An undervoltage detection circuit includes a first transistor and a second
transistor coupled to a supply voltage node and arranged to form a
current mirror. The undervoltage detection circuit also includes a first
bipolar transistor and a second bipolar transistor. A collector of the
first bipolar transistor is coupled to the first transistor, and an
emitter of the first bipolar transistor is coupled to a reference voltage
node. A collector of the second bipolar transistor is coupled to the
second transistor and an emitter of the second bipolar transistor is
coupled to the reference voltage node through a first resistor. The
undervoltage detection circuit further includes a third transistor
coupled through a second resistor to an input voltage node. An output
signal indicative of an input voltage is derived from a voltage
established at the collector of the second bipolar transistor.