.but power integrations topswitch is a voltage mode flyback.
Thanks, ...yes that does happen, but not at or near full load....what you describe happens when its backed off from full load. On or near full load and its pure voltage mode.this is not strictly true - the current information is widely used inside these parts, often in conjunction with the internal state machine, a peak current is set and the number of pulses is modulated to get Vout, as the load varies the state machine increments or decrements the pk curr setting.
Oscillator and Switching Frequency
The internal oscillator linearly charges and discharges an
internal capacitance between two voltage levels to create a
triangular waveform for the timing of the pulse width modulator.
This oscillator sets the pulse width modulator/current limit latch
at the beginning of each cycle
Thanks, as described, there is nowhere in pushpull to put a blocking cap...this presumably is why Dr Ali says Pushpull is a no-no for current mode?Where would you put the blocking cap in a push-pull ? - sketch please
...Thanks, the method most are familiar with is adding resistance into the paths of each primary coil half...and making it the same resistance in each half....there are more exotic ways as you know, but generally these would be a waste of time....just pick another topology instead.Yes of course you can do a push pull with overall volt mode control - there are several simple methods to avoid flux walking.
Thanks, i see what you mean....though when someone comes to you with a topswitch flyback, with 24vout, and they have also used the "NPN in the feedback loop" so as to reduce the need for high optocoupler current, and its gone into CCM at low line, then you have to compensate it, and ccm voltage mode flyback needs a type 3 compensator if its going to avoid being overly slow in transient response...but i dont see them recommending or giving a type 3 compensator for it.actually this is not strictly true,
Thanks, and i know you are joking when you say zealots.typical load steps employed are, 10% - 50%, 50% - 100%, 10% - 90%, 0 - 20%, and 0 - 100% for the zealots.
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