gardenyu
Newbie level 4
**broken link removed**
Page2 to the right side, or shown at the attachment.
Here R16, Q4, D6 form a constant current feeding C12, once C12 voltage reaches a threshold of 1.2V, it discharges through a 30ohm resistor inside that IC, so that a constant off-time is programmed.
(when switch is on, inductor current climbs as dV/dt and peak current is limited by R14, as the off-time is also set, the flyback converter output current is thus fixed regardless of input voltage, but is open loop controlled from the application note).
I'd like to move this off-time programming circuit to the flyback output so as to form a current feedback loop instead of open-loop control. Is it doable by inserting an optocoupler somewhere in this piece of circuit? Thanks a lot.
Page2 to the right side, or shown at the attachment.
Here R16, Q4, D6 form a constant current feeding C12, once C12 voltage reaches a threshold of 1.2V, it discharges through a 30ohm resistor inside that IC, so that a constant off-time is programmed.
(when switch is on, inductor current climbs as dV/dt and peak current is limited by R14, as the off-time is also set, the flyback converter output current is thus fixed regardless of input voltage, but is open loop controlled from the application note).
I'd like to move this off-time programming circuit to the flyback output so as to form a current feedback loop instead of open-loop control. Is it doable by inserting an optocoupler somewhere in this piece of circuit? Thanks a lot.