Other Parts Discussed in Thread: TL431, UCC25600
Hi,
Anybody can explain the working of current sharing control portion in PMP11064 ?.
Regards
Aneesh
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Hello Aneesh,
If circuit 3 is removed you are correct the 20V will be regulator through feedback circuitry 2 and the 12V output will be regulated with feedback circuitry 1. Please note that these two feedback circuircuits are trying to ajust the frequency of the UCC25600 to control both output voltages.
Once circtry three is added it will sense the current load on the 20V output and will adjust feedback circuitry 1. As the current increasees on the 20V output the voltage on U506 reference is pulled high. This will cause more current to go through U503 causing the UCC25600 to operate at higher freqeuncy decreasing the LLC gain.
These three feedback paths are trying to modify the oscillator freqency to control the output. This is a complicated control scheme and the three could fight each other if not designed correctly.
Regards,
Mike