Patent ID: 7436161
Filing Date: 2008-10-14
Classification: G05F,H02M

Abstract:
1. A feedback circuit for a switch mode power supply, comprising: a first signal feedback stage, an input of said first signal feedback stage coupled to a load of the switch mode power supply, wherein the first signal feedback stage comprises: a first amplifier, a first input of said first amplifier coupled to said load; a first reference device, a first connection of said first reference device connected to a second input of said first amplifier, said first reference device operable to select a reference voltage level as a comparison level for a signal sensed at said first input of said first amplifier; and a first transistor device, a base of said first transistor device connected to an output of said first amplifier, an emitter of said first transistor device connected to a second connection of said first reference device, and a collector of said first transistor device coupled to an output of said first signal feedback stage, said first transistor device operable to pass or block current flow from or to said output of said first amplifier and said output of said first signal feedback stage; and a second signal feedback stage, an input of said second signal feedback stage coupled to said load of the switch mode power supply, and an output of said second signal feedback stage coupled to said output of said first signal feedback stage, wherein said second signal feedback stage comprises: a second amplifier, a first input of said second amplifier coupled to said load; a second reference device coupled to a second input of said second amplifier, a first connection of said second reference device connected to a second input of said second amplifier, said second reference device operable to select a reference current level as a comparison level for a signal sensed at said first input of said second amplifier; and a second transistor device, a base of said second transistor device connected to an output of said second amplifier, an emitter of said second transistor device connected to a second connection of said second reference device, and a collector of said second transistor coupled to said output of said second signal feedback stage, said second transistor device operable to pass or block current flow from or to said output of said second amplifier and said output of said second signal feedback stage.