Board mountable power supply module with current sharing circuit and a

Abstract

A circuit and a method for providing current sharing between parallel power supplies using a modified master/slave scheme in which any of the parallel modules can be designated the master is described. A current-share circuit is incorporated into each power supply which includes its own controller producing an internal control signal and is interconnected to the other power supply modules on a current-share bus. The current-share circuit includes a switch, which is operable to connect the power supplies internal control signal to the current-share bus when closed and disconnect the internal control signal from the current-share bus when open. The switch is controlled by master/slave logic, which determines whether the power supply is the master or a slave and controls the switch accordingly. The master is determined by closing all of the switches, thereby placing all of the power supplies' internal control signals on the bus. The power supply whose control signal reaches the bus first is determined to be the master and the switches for all of the other parallel power supplies are then opened by the master/slave logic designating them as slaves.