Switching power supply device and switching power supply system

• US 20040004470A1
• Filed: 06/03/2003
• Published: 01/08/2004
• Est. Priority Date: 06/07/2002
• Status: Active Grant

• Current Assignee: Renesas Electronics Corporation
• Original Assignee: Hitachi, Ltd.
• Inventors: Yoshida, Shinichi, Sase, Takashi, Tazawa, Tomohiro, Tateno, Kouji
• Granted Patent: US 6,979,985 B2
• Time in Patent Office: Days
• US Class Current: 323/284
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 3/1563 without using an external clock H02M3/158 takes precedence
• CPC Class Codes: H02M 3/1588 comprising at least one synchronous rectifier element H02M3/1582, H02M3/1584 take precedence
• CPC Class Codes: H02M 3/3385 with automatic control of output voltage or current H02M3/33561 takes precedence
• 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

There is provided a switching power supply device of hysteresis current mode control system which assures excellent response characteristic for change of output current and reduction of power consumption. In a switching regulator of hysteresis current mode control system, a sense resistor connected in series to a coil is eliminated, a serially connected resistor and a capacitor are connected in parallel to a coil in place of such sense resistor. Thereby, a potential of a connection node of these resistor and capacitor is inputted to a comparator circuit having the hysteresis characteristic for comparison with the reference voltage. Accordingly, a switch may be controlled for ON and OFF states.

Claims

1. A switching power supply device for generating the predetermined voltage through switching control of the current flowing into an inductor, comprising

a switching element for controlling the current flowing into said inductor and a comparison circuit having the hysteresis characteristic, whereby the current flowing into said inductor is changed depending on variation of load by providing a circuit including a serially connected resistance element and a capacitance element, connecting said circuit in parallel to said inductor, extracting voltage of said inductor through said capacitor and resistor, inputting said extracted voltage to said comparison circuit, discriminating said voltage with a first threshold value and a second threshold value, and then sending said voltage to said switching element.

3. A switching power supply device according to claim 1 or 2, wherein said comparison circuit comprises a comparator for outputting a signal depending on the level by comparing an input potential to a first input terminal with an input potential to a second input terminal and a switching means for switching the level of the reference voltage inputted to one input terminal of said comparator so that said comparator has the hysteresis characteristic.

4. A switching power supply device according to claim 3, wherein said switching means comprises a resistance dividing circuit for dividing the reference voltage with a plurality of serially connected resistors and a second switching element connected in parallel to any one of said resistors so that the level of the reference voltage inputted to said comparator is changed depending on the ON and OFF states of said second switching element.

5. A switching power supply device according to claim 1 or 2, wherein said comparison circuit comprises a first comparator for outputting a signal depending on the level by comparing an input potential to a first input terminal with an input potential to a second input terminal, a second comparator for outputting a signal depending on the level by comparing an input potential to a third input terminal with an input potential to a fourth input terminal, and an RS flip-flop circuit having a reset input terminal and a set input terminal and moreover said comparison circuit is given the hysteresis characteristic by inputting the first threshold value voltage to said second input terminal, inputting the second threshold value voltage to said fourth input terminal, inputting the extracted voltage of said inductor or the voltage of said connection node to said first and third input terminals, inputting an output of said first comparator to the reset terminal of said RS flip-flop circuit, and by inputting an output of said second comparator to the set terminal of said RS flip-flop circuit.

6. A switching power supply device according to claim 1 or 2, comprising a voltage dividing means for dividing output voltage to be inputted to said load and a differential amplifier for outputting voltage depending on potential difference between the voltage generated by said voltage dividing means and the reference voltage, whereby an output of said differential amplifier and voltage of connection node of said resistance element and capacitance element are inputted to said comparison circuit for discrimination with said first threshold value and said second threshold value.

7. A switching power supply device according to any one of claims 1 to 6, wherein a second resistance element is connected between the connection node of said resistance element and capacitance element and the fixed potential terminal.

8. A switching power supply device according to any one of claims 1 to 7, wherein a third capacitance element is connected between the connection node of said resistance element and capacitance element and the fixed potential terminal or between the connection node of a second capacitance element connected in series to said capacitance element and the fixed potential terminal.

2. A switching power supply device for generating the predetermined voltage through switching control of the current flowing into an inductor, comprising

a switching element for controlling the current flowing into said inductor, a comparison circuit having the hystreresis characteristic and a serially connected resistance element and a capacitance element which are connected in parallel to said inductor, whereby the current flowing into said inductor is changed depending on variation of load by inputting voltage of the connection node of said resistance element and capacitance element or voltage of the connection node of one of said capacitance element and said another capacitance element to said comparison circuit, discriminating this voltage with a first threshold value and a second threshold value and then sending the voltage to said switching element.

25. A switching power supply circuit according to claim 2, wherein said switching element is comprised of two switches which are complementarily controlled and not to be turned ON simultaneously.

9. A switching power supply device comprising an inductor, a first switching element for controlling the current flowing into said inductor, a second switching element or a rectifying element connected in series to said inductor between a voltage input terminal and a voltage output terminal, a control circuit for controlling said first and second switching elemenst, a comparator for outputting a signal depending on the level by comparing an input potential to a first input terminal with an input potential to a second input terminal, a switching means for switching the level of the reference voltage inputted to one input terminal of said comparator, and a serially connected resistance element and a capacitance element connected in parallel to said second switching element or rectifying element, whereby the current flowing into said inductor is changed depending on variation of load by inputting voltage of the connection node of said resistance element and capacitance element to said comparison circuit, discriminating this voltage with a first threshold value and a second threshold value and then sending the signal to said control circuit.

