Switch device and method

• US 10,454,469 B2
• Filed: 12/13/2017
• Issued: 10/22/2019
• Est. Priority Date: 12/16/2016
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Romano, Francesca, Mayer, Alexander, Petruzzi, Luca
• Primary Examiner(s): Hernandez, William
• Application Number:
  US15/840,194
• Publication Number:
  US 20180175855A1
• Time in Patent Office: 678 Days
• Field of Search: 327108, 327109, 327419, 327427, 327434, 327574, 327581
• CPC Class Codes: H03K 17/08104 in field-effect transistor switches H03K17/0812, H03K17/0814 take precedence
• CPC Class Codes: H03K 17/08112 in bipolar transistor switches H03K17/0812, H03K17/0814 take precedence
• CPC Class Codes: H03K 17/166 Soft switching
• CPC Class Codes: H03K 17/18 Modifications for indicating state of switch
• CPC Class Codes: H03K 17/30 Modifications for providing a predetermined threshold before switching shaping pulses by thresholding H03K5/08
• CPC Class Codes: H03K 17/302 in field-effect transistor switches

Abstract

An embodiment method includes detecting an inverse current condition at a switch, and driving a node associated with a switch driver driving the switch to a predetermined voltage in response to the detection of an inverse current condition at the switch. An embodiment switch device includes a switch driver configured to be coupled to a control terminal of a switch, an inverse current detector configured to detect an inverse current condition at the first and second load terminals of the switch, and a voltage driver configured to drive a node associated with the switch driver to a predetermined voltage in response to the inverse current detector detecting an inverse current condition.

Claims

1. A switch device, comprising:

a switch driver configured to be coupled to a control terminal of a switch,

an inverse current detector configured to detect an inverse current at a first load terminal and a second load terminal of the switch, and

a voltage driver configured to drive a node associated with the switch driver to a predetermined voltage in response to the inverse current detector detecting the inverse current, wherein the predetermined voltage is configured to turn-on the switch.

2. The switch device of claim 1, wherein the switch driver is coupled between the node and the control terminal of the switch.

3. The switch device of claim 1, wherein the inverse current detector comprises a comparator.

4. The switch device of claim 3, wherein the first load terminal of the switch is configured to be coupled to a supply voltage terminal, wherein a first input terminal of the comparator is coupled to the second load terminal of the switch, and wherein a second input terminal of the comparator is coupled to the supply voltage terminal.

5. The switch device of claim 4, wherein the comparator has an offset.

6. The switch device of claim 4, further comprising a voltage offset element coupled between the second input terminal of the comparator and the supply voltage terminal.

7. The switch device of claim 1, wherein the voltage driver comprises a first switch configured to couple the node to the predetermined voltage in case the inverse current detector detects the inverse current.

8. The switch device of claim 7, wherein the voltage driver further comprises a second switch configured to decouple the node from the second load terminal of the switch in case the inverse current detector detects the inverse current.

9. The switch device of claim 8, further comprising:

a current source element coupled between a bulk terminal of the second switch and the node,

and a third switch coupled between the bulk terminal of the second switch and the second load terminal of the switch.

10. The switch device of claim 9, wherein at least one of the current source element or the third switch is configured to be controlled by the inverse current detector.

11. The switch device of claim 9, wherein the current source element comprises at least one of a depletion transistor, a current source or a resistor.

12. The switch device of claim 1, wherein the first load terminal of the switch is configured to be coupled to a supply voltage, and the second load terminal of the switch is configured to be coupled to a load.

13. The switch device of claim 12, wherein the predetermined voltage is the supply voltage.

14. The switch device of claim 1, wherein the switch driver comprises a semiconductor structure including a parasitic bipolar transistor, the voltage driver being configured to prevent the parasitic bipolar transistor from drawing the node to a potential preventing a closing of the switch when the inverse current is detected at the first load terminal and the second load terminal of the switch.

15. The switch device of claim 1, further comprising the switch.

16. A method, comprising:

detecting an inverse current at a switch, and

turning on the switch in response to detecting the inverse current, wherein turning on the switch comprises driving a node associated with a switch driver driving the switch to a predetermined voltage.

17. The method of claim 16, wherein driving the node comprises coupling the node to a supply voltage.

18. The method of claim 17, wherein driving the node further comprises decoupling the node from a second load terminal of the switch, the second load terminal being coupled to a load.

19. The method of claim 18, further comprising selectively coupling a bulk terminal of a further switch to the node or to the second load terminal dependent on the detecting the inverse current, wherein a load path of the further switch is coupled between the node and the second load terminal of the switch.

20. The method of claim 18, wherein a first load terminal of the switch is coupled to the supply voltage, and wherein the predetermined voltage corresponds to the supply voltage.

21. The method of claim 20, wherein detecting the inverse current comprises comparing a voltage at the second load terminal of the switch to at least one of the supply voltage or a voltage at the first load terminal of the switch.

22. A switch control circuit, comprising:

a driver having an output terminal configured to be coupled to a control terminal of a switching transistor;

a first switch having a first terminal coupled to a reference terminal of the driver and a second terminal configured to be coupled to a first load terminal of the switching transistor;

a second switch coupled between a power supply terminal and the reference terminal of the driver; and

an inverse current detector having an output coupled to control terminals of the first switch and the second switch, and an input configured to be coupled to the switching transistor, wherein the inverse current detector is configured to detect an inverse current condition of the switching transistor, open the first switch and close the second switch when the inverse current condition is detected, and close the first switch and open the second switch when the inverse current condition is not detected.

23. The switch control circuit of claim 22, wherein the inverse current detector comprises a comparator having a first input configured to be coupled to the reference terminal of the driver and a second input configured to be coupled to a second load terminal of the switching transistor.

24. The switch control circuit of claim 23, further comprising a level shifter coupled between an output of the comparator and the control terminal of the first switch.