Patent Publication Number: US-8970175-B2

Title: Charging circuit employing a southbridge microchip to control charging when the electronic apparatus is shut down

Description:
BACKGROUND 
     1. Technical Field 
     The disclosure generally relates to charge circuits, and more particularly relates to a charging circuit using universal serial bus (USB) interface sleep technology. 
     2. Description of the Related Art 
     When the voltage of a battery of a portable electronic device, such as a mobile phone is insufficient, the battery can be charged via connecting the portable electronic device to a USB interface of a personal computer which implements USB interface sleep technology. 
     Referring to  FIG. 3 , a USB charging control system  1  used in a personal computer that implements the USB interface sleep technology often includes a charging control microchip  2 , a USB transceiver  3 , a southbridge microchip  4 , and a USB connector  5 . Control terminals S 0  and S 1  of the charging microchip  2  are operable to control data terminals D+ and D− of the charging control microchip  2 . When the control terminals S 0  and S 1  are both set to logic 0, the USB charging control system  1  can be in a charging mode, and then the portable electronic device is electronically connected to the two data terminals D+ and D− via the USB connector  5 , to obtain power from the charging control microchip  2 . When the control terminals S 0  and S 1  are both set to logic 1, the data terminals D+ and D− are respectively connected to transmission terminals Y+ and Y− of the charging control microchip  2 , then the USB charging control system  1  can be in a data transmission mode, and the portable electronic device can receive data from the personal computer via the USB connector  5 , the USB transceiver  3 , and the southbridge microchip  4 . 
     However, it is a defect in the USB charging control system  1  that the portable electronic device can not obtain power from the personal computer before the operating system of the personal computer has been started. Furthermore, the charging mode and the data transmission mode are not interchangeable when the personal computer is in a sleep mode. Thus, inconvenience is caused. 
     Therefore, there is room for improvement within the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of an exemplary charging circuit can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the exemplary charging circuit. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like elements of an embodiment. 
         FIG. 1  is a block diagram of a charging circuit comprising a logic control circuit, according to an exemplary embodiment. 
         FIG. 2  is a circuit view of one embodiment of the logic control circuit of  FIG. 1 . 
         FIG. 3  is a block diagram of a conventional USB charging control system. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a charging circuit  100  comprising a logic control circuit  40 , according to an exemplary embodiment. The charging circuit  100  can be employed in a personal computer or other electronic apparatus and is capable of charging a battery of a portable electronic device  200  through a USB cable. The charging circuit  100  further includes a charging control microchip  10 , a southbridge microchip  20 , and a basic input/output system (BIOS)  30 . 
     Also referring to  FIG. 2 , the charging control microchip  10  can be a traditional charging control microchip same as prior art and includes data terminals D+ and D−, transmission terminals Y+ and Y−, and control terminals S 0  and S 1 . The data terminals D+ and D− are electronically connected to the portable electronic device  200  via a USB connector (not shown). The transmission terminals Y+ and Y− are electronically connected to the southbridge microchip  20 , and the control terminal S 0  connects to the control terminal S 1 . When the control terminals S 0  and S 1  are both set to logic 0, the charging control microchip  10  can be in a charging mode, and then the portable electronic device  200  can obtain power from the charging control microchip  10 . When the control terminals S 0  and S 1  are both set to logic 1, the data terminals D+ and D− are respectively connected to the transmission terminals Y+ and Y−, then the charging control microchip  10  can be in a data transmission mode, and the portable electronic device  200  is electronically connected to the southbridge microchip  20  via the charging control microchip  10 . Thus, the portable electronic device  200  can exchange data with the personal computer. 
     The southbridge microchip  20  is electronically connected to the logic control circuit  40  to output different control signals to the logic control circuit  40  at different times. Specifically, when the personal computer is powered on (represented as a T 0  period), the southbridge microchip  20  outputs a power level control signal, which is logic 0. When the personal computer is under the control of the operating system (represented as a T 1  period), the power level control signal changes to logic 1. When the personal computer enters a sleep mode (represented as a T 3  period), the power level control signal maintains the logic 1 signal. When the personal computer is in a deep sleep mode (represented as a T 4  period) or the personal computer is powered off (represented as a T 5  period), the power level control signal changes to logic 0. 
     The BIOS  30  is electronically connected to the logic control circuit  40  via a general purpose input/output (GPIO) interface. The BIOS  30  is operable to output a GPIO control signal to the logic control circuit  40  when the personal computer is in the sleep mode (the T 3  period). The GPIO control signal can be predetermined as logic 0 or logic 1. 
