Elimination of recirculation current loss in load-shared switching mode power supplies
AssigneeMicrel, Inc.
InventorsBruce Inn, Ramesh Selvaraj
Life of this patent
Estimating the term…
Abstract
In master-slave current-tracking load-share systems using switching power supplies, a method and apparatus for preventing current recirculation at light-load and no-load operational conditions. The slave power supply is run in a discontinuous mode when load current falls to light-load or no-load state, preventing the slave from sinking current, therefore preventing recirculation from the master to the slave. The slave power supply is run at a lower current level than the master, preventing recirculation from the slave to the master.
Claims13
A load-shared power supply regulating system comprising:
- a first power regulating means for providing a first electrical current to a load;
- and
- a second regulating means for providing a second electrical current to the load, wherein said second regulating means provides the second electrical current at a level that is substantially constantly less than said first electrical current, and said second regulating means is switched to a discontinuous mode when said first electrical current level is approximately less than a predetermined reference level.
A load-sharing switching power supply system for a given load, the system comprising:
- a first power source;
- connecting the first power source to the load, a master regulator supplying a first electrical current to said load;
- a second power source;
- connecting the second power source to the load, a slave regulator supplying a second electrical current to said load such that said second electrical current is substantially always offset to be less than said first electrical current and wherein said slave regulator is controlled such that when power demand by the load is approximately less than a predetermined demand, the slave regulator discontinues providing said second electrical current and prevents sinking of substantially any part of said first electrical current by said slave regulator.
A method for substantially eliminating electrical current recirculation in a load-shared switching mode power supply system for a given load, the method comprising:
- during normal-to-heavy load conditions, running a slave power supply subsystem at a first electrical output current to said given load that is substantially consistent at an offset value less than a second electrical output current of a master power supply subsystem to said load such that said master power supply subsystem can not operate as an electrical current sink with respect to said slave power supply subsystem;
- and
- during light-to-no load conditions, discontinuing the first electrical output current from said slave power supply and blocking said slave power supply from operating as an electrical current sink with respect to said master power supply subsystem.
Dependencies are inferred from the claim text.