Electronic component for power supply and a power supply device

• US 7,166,992 B2
• Filed: 01/25/2006
• Issued: 01/23/2007
• Est. Priority Date: 01/26/2005
• Status: Active Grant

• Current Assignee: Renesas Electronics Corporation
• Original Assignee: Renesas Technology Corporation (Renesas Electronics Corporation)
• Inventors: Kudo, Ryotaro, Hosokawa, Kyoichi, Tateno, Koji
• Primary Examiner(s): BERHANE, ADOLF D
• Application Number:
  US11/338,711
• Publication Number:
  US 20060164057A1
• Time in Patent Office: 363 Days
• Field of Search: 323/282, 323/283, 323/284, 323/285, 323/351
• US Class Current: 323/282
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 3/1588 comprising at least one synchronous rectifier element H02M3/1582, H02M3/1584 take 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

This invention provides a semiconductor integrated circuit for drive and a module for building a synchronous rectifier type switching regulator that is able to correctly detect and prevent a reverse current flowing through a coil (inductance element) during light load using a comparator and has a good power efficiency. In a synchronous rectifier type switching regulator including a reverse current detection circuit that is able to detect a state in which a reverse current flows through the inductance element (coil) and a reverse current prevention function, a switching element for synchronous rectification is formed by a plurality of parallel transistors and the transistors are controlled so that a part of them are not driven during light load.

Claims

1. A power supply control device which performs complementary on/off control of a first switching element and a second switching element which are coupled in series between an voltage input terminal and a reference potential terminal, allows current to flow through an inductance element coupled to a node coupling said first and second switching elements, thereby converting a voltage being applied to said voltage input terminal into a voltage which is output, includes a reverse current detection circuit to detect a reverse current state of said second switching element, and has a reverse current prevention function which prevents said second switching element from being turned on for a period during which said second switching element is to be turned on when the reverse current detection circuit detects the reverse current state,

wherein said second switching element comprises a plurality of transistors coupled in parallel and the plurality of transistors are controlled so that more transistors will be kept off during a lighter load.

2. The power supply control device according to claim 1, wherein said second switching element comprises two transistors and a larger one of said two transistors is kept off during light load.

3. The power supply control device according to claim 1, wherein said reverse current detection circuit includes a comparator which compares a potential at the node coupling said first switching element and said second switching element to a given potential and detects a reverse current state.

4. An electronic component for power supply, the electronic component comprising:

a first switching element and a second switching element which are coupled in series between an voltage input terminal and a reference potential terminal; and

a semiconductor integrated circuit for drive, the semiconductor integrated circuit performing complementary on/off control of the switching elements, the first and second switching elements and the semiconductor integrated circuit being mounted in a single package, the electronic component allowing current to flow through an inductance element coupled to a node coupling said first and second switching elements, thereby converting a voltage being applied to said voltage input terminal into a voltage which is output,

wherein said second switching element comprises two transistors coupled in parallel,

wherein said semiconductor integrated circuit includes a reverse current detection circuit to detect a reverse current state of said second switching element, has a reverse current prevention function which prevents said second switching element from being turned on for a period during which said second switching element is to be turned on, when the reverse current detection circuit detects the reverse current state, and causes one of said two transistors coupled in parallel to be kept off during light load.

5. The electronic component for power supply according to claim 4, wherein said reverse current detection circuit includes a comparator which compares a potential at the node connecting said first switching element and said second switching element to a given potential and detects a reverse current state.

6. The electronic component for power supply according to claim 4, wherein said semiconductor integrated circuit is equipped with a terminal for receiving a control signal indicating whether a load supplied from external is light or heavy, and causes either of said two transistors to be kept off when said control signal indicates a state equivalent to the light load state.

7. A power supply device comprising:

the electronic component for power supply as recited in claim 4;

an integrated circuit for control, the integrated circuit generating PWM control pulses with a duty adjusted according to an output voltage and supplying the PWM control pulses to said semiconductor integrated circuit;

an inductance element coupled to an output terminal of said electronic component for power supply; and

a smoothing capacitor coupled to the other terminal of the inductance element.

8. A power supply device comprising:

the electronic component for power supply as recited in claim 6;

an integrated circuit for control, the integrated circuit generating PWM control pulses with a duty adjusted according to an output voltage and supplying the PWM control pulses to said semiconductor integrated circuit;

an inductance element coupled to an output terminal of said electronic component for power supply; and

a smoothing capacitor coupled to the other terminal of the inductance element,

wherein said control signal is supplied from said integrated circuit for control to said semiconductor integrated circuit.

9. The power supply device according to claim 8, wherein a plurality of said electronic components for power supply are coupled to said integrated circuit for control and the PWM control pulses with different phases from each other are supplied from said integrated circuit for control to said plurality of electronic components for power supply.

10. The power supply device according to claim 7, wherein an output voltage is lower than an input voltage.