Digital Battery Management Unit With Built-In Resistance Compensation, Modulated Frequency Detection and Multi-Mode Protection for Fast, Efficient and Safe Charging

This paper presents a digital battery management unit (BMU) with built-in resistance (BIR) compensation, modulated frequency detection (MFD), and multi-mode protection (MMP) techniques to realize fast, efficient and safe charging. The charger incorporates the proposed BMU based on the low-dropout (LDO) regulator. With BIR compensation, a large rated current in the proposed pulsed constant current (PCC) mode charges the battery, and reduces the charging time by omitting the constant-voltage (CV) mode. The MFD technique allows continuous monitoring and obtains precise BIR compensation with accelerating sampling speed. The MMP technique can alleviate safety concerns while charging, including over-voltage protection (OVP), over-current protection (OCP), and the proposed accidental fluctuation protection (AFP). The digital BMU, implemented in 28 nm CMOS, occupies 0.014 mm
²
of silicon area. Experimental results show that the proposed circuit saves 73.3% of charging time with 1.5A charging current, and 21.5% ADC dynamic power with 1A charging current. For the digital controller IC, the power consumption is 59.1μW .