Power supply control method, current-to-voltage conversion circuit and electronic apparatus

• US 20040105285A1
• Filed: 11/19/2003
• Published: 06/03/2004
• Est. Priority Date: 11/29/2002
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Ozawa, Hidekiyo, Tanaka, Shigeo
• Granted Patent: US 7,489,528 B2
• Time in Patent Office: Days
• US Class Current: 363/73
• CPC Class Codes: H02M 1/36 Means for starting or stopping converters
• 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: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop
• 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 power supply control method is adapted to a current-to-voltage conversion circuit which has a transformer for converting and outputting an input power. The power supply control method stops a power supply to the transformer when an output side of the current-to-voltage conversion circuit is in a no-load state, and starts a power supply to the transformer when an external voltage is applied to the output side of the current-to-voltage conversion circuit.

Claims

1. A power supply control method adapted to a current-to-voltage conversion circuit which has a transformer for converting and outputting an input power, comprising:

stopping a power supply to the transformer when an output side of the current-to-voltage conversion circuit is in a no-load state; and

starting a power supply to the transformer when an external voltage is applied to the output side of the current-to-voltage conversion circuit.

2. The power supply control method as claimed in claim 1, wherein the external voltage is applied to the output side of the current-to-voltage conversion circuit in a deactivated state, by controlling ON and OFF states of a switching circuit within an electronic apparatus to which the current-to-voltage conversion circuit is coupled.

3. A current-to-voltage conversion circuit having an active state and a deactivated state, comprising:

an input section to input an input power;

a transformer to convert the input power into an output power;

an output section to output the output power;

a first circuit to stop a power supply to the transformer and put the current-to-voltage conversion circuit into a deactivated state when the output section is in a no-load state; and

a second circuit to start a power supply to the transformer and put the current-to-voltage conversion circuit into an active state when an external voltage is applied to the output section.

4. The current-to-voltage conversion circuit as claimed in claim 3, wherein said first circuit includes a first comparator to compare an output current on a secondary side of the transformer and a threshold current.

5. The current-to-voltage conversion circuit as claimed in claim 4, further comprising:

a drive control circuit to drive the transformer; and

a first coupler circuit including a photo-coupler to couple an output of the first comparator and an input of the drive control circuit.

6. The current-to-voltage conversion circuit as claimed in claim 3, wherein said second circuit includes a second comparator to compare an output voltage on a secondary side of the transformer and a threshold voltage.

7. The current-to-voltage conversion circuit as claimed in claim 4, wherein said second circuit includes a second comparator to compare an output voltage on a secondary side of the transformer and a threshold voltage.

8. The current-to-voltage conversion circuit as claimed in claim 5, wherein said second circuit includes a second comparator to compare an output voltage on a secondary side of the transformer and a threshold voltage.

9. The current-to-voltage conversion circuit as claimed in claim 6, further comprising:

a drive control circuit to drive the transformer; and

a second coupler circuit including a photo-coupler to couple an output of the second comparator and an input of the drive control circuit.

10. The current-to-voltage conversion circuit as claimed in claim 7, further comprising:

a drive control circuit to drive the transformer; and

a second coupler circuit including a photo-coupler to couple an output of the second comparator and an input of the drive control circuit.

11. The current-to-voltage conversion circuit as claimed in claim 8, further comprising:

a second coupler circuit including a photo-coupler to couple an output of the second comparator and the input of the drive control circuit.

12. An electronic apparatus connectable to a current-to-voltage conversion circuit having an output side,

said current-to-voltage conversion circuit assuming a deactivated state when the output side is in a no-load state and assuming an active state when an external voltage is applied to the output side,

said electronic apparatus comprising:

a switching circuit to apply the external voltage to the output side of the current-to-voltage conversion circuit in the deactivated state.

13. An electronic apparatus comprising:

a current-to-voltage conversion circuit comprising an input section to receive an input power, a transformer to convert the input power into an output power, an output section to output the output power, a first circuit to stop a power supply to the transformer and put the current-to-voltage conversion circuit into a deactivated state when the output section is in a no-load state, and a second circuit to start a power supply to the transformer and put the current-to-voltage conversion circuit into an active state when an external voltage is applied to the output section; and

a control section to apply the external voltage to the output section of the current-to-voltage conversion circuit in the deactivated state.

14. A power supply control method adapted to a current-to-voltage conversion circuit which has a transformer for converting and outputting an input power, comprising:

detecting a no-load state of an output side of the current-to-voltage conversion circuit; and

stopping a power supply to the transformer when the output side of the current-to-voltage conversion circuit is in the no-load state.

15. A current-to-voltage conversion circuit having an active state and a deactivated state, comprising:

an input section to input an input power;

a transformer to convert the input power into an output power;

an output section to output the output power;

a detecting section to detect a no-load state of the output section; and

a circuit to stop a power supply to the transformer and put the current-to-voltage conversion circuit into a deactivated state when the output section is in the no-load state.