Flying capacitor type voltage detecting circuit and battery protection integrated circuit

摘要

A voltage-detecting circuit includes a flying capacitor; a first switch circuit allowing plural electric cells connected in series, so that polarity of voltage across electrodes of the flying capacitor charged by one of the electric cells is opposite to polarity of voltage across the electrodes of the flying capacitor charged by an adjacent one of the electric cells; a second switch circuit discharging the flying capacitor; an output circuit outputting a signal depending on the voltage across the flying capacitor; a shield arranged around the flying capacitor electrodes to substantially equalize parasitic capacitances between the shield and each of the electrodes; and a voltage-controlling circuit equalizing voltage between one of the electrodes of the flying capacitor and the shield when charging the flying capacitor, with voltage between another one of the electrodes of the flying capacitor and the shield when discharging the flying capacitor.

主权项

1. A flying capacitor type voltage detecting circuit comprising:
a flying capacitor; a first switch circuit that allows each of plural electric cells that are connected in series constituting an assembled battery to individually charge the flying capacitor, so that polarity of voltage across electrodes of the flying capacitor when charged by a first one of the plural electric cells is opposite to polarity of voltage across the electrodes of the flying capacitor when charged by a second one of the plural electric cells, wherein the second one of the plural electric cells is adjacent to the first one of the plural electric cells; a second switch circuit that discharges the flying capacitor; an output circuit that outputs a signal depending on the voltage across the flying capacitor; a first shielding section that is arranged around the electrodes of the flying capacitor to substantially equalize parasitic capacitances between the first shielding section and each of the electrodes; and an electric potential difference controlling circuit that substantially equalizes voltage between one of the electrodes of the flying capacitor and the first shielding section when the flying capacitor is charged, and equalizes voltage between another one of the electrodes of the flying capacitor and the first shielding section when the flying capacitor is discharged.