SWITCHING POWER SUPPLY CIRCUIT CAPABLE OF TIMING ADJUSTMENT OF SIGNAL

• US 20090195071A1
• Filed: 01/23/2009
• Published: 08/06/2009
• Est. Priority Date: 01/31/2008
• Status: Active Grant

• Current Assignee: RICOH Electronic Devices Co., Ltd. (Nisshinbo Holdings Incorporated)
• Original Assignee: Ricoh Company Limited
• Inventors: Ishizaka, Yasuhiro, Sekido, Senta, FURUSE, Katsuhisa
• Granted Patent: US 7,923,860 B2
• Time in Patent Office: Days
• US Class Current: 307/31
• CPC Class Codes: H02M 1/008 Plural converter units for generating at two or more independent and non-parallel outputs, e.g. systems with plural point of load switching regulators
• CPC Class Codes: H02M 1/44 Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators

Abstract

A switching power supply circuit includes a plurality of switching regulators and a timing adjustment circuit. The plurality of switching regulators converts an input voltage input to an input terminal into a plurality of predetermined constant voltages, and outputs the plurality of predetermined constant voltages from a plurality of output terminals, respectively. The timing adjustment circuit adjusts phases of a plurality of pulse signals generated by the plurality of switching regulators so that the phases of the plurality of pulse signals are different from each other, and outputs the plurality of adjusted pulse signals to respective switch circuits of the plurality of switching regulators.

Claims

1. A switching power supply circuit, comprising:

a plurality of switching regulators configured to convert an input voltage input to an input terminal into a plurality of predetermined constant voltages and to output the plurality of predetermined constant voltages from a plurality of output terminals, respectively,

each of the plurality of switching regulators comprising;

a switch circuit configured to perform switching according to an input control signal;

a coil charged with the input voltage by the switching performed by the switch circuit; and

a control circuit configured to compare a voltage of a triangular wave signal with a voltage of a signal obtained by amplifying a difference voltage between a proportional voltage proportional to an output voltage to be output from the output terminal and a predetermined reference voltage,

the control circuit configured to output a pulse signal indicating a result of the comparison to control the switching performed by the switch circuit; and

a timing adjustment circuit configured to adjust phases of a plurality of pulse signals generated by the plurality of switching regulators so that the phases of the plurality of pulse signals are different from each other, and to output the plurality of adjusted pulse signals to the respective switch circuits of the plurality of switching regulators.

2. The switching power supply circuit according to claim 1,

wherein the timing adjustment circuit detects edges of the plurality of pulse signals for turning off and interrupting the switch circuits, adjusts timings of the edges of the plurality of pulse signals to be shifted from each other by at least a predetermined time period, and outputs the plurality of adjusted pulse signals to the respective switch circuits.

3. The switching power supply circuit according to claim 2,

wherein the timing adjustment circuit adjusts a timing of a first-input pulse signal among the plurality of pulse signals when the timing adjustment circuit detects the edges of the plurality of pulse signals.

4. The switching power supply circuit according to claim 3,

wherein the timing adjustment circuit corrects fluctuation of a duty cycle caused by the timing adjustment by adjusting a timing of an edge for turning on the switch circuit to be conductive.

5. The switching power supply circuit according to claim 2,

wherein the timing adjustment circuit changes the predetermined time period used for adjusting the timings of the edges of the plurality of pulse signals to be shifted from each other.

6. The switching power supply circuit according to claim 2,

wherein the timing adjustment circuit changes an amount of the timing adjustment.