Switching regulator

• US 7,564,228 B2
• Filed: 09/07/2007
• Issued: 07/21/2009
• Est. Priority Date: 09/15/2006
• Status: Expired due to Fees

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Inventors: Yabuzaki, Jun
• Primary Examiner(s): Laxton; Gary L
• Application Number:
  US11/898,044
• Publication Number:
  US 20080067988A1
• Time in Patent Office: 683 Days
• Field of Search: 323/224, 323/247, 323/255, 323/258, 323/282, 323/284, 323/328, 323/240, 323/343
• US Class Current: 323/258
• CPC Class Codes: H02M 1/0025 Arrangements for modifying reference values, feedback values or error values in the control loop of a converter
• CPC Class Codes: H02M 1/0048 Circuits or arrangements for reducing losses using snubbers H02M1/34
• CPC Class Codes: H02M 3/1566 with means for compensating against rapid load changes, e.g. with auxiliary current source, with dual mode control or with inductance variation
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• 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

In a switching regulator, an inductor L1 (in FIG. 1) and an output capacitor C1 are connected on the output side of a series circuit consisting of a switching element (MOS transistor P1) and a synchronous rectification element (MOS transistor N1), and an N-channel MOS transistor Q1 is connected between an intermediate point of the inductor L1 and one terminal thereof. In addition, the frequency of oscillator 2 and the turning ON/OFF of MOS transistor Q1 are controlled by control unit 1. When output voltage Vout is to be altered, the switching frequency of MOS transistors P1 and N1 is increased, and the inductance of inductor L1 is reduced, whereby a fast output change is permitted. On the other hand, during ordinary constant output voltage operation, the switching frequency is reduced, and the inductance value is increased, whereby high efficiency is attained.

Claims

1. A switching regulator wherein an inputted DC current is turned ON/OFF so as to control an output voltage, comprising:

a first switching element that turns the inputted DC current ON/OFF;

a driver that drives said the first switching element with a pulse width modulation signal; and

an inductor of variable inductance value, which is connected on an output side of said first switching element;

wherein, when the output voltage is to be altered, both a switching frequency of said first switching element and the variable inductance value of said inductor are changed.

2. The switching regulator according to claim 1, further comprising a second switching element which is connected between an intermediate point of said inductor and a terminal point of said inductor;

wherein the variable inductance value of said inductor is changed by turning said second switching element ON or OFF.

3. The switching regulator according to claim 1, wherein:

said inductor includes first and second inductance elements connected in series with each other; and

said switching regulator further comprises a second switching element connected between a node joining said first and second inductance elements and a terminal point of one of said first and said second inductance elements remote from the node;

wherein the inductance value of said inductor is changed by turning said second switching element ON or OFF.

4. The switching regulator according to claim 1, wherein:

said inductor includes first and second inductance elements connected in parallel with each other; and

said switching regulator further comprises a second switching element connected in series with one of said first and said second inductance elements;

wherein the variable inductance value of said inductor is changed by turning said second switching element ON or OFF.

5. The switching regulator according to claim 1, wherein:

said inductor includes first and second inductance elements connected in series with each other; and

said switching regulator further comprises a second switching element, a first terminal of said second switching element connected to a terminal point of said first switching element that is not connected to said inductor, and a second terminal of said second switching element connected to a node between said first and second inductance elements;

wherein the variable inductance value of said inductor is changed by controlling ON and OFF operations of said first and second switching elements through said driver.

6. The switching regulator according to claim 1, wherein said switching regulator is a DC/DC converter.

7. The switching regulator according to claim 6, wherein said switching regulator is a step-down converter.