An active droop current sharing technique combined with current limiting
function is employed in a parallel power supply. The parallel power
supply is characterized with a current sensing amplifier that generates a
current feedback signal representing a difference between a nominal
output voltage and a fractional output voltage. The current sensing
amplifier is coupled to a threshold level generator providing a threshold
level defining a voltage level corresponding to a maximum allowed output
current of the parallel power supply. If the voltage level of the current
feedback signal exceeds the threshold level, the threshold level
generator is turned on and the current feedback signal is coupled to a
switching controller to adjust the output voltage of the power converter
for properly addressing the current imbalance among plural parallel power
supplies. Meanwhile, the threshold level generator induces a current to
the current sense input of the switching controller, thereby limiting the
output current of the power converter from exceeding the maximum allowed
output current.