Patent Abstract:
Intelligent power supply and control method thereof. A power supply for altering an output power by detecting a power requirement of an electronic device and the electronic device having a memory. The power supply comprises a converter, a control device and a switch. The converter is able to convert an input power into the output power applied to the electronic device. The control device is coupled to the converter reads power information concerning the power requirement from the electronic device and accordingly controlling the converter to adjust the output power. The switch coupled both the converter and the control device receives a control signal of the control device and switches an output port of the power supply to the converter to transfer the output power from the converter to the electronic device.

Full Description:
BACKGROUND 
   The invention relates to a power supply and a control method thereof, and more particularly to a power supply and a control method which can detect a power requirement of an electronic device and accordingly provide an output power thereto. 
   Currently, conventional power supplies provide a fixed output voltage or a manually-selectable output voltage according to output numbers of the power supplies. 
     FIG. 1  is a block diagram of a conventional power supply with a fixed output voltage. The power supply  1  coupled to an alternating current (AC) power source outputs direct current (DC) power to an electronic device  2  at a predetermined voltage by a transformer  11  and a rectifier  12 . 
     FIG. 2  is a block diagram of a conventional power supply with a plurality of selectable output voltages. The variable output power supply  3  is capable of providing different levels of output power to meet power requirements for various electronic devices. For example, a potential selector  32  can be manually switched to various voltage levels for the power requirements of the electronic device  20 , and thus the power supply outputs power at a selected potential to the electronic device  20 . 
   With manual determination or selection of output voltage, however, it is easy to erroneously execute and generate mismatched output voltage, potentially damaging the device. For example, a 5-volt output power from a power supply to an electronic device requiring power of 12 volts causes the electronic device to malfunction. Similarly, device damage, such as circuit burnout, occurs if 12 volts of power is provided to a 5-volt electronic device. 
   Thus, the invention is to prevent the mismatched output voltage arising from manual operation of the conventional power supply, thereby improving convenience and safety of utility. 
   SUMMARY 
   An aspect of the invention provides a power supply capable of detecting power requirements based on power information from an electronic device, and selecting an output power accordingly. A memory of the electronic device is used to store the information concerning the power requirements. 
   An embodiment of the power supply comprises a converter, a control device, and a switch. An output power generated from the power supply is transformed into an input power by means of the converter to be applied to an electronic device coupled to the power supply. The control device coupled to the converter accesses the power information concerning the power requirements of the electronic device, accordingly controls the converter to adjust the output power, and outputs a control signal after adjusting the output power. The switch is coupled to the converter and the control device to switch an output port of the power supply to the converter after receiving the control signal, thereby transferring the output power from the converter to the electronic device. 
   In the embodiment, the power supply is also capable of returning the output port of the power supply to its original state, for efficient processing of subsequent detections. Thus, the power supply further comprises a current detector to detect whether the output power is applied to the electronic device. The switch disconnects the converter from an output port of the power supply and couples the control device to the output port when the output power is not applied to the electronic device. 
   Another aspect of the invention also sets forth an electronic device to provide the power information to a power supply. The electronic device comprises a major circuit, an input port, a memory storing the power information, and a gate switch including a first gate device and a second gate device. The first gate device is coupled between the input port and the memory, and the second gate device is coupled between the input port and the major circuit. 
   When the voltage of the input port meets first requirements, the memory is coupled with the input port by means of the gate switch as the power information is read from the input port. When the voltage of the input port meets second requirements, the input port is coupled with the major circuit by means of the gate switch so that the power supply provides output power to the major circuit for normal operation. 
   Furthermore, another aspect of the invention provides a control method of the power supply. An electronic device is coupled to a power supply. An input power from an external power source is then converted into an output power. Power information from the electronic device is read. An adjusted output power is finally applied to the electronic device. 
