Boost converter with enhanced control capabilities of emulating an inductor current

• US 7,615,981 B2
• Filed: 09/17/2004
• Issued: 11/10/2009
• Est. Priority Date: 06/09/2004
• Status: Active Grant

• Current Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Original Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Inventors: Han, Ming Kwang, Popescu-Stanesti, Vlad Mihail, Wong, Foot Shen
• Primary Examiner(s): Berhane; Adolf
• Assistant Examiner(s): BEHM, HARRY RAYMOND
• Application Number:
  US10/944,263
• Publication Number:
  US 20050275392A1
• Time in Patent Office: 1,880 Days
• Field of Search: 323/285, 323/222, 323/299, 323/300, 323/301, 323/303, 323/288
• US Class Current: 323/285
• CPC Class Codes: H02M 1/0022 the disturbance parameters being input voltage fluctuations
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators

Abstract

A DC to DC converter for converting an input DC voltage to an output DC voltage. The DC to DC converter may include at least one switch, an inductor coupled to the at least one switch, and a controller capable of providing a control signal. The at least one switch may be responsive to the control signal in a first state to enter an ON state for an ON time interval, the ON time interval based on the input DC voltage and a constant. An electronic device including such a DC to DC converter and related methods are also provided.

Claims

1. A DC to DC converter for converting a DC input voltage to a DC output voltage, said DC to DC converter comprising:

an inductor for receiving said DC input voltage and a current flowing through said inductor;

a controller coupled to said inductor and comprising a capacitor having a voltage capable of emulating said current of said inductor in a continuous current mode and a discontinuous current mode, wherein said controller is capable of generating at least one pulse frequency modulation signal according to a first comparison between said voltage of said capacitor and a first predetermined level and according to a second comparison between said voltage of said capacitor and a second predetermined level;

at least one switch coupled to said inductor, wherein said at least one switch is controlled by said at least one pulse frequency modulation signal from said controller and provides said DC output voltage; and

a feedback circuit coupled to said inductor, wherein said feedback circuit selectively senses said DC output voltage or a voltage at a terminal of said at least one switch and generates a feedback signal.

2. A DC to DC converter for converting a DC input voltage to a DC output voltage, said DC to DC converter comprising:

an inductor for receiving said DC input voltage and a current flowing through said inductor;

a controller coupled to said inductor and capable of generating at least one pulse frequency modulation signal;

at least one switch coupled to said inductor, wherein said at least one switch is controlled by said at least one pulse frequency modulation signal from said controller and provides said DC output voltage; and

a feedback circuit coupled to said inductor, wherein said feedback circuit selectively senses said DC output voltage or a voltage at a terminal of said at least one switch and generates a feedback signal;

wherein said controller comprises;

a capacitor having a voltage that is capable of emulating said current of said inductor in a continuous current mode and a discontinuous current mode;

an activation generator capable of providing a first pulse signal;

a disactivation generator capable of providing a second pulse signal;

a control logic circuit coupled to said activation generator and said disactivation generator, wherein said control logic circuit is triggered by said feedback signal from said feedback circuit and is capable of receiving said first pulse signal, said second pulse signal and said feedback signal and generating a charge current, a discharge current and a plurality of control signals; and

a driver for receiving said plurality of control signals from said control logic circuit and generating said at least one pulse frequency modulation signal to control said at least one switch.

3. The DC to DC converter of claim 2, wherein said first pulse signal has a first duration, said first duration is determined by said charge current, said capacitor is charged by said charge current during said first duration, and said charge current is proportional to said DC input voltage during said first duration.

4. The DC to DC converter of claim 3, wherein said inductor is charged when said at least one switch is turned on during said first duration, and wherein a rate of change in current with time of said inductor is proportional to said DC input voltage during said first duration.

5. The DC to DC converter of claim 2, wherein said second pulse signal has a second duration, said second duration depends on said feedback signal from said feedback circuit, said second duration includes a discharging duration and a skip duration, said discharging duration is determined by said discharge current, said capacitor is discharged by said discharge current during said discharging duration, and said discharge current is proportional to voltage variance between said DC output voltage and said DC input voltage during said discharging duration.

6. The DC to DC converter of claim 5, wherein said inductor is discharged when said at least one switch is turned off during said discharging duration, and wherein a rate of change in current with time of said inductor is proportional to said voltage variance between said DC output voltage and said DC input voltage during said discharging duration.

