Hello.
I have to say right away that this is probably a very stupid question, but I really need to ask. It's about switching power supplies in general, feedback contorl in parcitular. I've been using them quite successfully for quite a while, but never got to thinking about it. The question is this.
The purpose of the error amplifiers in the feedback control circuitry is te eventually bring the output voltage (divided according to the requirements) as close as possible to the reference voltage. If that is so, that means that whenever the difference between these voltages is zero (which is the point of it all), the resulting duty cycle of the pwm controller seems to always be the same. In that case, how does it come about that by varying the resistor divider ratio one gets to acquire different output voltages?
Bear with me please.
Thank you in advance.
I have to say right away that this is probably a very stupid question, but I really need to ask. It's about switching power supplies in general, feedback contorl in parcitular. I've been using them quite successfully for quite a while, but never got to thinking about it. The question is this.
The purpose of the error amplifiers in the feedback control circuitry is te eventually bring the output voltage (divided according to the requirements) as close as possible to the reference voltage. If that is so, that means that whenever the difference between these voltages is zero (which is the point of it all), the resulting duty cycle of the pwm controller seems to always be the same. In that case, how does it come about that by varying the resistor divider ratio one gets to acquire different output voltages?
Bear with me please.
Thank you in advance.