Driver for a Synchronous Rectifier and Power Converter Employing the Same

• US 20100123486A1
• Filed: 11/13/2009
• Published: 05/20/2010
• Est. Priority Date: 11/14/2008
• Status: Active Grant

• Current Assignee: Power Systems Technologies Company Limited (Flex, Ltd.)
• Original Assignee: Power Systems Technologies Company Limited (Flex, Ltd.)
• Inventors: Berghegger, Ralf Schroeder genannt
• Granted Patent: US 8,488,355 B2
• Time in Patent Office: Days
• US Class Current: 327/109
• CPC Class Codes: H02M 3/33592 having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A driver for a switch, method of driving a switch, and a power converter employing the same. In one embodiment, the driver for the switch includes a first driver switch coupled to a terminal of the switch. The driver also includes a second driver switch inverted with respect to the first driver switch and coupled to another terminal of the switch, wherein the first and second driver switches are configured to provide a drive signal to a control terminal of the switch.

Claims

1. A driver for a switch, comprising:

a first driver switch coupled to a terminal of said switch; and

a second driver switch inverted with respect to said first driver switch and coupled to another terminal of said switch, wherein said first and second driver switches are configured to provide a drive signal to a control terminal of said switch.

2. The driver as recited in claim 1 wherein said first and second driver switches form at least a portion of a differential amplifier.

3. The driver as recited in claim 1 wherein said first and second driver switches are matched transistors.

4. The driver as recited in claim 1 further comprising at least one additional driver switch configured to cooperate with said first and second driver switches to provide said drive signal to said control terminal of said switch.

5. The driver as recited in claim 1 further comprising a diode coupled between a terminal of said first driver switch and a terminal of a third driver switch.

6. The driver as recited in claim 1 further comprising a diode coupled between a terminal of said first driver switch and a terminal of a third driver switch, and a resistor coupled across said diode.

7. The driver as recited in claim 1 further comprising a resistor coupled across a terminal and a control terminal of said second driver switch.

8. The driver as recited in claim 1 wherein terminals of said second driver switch are coupled together.

9. The driver as recited in claim 1, further comprising:

a third driver switch coupled between a terminal of said first driver switch and said control terminal of said switch; and

a fourth driver switch coupled between said terminal of said first driver switch and a terminal of said third driver switch.

10. The driver as recited in claim 1 further comprising a diode parallel-coupled to said switch.

11. A method comprising providing a drive signal to a control terminal of a switch with a first driver switch coupled to a terminal of said switch, and a second driver switch inverted with respect to said first driver switch and coupled to another terminal of said switch.

12. The method as recited in claim 11 further comprising turning off said switch with a diode coupled between a terminal of said first driver switch and a terminal of a third driver switch.

13. The method as recited in claim 11 further comprising turning off said switch with a diode coupled between a terminal of said first driver switch and a terminal of a third driver switch and lowering a switch-off voltage of said switch with a resistor coupled across said diode.

14. The method as recited in claim 11 further comprising reducing a voltage across said second driver switch with a resistor coupled across a terminal and a control terminal of said second driver switch.

15. The method as recited in claim 11, further comprising:

turning on said switch with a third driver switch coupled between a terminal of said first driver switch and said control terminal of said switch; and

decreasing a switch-off time of said switch with a fourth driver switch coupled between said terminal of said first driver switch and a terminal of said third driver switch.

16. A power converter, comprising:

a power switch coupled to a source of electrical power;

a synchronous rectifier switch configured to provide an output voltage for said power converter; and

a driver for said synchronous rectifier switch, including;

a first driver switch coupled to a terminal of said synchronous rectifier switch, and

a second driver switch inverted with respect to said first driver switch and coupled to another terminal of said synchronous rectifier switch, wherein said first and second driver switches are configured to provide a drive signal to a control terminal of said synchronous rectifier switch.

17. The power converter as recited in claim 16 wherein said driver further comprises at least one additional driver switch configured to cooperate with said first and second driver switches to provide said drive signal to said control terminal of said synchronous rectifier switch.

18. The power converter as recited in claim 16 wherein said driver, further comprises:

a diode coupled between a terminal of said first driver switch and a terminal of a third driver switch configured to turn off said synchronous rectifier switch; and

a resistor coupled across said diode configured to lower a switch-off voltage of said synchronous rectifier switch.

19. The power converter as recited in claim 16 wherein said driver further comprises a resistor coupled across a terminal and a control terminal of said second driver switch configured to reduce a voltage thereacross.

20. The power converter as recited in claim 16 wherein said driver, further comprises:

a third driver switch coupled between a terminal of said first driver switch and said control terminal of said synchronous rectifier switch configured to turn on said synchronous rectifier switch; and

a fourth driver switch coupled between said terminal of said first driver switch and a terminal of said third driver switch configured to decrease a switch-off time of said synchronous rectifier switch.

21. A driver for a switch, comprising:

a driver switch coupled to a terminal of said switch; and

a diode coupled to a control terminal of said driver switch and another terminal of said switch, wherein said driver switch and said diode are configured to provide a drive signal to a control terminal of said switch.

22. The driver as recited in claim 21 wherein said switch is a synchronous rectifier switch employable in a power converter.

23. The driver as recited in claim 21 wherein said driver switch and said diode form at least a portion of a differential amplifier.

24. The driver as recited in claim 21 further comprising at least one additional driver switch configured to cooperate with said driver switch and said diode to provide said drive signal to said control terminal of said switch.

25. The driver as recited in claim 21 further comprising another diode coupled between a terminal of said driver switch and a terminal of another driver switch.

26. The driver as recited in claim 21 further comprising a resistor coupled to a terminal of said driver switch.

27. The driver as recited in claim 21 further comprising a resistor coupled to a node between said diode and said control terminal of said driver switch.

28. A method comprising providing a drive signal to a control terminal of a switch with a driver switch coupled to a terminal of said switch, and a diode coupled to a control terminal of said driver switch and another terminal of said switch.

29. The method as recited in claim 28 further comprising providing said drive signal to said control terminal of said switch with at least one additional driver switch.

30. The driver as recited in claim 28 further comprising turning off said switch with another diode coupled between a terminal of said driver switch and a terminal of another driver switch.

31. A power converter, comprising:

a power switch coupled to a source of electrical power;

a synchronous rectifier switch configured to provide an output voltage for said power converter; and

a driver for said synchronous rectifier switch, including;

a driver switch coupled to a terminal of said switch; and

a diode coupled to a control terminal of said driver switch and another terminal of said switch, wherein said driver switch and said diode are configured to provide a drive signal to a control terminal of said switch.

32. The power converter as recited in claim 31 wherein said driver switch and said diode form at least a portion of a differential amplifier.

33. The power converter as recited in claim 31 wherein said driver further comprises at least one additional driver switch configured to cooperate with said driver switch and said diode to provide said drive signal to said control terminal of said switch.

34. The power converter as recited in claim 31 wherein said driver further comprises another diode coupled between a terminal of said driver switch and a terminal of another driver switch configured to turn off said switch.

35. The power converter as recited in claim 31 wherein said driver further comprises a resistor coupled to a node between said diode and said control terminal of said driver switch.