7. The DC to DC converter of claim 6, wherein said voltage of said capacitor reaches a lowest value after said discharging duration, said current of said inductor is discharged to zero after said discharging duration, and said at least one switch is turned off in said skip duration.

8. The DC to DC converter of claim 7, wherein said voltage of said capacitor emulates said current of said inductor during said discharging duration.

9. An electronic device comprising:

a DC to DC converter for converting a DC input voltage to a DC output voltage, said DC to DC converter comprising;

an inductor for receiving said DC input voltage and a current flowing through said inductor;

a controller coupled to said inductor and comprising a capacitor having a voltage that is capable of emulating said current of said inductor in a continuous current mode and a discontinuous current mode, wherein said controller is capable of generating at least one pulse frequency modulation signal according to a first comparison between said voltage of said capacitor and a first predetermined level and according to a second comparison between said voltage of said capacitor and a second predetermined level;

at least one switch coupled to said inductor, wherein said at least one switch is controlled by said at least one pulse frequency modulation signal from said controller and provides said DC output voltage; and

a feedback circuit coupled to said inductor, wherein said feedback circuit selectively senses said DC output voltage or a voltage at a terminal of said at least one switch and generates a feedback signal.

10. An electronic device comprising:

a DC to DC converter for converting a DC input voltage to a DC output voltage, said DC to DC converter comprising;

an inductor for receiving said DC input voltage and a current flowing through said inductor;

a controller coupled to said inductor and capable of generating at least one pulse frequency modulation signal;

at least one switch coupled to said inductor, wherein said at least one switch is controlled by said at least one pulse frequency modulation signal from said controller and provides said DC output voltage; and

a feedback circuit coupled to said inductor, wherein said feedback circuit selectively senses said DC output voltage or a voltage at a terminal of said at least one switch and generates a feedback signal;

wherein said controller comprises;

a capacitor having a voltage that is capable of emulating said current of said inductor in a continuous current mode and a discontinuous current mode;

an activation generator capable of providing a first pulse signal;

a disactivation generator capable of providing a second pulse signal;

a control logic circuit coupled to said activation generator and said disactivation generator, wherein said control logic circuit is triggered by said feedback signal from said feedback circuit and is capable of receiving said first pulse signal, said second pulse signal and said feedback signal and generating a charge current, a discharge current and a plurality of control signals; and

a driver for receiving said plurality of control signals from said control logic circuit and generating said at least one pulse frequency modulation signal to control said at least one switch.

11. The electronic device of claim 10, wherein said first pulse signal has a first duration, said first duration is determined by said charge current, said capacitor is charged by said charge current during said first duration, and said charge current is proportional to said DC input voltage during said first duration.

12. The electronic device of claim 11, wherein said inductor is charged when said at least one switch is turned on during said first duration, wherein a rate of change in current with time of said inductor is proportional to said DC input voltage during said first duration.

13. The electronic device of claim 10, wherein said second pulse signal has a second duration, said second duration depends on said feedback signal from said feedback circuit, said second duration includes a discharging duration and a skip duration, said discharging duration is determined by said discharge current, said capacitor is discharged by said discharge current during said discharging duration, and said discharge current is proportional to voltage variance between said DC output voltage and said DC input voltage during said discharging duration.

14. The electronic device of claim 13,wherein said inductor is discharged when said at least one switch is turned off during said discharging duration, wherein a rate of change in current with time of said inductor is proportional to said voltage variance between said DC output voltage and said DC input voltage during said discharging duration.

15. The electronic device of claim 14, wherein said voltage of said capacitor reaches a lowest value after said discharging duration, said current of said inductor is discharged to zero after said discharging duration, and said at least one switch is turned off in said skip duration.

16. The electronic device of claim 15, wherein said voltage of said capacitor emulates said current of said inductor during said discharging duration.

