Electronic device

• US 8,842,405 B2
• Filed: 09/22/2011
• Issued: 09/23/2014
• Est. Priority Date: 09/24/2010
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Miura, Ryotaro, Takagi, Noriyuki, Tanimura, Yasunari
• Primary Examiner(s): Jackson, Stephen W
• Application Number:
  US13/239,749
• Publication Number:
  US 20120075761A1
• Time in Patent Office: 1,097 Days
• Field of Search: 361/93.1
• US Class Current: 361/93.1
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 7/53871 with automatic control of output voltage or current
• CPC Class Codes: H03K 17/0828 in composite switches

Abstract

An electronic device that is capable of detecting an abnormal state such that a switching element is unable to be turned off in spite of a drive signal instructing turn-off of the switching element. The device includes a switching element that is driven by controlling a voltage on its control terminal, a drive circuit that controls the voltage on the control terminal of the switching element on the basis on an inputted drive signal to drive the switching element. In cases where there exists a current flowing through the switching element in spite of the drive signal instructing turn-off of the switching element, the drive circuit determines that the switching element is in an abnormal state, and cuts off supply of voltage from a drive power supply circuit to the control terminal of the switching element to thereby turn off the switching element.

Claims

1. An electronic device comprising:

a first switching element that is driven by controlling a voltage on its control terminal; and

a first drive circuit that controls the voltage on the control terminal of the first switching element on the basis of an inputted drive signal to drive the first switching element;

wherein in cases where there exists a current flowing through the first switching element in spite of the drive signal instructing turn-off of the first switching element, the first drive circuit determines that the first switching element is in an abnormal state.

2. The device of claim 1, further comprising a drive power supply circuit that supplies a voltage for driving the first switching element,

wherein in cases where the first drive circuit determines that the first switching element is in the abnormal state, the first drive circuit cuts off the supply of voltage from the drive power supply circuit to the control terminal of the first switching element to thereby turn off the first switching element.

3. The device of claim 1, further comprising a turn-on drive switching element that is electrically connected to the control terminal of the first switching element, the turn-on drive switching element being operative to, when turned on, charge the control terminal of the first switching element,

wherein when the inputted drive signal instructs turn-on of the first switching element, the first drive circuit controls the turn-on drive switching element to turn on the first switching element.

4. The device of claim 1, further comprising a turn-off drive switching element that is electrically connected to the control terminal of the first switching element, the turn-off drive switching element being operative to, when turned on, discharge the control terminal of the first switching element,

wherein when the inputted drive signal instructs turn-off of the first switching element, the first drive circuit controls the turn-off drive switching element to turn off the first switching element.

5. The device of claim 4, wherein in cases where the first drive circuit determines that the first switching element is in the abnormal state, the first drive circuit controls the turn-off drive switching element to turn off the first switching element.

6. The device of claim 1, further comprising an off-state holding switching element that is electrically connected to the control terminal of the first switching element, the off-state holding switching element being operative to, when turned on, discharge the control terminal of the first switching element,

wherein when the voltage on the control terminal of the first switching element becomes equal to or lower than an off-state holding threshold that is lower than a turn-on/off threshold for turning on and off the first switching element, the first drive circuit controls the off-state holding switching element to hold an off-state of the first switching element.

7. The device of claim 6, wherein in cases where the first drive circuit determines that the first switching element is in the abnormal state, the first drive circuit controls the off-state holding switching element to turn off the first switching element.

8. The device of claim 6, further comprising a voltage clamp circuit that clamps the voltage on the control terminal of the first switching element at a voltage that is equal to or lower than the off-state holding threshold,

wherein in cases where the first drive circuit determines that the first switching element is in the abnormal state, the first drive circuit triggers the voltage clamp circuit to clamp the voltage on the control terminal of the first switching element at the voltage that is equal to or lower than the off-state holding threshold to thereby turn off the first switching element via the off-state holding switching element.

9. The device of claim 1, further comprising:

a second switching element that is electrically connected in series with the first switching element, the second switching element being driven by controlling a voltage on its control terminal; and

a second drive circuit that controls the voltage on the control terminal of the second switching element to drive the second switching element on the basis on an inputted drive signal, the second drive circuit being operative to, in cases where there exists an abnormal current flowing through the second switching element, turn off the second switching element,

wherein in cases where the first drive circuit determines that the first switching element is in the abnormal state, the first drive circuit turns on the first switching element.

10. The device of claim 1, wherein in cases where the first drive circuit determines that the first switching element is in the abnormal state, the first drive circuit electrically insulates the control terminal of the first switching element from the first drive circuit.

11. The device of claim 2, further comprising a current detection circuit that, when a current flowing through the first switching element becomes larger than a current threshold, determines that there exists an actual current flowing through the first switching element,

wherein in cases where the first drive circuit determines on the basis of the detection of the current detection circuit that there exists the actual current flowing through the first switching element in spite of the drive signal instructing turn-off of the first switching element, the first drive circuit determines that the first switching element is in the abnormal state, and then cuts off the supply of voltage from the drive power supply circuit to the control terminal of the first switching element to thereby turn off the first switching element.

