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siliconmike
Guest
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 Posted:
Wed Dec 07, 2005 12:29 am Post subject:
Can change of load on one winding affect output of other win |
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For a flyback SMPS, if the output [with feedback] is loaded, 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?)
Please explain.
Mike
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Gerard Bok
Guest
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| Posted:
Wed Dec 07, 2005 1:35 am Post subject:
Re: Can change of load on one winding affect output of other |
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| Quote: | For a flyback SMPS, if the output [with feedback] is loaded, 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?)
|
Why guess that they would remain the same if you think they shoot
up?
Why would the other output go up as well ?
If it did, by how much ?
Sounds like homework.
We've done ours :-)
Hint: you may be looking at more than one phenomenon at the same
time.
--
Kind regards,
Gerard Bok |
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Jasen Betts
Guest
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| Posted:
Wed Dec 07, 2005 1:38 pm Post subject:
Re: Can change of load on one winding affect output of other |
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| Quote: | For a flyback SMPS, if the output [with feedback] is loaded, 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?)
Please explain.
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they are fed from diodes from the transformer secondary,
as soon as one of the diodes is conducting the secondary voltage rises
no higher.
Bye.
Jasen
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Bob Myers
Guest
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| Posted:
Fri Dec 09, 2005 1:35 am Post subject:
Re: Can change of load on one winding affect output of other |
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"Charles Schuler" <charleschuler@comcast.net> wrote in message
news:7uKdnb2fkbuMOgXenZ2dnUVZ_t6dnZ2d@comcast.com...
| Quote: |
"siliconmike" <siliconmike@yahoo.com> wrote in message
news:1133893786.033243.85990@o13g2000cwo.googlegroups.com...
For a flyback SMPS, if the output [with feedback] is loaded, 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?)
They will go up, unless the other outputs also contribute to the feedback
loop.
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Or unless the other outputs have some sort of secondary-side
regulation (i.e., the addition of a linear regulator - not uncommon
in switch-mode power supplies for the more lightly-loaded
and otherwise unregulated/unmonitored outputs.
Bob M. |
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Charles Schuler
Guest
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| Posted:
Fri Dec 09, 2005 1:35 am Post subject:
Re: Can change of load on one winding affect output of other |
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"siliconmike" <siliconmike@yahoo.com> wrote in message
news:1133893786.033243.85990@o13g2000cwo.googlegroups.com...
| Quote: | For a flyback SMPS, if the output [with feedback] is loaded, 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?)
|
They will go up, unless the other outputs also contribute to the feedback
loop. |
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highpower
Joined: 10 Dec 2005
Posts: 3
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| Posted:
Sat Dec 10, 2005 4:25 pm Post subject:
re:Can change of load on one winding affect output of other |
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For an ideal flyback, all of the secondary output voltages will track the one used for feedback. Practically though, when the output used for feedback is loaded more, the voltage coupled to the other windings will be higher due to the uncoupled inductance (leakage L) of the feedback winding. The other output voltages will go up slightly. You can see this small bump of voltage on any lower-loaded output. It will be higher during the interval while the current in the feedback winding is increasing as the primary switch is turning off.
_________________
Darrell - SENTEK Engineering |
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