grizedale
Advanced Member level 3
Hello,
I wish to make out a feedback loop for a CCM current mode full bridge 250W.
It has TL431 /opto feedback but not with the fast lane.
Basically the TL431 has been set up like a type 3 opamp.
then thers the opto with secondary side led resistor and a pullup resistor on the primary side, in the standard way
controller is uc38025.
I notE Basso doesnt refer specifically to this type of occasion and i wondered for pointers about the error amp transfer function?
Is the DC gain = [ R(pullup)/ R(led) ] * CTR.
i take it i will have to accounf for the optocoupler pole , and i suppose i have to just add in the -20dB/decade starting from the pole frequency on the error amp bode plot?
Also, their is a current sense transformer, but i suppose since i know that current sense limit is 1V, i just have to use the equivalent resistor, which used instead of the current sense trafo setup, would give the same behaviour as the current sense trafo.
I wish to make out a feedback loop for a CCM current mode full bridge 250W.
It has TL431 /opto feedback but not with the fast lane.
Basically the TL431 has been set up like a type 3 opamp.
then thers the opto with secondary side led resistor and a pullup resistor on the primary side, in the standard way
controller is uc38025.
I notE Basso doesnt refer specifically to this type of occasion and i wondered for pointers about the error amp transfer function?
Is the DC gain = [ R(pullup)/ R(led) ] * CTR.
i take it i will have to accounf for the optocoupler pole , and i suppose i have to just add in the -20dB/decade starting from the pole frequency on the error amp bode plot?
Also, their is a current sense transformer, but i suppose since i know that current sense limit is 1V, i just have to use the equivalent resistor, which used instead of the current sense trafo setup, would give the same behaviour as the current sense trafo.