Switching device
A switching device has, for example, a first terminal configured to be connected to an application node for a first voltage, a second terminal configured to be connected to the first end of a load, a third terminal configured to be connected to the second end of the load and to an application node for a second voltage, a switching element configured to be connected between the first and second terminals, a first active clamper configured to limit the output voltage at the second terminal with reference to the first voltage in a first state, and a second active clamper configured to limit the output voltage with reference to the second voltage in a second state different from the first state.
1. A switching device comprising:
a first terminal configured to be connected to an application node for a first voltage;
a second terminal configured to be connected to a first end of a load;
a third terminal configured to be connected to a second end of the load and to an application node for a second voltage;
a switching element configured to be connected between the first and second terminals;
a first active clamper configured to limit an output voltage at the second terminal with reference to the first voltage in a first state; and
a second active clamper configured to limit the output voltage with reference to the second voltage in a second state different from the first state,
wherein the second active clamper includes
a switch circuit configured to be on in the second state,
a diode of which a cathode is connected to a first end of the switch circuit and of which an anode is connected to the third terminal, and
a first Zener diode of which a cathode is connected to a second end of the switch circuit and of which an anode is connected to the second terminal.
2. The switching device according to claim 1 , wherein
the first active damper is configured to limit a terminal-to-terminal voltage across the switching element to equal to or lower than a first clamp voltage, and
the second active clamper is configured to limit the terminal-to-terminal voltage across the switching element to equal to or lower than a second clamp voltage lower than the first clamp voltage.
3. The switching device according to claim 1 , wherein
the first active damper is configured to limit the output voltage to equal to or higher than a first lower limit voltage lower than the first voltage by a predetermined value, and
the second active damper is configured to limit the output voltage to equal to or higher than a second lower limit voltage lower than the second voltage by a predetermined value but higher than the first lower limit voltage by a predetermined value.
4. The switching device according to claim 1 , wherein
the second active damper further includes a second Zener diode of which a cathode is connected to the second end of the switch circuit and of which an anode is connected to a control terminal of the switching element.
5. The switching device according to claim 1 , wherein the first active damper includes
a Zener diode of which a cathode is connected to the first terminal,
a diode of which an anode is connected to an anode of the Zener diode, and
a transistor of which a first terminal, a second terminal, and a control terminal are connected respectively to the first terminal, a control terminal of the switching element, and the cathode of the diode.
6. The switching device according to claim 1 , wherein the first voltage is a supply voltage and the second voltage is a ground voltage.
7. The switching device according to claim 1 , wherein the first state is a state where no overheating is being detected and the second state is a state where overheating is being detected.
8. An electronic appliance comprising:
the switching device according to claim 1 ; and
a load connected to the switching device.
9. The electronic appliance according to claim 8 , wherein
the load is a bulb lamp, a relay coil, a solenoid, a light emitting diode, or a motor.
10. A vehicle comprising the electronic appliance according to claim 8 .
11. A switching device comprising:
a first terminal configured to be connected to an application node for a first voltage;
a second terminal configured to be connected to a first end of a load;
a third terminal configured to be connected to a second end of the load and to an application node for a second voltage;
a switching element configured to be connected between the first and second terminals;
a first active clamper configured to limit an output voltage at the second terminal with reference to the first voltage in a first state; and
a second active clamper configured to limit the output voltage with reference to the second voltage in a second state different from the first state,
wherein the first active clamper includes
a Zener diode of which a cathode is connected to the first terminal,
a diode of which an anode is connected to an anode of the Zener diode, and
a transistor of which a first terminal, a second terminal, and a control terminal are connected respectively to the first terminal, a control terminal of the switching element, and the cathode of the diode.
12. The switching device according to claim 11 , wherein
the first active damper is configured to limit a terminal-to-terminal voltage across the switching element to equal to or lower than a first clamp voltage, and
the second active clamper is configured to limit the terminal-to-terminal voltage across the switching element to equal to or lower than a second clamp voltage lower than the first clamp voltage.
13. The switching device according to claim 11 , wherein
the first active damper is configured to limit the output voltage to equal to or higher than a first lower limit voltage lower than the first voltage by a predetermined value, and
the second active damper is configured to limit the output voltage to equal to or higher than a second lower limit voltage lower than the second voltage by a predetermined value but higher than the first lower limit voltage by a predetermined value.
14. The switching device according to claim 11 , wherein the first voltage is a supply voltage and the second voltage is a ground voltage.
15. The switching device according to claim 11 , wherein the first state is a state where no overheating is being detected and the second state is a state where overheating is being detected.
16. An electronic appliance comprising:
the switching device according to claim 11 ; and
a load connected to the switching device.
17. The electronic appliance according to claim 16 , wherein the load is a bulb lamp, a relay coil, a solenoid, a light emitting diode, or a motor.
18. A vehicle comprising the electronic appliance according to claim 16 .