Re: Can change of load on one winding affect output of other windings (Flyback SMPS)?
- From: "Tim Williams" <tmoranwms@xxxxxxxxxxx>
- Date: Tue, 6 Dec 2005 16:16:30 -0600
"siliconmike" <siliconmike@xxxxxxxxx> wrote in message
news:1133894044.883784.95370@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> For a flyback SMPS, if the output [with feedback] is loaded more, the
> switching duty cycle goes up.
>
> In this situation, what would happen to voltages on other outputs ?
>
> (They remain constant I guess, but why?? Shouldn't they shoot up?)
Nope-- the flyback peak has to do with the magnetic field itself. To a
reasonable approximation, this field is shared evenly by all windings, so
when one drags down the voltage, they all drag down in ratio. :)
Leakage inductance, winding (and wiring) resistance and other effects
contribute to reduce regulation by decoupling the windings from each other.
If you want one winding better regulated than any other, add feedback to its
output (use an op-amp and opto, if isolation is required). Otherwise, the
usual route (which also allows full isolation) is to add an additional
winding specifically to feed back voltage to the control chip.
Tim
--
Deep Fryer: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
.
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