Abstract:
A battery charging circuit includes a power management IC, a controller, and a feedback circuit. The power management IC is configured to manage the power charging to a battery. The controller is configured to provide a preset value of current and a preset value of voltage. The feedback circuit is coupled to the power management IC and the controller and the battery. The feedback circuit compares the preset value of current with a charging current to the battery, and compares the preset value of voltage with a charging voltage to the battery to obtain results of comparison, and provides a feedback signal to the power management IC according to the comparisons. The power management IC decreases or increases power output upon the comparisons.

Description:
FIELD 
       [0001]    The subject matter herein generally relates to charging circuits. 
       BACKGROUND 
       [0002]    Linear charging circuits are applied in electronic devices to provide energy. In general, there is variable potential difference between input voltages and output voltages of linear charging circuits and this variable potential difference wastes a lot of energy. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0003]    Implementations of the present technology will now be described, by way of example only, with reference to the attached FIGURE. 
           [0004]    The FIGURE is a diagrammatic view of one embodiment of a charging circuit. 
       
    
    
     DETAILED DESCRIPTION 
       [0005]    It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the embodiments described herein. The drawings are not necessarily to scale and the proportions of certain parts have been exaggerated to better illustrate details and features of the present disclosure. 
         [0006]    The term “coupled” is defined as connected, whether directly or indirectly through intervening components, and is not necessarily limited to physical connections. The connection can be such that the objects are permanently connected or releasably connected. The term “comprising,” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series and the like. 
         [0007]    The present disclosure is described in relation to a charging circuit. 
         [0008]    The FIGURE is a diagrammatic view of one embodiment of a charging circuit. In at least one embodiment, the charging circuit is configured to charge a battery  500 . The charging circuit includes a power management integrated circuit (IC)  100 , a controller  200 , a switching circuit  300 , a feedback circuit  400  and the battery  500 . The power management IC  100  is configured to manage the power charging to the battery  500  according to a feedback signal. The controller  200  is configured to output command signals to the power management IC  100 . The controller  200  and an input terminal of the power management IC  100  are coupled to power source Vin to receive electrical power. The switching circuit  300  is coupled between an enable terminal EN of the power management IC  100  and the controller  200 . When the controller  200  sends a controlling signal to the switching circuit  300 , the switching circuit  300  sends an enable signal to enable terminal EN to work the power management IC  100 . The feedback circuit  400  couples the power management IC  100 , the controller  200 , and the battery  500  to provide the feedback signal to the power management IC  100 . According to the feedback signal, the power management IC  100  adjusts the output power of the output terminal OUT. In at least one embodiment, when a voltage of the enable signal is low level, the power management IC  100  shuts off the output power of the output terminal OUT. When the voltage of the enable signal is high level, the power management IC  100  outputs the output power via the output terminal OUT. 
         [0009]    A first conducting end of a first metal oxide semiconductor (MOS) M 1  is coupled to the output terminal OUT of the power management IC  100  via a sampling resistor Rs and an inductor L 1 . A second conducting end of the first MOS M 1  is coupled to the battery  500 . The controlling end of the first MOS M 1  is coupled to the controller  200 . The inductor L 1  is configured to store energy. When the controller  200  sends a signal to the first MOS M 1 , the first MOS M 1  adjusts charging current to the battery  500 . In at least one embodiment, the first MOS M 1  is a high power MOS. The first conducting end of the first MOS M 1  is a MOS drain electrode, the second conducting end of the first MOS M 1  is a MOS source electrode, and the controlling end of the first MOS M 1  is a MOS gate electrode. 
         [0010]    The switching circuit  300  further includes a first resistor R 1  and a switch M 2 . The first conducting end of the switch M 2  is coupled to the power source Vin and the enable terminal EN of the power management IC  100 . The second conducting end of the switch M 2  is grounded. The controlling end of the switch M 2  is coupled to the controller  200  and receives the control signal of the controller  200 . In at least one embodiment, the switch M 2  is a MOS. The first conducting end of the switch M 2  is a MOS drain electrode, the second conducting end of the switch M 2  is a MOS source electrode, and the controlling end of the switch M 2  is a MOS gate electrode. The first conducting end of the switch M 2  is grounded, and the enable terminal EN of the power management IC  100  receives a control signal of low level voltage. Thus, the power management IC  100  shuts off the power being output to the battery. In other embodiments, the switching circuit  300  may be other controllable switches or transistor circuits. 
         [0011]    The feedback circuit  400  further includes a mixer U 1 , a first error amplifier U 2 , a second error amplifier U 3 , a third error amplifier U 4 , a first digital to analog converter (DAC) DAC 1 , a second DAC DAC 2 , a capacitor C 1 , a second resistor R 2 , a third resistor R 3 , and a feedback resistor Rf. 