     The logic control circuit  40  is directed by the southbridge microchip  20  and the BIOS  30  and is operable to set or reset the control terminals S 0  and S 1 . The logic control circuit  40  includes a first metal oxide semiconductor field effect transistor (MOSFET) Q 1 , a second MOSFET Q 2 , a first resistor R 1 , a second resistor R 2 , and a third resistor R 3 . The first MOSFET Q 1  includes a gate G 1 , a source S 11 , and a drain D 1 . The gate G 1  is electronically connected to the southbridge microchip  20  to receive the power level control signals. The source S 11  is connected to ground, and the drain D 1  is electronically connected to a power supply of about 5V through the first resistor R 1 . The second MOSFET Q 2  includes a gate G 2 , a source S 22 , and a drain D 2 . The gate G 2  of the second MOSFET Q 2  is connected to the drain D 1  of the first MOSFET Q 1 , the source S 22  is connected to ground, and the drain D 2  is electronically connected to the BIOS  30  via the GPIO interface to receive the GPIO control signal. Additionally, the drain D 2  is electronically connected to a power supply of about 3V through the second resistor R 2  and is also electronically connected to the control terminals S 0  and S 1  of the charging control microchip  10 . One end of the third resistor R 3  is connected between the drain D 2  and the control terminal S 0 , and the other end is connected to ground. 
     The working principle of the charging circuit  100  will be illustrated here according to the T 0 , T 1 , and T 3 -T 5  periods. 
     When the personal computer is powered on (the T 0  period), the southbridge microchip  20  outputs a power level control signal with logic 0 to the gate G 1  of the first MOSFET Q 1 . Then, the first MOSFET Q 1  is cut off, and the second MOSFET Q 2  is turned on to pull down the voltage of the drain D 2 . Then the control terminals S 0  and S 1  are both set to logic 0, thus, the charging control microchip  10  enters the charging mode to charge the portable electronic device  200 . Even though the operating system of the personal computer has not yet been started, the charging circuit  100  can also charge the portable electronic device  200  as long as the personal computer receives an alternating current. 
     When the personal computer is under the control of the operating system (the T 1  period), the southbridge microchip  20  outputs a power level control signal with logic 1 to the gate G 1  of the first MOSFET Q 1 . Then, the first MOSFET Q 1  is turned on, the second MOSFET Q 2  is cut off, and the voltage of the drain D 2  is not pulled down. Then the control terminals S 0  and S 1  are both set to logic 1, thus, the charging control microchip  10  enters the data transmission mode, and the portable electronic device  200  can send data to the personal computer, or receive data from the personal computer, via the transmission terminals Y+ and Y− of the charging control microchip  10  and the southbridge microchip  20 . Additionally, the charging circuit  100  continues to charge the portable electronic device  200  because a motherboard (not shown) of the personal computer is running in this period. 
     When the personal computer enters the sleep mode (the T 3  period), the power level control signal maintains the logic 1 signal, and the second MOSFET Q 2  is cut off. Then, if the GPIO control signal sent by the BIOS  30  is logic 0, the control terminals S 0  and S 1  are both set to logic 0, and the charging control microchip  10  enters the charging mode to charge the portable electronic device  200 . If the GPIO control signal is logic 1, the control terminals S 0  and S 1  are both set to logic 1, and the charging control microchip  10  enters the data transmission mode. In the data transmission mode, the charging circuit  100  can not charge the portable electronic device  200  because the motherboard of the personal computer is not running in the sleep mode. However, users can reset the GPIO control signal to change the mode, from data transmission to charging mode, to ensure that the portable electronic device  200  receives power from the personal computer. 
     When the personal computer is in the deep sleep mode (the T 4  period), the power level control signal changes to logic 0, and the second MOSFET Q 2  is turned on. Then the control terminals S 0  and S 1  are both set to logic 0, and the charging control microchip  10  enters the charging mode to charge the portable electronic device  200 . 
     When the personal computer is shut down (the T 5  period), the power level control signal maintains the logic 0 signal, and the charging circuit  100  continues to charge the portable electronic device  200  as long as the personal computer continues receiving an alternating current. 
     The logic control circuit  40  and the BIOS  30  can control the control terminals S 0  and S 1  of the charging control microchip  10 , so that the charging control microchip  10  can be in a charging mode or in a data transmission mode. The charging circuit  100  can charge the portable electronic device  200  so long as the personal computer is receiving an alternating current. Additionally, when the personal computer is in the sleep mode, users can reset the GPIO control signal to change charging mode for data transmission mode and vice versa, thus, the charging circuit  100  is convenient and efficient. 
     Although numerous characteristics and advantages of the exemplary disclosure have been set forth in the foregoing description, together with details of the structure and function of the exemplary disclosure, the disclosure is illustrative only, and changes may be made in detail, especially in the matters of shape, size, and arrangement of parts within the principles of exemplary disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.