17. A boost DC to DC converter for converting a DC input voltage to a DC output voltage higher than said DC input voltage, said boost DC to DC converter comprising:

an inductor for receiving said DC input voltage and a current flowing through said inductor;

a controller coupled to said inductor and comprising a capacitor having a voltage that is capable of emulating said current of said inductor in a continuous current mode and a discontinuous current mode, wherein said controller is capable of generating a first pulse frequency modulation signal and a second pulse frequency modulation signal according to a first comparison between said voltage of said capacitor and a first predetermined level and according to a second comparison between said voltage of said capacitor and a second predetermined level;

a high side switch and a low side switch coupled to said inductor, wherein said high side and low side switches are controlled respectively by said first and second pulse frequency modulation signals from said controller, and said high side switch is operable for providing said DC output voltage; and

a feedback circuit coupled to said inductor, wherein said feedback circuit selectively senses said DC output voltage or a voltage at a terminal of said high side switch and generates a feedback signal.

18. The boost DC to DC converter of claim 17, wherein said controller comprises:

a current source capable of generating a charge current to charge said capacitor;

a switchable current sink capable of generating a discharge current to discharge said capacitor, wherein said voltage of said capacitor depends on said charge current and said discharge current;

a control logic circuit, wherein said control logic circuit is triggered by said voltage of said capacitor and generates a plurality of control signals according to said first comparison and according to said second comparison, and

a driver, wherein said driver receives said plurality of control signals from said control logic circuit and generates said first pulse frequency modulation signal to control said high side switch and generates said second pulse frequency modulation signal to control said low side switch.

19. The boost DC to DC converter of claim 18, wherein said first pulse frequency modulation signal has a first duration, said first duration is determined by said first comparison between said voltage of said capacitor and said first predetermined level, said capacitor is charged by said charge current during said first duration, and said charge current is proportional to said DC input voltage during said first duration.

20. The boost DC to DC converter of claim 19, wherein said inductor is charged when said high side switch is turned off and said low side switch is turned on during said first duration, wherein a rate of change in current with time of said inductor is proportional to said DC input voltage during said first duration.

21. The boost DC to DC converter of claim 18, wherein said second pulse frequency modulation signal has a second duration, said second duration is determined by said second comparison between said voltage of said capacitor and said second predetermined level, said capacitor is discharged by a discharge current during said second duration, and said discharge current is proportional to voltage variance between said DC output voltage and said DC input voltage during said second duration.

22. The boost DC to DC converter of claim 21, wherein said inductor is discharged when said high side switch is turned on and said low side switch is turned off during said second duration, wherein a rate of change in current with time of said inductor is proportional to said voltage variance between said DC output voltage and said DC input voltage during said second duration.

23. The boost DC to DC converter of claim 22, wherein said voltage of said capacitor reaches a lowest value after said second duration, said current of said inductor is discharged to zero after said second duration, and said high side switch is turned off after said second duration.

24. The boost DC to DC converter of claim 23, wherein said voltage of said capacitor emulates said current of said inductor during said second duration.

25. The boost DC to DC converter of claim 18, wherein said current source comprises:

a voltage divider, wherein said voltage divider scales down said DC input voltage and generates a scaled-down voltage;

a voltage follower, wherein said voltage follower receives said scaled-down voltage and generates a first current;

a plurality of current mirrors, wherein said plurality of current mirrors mirror said first current and generate a second current; and

a switch coupled to said plurality of current mirrors, wherein said switch sends said second current to charge said capacitor when said switch is turned on.

26. The boost DC to DC converter of claim 18, wherein said switchable current sink comprises:

a voltage follower, wherein said voltage follower receives a predetermined voltage and converts said predetermined voltage to a first current;

a plurality of current mirrors, wherein said plurality of current mirrors receive said first current and generate a plurality of mirrored currents; and

a multiplex switch coupled to said plurality of current mirrors, wherein said multiplex switch selects one of said mirrored currents and a predetermined current as said discharge current to discharge said capacitor.

27. The boost DC to DC converter of claim 18, wherein said feedback circuit comprises:

a double throw switch coupled in parallel with said high side switch;

a voltage divider coupled to said double throw switch, wherein said voltage divider generates a scaled-down voltage; and

a comparator coupled to said voltage divider, wherein said comparator receives a reference voltage and said scaled-down voltage and generates said feedback signal, and wherein said feedback signal comprises a component of said current of said inductor and triggers said control logic circuit.

28. The boost DC to DC converter of claim 18, wherein said DC to DC converter further comprises a current sense circuit, wherein said current sense circuit detects said current of said inductor and generates a control signal to said control logic circuit.

