Series protection circuit
AssigneeSGS-Thomson Microelectronics S.A.
InventorAndre Bremond
Life of this patent
Estimating the term…
Abstract
An overvoltage protection circuit for a load having a determined resistance value is connected to a supply line with a predetermined polarity. An overvoltage detector is connected across the line. A first switch, normally on, is located in series with a conductor of the line and is controlled (i.e. switched to the off state) by the detector. A second switch, located in series with a resistance having the same determined value R, is disposed between the line conductors and is controlled by the detector in a complementary manner to the first switch.
Claims22
An overvoltage protection circuit for protection of a load, the load connected to the first and second terminals of a supply line, the circuit comprising:
- a first switch having a control terminal, the first switch connected in series between the second terminal and the load, the first switch being normally closed allowing current to run therethrough;
- a triggering circuit, connected between the first and second terminals, including an overvoltage detector, coupled between the first and second terminals, and a second switch, responsive to the overvoltage detector and disposed between the control terminal of the first switch and one of the first terminal and the second terminal;
- a first resistor having a resistance value approximately equal to an impedance of the load;
- and
- a third switch connected in series with the first resistor, the third switch and first resistor connected between the first and second terminals, each of the first switch and the third switch enabling current to flow therethrough when the respective switch is closed and preventing current from flowing therethrough when the respective switch is open, the first and third switches controlled by triggering circuit such that when the overvoltage detector detects an overvoltage, the first switch is opened and third switch is closed.
An overvoltage protection circuit, coupled between first and second terminals of line and in parallel with a load, the overvoltage protection circuit comprising:
- a first switch having a control terminal, the first switch connected in series between the second terminal and the load:
- a triggering circuit, connected between the first and second terminals, including an overvoltage detector, coupled between the first and second terminals of the line and a second switch responsive to the voltage detector;
- a first resistor having a value approximately equal to an impedance of the load;
- and
- a third switch connected in series with the first resistor, the third switch and first resistor coupled in parallel to the overvoltage detector across the first and second terminals of the line, each of the first switch and the third switch enabling current to flow therethrough when the respective switch is closed and preventing current from flowing therethrough when the respective switch is open, and the first and third switches controlled by the second switch such that when the overvoltage detector detects an overvoltage, the first switch is opened the third switch is closed.
An overvoltage protection circuit, coupled between first and second terminals of a transmission line and in parallel with a load, the overvoltage protection circuit comprising:
- a first means for switching between a conducting and a nonconducting state connected in series between the second terminal and the load;
- a control circuit, connected between the first and second terminals, including a overvoltage detector, coupled between the first and second terminals of the transmission line and a control device which is responsive to the detector;
- a resistor having a value approximately equal to the impedance of the load;
- a second means for switching between a conducting and a nonconducting stated connected in series with the resistor, the second means for switching and the resistor coupled in parallel to the detector across the first and second terminals, wherein the first and second means for switching are controlled by the control device such that when the overvoltage detector detects an overvoltage, the first means for switching is switched to the nonconducting state and the second means for switching is switched to the conducting state.
A method for protecting a load, connected between first and second terminals of a supply line, from overvoltages occurring across the first and second terminals, comprising the steps of:
- providing a first switch connected in series between the first terminal and the load;
- providing a second switch in series with a first resistor, having a resistance value approximately equal to an impedance of the load, between the first and second terminals of the supply line and in parallel with the load;
- detecting, with a detector, an overvoltage across the first and second terminals of the supply line;
- and
- biasing, with a control device responsive to the detector, the first switch to an open condition and the second switch to closed condition in response to the overvoltage.
Dependencies are inferred from the claim text.