12. The device of claim 4, further comprising a current detection circuit that, when a current flowing through the first switching element becomes larger than a current threshold, determines that there exists an actual current flowing through the first switching element,

wherein in cases where the first drive circuit determines on the basis of the detection of the current detection circuit that there exists the actual current flowing through the first switching element in spite of the drive signal instructing turn-off of the first switching element, the first drive circuit determines that the first switching element is in the abnormal state, and then controls the turn-off drive switching element to turn off the first switching element.

13. The device of claim 8, further comprising a current detection circuit that, when a current flowing through the first switching element becomes larger than a current threshold, determines that there exists an actual current flowing through the first switching element,

wherein in cases where the first drive circuit determines on the basis of the detection of the current detection circuit that there exists the actual current flowing through the first switching element in spite of the drive signal instructing turn-off of the first switching element, the first drive circuit determines that the first switching element is in the abnormal state, and then the first drive circuit triggers the voltage clamp circuit to clamp the voltage on the control terminal of the first switching element at the voltage that is equal to or lower than the off-state holding threshold.

14. The device of claim 12, further comprising an overcurrent detection circuit that, when a current flowing through the first switching element becomes larger than an overcurrent threshold that is larger than the current threshold, determines that there exists an overcurrent flowing through the first switching element;

and

a cut-off circuit that is electrically connected to the control terminal of the first switching element, the cut-off circuit being operative to, when activated, discharge the control terminal of the first switching element more gradually than the turn-off drive switching element,

wherein in cases where the first drive circuit determines on the basis of the detection of the overcurrent detection circuit that there exists the overcurrent flowing through the first switching element, the first drive circuit controls the cut-off circuit to turn off the first switching element.

15. The device of claim 12, further comprising an short-circuit current detection circuit that, when a current flowing through the first switching element becomes larger than an short-circuit current threshold that is larger than the current threshold, determines that there exists a short-circuit current flowing through the first switching element;

and

a cut-off circuit that is electrically connected to the control terminal of the first switching element, the cut-off circuit being operative to, when activated, discharge the control terminal of the first switching element more gradually than the turn-off drive switching element,

wherein in cases where the first drive circuit determines on the basis of the detection of the short-circuit current detection circuit that there exists the short-circuit current flowing through the first switching element, the first drive circuit controls the cut-off circuit to turn off the first switching element.

16. The device of claim 2, further comprising a current detection and overcurrent detection switchable circuit that is switchable between a current detection circuit and an overcurrent detection circuit, the current detection circuit being operable to, when a current flowing through the first switching element becomes larger than a current threshold, determine that there exists an actual current flowing through the first switching element, the overcurrent detection circuit being operable to, when a current flowing through the first switching element becomes larger than an overcurrent threshold that is larger than the current threshold, determine that there exists an overcurrent flowing through the first switching element, and the current detection and overcurrent detection switchable circuit including a first threshold selector switch that selects and switches to either one of the current threshold and the overcurrent threshold on the basis of instruction of the drive signal, and being operative to perform current detection on the basis of a threshold selected by the first threshold selector switch,

wherein the current detection and overcurrent detection switchable circuit switches to the current detection circuit through the first threshold selector switch selecting and switching to the current threshold, and the current detection and overcurrent detection switchable circuit switches to the overcurrent detection circuit through the first threshold selector switch selecting and switching to the overcurrent threshold.

17. The device of claim 2, further comprising a current detection and short-circuit current detection switchable circuit that is switchable between a current detection circuit and a short-circuit current detection circuit, the current detection circuit being operable to, when a current flowing through the first switching element becomes larger than a current threshold, determine that there exists an actual current flowing through the first switching element, the short-circuit current detection circuit being operable to, when a current flowing through the first switching element becomes larger than an short-circuit current threshold that is larger than the current threshold, determine that there exists a short-circuit current flowing through the first switching element, and the current detection and short-circuit current detection switchable circuit including a second threshold selector switch that selects and switches to either one of the current threshold and the short-circuit current threshold on the basis of instruction of the drive signal, and being operative to perform current detection on the basis of a threshold selected by the second threshold selector switch,

wherein the current detection and short-circuit current detection switchable circuit switches to the current detection circuit through the second threshold selector switch selecting and switching to the current threshold, and the current detection and short-circuit current detection switchable circuit switches to the short-circuit current detection circuit through the second threshold selector switch selecting and switching to the short-circuit current threshold.

18. The device of claim 16, wherein the first threshold selector switch selects and switches to the current threshold at timing when the drive signal instructs turn-off of the first switching element,

wherein in cases where the first drive circuit determines on the basis of the detection of the current detection circuit that there exists the actual current flowing through the first switching element in spite of the drive signal instructing turn-off of the first switching element, the first drive circuit determines that the first switching element is in the abnormal state, and then cuts off the supply of voltage from the drive power supply circuit to the control terminal of the first switching element to thereby turn off the first switching element.

19. The device of claim 16, wherein the first threshold selector switch selects and switches to the current threshold at timing when the first drive circuit regulates the voltage on the control terminal of the first switching element in response to the drive signal instructing turn-off of the first switching element,

wherein in cases where the first drive circuit determines on the basis of the detection of the current detection circuit that there exists the actual current flowing through the first switching element in spite of the drive signal instructing turn-off of the first switching element, the first drive circuit determines that the first switching element is in the abnormal state, and then cuts off the supply of voltage from the drive power supply circuit to the control terminal of the first switching element to thereby turn off the first switching element.

20. The device of claim 11, wherein the current threshold is regulated as a function of a temperature of the first switching element.