29. An electronic device comprising:

a boost DC to DC converter for converting a DC input voltage to a DC output voltage higher than said DC input voltage, said boost DC to DC converter comprising;

an inductor for receiving said DC input voltage and a current flowing through said inductor;

a controller coupled to said inductor and comprising a capacitor having a voltage capable of emulating said current of said inductor in a continuous current mode and a discontinuous current mode, wherein said controller is capable of generating a first pulse frequency modulation signal and a second pulse frequency modulation signal according to a first comparison between said voltage of said capacitor and a first predetermined level and according to a second comparison between said voltage of said capacitor and a second predetermined level;

a high side switch and a low side switch coupled to said inductor, wherein said high side and low side switches are controlled respectively by said first and second pulse frequency modulation signals from said controller, and said high side switch is operable for providing said DC output voltage; and

a feedback circuit coupled to said inductor, wherein said feedback circuit selectively senses said DC output voltage or a voltage at a terminal of said at least one switch and generates a feedback signal.

30. The electronic device of claim 29, wherein said controller comprises:

a current source capable of generating a charge current to charge said capacitor;

a switchable current sink capable of generating a discharge current to discharge said capacitor, wherein said voltage of said capacitor depends on said charge current and said discharge current;

a control logic circuit, wherein said control logic circuit is triggered by said voltage of said capacitor and generates a plurality of control signals according to said first comparison and according to said second comparison, and

a driver, wherein said driver receives said plurality of control signals from said control logic circuit and generates said first pulse frequency modulation signal to control said high side switch and said second pulse frequency modulation signal to control said low side switch.

31. The electronic device of claim 30, wherein said first pulse frequency modulation signal has a first duration, wherein said first duration is determined by said first comparison between said voltage of said capacitor and said first predetermined level, said capacitor is charged by said charge current during said first duration, and said charge current is proportional to said DC input voltage during said first duration.

32. The electronic device of claim 31, wherein said inductor is charged when said high side switch is turned off and said low side switch is turned on during said first duration, wherein a rate of change in current with time of said inductor is proportional to said DC input voltage during said first duration.

33. The electronic device of claim 30, wherein said second pulse frequency modulation signal has a second duration, said second duration is determined by said second comparison between said voltage of said capacitor and said second predetermined level, said capacitor is discharged by a discharge current during said second duration, and said discharge current is proportional to a voltage variance between said DC output voltage and said DC input voltage during said second duration.

34. The electronic device of claim 33, wherein said inductor is discharged when said high side switch is turned on and said low side switch is turned off during said second duration, wherein a rate of change in current with time of said inductor is proportional to said voltage variance between said DC output voltage and said DC input voltage during said second duration.

35. The electronic device of claim 34, wherein said voltage of said capacitor reaches a lowest value after said second duration, said current of said inductor is discharged to zero after said second duration, and said high side switch is turned off after said second duration.

36. The electronic device of claim 35, wherein said voltage of said capacitor emulates said current of said inductor during said second duration.

37. The electronic device of claim 30, wherein said current source comprises:

a voltage divider, wherein said voltage divider scales down said DC input voltage and generates a scaled-down voltage;

a voltage follower, wherein said voltage follower receives said scaled-down voltage and generates a first current;

a plurality of current mirrors, wherein said plurality of current mirrors mirror said first current and generate a second current; and

a switch coupled to said plurality of current mirrors, wherein said switch sends said second current to charge said capacitor when said switch is turned on.

38. The electronic device of claim 30, wherein said switchable current sink comprises:

a voltage follower, wherein said voltage follower receives a predetermined voltage and converts said predetermined voltage to a first current;

a plurality of current mirrors, wherein said plurality of current mirrors receive said first current and generate a plurality of mirrored currents; and

a multiplex switch coupled to said plurality of current mirrors, wherein said multiplex switch selects one of said mirrored currents and a predetermined current as said discharge current to discharge said capacitor.

39. The electronic device of claim 30, wherein said feedback circuit comprises:

a double throw switch coupled in parallel with said high side switch;

a voltage divider coupled to said double throw switch, wherein said voltage divider generates a scaled-down voltage; and

a comparator coupled to said voltage divider, wherein said comparator receives a reference voltage and said scaled-down voltage and generates said feedback signal, wherein said feedback signal comprises a component of said current of said inductor and triggers said control logic circuit.

40. The electronic device of claim 30, wherein said DC to DC converter further comprises a current sense circuit, wherein said current sense circuit detects said current of said inductor and generates a control signal to said control logic circuit.