Current sensor IC provides 9 bit+sign result without external sense resister

This paper describes a mixed signal integrated circuit for current measurement. Fabricated on a 1 /spl mu/m CMOS process, the IC employs a delta sigma analog to digital converter to generate a pulse-width modulated (PWM) output proportional to current. A metal loop stamped into the lead frame acts as a current sense resistor, providing a 5 mV full scale signal at 1 amp sense current. The IC measures the sense voltage, corrects for the temperature coefficient in the metal loop, and creates a 9 bit accurate PWM output. This circuit consumes less than 120 /spl mu/A in operating mode and less than 3 /spl mu/A in sleep mode.