DC-DC converter and power supply apparatus

• US 20080013345A1
• Filed: 03/27/2007
• Published: 01/17/2008
• Est. Priority Date: 07/14/2006
• Status: Active Grant

• Current Assignee: Mitsumi Electric Co., Ltd. (MinebeaMitsumi Inc.)
• Original Assignee: Mitsumi Electric Co., Ltd. (MinebeaMitsumi Inc.)
• Inventors: Terada, Yukihiro, Takeshita, Junji
• Granted Patent: US 7,782,028 B2
• Time in Patent Office: Days
• US Class Current: 363/21.01
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02M 1/0093 wherein the output is created by adding a regulated voltage to or subtracting it from an unregulated input
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators

Abstract

Disclosed is a DC-DC converter including: an inductance element and a rectifier element connected in series between a voltage input terminal to accept input direct current voltage and a first output terminal; a switching element connected between a connection node of the inductance element and the rectifier element and a reference potential point; and a controlling circuit to form a signal to control on/off of the switching element, wherein the controlling circuit controls on/off of the switching element to control current through the inductance element and a voltage applied to the voltage input terminal to accept the input direct current voltage is output to a second output terminal as a reference potential of a circuit at a latter stage, so that an output voltage is controllable from a lower to higher voltage than the input direct current voltage without switching step-up and step-down operations.

Claims

1. A DC-DC converter comprising:

an inductance element and a rectifier element connected in series between a voltage input terminal to accept input direct current voltage and a first output terminal;

a switching element connected between a connection node of the inductance element and the rectifier element and a reference potential point; and

a controlling circuit to form a signal to control on/off of the switching element,

wherein the controlling circuit controls on/off of the switching element to control current through the inductance element and a voltage applied to the voltage input terminal to accept the input direct current voltage is output to a second output terminal as a reference potential of a circuit at a latter stage, so that an output voltage is controllable from a lower to higher voltage than the input direct current voltage without switching step-up and step-down operations.

10. A power supply comprising:

the DC-DC converter of claim 1; and

a battery housing to which a battery is to be loaded, the battery supplying the input direct voltage to be applied to the voltage input terminal.

2. A DC-DC converter comprising:

a reference voltage input terminal to accept a reference potential;

a voltage input terminal to accept an input direct current voltage;

a step-up circuit to step-up the input direct current voltage;

a first output terminal to output a voltage stepped-up by the step-up circuit;

a second output terminal to output the voltage input from the voltage input terminal to a circuit at a latter stage as a reference potential of the circuit at the latter stage;

a smoothing capacitor connected between the first output terminal and the second output terminal,

wherein the DC-DC converter outputs the voltage stepped-up by the step-up circuit from the first output terminal where an output voltage of the second output terminal is a reference, and

wherein the step-up circuit comprises;

an inductance element and a rectifier element connected in series between the voltage input terminal and the first output terminal;

a switching element connected between a connection node of the inductance element and the rectifier element and the reference voltage input terminal;

a controlling circuit to form a signal to control on/off of the switching element; and

a current detection circuit to detect a level of an output current flowing through the first output terminal, and

the controlling circuit turns off the switching element when the output current exceeds a predetermined level.

3. The DC-DC converter according to claim 2, further comprising a resistance element connected between the rectifier element and the first output terminal, wherein the current detection circuit detects the output current based on a voltage across the resistance element.

4. The DC-DC converter according to claim 2, further comprising a resistance element connected between the switching element and the reference voltage input terminal, wherein the current detection circuit detects the output current based on a voltage across the resistance element.

5. The DC-DC converter according to claim 2, further comprising a resistance division circuit including two or more resistance elements connected in series between the switching element and the reference voltage input terminal, wherein the controlling circuit controls the switching element based on the current detected by the current detection circuit and a voltage divided by the resistance division circuit.

6. The DC-DC converter according to claim 5, wherein a switching transistor is connected between the resistance elements constituting the resistance division circuit, and the switching transistor turns off when a voltage output from the first output terminal is a predetermined level or less.

7. The DC-DC converter according to claim 6, wherein the switching transistor is a PNP bipolar transistor which accepts the voltage input to the voltage input terminal at a base terminal thereof.

8. The DC-DC converter according to claim 2, wherein the rectifier element is a diode connected in a forward direction toward the first output terminal.

9. The DC-DC converter according to claim 2, wherein the rectifier circuit is a transistor which is controlled to perform synchronous rectification.

11. A power supply comprising:

the DC-DC converter of claim 2; and

a battery housing to which a battery is to be loaded, the battery supplying the input direct voltage to be applied to the voltage input terminal.