Patent ID: 6424129
Filing Date: 2002-07-23
Classification: H02M,Y02B

Abstract:
In a multi-phase DC-to-DC voltage converter comprising a plurality of converter modules connected to a common load and having a common input voltage source, an output current sensing apparatus comprises:a first current sensor adapted to be coupled to an output inductor of at least one of said plurality of converter modules to derive a first current sense signal corresponding to current passing through an internal DC resistance of said at least one output inductor; a second current sensor adapted to be coupled to a sensing resistor disposed in series between said common input voltage source and said load to derive a second current sense signal corresponding to current passing through said sensing resistor; and a current sense circuit receiving said first and second current sense signals, said current sense circuit filtering said second current sense signal, integrating a difference between said first current sense signal and said filtered second current sense signal, and adjusting said first current sense signal based on said integrated difference, said current sense circuit thereby providing said first current sense signal as a slope signal for controlling a conduction duty cycle of said multi-phase DC-to-DC converter and a DC level signal corresponding to a thermal drift error of said slope signal; wherein, said first current sense signal provides a fast indication of output current of said multi-phase DC-to-DC converter that is susceptible to thermal variation of said at least one output inductor, and said second current sense signal provides a slow but accurate indication of output current that is not affected by said thermal variation.