10. A switching power supply device comprising an inductor, a switching element for controlling the current flowing into said inductor, a control circuit for controlling said switching element, a comparator for outputting a signal depending on the level by comparing an input potential to a first input terminal with an input potential to a second input terminal, a reference voltage generating circuit for generating the reference voltage inputted to one input terminal of said comparator, and a frequency difference detecting circuit for detecting frequency difference between the control signal of said switching element or potential of the connection node of said switching element and said inductor and the reference clock signal,

whereby the current flowing into said inductor is changed depending on variation of load by inputting voltage depending on the output voltage to said comparison circuit, discriminating the voltage with a first threshold value and a second threshold value and then sending the signal to said control circuit, and

wherein said reference voltage generating circuit compensates for the reference voltage generated depending on the detected frequency difference with said frequency difference detecting circuit to attain the matching of the switching frequency of said switching element with the frequency of said reference clock signal.

11. A switching power supply device according to claim 10, wherein said control circuit varies the current flowing into said inductor by changing a ratio of the ON period to OFF period of said switching element.

12. A switching power supply device according to claim 10 or 11, comprising a monitoring circuit for detecting the output current changing period, wherein said reference voltage generating circuit does not compensate for said reference voltage during the output current changing period.

13. A portable electronic device comprising said switching power supply device according to any one of claims 10 to 12 for generating voltage of the predetermined DC level using a battery as the power supply and a semiconductor integrated circuit for control operated with the current outputted from said switching power supply device, whereby the operation clock signal of said semiconductor integrated circuit for control is supplied, as said reference clock signal, to said switching power supply device.

14. A power supply device for generating the predetermined voltage through control of the current flowing into a diode via an inductor, comprising a circuit including a serially connected resistance element and a first capacitance element, whereby said circuit is connected in parallel to said diode and the current flowing into said diode is changed depending on variation of load by detecting voltage of the first connection node between said resistance element and said first capacitance element and then controlling the operation based on said detected voltage.

15. A power supply device according to claim 14, wherein a second capacitance element is provided between said first connection node and said resistance element.

16. A power supply device according to claim 14 for generating the predetermined voltage through switching control of the current flowing into said diode, wherein said power supply device is a switching power supply device comprising

a switching element for controlling the current flowing into said diode and a comparison circuit having the hysteresis characteristic,

whereby said switching element is controlled by inputting voltage of said second connection node to said comparison circuit, discriminating the voltage with a first threshold value and a second threshold value, and then sending the signal to said switching element.

17. A power supply device for generating the predetermined voltage by controlling the current flowing into an inductor, comprising

a circuit including a serially connected resistance element and a first capacitance element, whereby the current flowing into said inductor is changed depending on variation of load by connecting said circuit in parallel to said inductor, providing a second capacitance element between the first connection node between said resistance element and said first capacitance element and said resistance element, detecting voltage of second connection node between said first capacitance element and said second capacitance element, and then controlling the operation based on said detected voltage.

18. A power supply device according to claim 17 as the switching power supply device for generating the predetermined voltage by controlling the current flowing into said inductor, comprising

a switching element for controlling the current flowing into said inductor and a comparison circuit having the hysteresis characteristic,

whereby said switching element is controlled by inputting voltage of said second connection node to said comparison circuit, discriminating the voltage with a first threshold value and a second threshold value, and then sending the signal to said switching element.

19. A power supply device for generating the predetermined voltage by controlling the current flowing into a switch via an inductor, comprising

a circuit including a serially connected resistance element and a first capacitance element, whereby the current flowing into said switch is changed depending on variation of load by connecting said circuit in parallel to said switch, detecting voltage of the first connection node between said resistance element and said first capacitance element, and then controlling the operation based on said detected voltage.

20. A power supply device according to claim 19, wherein a second capacitance element is provided between said first connection node and said resistance element.

21. A power supply device according to claim 19 as a switching power supply device for generating the predetermined voltage through switching control of the current flowing into said switch, comprising

a comparison circuit having the hysteresis characteristic,

whereby said switch is controlled by inputting voltage of said second connection node to said comparison circuit, discriminating this voltage with a first threshold value and a second threshold value, and then sending the signal to said switch.

22. A power supply device for generating the predetermined voltage by controlling the current flowing into a transformer, comprising

a circuit including a serially connected resistance element and a first capacitance element, whereby the current flowing into said transformer is changed depending on variation of load by connecting said circuit in parallel to said transformer, detecting voltage of the first connection node between said resistance element and said first capacitance element, then controlling the operation based on said detected voltage.

23. A power supply device according to claim 22, wherein a second capacitance element is provided between said first connection node and said resistance element.

24. A power supply device according to claim 22 as a switching power supply device for generating the predetermined voltage through switching control of the current flowing into said transformer, comprising

a switching element for controlling the current flowing into said transformer and a comparison circuit having the hysteresis characteristic,

whereby said switching element is controlled by inputting voltage of said second connection node to said comparison circuit, discriminating the voltage with a first threshold value and a second threshold value, and then sending the signal to said switching element.