.
Comparing fixed hysteresis vs. UcD - I would prefer UcD.
Stepping to a dynamic hysteresis vs. UcD - I prefer dynamic hysteresis.

No experience on sigma delta - so I cannot vote for it.

 

[Osvaldo de Banfield]

Self oscillating may be easy to design, but they're strong electrical noise generators as frequency varies with signal, not too adequate to use near an AM receiver.

 

[gmarsh]

Self oscillating may be easy to design, but they're strong electrical noise generators as frequency varies with signal, not too adequate to use near an AM receiver.

Keeping the class D carrier inside the amplifier is a matter of proper design, not topology.

 

[manojtm]

Keeping the class D carrier inside the amplifier is a matter of proper design, not topology.

Hi ALL

true and i vote for this

{ my experience sigma-delta produce/generate less EMI, Noise and cross talk }

Regards
MANOJ

 

[Osvaldo de Banfield]

Ok, but let's to agree that it is easily to eliminate or filter a narrow width frequency variation that a large one. I can say it as ham radio from 1987.

 

[Tekko]

About the UcD, which came first, the Hypex one or the philips one ? /usr/hosting_files2/main/previews/doc389288187/preview <- the philips one is seen here.

 

[ChocoHolic]

About the UcD, which came first, the Hypex one or the philips one ? /usr/hosting_files2/main/previews/doc389288187/preview <- the philips one is seen here.

First came the Philips. Bruno was working for Philips, when he invented UcD.
The UcD from Hypex are using the same principle, just with some evolution in implementation.

 

[gmarsh]

Ok, but let's to agree that it is easily to eliminate or filter a narrow width frequency variation that a large one. I can say it as ham radio from 1987.

You can't notch filter a fixed frequency class D amplifier output - the carrier has harmonics which a notch won't take out, and secondly the carrier is modulated by the audio frequency. You're stuck with lowpass filtering.