Patent ID: 6747492
Filing Date: 2004-06-08
Classification: H03K

Abstract:
A power-on reset circuit input stage, comprising:first and second transistors each having first and second terminals and a control terminal, the first terminal of each of the first and second transistors being connected to a first power supply voltage, and the control terminals of the first and second transistors being connected to each other and to the second terminal of the first transistor; a first capacitor connected between the second terminal of the second transistor and a second power supply voltage; a third transistor having first and second terminals and a control terminal, the second terminal of the third transistor being connected to the second power supply voltage; a resistor connected between the second terminal of the first transistor and the first terminal of the third transistor; and a second capacitor that is one of (1) directly connected in series between the second terminal of the second transistor and the first capacitor and (2) connected between the control terminal of the third transistor and the second power supply terminal, wherein the control terminal of the third transistor is adapted to respond to a voltage across the first capacitor to selectively turn on and turn off the third transistor and a current charging the first capacitor.