High-voltage on-chip current sensor design and analysis for battery modules

Large current sensing in a high-voltage (HV) battery module or string is hard to be realised on-chip. Thus, it is a disadvantage for the system to be miniaturised. A current sensor with a HV sense stage on silicon for HV battery modules is designed and analysed in this investigation. The proposed HV current sensor takes advantage of HV CMOS processes and resolves the problems caused by the voltage drop limitation thereof. The design methodology and analysis, including aspect sizes, are also presented. The physical on-chip and system measurement of the proposed HV current sensor demonstrates maximum error +/- 0.7% provided that the sensing voltage is 36-55 V, and the sensing current is 0.5-2.2 A.