Patent ID: 7459887
Filing Date: 2008-12-02
Classification: G01R,H02J

Abstract:
1. A voltage detection circuit, comprising: a first input terminal that inputs a first input voltage; a second input terminal that inputs a second input voltage; a third input terminal to provide a ground potential; a voltage divider circuit having a first serial resistor and a second serial resistor, the first serial resister having a plurality of resistors connected in series and a first voltage dividing terminal at the intermediate connecting point of the plurality of resistors, the second serial resistor having a plurality of resistors connected in series and a second voltage dividing terminal at the intermediate connecting point of the plurality of resistors; and a first switch circuit including a first plurality of switches and a second plurality of switches, the first plurality of switches turning on or off based on a first signal for turning on the switches for a first period, the second plurality of switches turning on or off based on a second signal for turning on the switches for a second period, the second period being different from the first period, the first switch circuit switching the state of connection of each of the input terminals to the first serial resistor and the second serial resistor in the first period and the second period to reverse polarity of voltage inputted to the voltage divider circuit; wherein in the first period, the first plurality of switches of the first switch circuit connects the first input terminal to one end of the first serial resistor, connects the second input terminal to one end of the second serial resistor, and connects the third input terminal to the other end of the first serial resistor and the other end of the second serial resistor, and in the second period, the second plurality of switches of the first switch circuit connects the third input terminal to one end of the first serial resistor and one end of the second serial resistor, connects the first input terminal to the other end of the first serial resistor, and connects the second input terminal to the other end of the second serial resistor, and the voltage detection circuit detects a difference between the first input voltage and the second input voltage, based on the voltages output from the voltage divider circuit.