Voltage conversion circuit

• US 8,351,228 B2
• Filed: 09/17/2008
• Issued: 01/08/2013
• Est. Priority Date: 09/27/2007
• Status: Expired due to Fees

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Izumi, Makoto
• Primary Examiner(s): Tran, Nguyen
• Application Number:
  US12/679,568
• Publication Number:
  US 20100207682A1
• Time in Patent Office: 1,574 Days
• Field of Search: 363/59, 363/60, 363/61, 363/62, 363/123, 363/125, 363/127, 363/132, 363/133, 307/109, 307/110
• US Class Current: 363/60
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps
• CPC Class Codes: H02M 3/072 adapted to generate an output voltage whose value is lower than the input voltage

Abstract

A voltage conversion circuit with reduced power consumption can be used for a power supply device (100). The power supply device (100) is composed of a power supply circuit (3) including an alternating power supply (1) and a rectifying circuit (2); a voltage conversion circuit (6) including a plurality of capacitors (4) and a switching circuit (5); and a load circuit (7). The voltage conversion circuit (6) is connected between the power supply circuit (3) and the load circuit (7). The alternating power supply (1) is connected to a switching circuit (5) of the voltage conversion circuit (6) without having the rectifying circuit (2) in between. An output voltage (potential fluctuation: a potential difference generated in the signal waveform of the power supply voltage) from the alternating power supply (1) prior to rectification is applied to the switching circuit (5). The alternating power supply (1) is also connected to the capacitors (4) through the rectifying circuit (2), and output power after rectification is applied to the capacitors. The voltage conversion circuit (6) supplies the load circuit (7) with the power supply voltage inputted from the power supply circuit (3) by increasing or reducing the voltage.

Claims

1. A voltage conversion circuit connected between a power supply circuit and a load circuit, the voltage conversion circuit comprising:

a plurality of capacitors;

a switching circuit which switches the plurality of capacitors between serial connection and parallel connection to the power supply circuit and the load circuit, with a voltage input to the voltage conversion circuit from the power supply circuit being increased or decreased in accordance with the connection state of the plurality of capacitors;

wherein the power supply circuit includes an AC power supply and a rectification circuit, which rectifies a voltage from the AC power supply;

the switching circuit is connected to the AC power supply bypassing the rectification circuit and performs switching in accordance with a potential variation in the AC power supply; and

a waveform shaping circuit which shapes a signal waveform of the potential variation into a rectangular signal waveform,

wherein the switching circuit is connected to the power supply circuit via the waveform shaping circuit.

2. The voltage conversion circuit according to claim 1, wherein the switching circuit includes a first circuit, which switches the plurality of capacitors to a serial connection state, and a second circuit, which switches the plurality of capacitors to a parallel connection state, the voltage conversion circuit further comprising:

a timing adjustment circuit which applies the potential difference to the first circuit and the second circuit at different timings;

wherein the first circuit and the second circuit are each connected to the waveform shaping circuit via the timing adjustment circuit.

3. The voltage conversion circuit according to claim 2, wherein the timing adjustment circuit includes a constant current circuit having a resistor and a transistor;

and

the first circuit and the second circuit are respectively connected to one end and another end of the constant current circuit.

4. A power supply device comprising:

a power supply circuit including an AC power supply and a rectification circuit, which rectifies an AC voltage of the AC power supply to generate a rectified voltage;

a voltage conversion circuit connected between the power supply circuit and a load circuit to increase or decrease a voltage supplied from the power supply circuit;

wherein the voltage conversion circuit includes a plurality of capacitors and a switching circuit, which switches the plurality of capacitors between serial connection and parallel connection to the power supply circuit and the load circuit; and

the switching circuit is connected to the AC power supply bypassing the rectification circuit and performs switching in accordance with a potential variation in the AC voltage of the AC power supply; and

a waveform shaping circuit which shapes a signal waveform of the potential variation into a rectangular signal waveform,

wherein the switching circuit is connected to the power supply circuit via the waveform shaping circuit.