The way the circuit is drawn uses another PWM to analog step to transfer the analog ouput of the error amplier to the stages. This additional dealy gives extra slow down and is not a good idea.
Thanks, yes you are right...that is one of my dislikes of it.....but where that slow bandwidth can be tolerated it could be ok.
The slow bandwidth can unfortunately result in a high overvoltage when the load is suddenly turned off....so i was thinking of bringing in a comparator stage to slam off the converters whenever vout goes up to vout+5%, say.
The great thing about the PWM is that it can be made isolated by passing it through a digital isolater......this is a great thing, as chips like the UC3907 suffer when there are many paralleled modules as the large anlog loop is problematic for noise, not to mention, that the ground potential at each converter will be different.
Instead of isolators use simple solution known for more than 100 years, star ground.
Thanks yes, star grounding is good......though when the number of paralleled modules gets really high, then eventually it unfortunately becomes more impractical...and the ease of an isolated control signal, that doesnt care what all the local grounds are at, seems attractive?
Running muplitple SMPs in parallel with deparate clocks is calling for trouble from beating and would need a relatively slow control loop.
Thanks, yes i agree, the beating is an issue...though with large-ish capacitor banks at the output of every smps, then it gets lessened a little.
Also, even if there was beating, as you know, some loads can tolerate the overvoltage spike associated with the beating.
Multi-phase SMPS do not consist of separate SMPSs!
Thanks, your ti.com example is excellent. It does appear to be the best way to do multiphase controllers when number of phases is <6.
As you know, there are other multiphase bucks, eg, the linear.com ones, where they are literally 6 separate Buck smps's (phase interleave switched) acting as a multiphase system, into one common load.
In the case of the linear.com bucks, they share current by literally connecting together their error amplifier outputs....and since they are transconductance error amplifiers they can indeed do this.
It does beg the question.....which is better for eg <6 phases?....
...Is it the linear.com system where they literally have 6 separate, individual bucks acting together.?
...or is it the ti.com one where there is a single controller, and then 6 raw power stages?
And if there are many more than 6 phases, then we must consider that another entirely different approach is needed altogether.