Adaptive gate drive voltage circuit

• US 20060038547A1
• Filed: 08/19/2005
• Published: 02/23/2006
• Est. Priority Date: 08/23/2004
• Status: Active Grant

• Current Assignee: Infineon Technologies Americas Corp. (Infineon Technologies AG)
• Original Assignee: International Rectifier Corporation (Infineon Technologies AG)
• Inventors: Ahmad, Faisal
• Granted Patent: US 7,265,601 B2
• Time in Patent Office: Days
• US Class Current: 323/284
• CPC Class Codes: H02M 1/08 Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
• CPC Class Codes: H03F 3/217 Class D power amplifiers; Switching amplifiers
• CPC Class Codes: H03K 17/063 in field-effect transistor switches
• CPC Class Codes: H03K 17/0822 in field-effect transistor switches
• CPC Class Codes: H03K 17/6871 the output circuit comprising more than one controlled field-effect transistor
• CPC Class Codes: H03K 2217/0036 Means reducing energy consumption

Abstract

A circuit and method for reducing losses in a DC/DC converter by optimizing gate drive voltage. The circuit and method detect a change in the output load, or more specifically the output current, and adjust the gate voltage accordingly; in other words, providing adaptive gate drive voltage. In response to a reduction of output current, the invention reduces the gate voltage so as to reduce both conduction and switching losses in the semiconductor switching devices in the output stage.

Claims

1. A DC/DC converter comprising:

at least one switching device responsive to a drive signal having a drive voltage level, for receiving DC input power and delivering DC output current to an output circuit of said converter;

a driver for supplying said drive signal to said switching device; and

an adaptive drive voltage circuit which senses said DC output current, and in response thereto, sets said drive voltage level to be supplied by said driver to said switching device.

2. The DC/DC converter of claim 1, wherein said adaptive drive voltage circuit, in response to a reduction of output current, reduces said drive voltage level so as to reduce losses in said switching device.

3. The DC/DC converter of claim 2, wherein said adaptive drive voltage circuit defines at least one current threshold, and selects one of at least two predetermined drive voltage levels, in response to whether said output current is above or below said threshold.

4. The DC/DC converter of claim 2, wherein said adaptive drive voltage circuit defines a first plurality of current thresholds, and selects one of a second plurality of predetermined drive voltage levels in response to whether said output current is above, below or between said first plurality of current thresholds.

5. The DC/DC converter of claim 2, wherein said adaptive drive voltage circuit generates a variable drive voltage level in response to variations in said DC output current.

6. A method of controlling a DC/DC converter, said converter comprising:

at least one switching device responsive to a drive signal having a drive voltage level, for receiving DC input power and delivering DC output current to an output circuit of said converter; and

a driver for supplying said drive signal to said switching device;

said method comprising the steps of;

sensing said DC output current, and

in response thereto, setting said drive voltage level to be supplied by said driver to said switching device.

7. The method of claim 6, wherein said adaptive drive voltage circuit, in response to a reduction of output current, reduces said drive voltage level so as to reduce losses in said switching device.

8. The method of claim 7, wherein said adaptive drive voltage circuit defines at least one current threshold, and selects one of at least two predetermined drive voltage levels, in response to whether said output current is above or below said threshold.

9. The method of claim 7, wherein said adaptive drive voltage circuit defines a first plurality of current thresholds, and selects one of a second plurality of predetermined drive voltage levels in response to whether said output current is above, below or between said first plurality of current thresholds.

10. The method of claim 7, wherein said adaptive drive voltage circuit generates a variable drive voltage level in response to variations in said DC output current.

11. A DC/DC converter comprising:

a pair of semiconductor switching devices for receiving DC input power and delivering DC output current to an output circuit of said converter connected to said pair of semiconductor switching devices;

a pair of drivers, each for supplying a respective gate drive signal to a corresponding gate of one of said switching devices, said gate drive signals having a gate drive voltage level; and

an adaptive drive voltage circuit which senses said DC output current, and in response thereto, sets said gate drive voltage level of said gate drive signals to be supplied by said drivers to said switching devices.

12. The converter of claim 11, wherein said pair of semiconductor switching devices are connected in a totem-pole arrangement and said output circuit is connected to a junction point between said pair of semiconductor switching devices.

13. The converter of claim 11, comprising setting circuitry which responds to a reduction of said output current by reducing said gate drive voltage level, thereby reducing losses in said switching devices.

14. The converter of claim 13, wherein said reduction of said gate drive voltage level results in a reduction of switching losses and gate drive losses.

15. The converter of claim 13, wherein said setting circuitry defines at least one current threshold, and selects one of at least two predetermined gate drive voltage levels, in response to whether said output current is above or below said threshold.

16. The converter of claim 13, wherein said setting circuitry defines a first plurality of current thresholds, and selects one of a second plurality of predetermined drive voltage levels in response to whether said output current is above, below or between said first plurality of current thresholds.

17. The converter of claim 13, wherein said setting circuitry generates a variable drive voltage level in response to variations in said DC output current.

18. The converter of claim 13, wherein said setting circuitry selects one of at least two reference voltages corresponding to said gate drive voltage level.

19. The converter of claim 18, wherein said setting circuitry comprises a multiplexer responsive to said output current and connected to said at least two reference voltages, and delivers one of said at least two reference voltages for controlling said gate drive voltage level.

20. The converter of claim 19, wherein said multiplexer delivers said reference voltage to a linear regulator, which generates said gate drive voltage level in response thereto.

21. The converter of claim 13, wherein said setting circuitry increases said gate drive voltage level in response to an increase in said output current, thereby reducing conduction losses in said switching devices.