Voltage measuring device

A voltage measuring device comprising:

• a switching unit configured such that, in order to measure a voltage of each battery cell in a battery cell array in which a plurality of battery cells are connected in series,
• voltages at connecting ends of the plurality of battery cells are inputted to the switching unit,
• a voltage of at least one management-voltage-measuring power supply provided separately from the plurality of battery cells is inputted to the switching unit, and
• the switching unit outputs one of the inputted voltages;
• and
• a signal processor configured to perform operational processing on the voltage of each battery cell based on an inter-cell voltage between the plurality of battery cells, the inter-cell voltage being outputted from the switching unit, wherein
• the switching unit includes a plurality of multiplexers each including:
• a plurality of input terminals;
• an output terminal configured to output one of voltages inputted from the plurality of input terminals;
• and
• a plurality of first switches provided for the respective input terminals and provided between the plurality of input terminals and the output terminal, the plurality of first switches selectively connecting one of the input terminals to the output terminal,
• the signal processor includes:
• a plurality of first capacitors provided for the respective output terminals of the plurality of multiplexers, the first capacitors having their one ends connected to the respective output terminals of the multiplexers, the first capacitors being charged in accordance with voltages outputted from the respective output terminals;
• a differential amplifier including an inverting input terminal and a non-inverting input terminal, one input terminal of which is connected to the other ends of the first capacitors;
• a second capacitor connected between the one input terminal and an output terminal of the differential amplifier;
• and
• a second switch connected parallel to the second capacitor, and
• the first switches included in at least one of the plurality of multiplexers are configured as high-voltage switches that allow operation at a voltage higher than an operating voltage of the first switches included in the other multiplexer or multiplexers.