Hello,
Fig 13, page 9 of this app note shows an improvement on the "normal" optocoupler feedback connection for transformer isolated SMPS's.....
https://www.electro-tech-online.com/custompdfs/2013/03/AND8273-DPDF.pdf
....On page 9 it says that the opto diode is driven by a current source.
Does this configuration, with the extra BJT, Q1, absoluteley need have to have a current source to drive the opto diode?
What would happen if i drove the opto diode with a typical TL431 circuit as in the following......
(please see schematic on bottom right of page 5 of the following)
https://www.electro-tech-online.com/custompdfs/2013/03/TND381-DPDF.pdf
Also, since using the BJT, Q1, in fig 13 of the first app note gets rid of the opto-diode pole problem, why is this method not more frequently used?
Fig 13, page 9 of this app note shows an improvement on the "normal" optocoupler feedback connection for transformer isolated SMPS's.....
https://www.electro-tech-online.com/custompdfs/2013/03/AND8273-DPDF.pdf
....On page 9 it says that the opto diode is driven by a current source.
Does this configuration, with the extra BJT, Q1, absoluteley need have to have a current source to drive the opto diode?
What would happen if i drove the opto diode with a typical TL431 circuit as in the following......
(please see schematic on bottom right of page 5 of the following)
https://www.electro-tech-online.com/custompdfs/2013/03/TND381-DPDF.pdf
Also, since using the BJT, Q1, in fig 13 of the first app note gets rid of the opto-diode pole problem, why is this method not more frequently used?