A micropower battery current sensor with ±0.03% (3σ) inaccuracy from −40 to +85°C

Abstract

This paper presents a micropower current-sensing system (CSS) for battery monitoring, which consists of a calibrated shunt resistor, a ΔΣ ADC, and a dynamic bandgap reference (BGR). For currents ranging from 0 to 1A over the industrial temperature range (-40°C to +85°C), it exhibits 10μA offset and ±0.03% (3σ) gain error, which is a 3× improvement on systems with off-chip external references [1,2]. This level of accuracy is achieved by the use of dynamic error-correction techniques, digital temperature compensation, and an on-chip dynamic BGR, whose spread is corrected by a single room-temperature trim.