US 8,410,809 B2 · Under-voltage and over-voltage detection circuit and driving method thereof

Abstract

A low-voltage and over-voltage detection circuit receives a power source voltage, generates a shift voltage by shifting the received voltage to a predetermined level, and fixes the shift voltage as a clamping voltage when the shift voltage is higher than a predetermined clamping voltage. The low-voltage and over-voltage detection circuit includes a first transistor and a second transistor. The first transistor generates a regulator voltage that varies according to the power source voltage and performs a switching operation according to the shift voltage and the regulator voltage, and the second transistor is connected in parallel with the first transistor and generates hysteresis. The low-voltage and over-voltage detection circuit determines whether the power source voltage is a low-voltage or an over-voltage by using a drain voltage generated according to currents flowing to the first and second transistors.

Claims16

Dependent claims

A low-voltage and over-voltage detection circuit comprising:

a level shifter receiving a power source voltage and shifting an input voltage to a predetermined level to generate a shift voltage;
a voltage clamper maintaining the shift voltage at a clamping voltage when the shift voltage is higher than a predetermined clamping voltage;
a voltage regulator generating a regulator voltage that varies according to the power source voltage;
and
a voltage detector receiving the shift voltage and the regulator voltage, including first and second transistors, and determining whether the power source voltage is a low-voltage or an over-voltage by using a drain voltage generated according to currents flowing to the first and second transistors, the first transistor performing a switching operation according to the shift voltage and the regulator voltage and the second transistor connected to the first transistor in parallel and generating hysteresis.

2 more elements

A driving method of a low-voltage and over-voltage detection circuit including a first transistor and a second transistor connected in parallel with the first transistor, comprising:

receiving a power source voltage and generating a shift voltage by shifting the power source voltage to a predetermined level;
when the shift voltage is higher than a predetermined clamping voltage, fixing the shift voltage as a clamping voltage;
generating a regulator voltage that varies according to the power source voltage;
switching the first transistor according to the shift voltage and the regulator voltage;
determining the power source voltage to be included in a normal range when drain voltages of the first and second transistors are close to the regulator voltage and generating a first-level detection signal, and determining the power source voltage to be a low-voltage or an over-voltage when the drain voltages are close to the power source voltage and generating a second-level detection signal;
and
switching the second transistor according to a reverse detection signal that is opposite to the detection signal.

4 more elements

Dependencies are inferred from the claim text.

Under-voltage and over-voltage detection circuit and driving method thereof

Life of this patent

Under-voltage and over-voltage detection circuit and driving method thereof

Life of this patent

Abstract

Claims16