DC/DC converter control circuits and DC/DC converter systems with power saving mode in accordance with an external control signal

• US 6,882,133 B2
• Filed: 04/30/2002
• Issued: 04/19/2005
• Est. Priority Date: 11/27/2001
• Status: Expired due to Term

• Current Assignee: Monterey Research, LLC (Vector Capital Corporation)
• Original Assignee: Fujitsu Limited
• Inventors: Matsumoto, Takashi, Haraguchi, Akira, Takimoto, Kyuichi
• Primary Examiner(s): Riley, Shawn
• Application Number:
  US10/134,751
• Publication Number:
  US 20030098678A1
• Time in Patent Office: 1,085 Days
• Field of Search: 713/340, 713/330, 713/323, 713/322, 323/901, 323/364, 323/369
• US Class Current: 323/284
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 1/36 Means for starting or stopping converters
• CPC Class Codes: H02M 3/155 using semiconductor devices only
• 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
• CPC Class Codes: Y10S 323/901 Starting circuits

Abstract

There are provided a DC/DC converter control circuit and a DC/DC converter system having high degree of freedom of mounting and achieving the following matters: (1) housing a DC/DC converter control circuit in a package miniaturized by reducing the number of terminals; and (2) starting-up a power saving mode in response to an input of an external control signal to a DC/DC converter system. A frequency setting terminal (RT) is connected to a resistance element RT and a switching section 1 in series, between the terminal and ground voltage. An external control signal CTL is inputted to the switching section 1. When an external control signal CTL turns off the switching section 1, connection to the ground voltage is opened and an oscillation driving section 4 does not operate. Thereby, power saving mode is kept. When the switching section 1 is turned on, connection to the ground voltage is closed and the oscillation driving section 4 starts up. Subsequently, a bias control section 5 starts up and bias condition toward the resistance element RT is controlled. Thereby oscillation frequencies approximate to a setting value. Control of power saving mode can be thus carried out without a dedicated terminal for an external control signal CTL.

Claims

1. A DC/DC converter control circuit capable of switching internal operation state between active state and non-active state, the DC/DC converter control circuit comprising:

a frequency setting terminal for externally connecting an external impedance element to a point between the frequency setting terminal and external predetermined voltage;

a bias section for getting the external impedance element biased, the bias section being connected to the frequency setting terminal; and

an oscillation driving section for controlling oscillation frequencies depending on an impedance value of the external impedance element, the oscillation driving section being connected to the external impedance element through the bias section;

wherein the DC/DC converter control circuit further comprises a control section for controlling the internal operation, the control section being activated based on a signal from the oscillation driving section, an auxiliary activator section for keeping the bias section in an active state when the internal operation is in a non-active state, and the oscillation driving section starts-up when a path between the frequency setting terminal and the external predetermined voltage which passes through the external impedance element is closed to be conductive by an external switching section which opens and closes the path.

2. A DC/DC converter control circuit according to claim 1, wherein switching between active state and non-active state is controlled by an external control signal inputted to the external switching section.

3. A DC/DC converter control circuit according to claim 1, wherein the control section includes a bias control section for controlling and adjusting a bias value of the external impedance element to a predetermined bias value by controlling the bias section.

4. A DC/DC converter control circuit according to claim 1, wherein the auxiliary activator section includes a bias supply element for supplying bias to the bias section from an externally-applied power source.

5. A DC/DC converter control circuit according to claim 4, wherein the externally-applied power source is power source voltage supplied from an external or ground voltage.

6. A DC/DC converter control circuit according to claim 1, wherein the bias section includes a bipolar transistor connected toward the frequency setting terminal in a manner of emitter connection.

7. A DC/DC converter control circuit according to claim 1, wherein the bias section includes a MOS transistor connected toward the frequency setting terminal in a manner of source connection.

8. A DC/DC converter control circuit according to claim 4, wherein the bias supply element includes a bias supply resistance element.

9. A DC/DC converter control circuit capable of switching internal operation state between active state and non-active state, the DC/DC converter control circuit comprising:

a frequency setting terminal for externally connecting an external resistance element to a point between the frequency setting terminal and external predetermined voltage;

a transistor for getting the external resistance element voltage biased, the transistor being connected to the frequency setting terminal; and

an oscillation current source for controlling oscillation frequencies by outputting bias current depending on a resistance value of the external resistance element, the oscillation current source being connected to the external resistance element through the transistor;

wherein the DC/DC converter control circuit further comprises a bias control section for controlling and adjusting voltage bias of the external resistance element to a predetermined voltage value by controlling the transistor, the bias control section being activated based on bias current from current source connected to the oscillation current source in a manner of mirror connection, other control sections for controlling the internal operation, the other control sections being activated based on bias current from current source connected to the oscillation current source in a manner of mirror connection, and a bias resistance element for getting the transistor biased when the bias control section is in a non-active state, and the oscillation current source starts-up when a path between the frequency setting terminal and the external predetermined voltage which passes through the external resistance element is closed to be conductive by an external switching transistor which opens and closes the path.

10. A DC/DC converter control circuit according to claim 9 further including a reference voltage section, wherein one of driving bias signals for driving the reference voltage section is selected at the time of start-up and after start-up where internal operation is in a active state.

11. A DC/DC converter control circuit according to claim 9 further including a reference voltage section, wherein one of driving bias current signals for driving the reference voltage section is selected at the time of start-up and after start-up where internal operation is in an active state.

