Patent Publication Number: US-2013234676-A1

Title: Charge indicator circuit

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to circuits and, more particularly, to a charge indicator circuit. 
     2. Description of Related Art 
     A charge indicator circuit controls an indicator to be on or to be off through a software control method, such as the one within a controller, thus a conventional charge indicator circuit is complicated. Moreover, when the controller is powered off, the controller will be disabled and cannot control the indicator to be on or to be off. 
     It is desirable to provide a new charge indicator circuit to resolve the above problems. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the charge indicator circuit. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a block diagram of a charge indicator circuit in accordance with an exemplary embodiment. 
         FIG. 2  is a circuit diagram of the charge indicator circuit of  FIG. 1 , in accordance with an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     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. 
     Referring to  FIG. 1 , a block diagram of a charge indicator circuit  1  is shown. The circuit  1  includes a connection jack  10 , a voltage detection module  20 , an indicator module  30 , and a path connection module  40 . The connection jack  10  is connected to a power supply  50  to receive power from the power supply  50 . The path connection module  40  is connected to a charger IC  60  and is in a shunt circuit of the indicator module  30  to enable or disable the shunt circuit of the indicator module  30 . 
     The charger IC  60  manages the charging of a battery  70 . When a condition of the battery  70  is satisfied, for example, such as the battery  70  is not fully charged, the charger IC  60  outputs a low level signal (logic 0). When the condition of the battery  70  is not satisfied, for example, such as the battery  70  is fully charged, the charger IC  60  outputs a high level signal (logic 1). 
     The voltage detection module  20  outputs a first response signal when the connection jack  10  is connected to the power supply  50 , the path connection module  40  enables the shunt circuit of the indicator module  30  when the voltage detection module  20  outputs the first response signal and the charger IC  60  outputs the low level signal logic 0. The voltage detection module  20  further outputs a second response signal when the connection jack  10  is not connected to the power supply  50 , the path connection module  40  disables the shunt circuit of the indicator module  30  when the voltage detection module  20  outputs the second response signal or the charger IC  60  outputs the high level signal logic 1. 
     Referring to  FIG. 2 , a circuit diagram of the charge indicator circuit  1  is shown. The connection jack  10  includes an anode input port  101  and a cathode input port  102  respectively connected to an anode and a cathode of the power supply  50 . The voltage detection module  20  includes a first resistor R 1  and a second resistor R 2 . The first resistor R 1  and the second resistor R 2  are connected in series between the anode input port  101  and ground. The node N formed between the first resistor R 1  and the second resistor R 2  is connected to the path connection module  40 . When the connection jack  10  is connected to the power supply  50 , the voltage of the power supply  50  is divided by the first resistor R 1  and the second resistor R 2  to form a divided voltage V 0  at the node N. 
     The indicator module  30  includes an indicator  301  and a power supply  302 . In the embodiment, the indicator  301  is a light emitting diode (LED) D 1 . The anode of the LED D 1  is connected to the power supply  302 , and the cathode of the LED D 1  is connected to the path connection module  40 . In the embodiment, the anode of the LED D 1  is connected to the power supply  302  through a resistor R 3 . 
     The path connection module  40  includes a high voltage activated switch  401 . In the embodiment, an npn bipolar junction transistor (BJT) Q 1  is taken as an example to illustrate the high voltage activated switch. The npn BJT Q 1  includes a base, a collector, and an emitter. The base of the npn BJT Q 1  is connected to the node N formed between the first resistor R 1  and the second resistor R 2 , the collector of the npn BJT Q 1  is connected to the cathode of the LED D 1 , and the emitter of the npn BJT Q 1  is connected to the charger IC  60 . 
     When the connection jack  10  is connected to the power supply  50 , the power supply  50  produces a voltage V 0  at the node N, thus the voltage detection module  20  outputs a high level signal logic 1 to the base of the npn BJT Q 1 . When the condition of the battery  70  is satisfied, the charger IC  60  outputs a low level signal logic 0 to the emitter of the npn BJT Q 1 , causing the base voltage of the npn BJT Q 1  to be lower than the emitter voltage of the npn BJT Q 1 , and the npn BJT Q 1  is correspondingly turned on. Thus, the shunt circuit of the indicator module  30  is turned on, resulting in the LED D 1  being enabled to be on, to indicate that the battery  70  is being charged. 
     When the connection jack  10  is not connected to the power supply  50 , the voltage detection module  20  outputs a low level signal logic 0 to the base of the npn BJT Q 1 . No matter whether the charger IC  60  outputs the low level signal logic 0 or outputs the high level signal logic 1, the base voltage of the npn BJT Q 1  is higher than or equal to the emitter voltage of the npn BJT Q 1 , and the npn BJT Q 1  is correspondingly turned off. Thus, the shunt circuit of the indicator module  30  is turned off, resulting in the LED D 1  being disabled, to indicate that the battery  70  is not being charged. 
     When the condition of the battery  70  is not satisfied, the charger IC  60  outputs a high level signal logic 1 to the emitter of the npn BJT Q 1 . No matter whether the connection jack  10  is connected to the power supply  50 , the base voltage of the npn BJT Q 1  is higher than or equal to the emitter voltage of the npn BJT Q 1 , and the npn BJT Q 1  is correspondingly turned off. Thus, the shunt circuit of the indicator module  30  is turned off, resulting in the LED D 1  being disabled. 
     With this configuration, the voltage detection module  20  outputs a high level signal logic 1 to turn on the path connection module  40  when the connection jack  10  is connected to the power supply  50  and the condition of the battery  70  is satisfied. Thus the shunt circuit of the indicator module  30  is enabled, causing the LED D 1  to be on. In this way, the charge indicator circuit  1  does not need the controller to control the LED D 1  to be on or to be off, to indicate that the battery  70  is being charged or not. 
     Although the current disclosure has been specifically described on the basis of the exemplary embodiment thereof, the disclosure is not to be construed as being limited thereto. Various changes or modifications may be made to the embodiment without departing from the scope and spirit of the disclosure.