Abstract:
An electrical device includes a motherboard and a daughter board. The daughter board includes a plurality of signal pins to output signals for denoting a type of the daughter board. The motherboard includes a controller and a voltage adjusting unit. The controller receives the signals from the signal pins of the daughter board to identify the type of the daughter board and outputs control signals according to the signals received from the daughter board. The voltage adjusting unit receives the control signals and adjusts a voltage from a voltage source into a work voltage according the control signal, and outputs the work voltage to the electrical element.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates to devices, and particularly to an electronic device and a motherboard thereof. 
         [0003]    2. Description of Related Art 
         [0004]    Digital multifunctional cameras such as network cameras include a motherboard and a sensor board. When the sensor board is connected to the motherboard, the motherboard supplies a work voltage for sensors mounted on the sensor board and a system voltage for the sensor board. The sensors may include complementary metal-oxide-semiconductor transistor image sensors and charge coupled device image sensors of which there are many different types and so can have different voltage demands. If a sensor board is changed, it is likely that the new sensor board will have different voltage needs and so the motherboard must be modified. It is inconvenient, time-consuming, and expensive to modify the motherboard. 
       BRIEF DESCRIPTION OF THE DRAWINGS 
       [0005]    The drawing is a block diagram of one embodiment of an electronic device. 
     
    
     DETAILED DESCRIPTION 
       [0006]    Referring to the drawing, an exemplary embodiment of an electronic device  100  includes a motherboard  1  and a daughter board such as a sensor board  2  connected to the motherboard  1 . The motherboard  1  is used to supply system voltage to the sensor board  2  and work voltage to a plurality of electrical elements mounted on the sensor board  2 . In the embodiments, the electronic device  100  is a network camera. 
         [0007]    The sensor board  2  includes an electrical element such as a sensor  20  and two signal pins such as identity (ID) signal pins  23  and  24 . The ID signal pins are used to output signals to denote a type of the sensor board  2 . The sensor  20  is a complementary metal-oxide-semiconductor transistor (CMOS) image sensor. The motherboard  1  supplies a work voltage to the sensor  20  according to the type of the sensor  20 . 
         [0008]    The motherboard  1  includes a voltage adjusting unit  50  and a controller such as a demultiplexer  30  connected to the voltage adjusting unit  50  to output a control signal to the voltage adjusting unit to output the work voltage. The voltage adjusting unit  50  includes a voltage converter  10 , a resistor regulator  60 , a first capacitor C 1 , a second capacitor C 2 , a power terminal  40 , and a first resistor R 1 . The voltage converter  10  includes a voltage input terminal VIN, a voltage output terminal VOUT, and a reference terminal Vref. The resistor regulator  60  includes a second to a fifth resistors R 2 -R 5 , and a first to a fourth electrical switches Q 1 -Q 4 . Each of the first to fourth electrical switches Q 1 -Q 4  includes a control terminal, a first terminal, and a second terminal. The demultiplexer  30  includes two signal selecting pins L 1  and L 2 , a signal input pin , and first to fourth signal output pins Y 0 -Y 3 . 
         [0009]    The voltage input terminal VIN of the voltage converter  10  is connected to the power terminal  40 . The voltage output terminal VOUT of the voltage converter  10  is connected to a voltage input terminal  22  of the sensor  20  mounted on the sensor board  2 . The reference terminal Vref of the voltage converter  10  is connected to the first terminal D 1  of the first electrical switch Q 1  via the second resistor R 2 , the first terminal D 2  of the second electrical switch Q 2  via the third resistor R 3 , the first terminal D 3  of the third electrical switch Q 3  via the fourth resistor R 4 , and the first terminal D 4  of the fourth electrical switch Q 4  via the fifth resistor R 5 . The first resistor R 1  is connected between the reference terminal Vref and the voltage output terminal VOUT of the voltage converter  10 . The second terminals S 1 -S 4  of the first to fourth electrical switches Q 1 -Q 4  are grounded. The first to fourth signal output pins Y 0 -Y 3  of the demultiplexer  30  are connected to the control terminals G 1 -G 4  of the first to fourth electrical switches Q 1 -Q 4 , respectively. The signal input pin I of the demultiplexer  30  is set to be high level signal “1”. The two signal selecting pins L 1  and L 2  are connected to the two ID pins  23  and  24  of the sensor board  2  to select one signal output pin from the first to fourth signal output pins Y 0 -Y 3 , according to signals output by the two ID pins  23 ,  24 , to output a control signal to the corresponding electrical switch. 
         [0010]    In the embodiment, there are a first to a fourth types of sensor boards  2 . The first to fourth types of sensor boards  2  each require different work voltages. The two ID pins  23 ,  24  of each type are set to different ID signals correspondingly, such as, the two ID pins  23 ,  24  are set to “00” on the first type sensor board  2 ; the two ID pins  23 ,  24  are set to “01” on the second type sensor board  2 ; the two ID pins  23 ,  24  are set to “10” on the third type sensor board  2 ; and the two ID pins  23 ,  24  are set to “11” on the fourth type sensor board  2 . The first to fourth electrical switches Q 1 -Q 4  are N type field-effect-transistors (FET). The control terminals G 1 -G 4  are gates of the first to fourth FETs. The first terminals D 1 -D 4  are drains of the first to fourth FETs. The second terminals S 1 -S 4  are sources of the first to fourth FETs. Resistances of the second to fifth resistors R 2 -R 5  are all different from each other. 
         [0011]    When the first type sensor board  2  is connected to the motherboard  1 , the motherboard  1  supplies the system voltage to the sensor board  2  as follows. The two ID pins  23  and  24  output the signal “00”. The two selecting pins L 1  and L 2  of the demultiplexer  30  receive the signal “00”. The demultiplexer  30  controls the first signal output pin Y 0  to output a high level as the control signal to the control terminal G 1  of the first electrical switch Q 1 , control the second to fourth signal output pins Y 1 -Y 3  to output the low level as the control signal to the control terminal G 2 -G 4  of the second to fourth electrical switches Q 2 -Q 4 . The first electrical switch Q 1  is turned on, the voltage output terminal VOUT of the voltage converter  10  outputs the work voltage Vout=Vref*(1+R 1 /R 2 ) to the voltage input terminal  22  of the sensor  20 . If the sensor board  2  is the second, third, or fourth type, correspondingly, the second, third, or fourth electrical switch Q 2 , Q 3 , or Q 4  is turned on. The voltage output terminal VOUT of the voltage converter  10  outputs the work voltage Vout=Vref*(1+R 1 /R 3 ), Vout=Vref*(1+R 1 /R 4 ), or Vout=Vref*(1+R 1 /R 5 ) to the voltage input terminal  22  of the sensor  20 . The reference voltage Vref is supplied by the voltage converter  10 . The work voltages demanded by each type sensor board  2  can be obtained via selecting proper resistances of the first to fifth resistors R 1 -R 5  and the reference voltage Vref of the voltage converter  10  according to the work voltage demanded by each type sensor board  2 . The first and second capacitors C 1  and C 2  are used for filtering noise, and can be omitted to save manufacture cost. 
         [0012]    It is to be understood, however, that even though numerous characteristics and advantages of the embodiments have been set forth in the foregoing description, together with details of the structure and function of the embodiments, the disclosure is illustrative only, and changes may be made in details, especially in matters of shape, size, and arrangement of parts within the principles of the embodiments to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.