         [0012]    In order to compare the preset value of current with a charging current to the battery, two input terminals of the first error amplifier U 2  are respectively coupled to two terminals of the sampling resistor Rs to acquire and amplify the charging current to the battery  500 . An output terminal of the first error amplifier U 2  is coupled to an input terminal of the second error amplifier U 3 . An input terminal of the first DAC DAC 1  is coupled to the controller  200 . On receiving a preset value of current sent by the controller  200 , the first DAC DAC 1  converts the preset value of current into an analog current signal. An input terminal of the second error amplifier U 3  is coupled to an output terminal of the first error amplifier U 2  and another input terminal of the second error amplifier U 3  is coupled to an output terminal of the first DAC DAC 1 . The second error amplifier U 3  compares the analog current signal with an amount of current output by the first error amplifier U 2 . Then the second error amplifier U 3  outputs a result of comparing between the preset value of current and the charging current to the battery  500 . An input terminal of the mixer U 1  is coupled to an output terminal of the second error amplifier U 3  to receive the result of comparing currents. 
         [0013]    An output terminal of the mixer U 1  is coupled to a feedback terminal of the power management IC  100  via the feedback resistor Rf. The mixer U 1  outputs a feedback signal to the power management IC  100 . The capacitor C 1  and the third resistor R 3  are coupled in series and are coupled to the second resistor R 2  in parallel. A conducting end of the feedback resistor Rf is coupled between the second resistor R 2  and the third resistor R 3  so that a voltage of the feedback signal to the power management IC can be adjusted. 
         [0014]    For example, the first error amplifier U 2  acquires the charging current to the battery  500  from the sampling resistor Rs and outputs an amplified charging current to the second error amplifier U 3 . The second error amplifier U 3  compares the amplified charging current with the analog signal representing the preset value of current. The second error amplifier U 3  then outputs the result of comparing the levels of current to the mixer U 1 . As the result of comparing amounts of current, if the charging current to the battery  500  is higher than the preset value of current, the second error amplifier U 3  outputs a higher voltage to the power management IC  100  and the power management IC  100  decreases the output power. If the charging current to the battery  500  is lower than the preset value of current, the second error amplifier U 3  outputs a lower voltage to the power management IC  100  and the power management IC  100  increases the output power. 
         [0015]    An input terminal of the third error amplifier U 4  is coupled to an input terminal to the battery  500  to acquire the charging voltage to the battery  500 . Another input terminal of the third error amplifier U 4  is coupled to an output terminal of the second DAC DAC 2 . An output terminal of the third error amplifier U 4  is coupled to an input terminal of the mixer U 1 . An input terminal of the second DAC DAC 2  is coupled to the controller  20  to acquire a preset value of voltage from the controller  200 . Then the second DAC DAC 2  converts the preset value of voltage into an analog voltage signal. The third error amplifier U 4  compares the analog voltage signal with the charging voltage to the battery  500 . Then the third error amplifier U 4  outputs a result of comparing the preset value of voltage and the charging voltage to the battery  500 . Another input terminal of the mixer U 1  is coupled to an output terminal of the third error amplifier U 4  to receive the result of comparing voltages. 
         [0016]    For example, the third error amplifier U 4  acquires the charging voltage from the battery  500 . The third error amplifier U 4  compares the charging voltage with the analog voltage signal converted from the preset value of voltage. Then the third error amplifier U 4  outputs the result of comparing voltages to the mixer U 1 . If the charging voltage to the battery  500  is higher than the preset value of voltage, the third error amplifier U 4  outputs a higher voltage to the power management IC  100  and the power management IC  100  decreases the output power. If the charging voltage to the battery  500  is lower than the preset value of voltage the third error amplifier U 4  outputs a lower voltage to the power management IC  100 , and the power management IC  100  increases the output power. 
         [0017]    In at least one embodiment, if a feedback terminal FB of the power management IC  100  receives a higher voltage, the output power will be lower. If the feedback terminal FB of the power management IC  100  receives a lower voltage, the output power will be higher. 
         [0018]    Many details are often found in art including other features of the charging circuit. Therefore, many such details are neither shown nor described. Even though numerous characteristics and advantages of the present technology have been set forth in the foregoing description, together with details of the structure and function of the present disclosure, the disclosure is illustrative only, and changes may be made in the detail, especially in matters of shape, size, and arrangement of the parts within the principles of the present disclosure, up to and including the full extent established by the broad general meaning of the terms used in the claims. It will therefore be appreciated that the embodiments described above may be modified within the scope of the claims.