Re: Synchronous rectifier

In article <1140441609.062899.218000@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
kell <kellrobinson@xxxxxxxxxxxx> wrote:

supermos@xxxxxxxxx wrote:
Hi, I am working on a integrated synchronous rectifier, in which a
comparator sense the Vds of a MOSFET to control the turning on and off
of the MOSFET. So the comparator is a zero-crossing detector. In the
design of the comparator, the offset is well controled to enhance the
efficiency. But in very light load/zero load, there is some
oscillation. Thus my question is: is anyone of you once meet this
instability problem and could anyone give some advice on this?

Thanks...
Eric

I don't have much experience with synchronous rectification, but lack
of experience never stopped me from shooting my mouth.
Get some hysteresis by using a little positive feedback on the
comparator, maybe.
What's this for, a SMPS?

Or...

If the oscillation happens right at the point where the thing is supposed
to turn off, you can include a latch to hold it off.


--
--
kensmith@xxxxxxxxx forging knowledge

.

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