Feedback loop for TOPswitch-HX
Posted by: treez
on
Hi,
In the attached AN-57, do you know what is the "K(TL431)" value? (page 14).....the open loop gain of the TL431.
We are trying to stabilise a 20W TOP256GN Flyback, and need to know the K(TL431) so we can calculate the feedback bodes.
Files
| Attachment | Size |
|---|---|
| an57.pdf | 3.25 MB |
Comments
Hi,
Thank you for showing interest in Power Integrations' products.
The open-loop gain referred to in AN-57 Page14 is the gain of the TL431 itself.
Please refer to the datasheet of the specific TL431 device you are using in your design.
Typically, manufacturers provide an open-loop voltage gain vs frequency chart in their datasheets.
As such.... i assume that by the "open loop gain of the TL431", the AN-57 means Z(FB)/Z(in) of the TL431 circuit in Fig 5, page 4 of the AN-57 Application note.....
where:
Z(FB) = 1/(2.pi.f.CF1)
and
Z(IN) = RF2
?
(The AN-57 App Note is attached in the Top Post here)