This application claims the benefit of Taiwan application Serial No. 95123724, filed Jun. 30, 2006, the subject matter of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a power supply apparatus and a method for providing a voltage, and more particularly relates to a power supply apparatus, which can automatically adjust the output voltage, and the method thereof.
2. Description of the Prior Art
A power supply usually provides only a fixed output voltage. When a couple of different voltages are required, a user should prepare either several different power supplies, each of which provides a specific fixed output voltage, or a power supply that provides a limited number of different output voltages selectable by user switching. However, this kind of power supply should be switched manually to a desired voltage corresponding to different output objectives, and therefore it is inconvenient to use such power supplies. In addition, a stock of too many power supplies is uneconomic and hard to manage.
It is therefore an object of the present invention to provide a power supply apparatus and method for automatically adjusting the output voltage.
The present invention discloses a power supply apparatus having an output terminal coupled to a load, wherein the power supply apparatus outputs an output voltage through the output terminal. The power supply apparatus includes a current modulation unit, a voltage converting unit, a current detector and a control unit. The current modulation unit is used for receiving an input voltage and a control signal, and generating an output current. The current modulation unit adjusts the amount of the output current according to the control signal. The voltage converting unit, which is coupled to the current modulation unit, converts the output current into the output voltage. The current detector, which is coupled between the voltage converting unit and the output terminal, detects the current flowing through the load and outputs a current detection result. The control unit, which is coupled to the current modulation unit, the current detector and the output terminal, receives the current detection result and the output voltage, and generates the control signal according to the current detection result and the output voltage.
The present invention also discloses a method for providing an output voltage to a load. The method includes: providing a current; converting the current into the output voltage; detecting the current flowing through the load and generating a current detection result; and generating a control signal according to the current detection result and the output voltage, and controlling the amount of the current according to the control signal.
The present invention discloses a power supply apparatus having an output terminal coupled to a load, wherein the power supply apparatus outputs an output voltage through the output terminal. The power supply apparatus includes a current modulation unit, a voltage converting unit, a current detector, a determination circuit, a digital control unit, and a digital to analog converter. The current modulation unit receives an input voltage and a control signal, generates an output current, and adjusts the amount of the output current according to the control signal. The voltage converting unit, which is coupled to the current modulation unit, converts the output current into the output voltage. The current detector, which is coupled between the voltage converting unit and the output terminal, detects the current flowing through the load and outputting a current detection result. The determination circuit, which is coupled to the current detector and the output terminal, determines the output voltage and the current detection result and outputs a starting signal and a holding signal. The digital control unit, which is coupled to the determination circuit, generates a digital signal according to the starting signal and the holding signal. The digital to analog converter, which is coupled to the digital control unit and the current modulation unit, converts the digital signal into the control signal.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
Certain terms are used throughout the description and following claims to refer to particular components. As one skilled in the art will appreciate, electronic equipment manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms “include” and “comprise” are used in an open-ended fashion, and thus should be interpreted to mean “include, but not limited to . . . ”. Also, the term “couple” is intended to mean either an indirect or direct electrical connection. Accordingly, if one device is coupled to another device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections.
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The current detector 130 has another function. The power supply apparatus 100 initially outputs a small voltage before any load is connected. Meanwhile, the current detector 130 detects the variation of the load current, and the control unit 140 compares the detection result Vs with a threshold value. When a load is connected to the power supply apparatus 100, there will be a change in the detection result Vs. Therefore, when the detection result Vs becomes larger than the threshold value, the control unit 140 resets the value of the digital signal and regenerates the digital signal. In brief, the power supply apparatus 100 staffs to gradually increase the output voltage Vout provided to the load after the load is connected to the power supply apparatus 100. The increasing rate of the output voltage Vout can be determined according to the frequency of the clock signal of the control unit 140. The current detector 130 detects the load current flowing through the load when the output voltage Vout increases. The power supply apparatus 100 stops increasing the output voltage Vout and utilizes the present output voltage Vout as the output voltage when the load current stops increasing. Thereby the load can operate in a stable state. Please refer to
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The present invention provides a power supply apparatus and a method for automatically providing a suitable voltage to a load. The apparatus and method can automatically generate a suitable voltage corresponding to the load, and thereby only a single power supply apparatus is required for various kinds of loadings. There will be no need to manually switch the value of the output voltage; therefore, the problems in the prior art can be solved.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
Number | Date | Country | Kind |
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95123724 A | Jun 2006 | TW | national |
Number | Name | Date | Kind |
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5420778 | Yoshino | May 1995 | A |
5982644 | Hulsey et al. | Nov 1999 | A |
7282895 | Thiele et al. | Oct 2007 | B2 |
7450407 | Wu et al. | Nov 2008 | B2 |
Number | Date | Country | |
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20080001584 A1 | Jan 2008 | US |