Patent ID: 7440249
Filing Date: 2008-10-21
Classification: G01R

Abstract:
1. An undervoltage detection circuit comprising: a first transistor and a second transistor coupled to a supply voltage node and arranged to form a current mirror; a first bipolar transistor having a collector coupled to the first transistor and an emitter coupled to a reference voltage node; a second bipolar transistor having a collector coupled to the second transistor and an emitter coupled to the reference voltage node through a first resistor; a third transistor coupled through a second resistor to an input voltage node, wherein a node between the third transistor and the second resistor is coupled to provide a voltage corresponding to an input voltage to a base of the first bipolar transistor; a third resistor coupled between the base of the first bipolar transistor and a base of the second bipolar transistor; and a fourth resistor coupled between the reference voltage node and the base of the third transistor; wherein an output signal indicative of the input voltage is derived from a voltage established at the collector of the second bipolar transistor.