| 主权项 |
1. An over-voltage protection circuit for a transistor switch, wherein the transistor switch has a control terminal, an input terminal receiving an input voltage and an output terminal providing an output voltage, the protection circuit comprises:
an error detecting circuit having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is coupled to the output terminal of the transistor switch, and wherein the second input terminal is configured to receive a reference signal, and wherein based on the reference signal and the output voltage, the error detecting circuit provides an amplified error signal at the output terminal; a dummy load circuit having a control terminal, a first terminal and a second terminal, wherein the control terminal is coupled to the output terminal of the error detecting circuit, and wherein the first terminal is coupled to the control terminal of the transistor switch, and wherein the second terminal is connected to ground, and wherein the dummy load circuit is configured to establish a conductive path between the output terminal of the transistor switch and ground if a voltage difference between the second terminal of the error detecting circuit and the first terminal of the error detecting circuit is smaller than a second value; and a driving circuit having an input terminal and an output terminal, wherein the input terminal is coupled to the output terminal of the error detecting circuit, and wherein the output terminal is coupled to the control terminal of the transistor switch, and wherein the driving circuit is configured to increase the on-resistance of the transistor switch if the voltage difference between the second terminal of the error detecting circuit and the first terminal of the error detecting circuit is smaller than a first value, and wherein the second value is larger than the first value. |