   Thus, the power supply control method detects automatically the connected electronic device and outputs the appropriate adjusted power additionally, thus preventing problems arising from manual operation. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An embodiment of the invention will become more fully understood by referring to the following detailed description and accompanying drawings, wherein: 
       FIG. 1  is a block diagram of a conventional fixed output power supply; 
       FIG. 2  is a block diagram of a conventional power supply with selectable output voltage; 
       FIG. 3  is a schematic diagram of a power supply of the invention; 
       FIG. 4A  is a schematic diagram of an electronic device of the invention; 
       FIG. 4B  is a diagram of the electronic device of  FIG. 4A  of the invention; and 
       FIG. 5  shows a flowchart of the power supply control method of the invention. 
   

   DETAILED DESCRIPTION 
   An aspect of the invention provides a power supply capable of detecting power requirements based on information from an electronic device, and selecting a power output accordingly. 
     FIG. 3  is a schematic diagram of a power supply of an embodiment of the invention. The power supply  4  comprises a converter  40 , a control device  50 , a switch  60 , and a current detector  70 . When an input port and an output port of the power supply  4  are coupled to an alternative power current (AC) power source and a electronic device  8  having a memory  80 , respectively, and a common node COM and a normally closed node N.C of the switch  60  are coupled to the output port of the power supply  4  and a detection node of the control device  50 , respectively, the control device  50  detects power information stored in the memory  80  via the switch  60 . The power information comprises a rated potential, a rated current, or a rated power, of the electronic device  8 . 
   In the present embodiment, the memory  80  is a non-volatile random access memory (NVRAM), and the switch  60  is an electrical or a mechanical switch such as a relay or an optical coupler. 
   When obtaining the power information, the control device  50  first controls the potential selector  42  to select an output power of a transformer  41  corresponding to the power information. The rectifier  43  rectifies and stabilizes the output power of the potential selector  42 , and then the control device  50  controls the switch  60  to change a passage from the normally closed node N.C to a normally opened node N.O. Thus, the converter  40  can provide an adjusted output power to the electronic device  8  via the switch  60 . 
   The power supply  4  further comprises a current detector  70  to detect whether the output power is applied to the electronic device  8 . Additionally, the current detector  70  can operate in coordination with the control device  50  to determine whether the power supply  4  unloads the electronic device  8 , whereby the passage of the switch  60  can be returned to it original state. For example, when the power supply  4  unloads the electronic device  8 , the current of the current detector  70  is zero, accordingly the control device  50  adjusts the passage of the switch  60 . Thus, the control device  50  can be coupled to the output port of the power supply  4  or returned to its original state. 
   In the present embodiment, the current detector  70  is a hall sensor or a magnetic sensor, and the power supply  4  is an AC/DC, AC/AC, DC/AC, or DC/DC mode power supply. 
   In  FIG. 3 , if being coupled to an electronic device  8  without the memory  80 , the power supply  4  can be manually switched to provide a required power of the electronic device. 
     FIG. 4A  is a schematic diagram of an electronic device of the invention. The electronic device  9  comprises a major circuit  90 , a memory  91 , and a gate switch  10  having a first gate device  92  and a second gate device  93 . When the electronic device  9  is coupled to the power supply  4 , the gate switch  10  determines whether the voltage of the input port Vin meets a first requirement or a second requirement. When the input port Vin is coupled to an output port of the control device  50  of  FIG. 3 , the first gate device  92  is turned on and second gate device  93  is turned off, whereby the input port Vin can be coupled to the memory  91 . Hence, the power supply  4  can detect the power information stored in the memory  91  via the first gate device  91 . Additionally, if the power supply  4  provides the adjusted output power according to the power information, the first gate device  92  is turned off and the second gate device  93  is turned on, whereby the input port Vin can be coupled to the major circuit  90 . Hence, the power supply  4  can provide the adjusted output power to the major circuit  90  via the second gate device  93 . 
     FIG. 4B  is a diagram of the electronic device of  FIG. 4A  of the invention. The first gate device  92  comprises resistors R 1  and R 2  and a first transistor  900 . The resistors R 1  and R 2  are connected in series and coupled between the input port Vin and reference node GND. The first transistor  900  is connected between the input port Vin and the memory  91 , and a gate electrode of the first transistor  900  is connected to the series point of the resistors R 1  and R 2 . 
