Patent Publication Number: US-2022239133-A1

Title: Charging circuit and adapter

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Chinese Patent Application No. 202110098703.2 filed on Jan. 25, 2021, the contents of which are incorporated by reference herein. 
     FIELD 
     The subject matter herein generally relates to the field of charging, and particularly to a charging circuit and an adapter. 
     BACKGROUND 
     Use the charging interface, such as the USB Type-A interface to charge the super capacitor or battery. Because of the extremely low internal resistance of the super capacitor/battery, the output voltage will continue to exist when the power input to the charging interface is turned off. However, usually the charging IC does not have the function of blocking the reverse voltage, so when the power is turned off, the output voltage will be recharged to the input end through the charging IC, causing the input system to malfunction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Implementations of the present technology will now be described, by way of example only, with reference to the attached figures. 
         FIG. 1  is a schematic diagram of a module of an embodiment of the charging circuit of the present invention. 
         FIG. 2  is a schematic circuit diagram of an embodiment of the charging circuit of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     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. The disclosure is illustrated by way of example and not by way of limitation in the figures of the accompanying drawings, in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean at least one. 
     Several definitions that apply throughout this disclosure will now be presented. 
     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. 
       FIG. 1  is a schematic diagram of a module of an embodiment of the charging circuit of the present invention. The adapter  1  includes a charging circuit  10 , and the adapter  1  is used to connect to an external power source  2  and an external load  3  to charge the external load  3  through the external power source  2 . In the embodiment, the charging circuit  10  includes a first interface  100 , a charging unit  101 , a control unit  102 , a load switch  103 , and a charging unit  104 . 
     In the embodiment, the first interface  100  is configured to connect to the external power source  2 . Specifically, the first interface  100  may be but is not limited to a USB Type A interface. The charging unit  101  is configured to connect to the external load  3 , and the external power source  2  charges the external load  3  through the charging unit  101 . The control unit  102  is electrically connected to the first interface  100 , the load switch  103  and the charging unit  101 , and is configured to output a first control signal when the external power source  2  is activated, and when the external power source  2  stops charging the external load  3 , the second control signal is output. The load switch  103  is electrically connected to the first interface  100 , the control unit  102 , and the charging unit  101 , and is configured to turn on the load switch  103  when the first control signal is received, and the external power source  2  charges the external load  3 ; when the second control signal is received, the load switch  103  is turned off to prevent the voltage from being recharged to the first interface  100  through the charging unit  101 , so as to overcome the defect in the prior art that when the external power source  2  is turned off, the output voltage will be recharging to the input through the charging unit. 
     Refer to  FIG. 2 , which is a schematic circuit diagram of the charging circuit  10  of the present invention. In the embodiment, the control unit  102  includes a first resistor R 1 , a second resistor R 2 , a third resistor R 3 , a fourth resistor R 4  and a first electronic switch Q 1 . One end of the first resistor R 1  is electrically connected to a common end of the first interface  100  and the load switch  103 . One end of the second resistor R 2  is electrically connected to the other end of the first resistor R 1 , and the other end of the second resistor R 2  is grounded. One end of the third resistor R 3  is electrically connected to the common end of the first resistor R 1  and the second resistor R 2 , and the other end of the third resistor R 3  is electrically connected to the charging unit  102 . One end of the fourth resistor R 4  is electrically connected to the common end of the first interface  100  and the load switch  103 . The first electronic switch Q 1  includes a control end, a first end and a second end, and the control end is electrically connected to a common end of the resistor R 1  and the second resistor R 2 , the first end is electrically connected to the other end of the fourth resistor R 4  and the load switch  103 , and the second end is grounded. In a specific embodiment of the present invention, the first electronic switch Q 1  may be an N-type MOS transistor, the gate of the N-type MOS transistor is electrically connected to the common terminal of the first resistor R 1  and the second resistor R 2 , and the drain the N-type MOS transistor is electrically connected to the load switch  103  and the other end of the fourth resistor R 4 , the source of the N-type MOS transistor is grounded. 
     In the embodiment, the load switch  103  includes: an input end Vin, an enable terminal and an output end Vout. The input end Vin is electrically connected to the first interface  100 . The enable end Enable is electrically connected to the common end of the first electronic switch Q 1  and the fourth resistor R 4 , wherein the enable end Enable is active at low level. When the enable end Enable receives a low level signal, the load switch  103  is turned on; when the enable end Enable receives a high level signal, the load switch  103  is turned off; the output end Vout is electrically connected to the charging unit  101 . 
     In the embodiment, the charging unit  101  is a charging chip, and the charging chip includes: an input end Vin 1 , and LDO output end and an output end Vout 1 . The input end Vin 1  is electrically connected to the output end Vout of the load switch  103 ; the LDO output end is electrically connected to the other end of the third resistor R 3 . When the external power source  2  is activated, the LDO output end outputs the first voltage signal. The output end Vout 1  is electrically connected to the external load  3 . 
     Specifically, when the external power source  2  charges the external load  3 , a large capacitor C is formed between the charging unit  101  and the external load  3  to store charges, that is, a large capacitor is formed between the output end Vout 1  of the charging chip and the external load  3 . When the external power source  2  starts, the LDO output end of the charging unit  101  outputs the first voltage signal to the control end of the first electronic switch Q 1  through the third resistor R 3 , and the first electronic switch Q 1  is turned on to output the first electronic switch Q 1 . A control signal is sent to the enable end Enable of the load switch  103 , so that the load switch  103  is turned on, and the external power source  2  charges the external load  3  through the charging chip. When the external power source  2  stops charging, the first voltage signal becomes 0, the first electronic switch Q 1  is turned off, and the first electronic switch Q 1  outputs the second control signal to the enable end Enable of the load switch  103 , so that the load switch  103  is turned off to prevent the voltage of the large capacitor from being recharged to the first interface  100 , thereby overcoming the defect in the prior art that the output voltage is recharged to the input end through the charging unit when the external power source  2  is turned off. 
     In the embodiment, when the external power source  2  is activated, the current flowing through the first resistor R 1  is the sum of the current flowing through the second resistor R 2  and the third resistor R 3 . When the external power source  2  charges the external load  3 , the current flowing through the second resistor R 2  is the sum of the current flowing through the first resistor R 1  and the third resistor R 3 . When the external power source  2  stops charging, the current flowing through the first resistor R 1  is the sum of the current flowing through the second resistor R 2  and the third resistor R 3 . 
     Compared with the prior art, in the charging circuit provided by the embodiment of the present invention, the control unit outputs a first control signal when the external power source is activated, and outputs a second control signal when the external power source stops charging the external load, and then the load switch is turned on when receiving the first control signal, and the external power source charges the external load. The load switch is turned off when receiving the second control signal, thereby preventing the voltage from being recharged to the first interface through the charging unit. 
     Many details are often found in the art such as the other features of a mobile terminal. 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.