12. A DC/DC converter control circuit according to claim 10 further including a reference voltage monitoring section for monitoring level of reference voltage outputted from the reference voltage section and alarming that the reference voltage is same as or higher than a predetermined voltage value, wherein one of the driving bias signals is selected in accordance with a alarming signal from the reference voltage monitoring section.

13. A DC/DC converter control circuit according to claim 11 further including a reference voltage monitoring section for monitoring level of reference voltage outputted from the reference voltage section and alarming that the reference voltage is same as or higher than a predetermined voltage value, wherein one of the driving bias current signals is selected in accordance with a alarming signal from the reference voltage monitoring section.

14. A DC/DC converter control circuit according to claim 10, wherein the driving bias for the time of start-up is supplied by the oscillation driving section.

15. A DC/DC converter control circuit according to claim 11, wherein the driving bias current for the time of start-up is supplied by the oscillation current source.

16. A DC/DC converter control circuit according to claim 10, wherein the driving bias for the internal operation under active state is supplied from the reference voltage section.

17. A DC/DC converter control circuit according to claim 11, wherein the driving bias current for the internal operation under active state is supplied from the reference voltage section.

18. A DC/DC converter control circuit according to claim 16 further including a driving bias blocking section for blocking supply of the driving bias from the reference voltage section to the reference voltage section itself when the internal operation in active state is switched to non-active state.

19. A DC/DC converter control circuit according to claim 17 further including a driving bias blocking section for blocking supply of the driving bias current from the reference voltage section to the reference voltage section itself when the internal operation in active state is switched to non-active state.

20. A DC/DC converter control circuit according to claim 18, wherein the driving bias blocking section blocks supply of the driving bias in accordance with a signal from the oscillation driving section.

21. A DC/DC converter control circuit according to claim 19, wherein the driving bias blocking section blocks supply of the driving bias current in accordance with bias current from the oscillation current source.

22. A DC/DC converter control circuit capable of switching internal operation state between active state and non-active state, wherein the DC/DC converter control circuit includes a reference voltage section, and one of driving bias signals for driving the reference voltage section is selected at the time of start-up and after start-up where internal operation is in an active state, and

wherein the driving bias for the internal operation under active state is supplied from the reference voltage section;

and

further including a driving bias blocking section for blocking supply of the driving bias from the reference voltage section to the reference voltage section itself when the internal operation in active state is switched to non-active state.

23. A DC/DC converter system capable of switching internal operation state between active state and non-active state, the DC/DC converter system comprising:

a DC/DC converter control circuit including a bias section for getting a frequency setting terminal biased and an oscillation driving section connected to the frequency setting terminal through the bias section; and

an impedance element for controlling oscillation frequencies of the oscillation driving section depending on an impedance value, the impedance element being connected to a point between the frequency setting terminal and predetermined voltage;

wherein the DC/DC converter system further comprises a control section for controlling the internal operation, the control section being activated based on a signal from the oscillation driving section, an auxiliary activator section for keeping the bias section in an active state when the internal operation is in a non-active state, and the oscillation driving section starts-up when a path between the frequency setting terminal and the predetermined voltage which passes through the impedance element is closed to be conductive by a switching section which opens and closes the path.

24. A DC/DC converter system according to claim 23, wherein switching between active state and non-active state is controlled by an external control signal inputted to the switching section.

25. A DC/DC converter system according to claim 23, wherein the control section includes a bias control section for controlling and adjusting a bias value of the impedance element to a predetermined bias value by controlling the bias section.

26. A DC/DC converter system according to claim 23, wherein the auxiliary activator section includes a bias supply element for supplying bias to the bias section from an externally-applied power source.

27. A DC/DC converter system according to claim 26, wherein the externally-applied power source is power source voltage supplied from an external or ground voltage.

28. A DC/DC converter system according to claim 23, wherein the bias section includes a bipolar transistor connected toward the frequency setting terminal in a manner of emitter connection.

29. A DC/DC converter system according to claim 23, wherein the bias section includes a MOS transistor connected toward the frequency setting terminal in a manner of source connection.

30. A DC/DC converter system according to claim 26 wherein the bias supply element includes a bias supply resistance element.

32. A DC/DC converter system according to claim 23 further including a reference voltage section, wherein one of driving bias signals for driving the reference voltage section is selected at the time of start-up and after start-up where internal operation is in an active state.

31. A DC/DC converter system capable of switching internal operation state between active state and non-active state, the DC/DC converter system comprising:

a DC/DC converter control circuit including a transistor for getting a frequency setting terminal voltage biased and an oscillation current source connected to the frequency setting terminal through the transistor; and

a resistance element for controlling oscillation frequencies of the oscillation current source depending on a resistance value, the resistance element being connected to a point between the frequency setting terminal and predetermined voltage;

wherein the DC/DC converter system further comprises a bias control section for controlling and adjusting voltage bias of the resistance element to a predetermined voltage value by controlling the transistor, the bias control section being activated based on bias current from current source connected to the oscillation current source in a manner of mirror connection, other control sections for controlling the internal operation at the DC/DC converter control circuit, the other control sections being activated based on bias current from current source connected to the oscillation current source in a manner of mirror connection, and a bias resistance element for getting the transistor biased when the bias control section is in a non-active state, and the oscillation current source starts-up when a path between the frequency setting terminal and the predetermined voltage which passes through the resistance element is closed to be conductive by a switching transistor which opens and closes the path.

33. A DC/DC converter system according to claim 31 further including a reference voltage section, wherein one of driving bias current signals for driving the reference voltage section is selected at the time of start-up and after start-up where internal operation is in an active state.