   The second gate device  93  comprises a resistor RG, a second transistor  910 , a diode D, and a relay  920 . The resistor RG is connected between the input port Vin and the second transistor  910 . The diode D is coupled to a coil of the relay  920  in parallel, and coupled between the input port Vin and the second transistor  910  in series. The relay  920  is coupled to the input port Vin via the common node COM, and coupled to the major circuit  90  via the normally opened node N.O. 
   Suppose that the first transistor  900  is a depletion-type MOS transistor having a −4-volt threshold voltage, the second transistor  910  is an enhancement-type MOS transistor having a 4-volt threshold voltage, and the output power of the power supply  4  is between 0V to 24V. When the voltage of the input port Vin is less than 4V, according to a divided potential of the resistor R 1 , the reverse bias of the gate-source pole of the first transistor  910  is between 0V to −4V, which is greater than its threshold voltage −4V, thus the first transistor  900  operates in triode area or is turned on. At the same time, according to a divided potential of a resistor RG, the forward bias of the gate-source pole of the second transistor  910  is between 0V to 4V, which is less than its threshold voltage 4V, thus the second transistor  910  operates in cut-off state or is turned off. 
   When the voltage of the input port Vin is between 4V to 24V, the first transistor  900  operates in cut-off state or is turned off because the reverse bias is between −4V to −24V or less than its threshold voltage −4V. At the same time, the second transistor  910  operates in saturation state or is turned on because the forward bias is between 4V to 24V or greater than its threshold voltage 4V. 
   The first transistor  900  or the second transistor  910  can be replaced by JFET, which is switched by a bias of its gate-source pole. 
   Hence, the first transistor  900  and the second transistor  910  are controlled by a detecting signal and the output power from power supply  4 . When the voltage of the input port Vin equals to the detecting signal or is less than 4V, for example, the voltage of the input port Vin meets a first requirement, thus the first transistor  900  is turned on and the second transistor  910  is turned off. Additionally, when the voltage of the input port Vin equals to the output power or is greater than 4V, for example, the voltage of the input port Vin meets a second requirement, thus the first transistor  900  is turned off and the second transistor is turned on. 
   When the first transistor  900  is turned on, the detecting signal is provided to the memory  91  via the first transistor  90 , whereby the power supply  4  can obtain the power information. Furthermore, when the second transistor  910  is turned on, the major circuit  90  is driven indirectly via the relay  920  to perform a corresponding function when receiving the output power provided by the power supply  4 . The first transistor  900  is turned on when the second transistor  910  is turned off, and the first transistor  900  is turned off when the second transistor  910  is turned on. 
   Additionally, the electronic device  9  is also capable of being coupled to a conventional power supply. When the electronic device  9  is coupled to the conventional power supply, the voltage of the input port Vin can meets the second requirement, and the first transistor  900  is turned off and the second transistor  910  is turned on, whereby the major circuit  90  can receive the output power. 
     FIG. 5  shows a flowchart of a power supply control method of the invention. In step S 500 , an electronic device is coupled to and supplied with a power supply. Step S 520  follows, and the power supply transmits a detecting signal to detect whether the electronic device has a memory. 
   If the result of step S 520  is positive, step S 530  follows, and the power supply converts an input power from an external power source into an output power, and then reads and obtains power information stored in the electronic device in step S 540 . Subsequently step S 550  follows, the output power is adjusted according to the power information and the power supply supplies an adjusted output power to the electronic device. 
   Adjustment of the output power can be achieved by transforming the power source into output power sources with different potential levels and selecting one of the output power sources to provide the output power to the electronic device. A controller can be employed to read the power information and accordingly sends a control signal to a selector for selection. 
   If the result of step S 520  is negative, step S 600  follows, and the output power can be manually selected to provide the electronic device with required power. 
   Finally, while the invention has been described by way of example and in terms of the above, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements as would be apparent to those skilled in the art. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.

Technology Classification (CPC): 7