A ±5A battery current sensor with ±0.04% gain error from −55°C to +125°C

This paper describes a battery current sensor (CS) that consists of a calibrated 10mΩ shunt resistor, and a chip comprising a switched-capacitor (SC) ΔΣ ADC and a bandgap reference (BGR). The chip was realized in a standard 0.13μm CMOS process, occupies 1.15mm² and draws 55μA from a 1.5V supply. With an off-chip shunt it can digitize bi-directional currents ranging from -5A to +5A with 150μA offset and ±0.04% gain error over the military temperature range (-55°C to +125°C). This performance is achieved by using room temperature trimming, dynamic error correction techniques, a dynamic BGR and a low-leakage sensor front-end.