SWITCHING POWER SUPPLY UNIT

• US 20110133708A1
• Filed: 12/07/2010
• Published: 06/09/2011
• Est. Priority Date: 12/08/2009
• Status: Active Grant

• Current Assignee: RICOH Electronic Devices Co., Ltd. (Nisshinbo Holdings Incorporated)
• Original Assignee: Ricoh Company Limited
• Inventors: SHIWAYA, Yohichi
• Granted Patent: US 8,669,749 B2
• Time in Patent Office: Days
• US Class Current: 323/271
• CPC Class Codes: H02M 3/1584 with a plurality of power processing stages connected in parallel

Abstract

A switching power supply unit of a non-insulated, synchronous rectification type converts a voltage input to an input terminal into a predetermined voltage and outputs the voltage. The unit includes an inductor, a plurality of output switching elements, a plurality of rectifying switching elements, a switching element control circuit, a switching regulator integrated circuit, and a plurality of buffer circuits. The output switching elements, the rectifying switching elements, the switching element control circuit and the buffer circuits are integrated on the switching regulator integrated circuit.

Claims

1. A switching power supply unit of a non-insulated, synchronous rectification type which converts a voltage input to an input terminal into a predetermined voltage and outputs the voltage, comprising:

an inductor;

a plurality of output switching elements which perform switching in accordance with an on/off control signal input to a control electrode and charge the inductor with the input voltage;

a plurality of rectifying switching elements associated with the output switching elements and discharging the inductor when the associated output switching elements are turned off to stop charging the inductor;

a switching element control circuit which generates and outputs a switching control signal which allows the output switching elements to perform switching and the rectifying switching elements to perform reverse switching to the switching of the output switching elements so that the output voltage turns to the predetermined voltage;

a switching regulator integrated circuit including a select control terminal to which a select signal is input from an exterior; and

a plurality of buffer circuits associated with the output switching elements and the rectifying switching elements and each controlling, in response to the select signal, an associated pair of the output switching element and the rectifying switching element to operate in accordance with the switching control signal from the switching element control circuit, wherein

the output switching elements, the rectifying switching elements, the switching element control circuit and the buffer circuits are integrated on the switching regulator integrated circuit.

2. A switching power supply unit according to claim 1, wherein:

the output switching elements have different current supply capacities from each other; and

the rectifying switching elements have current supply capacities in accordance with those of the associated output switching elements, respectively.

3. A switching power supply unit according to claim 2, wherein

the buffer circuits drive the associated output switching elements and rectifying switching elements to turn on and off in an optimal length of time according to the respective current supply capacities.

4. A switching power supply unit according to claim 1, wherein:

the switching element control circuit comprises a reverse current preventive circuit which detects, from the output voltage, a reverse current flowing to the rectifying switching elements, and upon detecting the reverse current, generates and outputs a predetermined reverse current detection signal which places the rectifying switching elements into a break state; and

each of the buffer circuits places an associated one of the rectifying switching elements into a break state irrespective of the input switching control signal when receiving the predetermined reverse current detection signal from the reverse current preventive circuit.

5. A switching power supply unit according to claim 1, wherein

the switching power supply unit is of a buck type which steps down a voltage input to the input terminal to a predetermined voltage for output.

6. A switching power supply unit according to claim 1, wherein

the switching power supply unit is of a boost type which steps up a voltage input to the input terminal to a predetermined voltage for output.

7. A switching power supply unit of a non-insulated, non-synchronous rectification type which converts a voltage input to an input terminal into a predetermined voltage and outputs the voltage, comprising:

an inductor;

a plurality of output switching elements which perform switching in accordance with an on/off control signal input to a control electrode and charge the inductor with the input voltage;

a rectifying element which discharges the inductor when the output switching elements are turned off to stop charging the inductor;

a switching element control circuit which generates and outputs a switching control signal which allows the output switching elements to perform switching so that the output voltage turns to the predetermined voltage; and

a switching regulator integrated circuit including a select control terminal to which a select signal is input from exterior; and

a plurality of buffer circuits associated with the output switching elements and each controlling, in response to the select signal, the associated output switching element to operate in accordance with the switching control signal from the switching element control circuit, wherein

the output switching elements, the switching element control circuit and the buffer circuits are integrated on the switching regulator integrated circuit.

8. A switching power supply unit according to claim 7, wherein

the output switching elements have different current supply capacities from each other.

9. A switching power supply unit according to claim 8, wherein

the buffer circuits drive the associated output switching elements to turn on and off in an optimal length of time according to the respective current supply capacities.

10. A switching power supply unit according to claim 7, wherein

the switching power supply unit is of a buck type to step down a voltage input to the input terminal to a predetermined voltage for output.

11. A switching power supply unit according to claim 7, wherein

the switching power supply unit is of a boost type to step up a voltage input to the input terminal to a predetermined voltage for output.