My guess is that when the FB voltage is deviated from Vref, the pulse width will start to change to negative feedback; when the deviation disappears, the pulse width will not change.
Is this actually the case? I want to add the DAC output of the single-chip microcomputer to the FB pin to achieve program control of the output voltage. Is this reasonable?
thank you very much!
Leila Publicado en August 19, 2020
The actual situation is that the pulse width is constantly adjusted (small adjustment)
The application program is mainly to design the algorithm of the compensation network, such as PI. You can search for relevant information on the Internet for details.
Lila Publicado en August 19, 2020
B is sampled from the output, so if you plan to use a single-chip PWM instead of FB, you must sample the output DC through the single-chip, and then give the result through the PID calculation. This is completely feasible. Many power supplies actually do this.
Malik Publicado en August 19, 2020
The correct way is to connect the dac output to the fb pin through a resistor to form an addition circuit. At this time, the voltage regulation is still handled by the internal dcdc chip, which is much faster than software participation.
