Patent ID: 7142023
Filing Date: 2006-11-28
Classification: G01R,H03K

Abstract:
1. A voltage detection circuit comprising: a first transistor and a second transistor that have emitters thereof connected together to form a differential pair; a voltage division circuit that divides an input voltage into a first division voltage and a second division voltage, the voltage division circuit being connected directly to a base of the first transistor to apply the first division voltage to the base of the first transistor, the voltage division circuit being connected directly to a base of the second transistor to apply the second division voltage to the base of the second transistor; and a first resistor that has one end thereof connected to the base of the second transistor and that has another end thereof connected to the emitter of the second transistor, wherein whether the input voltage is equal to a predetermined level or not is checked based on an output from the differential pair, wherein the first and second transistors are both of a PNP type, wherein the voltage division circuit consists of: a serial circuit composed of a rectifying element and a second resistor; wherein the input voltage is applied to one end of the serial circuit, another end of the serial circuit is connected to one end of the third resistor, another end of the third resistor is connected to one end of the fourth resistor, another end of the fourth resistor is connected to ground, the first division voltage is outputted from a node between the serial circuit and the third resistor, and the second division voltage is outputted from a node between the third resistor and the fourth resistor.