Patent ID: 8866467

Claim:
A power measurement system for a buck regulator, comprising: a. an output transistor to provide a buck output current of the buck regulator; and b. a sense transistor and sense resistor coupled to the output transistor to sense a portion of the buck output current without degrading the efficiency of the buck regulator, wherein an output voltage is a measure of power output and directly proportional to an output current of the buck regulator and a power output of the buck regulator equals the output current multiplied by the output voltage, wherein a voltage V 1 is proportional to a power transistor on resistance RDSon and produces a voltage CS_voltage proportional to RDSon as RDSon=CS_voltage*( R 2 /R 3)/ I 1 where a test equipment generates a current I 1 and R 2 and R 3 are integrated circuit resistances of matching material and R 3 is larger than R 2 .