Dynamic Drive of Switching Transistor of Switching Power Converter

• US 20100202165A1
• Filed: 09/28/2007
• Published: 08/12/2010
• Est. Priority Date: 09/28/2007
• Status: Active Grant

• Current Assignee: Dialog Semiconductor Incorporated (Renesas Electronics Corporation)
• Original Assignee: iWatt, Inc. (Renesas Electronics Corporation)
• Inventors: Zheng, Jun, Bui, Hien Huu, Lee, Andrew Kwok-Cheung, Li, Yong, Zheng, Junjie, Kesterson, John William, Lin, Allan Ming-Lun, Seim, Carrie
• Granted Patent: US 8,576,586 B2
• Time in Patent Office: Days
• US Class Current: 363/21.130
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence
• CPC Class Codes: H03K 17/163 Soft switching
• CPC Class Codes: H03K 17/166 Soft switching
• 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 switching power converter comprises a transformer (110), a switch (108) coupled to the transformer (110), and a switch controller (200) coupled to the switch (108) for generating a switch drive signal (207) to turn on or off the switch (108). The drive current of the switch drive signal (207) is adjusted dynamically according to line or load conditions within a switching cycle and/or over a plurality of switching cycles. The magnitude of the drive current can be dynamically adjusted within a switching cycle and/or over a plurality of switching cycles, in addition to the pulse widths or pulse frequencies of the drive current.

Claims

1. A switching power converter comprising:

a transformer coupled between a power source and a load;

a switch coupled to the transformer for coupling or decoupling the load to or from the power source through the transformer; and

a switch controller coupled to the switch and generating a switch drive signal for turning on or off the switch, the switch controller dynamically adjusting a magnitude of the switch drive signal within a switching cycle of the switching power converter.

2. The switching power converter of claim 1, wherein the switch controller includes:

a pulse generator generating an output drive signal at a first logic state during a first part of the switching cycle and a second logic state during a second part of the switching cycle; and

a dynamic switch drive module receiving the output drive signal and dynamically adjusting the magnitude of the switch drive signal.

3. The switching power converter of claim 1, wherein the dynamic switch drive module adjusts the magnitude of the switch drive signal to be at a predetermined level for a predetermined period of time at a beginning of the first part of the switching cycle.

4. The switching power converter of claim 3, wherein the predetermined period of time is fixed according to device characteristics of one or more components of the switching power converter.

5. The switching power converter of claim 1, wherein the switch is a bipolar junction transistor and the switch drive signal is a base current of the bipolar junction transistor, and the dynamic switch drive module adjusts the magnitude of the base current to be substantially proportional to a collector current of the bipolar junction transistor.

6. The switching power converter of claim 5, wherein the magnitude of the switch drive signal is adjusted based on an input voltage to the switching power converter and the load of the switching power converter.

7. The switching power converter of claim 1, wherein the dynamic switch drive module adjusts the magnitude of the switch drive signal to be zero for a predetermined period of time at an end of the first part of the switching cycle.

8. The switching power converter of claim 7, wherein the predetermined period of time during which the switch drive signal is zero is determined based on an input voltage to the switching power converter and the load of the switching power converter.

9. The switching power converter of claim 1, wherein the dynamic switch drive module comprises:

a switch drive control signal generator generating a digital switch drive control signal that is dynamically adjusted within the switching cycle; and

a switch multiplex receiving a plurality of reference current inputs and generating the switch drive signal as a current signal, the magnitude of the switch drive current signal corresponding to a magnitude of the digital switch drive control signal.

10. The switching power converter of claim 9, wherein the plurality of reference current inputs include different weighted magnitudes of reference current.

11. The switching power converter of claim 10, wherein the plurality of reference current inputs are determined by a single resistor.

12. The switching power converter of claim 1, wherein the dynamic switch drive module comprises:

a switch drive control signal generator generating a digital switch drive control signal that is dynamically adjusted within the switching cycle; and

a switch multiplex receiving a plurality of reference voltage inputs and generating the switch drive signal as a voltage signal, the magnitude of the switch drive voltage signal corresponding to a magnitude of the digital switch drive control signal.

13. The switching power converter of claim 12, wherein the plurality of reference voltage inputs include different weighted magnitudes of reference voltages.

14. The switching power converter of claim 1, wherein the dynamic switch drive module comprises:

a switch drive control signal generator generating a digital switch drive control signal that is dynamically adjusted within the switching cycle; and

a switch multiplex receiving a plurality of reference resistance inputs and generating the switch drive signal as a voltage signal, the magnitude of the switch drive voltage signal corresponding to a magnitude of the digital switch drive control signal.

15. The switching power converter of claim 14, wherein the plurality of reference voltage inputs include different weighted resistances of a plurality of resistors.

16. The switching power converter of claim 1, wherein the switch is a bipolar junction transistor and the switch drive signal is a base current of the bipolar junction transistor, and the switching power converter further comprises another transistor coupled to the base of the bipolar junction transistor, said another transistor being configured to be turned on while the bipolar junction transistor is turned off to provide a discharge path for charges on the base of the bipolar junction transistor.

17. The switching power converter of claim 1, wherein the switch controller adjusts a duration during which the switch is turned on within the switching cycle in addition to dynamically adjusting the magnitude of the switch drive signal within the switching cycle.

18. The switching power converter of claim 1, wherein the switch controller dynamically adjusts the magnitude of the switch drive signal over the switching cycle and a subsequent switching cycle of the switching power converter.

19. The switching power converter of claim 1, wherein the switch is a bipolar junction transistor and the switching power converter further comprises a comparator including:

a first input receiving a base voltage at a base of the bipolar junction transistor;

a second input receiving a reference voltage corresponding to when the bipolar junction transistor is off; and

an output generating an output signal based upon a comparison of the base voltage to the reference voltage, the output signal transitioning from a first logic state to a second logic state indicating when the bipolar junction transistor actually turned off.

20. The switching power converter of claim 1, wherein the switch drive signal is a current signal.

21. The switching power converter of claim 1, wherein the switch drive signal is a voltage signal.

22. A switching power converter comprising:

a transformer coupled between a power source and a load;

a switch coupled to the transformer for coupling or decoupling the load to or from the power source through the transformer; and

a pulse generator generating an output drive signal for controlling on-times and off-times of the switch, the output drive signal being at a first logic state during a first part of a switching cycle and a second logic state during a second part of the switching cycle; and

a dynamic switch drive module receiving the output drive signal and generating a switch drive signal for driving the switch based upon the output drive signal, a magnitude of the switch drive signal being dynamically adjusted within the switching cycle based upon an input voltage to the switching power converter and the load.

23. The switching power converter of claim 22, wherein the dynamic switch drive module adjusts the magnitude of the switch drive signal to be at a predetermined level for a predetermined period of time at a beginning of the first part of the switching cycle.

24. The switching power converter of claim 22, wherein the switch is a bipolar junction transistor and the switch drive signal is a base current of the bipolar junction transistor, and the dynamic switch drive module adjusts the magnitude of the base current to be substantially proportional to a collector current of the bipolar junction transistor.

25. The switching power converter of claim 22, wherein the dynamic switch drive module adjusts the magnitude of the switch drive signal to be zero for a predetermined period of time at an end of the first part of the switching cycle.