US 7,924,539 B2 · Semiconductor integrated circuit

Abstract

A protection circuit with suppressed erroneous operation due to power source fluctuation has a first resistor and a capacitor connected in series between a power source line and a ground line, an inverter with an input connected between the first resistor and the capacitor, and a MOS transistor with a gate electrode that receives an output of the inverter and with a drain electrode and source electrode connected to the power source line and the ground line. When high voltage fluctuation occurs in the power source line, a level change at a connection point between the first resistor and the capacitor is delayed according to a time constant. By the delay, the MOS transistor that receives an output of the inverter is temporarily turned on and discharges a high voltage to the ground line.

Claims6

Dependent claims

A semiconductor integrated circuit having a protection circuit for protection against a fluctuation in high voltage between a power source line and a ground line,

wherein the protection circuit has a first resistor and a capacitor connected in series between the power source line and the ground line, and a first logic circuit and a first transistor and a second resistor,
wherein an input terminal of the first logic circuit is coupled between the first resistor and the capacitor,
wherein an output terminal of the first logic circuit is coupled to a control terminal of the first transistor,
wherein a first terminal of the first transistor is coupled to the power source line,
wherein a second terminal of the first transistor is coupled to the ground line,
wherein the control terminal of the first transistor is coupled to the ground line via the second resistor,
wherein the first transistor is comprised of a first conduction type well region, a plurality of second conduction type diffusion layers in the well region, and a first conduction type diffusion layer in the well region, and
wherein the control terminal is coupled to the first conduction type diffusion layer.

5 more elements

Dependencies are inferred from the claim text.

Semiconductor integrated circuit

Life of this patent

Semiconductor integrated circuit

Life of this patent

Abstract

Claims6