POWER SUPPLY APPARATUS

• US 20120294046A1
• Filed: 05/18/2012
• Published: 11/22/2012
• Est. Priority Date: 05/19/2011
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: NATE, Satoru, HAYASHI, Hiroshi
• Granted Patent: US 8,942,016 B2
• Time in Patent Office: Days
• US Class Current: 363/21.01
• CPC Class Codes: H02J 9/005 using a power saving mode for copiers G03G15/5004
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/42 Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 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
• CPC Class Codes: Y02B 70/30 Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
• CPC Class Codes: Y04S 20/20 End-user application control systems

Abstract

A second control circuit is configured to switch a pulse signal to a level which turns off a second switching transistor when a coil current that flows through a primary winding reaches a predetermined threshold current. The second control circuit is configured to start a switching operation when a power supply for an electronic device is turned on, to set the threshold current to a first value when an intermediate voltage is higher than a predetermined level, and to set the threshold current to a second value that is lower than the first value when the intermediate voltage is lower than a predetermined level. A first control circuit is configured to start a switching operation upon receiving an instruction from a microcontroller to start operating.

Claims

1. A power supply apparatus comprising:

a rectifier circuit configured to full-wave rectify AC voltage;

a power factor correction circuit including a non-insulation type DC/DC converter configured to receive an output voltage of the rectifier circuit, and to generate a DC intermediate voltage, and configured to operate such that the phase of the input current matches the phase of the AC voltage thus rectified;

an insulation type DC/DC converter configured to receive the intermediate voltage, and to convert the level of the intermediate voltage thus received; and

a microcontroller configured to operate receiving the output voltage of the insulation type DC/DC converter,

wherein the power factor correction circuit comprises;

an inductor arranged such that the output voltage of the rectifier circuit is applied to its first terminal;

a first switching transistor arranged between a second terminal of the inductor and a ground terminal; and

a first control circuit configured to generate a first pulse signal having a duty ratio such that the intermediate voltage matches its target voltage, and to drive the first switching transistor according to the first pulse signal,

and wherein the insulation type DC/DC converter comprises;

a transformer;

a second switching transistor arranged between a primary winding of the transformer and the ground terminal; and

a second control circuit configured to generate a second pulse signal having a duty ratio such that the output voltage of the insulation type DC/DC converter matches its target voltage, to drive the second switching transistor according to the second pulse signal, and to switch the pulse signal to a level which turns off the second switching transistor when a coil current that flows through the primary winding reaches a predetermined threshold current,

and wherein the second control circuit is configured to start a switching operation when a power supply for an electronic device is turned on, to set the threshold current to a first value when the intermediate voltage is higher than a predetermined level, and to set the threshold current to a second value that is lower than the first value when the intermediate voltage is lower than a predetermined level,

and wherein the first control circuit is configured to start a switching operation upon receiving an instruction from the microcontroller to start operating.

2. A power supply apparatus according to claim 1, wherein the first control circuit and the second control circuit are monolithically integrated on a single semiconductor substrate.

3. A power supply apparatus according to claim 1, wherein the first control circuit and the second control circuit are respectively integrated on separate respective semiconductor substrates,

and wherein the first control circuit is configured to detect whether or not the intermediate voltage reaches a predetermined level, and to be capable of notifying the second control circuit of the detection result.

4. An electronic device comprising a power supply apparatus according to claim 1.

5. A power supply apparatus comprising:

a rectifier circuit configured to full-wave rectify AC voltage;

a power factor correction circuit including a non-insulation type DC/DC converter configured to receive an output voltage of the rectifier circuit, and to generate a DC intermediate voltage, and configured to operate such that the phase of the input current matches the phase of the AC voltage thus rectified;

an insulation type DC/DC converter configured to receive the intermediate voltage, and to convert the level of the intermediate voltage thus received; and

a microcontroller configured to operate receiving the output voltage of the insulation type DC/DC converter,

wherein the power factor correction circuit comprises;

an inductor arranged such that the output voltage of the rectifier circuit is applied to its first terminal;

a first switching transistor arranged between a second terminal of the inductor and a ground terminal; and

a first control circuit configured to generate a first pulse signal having a duty ratio such that the intermediate voltage matches its target voltage, and to drive the first switching transistor according to the first pulse signal,

and wherein the insulation type DC/DC converter comprises;

a transformer;

a second switching transistor arranged between a primary winding of the transformer and the ground terminal; and

a second control circuit configured to generate a second pulse signal having a duty ratio such that the output voltage of the insulation type DC/DC converter matches its target voltage, to drive the second switching transistor according to the second pulse signal, and to switch the pulse signal to a level which turns off the second switching transistor when a coil current that flows through the primary winding reaches a predetermined threshold current,

and wherein the second control circuit is configured to start a switching operation when a power supply for an electronic device is turned on, to set the threshold current to a first value after a predetermined period of time elapses after the power supply is turned on, and to set the threshold current to a second value that is lower than the first value until the predetermined period of time elapses,

and wherein the first control circuit is configured to start a switching operation upon receiving an instruction from the microcontroller to start operating.

6. A power supply apparatus according to claim 5, wherein the first control circuit and the second control circuit are monolithically integrated on a single semiconductor substrate.

7. An electronic device comprising a power supply apparatus according to claim 5.