Abstract:
Circuits and devices related to overcurrent protection. In some embodiments, a voltage converter can include a voltage converting circuit configured to receive an input voltage and generate an output voltage. The voltage converter can further include an overcurrent protection circuit coupled to the voltage converting circuit and having a detection unit configured to detect an overcurrent condition associated with the voltage converting circuit and generate an overcurrent signal indicative of the overcurrent condition. The overcurrent protection circuit can further include a consumption unit in communication with the detection unit and configured to selectively consume and thereby reduce a current in a path associated with the voltage converting circuit upon receipt of the overcurrent signal.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application is a continuation of U.S. application Ser. No. 14/287,255 filed May 27, 2014, entitled OVERCURRENT PROTECTION DEVICE AND OVERCURRENT PROTECTION METHOD FOR ELECTRONIC MODULES, the benefit of the filing date of which is hereby claimed and the disclosure of which is hereby expressly incorporated by reference herein in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present application relates to a field of electronic circuits, and more particularly, to an overcurrent protection device for electronic modules and a correspond overcorrect protection method. 
       BACKGROUND 
       [0003]    Electronic modules such as a voltage converter, a power amplifier, a monitor or the like exist in various electronic apparatus, such as tablet computers, smart phones, music players etc., and each electronic module has a rated current When the current flowing in the electronic module exceeds the rated current, the electronic module will be burned out and cannot work. Therefore, it is necessary to set an overcurrent protection device in the electronic module so as to protect the entire electronic module when the current flowing through it is too large. 
         [0004]    The various electronic modules require a power source to supply power so that they can work. Conventional overcurrent protection devices can achieve overcurrent protection by disconnecting the electronic module from the power source. However, cutting off the power supply of the electronic module may cause disturbance of its operation, and it is difficult to restart the operation of the electronic module, which may affect operations of other modules or electronic circuits associated with the electronic module. 
         [0005]    Moreover, in the conventional overcurrent protection devices, overcurrent protection can also be achieved by controlling an internal current of the electronics module. However, it is difficult to effectively perform overcurrent protection in some cases. Discussion is provided below with the electronic module being a boost converter as example. 
         [0006]    The boost converter serves for converting a specific DC input voltage Vin to a larger output voltage Vout so as to supply power to a function module in the electronic apparatus. In the operation process of the boost converter, the input electricity is temporarily stored in an electricity storage element such as an inductor, a capacitor and others (i.e., performing a charging process), and then the electricity is released at an output terminal with different voltages (i.e., performing a discharging process so that the input voltage Vin is converted to the desired output voltage Vout. The boost converter includes a control element such as a switch, and the control element is driven by a driving signal to control the charging and discharging process. When the current in the boost converter is too large, the overcurrent protection device drives the control element to only discharge, not charge, so as to expect a gradual decrease in the current of the storage device in the discharge process. 
         [0007]    The overcurrent protection device in the above boost converter can protect the voltage converter well when the output voltage Vout is significantly greater than the input voltage Vin. However, when the output voltage Vout is close to the input voltage Vin, or when the load driven by the boost converter is too heavy and the output voltage Vout is caused to be lower than the input voltage Vin, the current reduction amount on the electricity storage element will be very small, even negative, i.e., it shows as a current increase on the electricity storage element. This can be seen from the following Equation (1) 
         [0000]    
       
         
           
             
               
                 
                   
                     Δ 
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                       I 
                       LD 
                     
                   
                   = 
                   
                     
                       
                         - 
                         
                           
                             
                               V 
                                
                               
                                   
                               
                                
                               out 
                             
                             - 
                             
                               V 
                                
                               
                                   
                               
                                
                               in 
                             
                           
                           L 
                         
                       
                       · 
                       T 
                     
                      
                     
                         
                     
                      
                     off 
                   
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   
                     ( 
                     1 
                     ) 
                   
                 
               
             
           
         
       
     
         [0000]    where ΔI LD  is a current reduction amount on the electricity storage element, Vout is an output voltage of the boost converter, Vin is an input voltage of the boost converter, L is an inductance value of an inductor that serves as the electricity storage element, and Toff is a turn-off time during which the control element controls the electricity storage element to discharge. It can be known from to Equation (1) that, when the output voltage Vout is close to the input voltage Vin, the current decrease on the electricity storage element current is very small; when the output voltage Vout is lower than the input voltage Vin, the current decrease on the storage device is negative. Therefore, even if the overcurrent protection device detects that the current in the boost converter is too large and turns off the control element to control the current in the boost converter, it is still hard to effectively reduce the current therein so as to perform overcurrent protection on the boost converter. Here, failure of the overcurrent protection device is described with the overcurrent protection device in the boost converter as an example, there are similar problems in electronic modules having a power input such as an amplifier, a monitor etc. 
       SUMMARY 
       [0008]    Aspects of the present application may relate to an overcurrent protection device, an electronic module (e.g., a voltage converter) including the overcurrent protection device, and a method for overcurrent protection. 
         [0009]    The electronic module to which the overcurrent protection device of the present application is applied may include: an electricity storage unit for temporarily storing input electricity and being capable of releasing the stored electricity through an electricity transmission path; an electricity storage control unit for controlling storage and release of electricity in the electricity storage unit. The electronic module for example is a boost converter, an amplifier, a monitor etc., the electricity storage unit for example is an inductor in the boost converter, a charge pump in the amplifier etc. 
         [0010]    The overcurrent protection device of the present application can detect an overcurrent event that occurs in the electronic module, and enable overcurrent protection when it detects an overcurrent event. When an overcurrent event occurs, the overcurrent protection device of the present application not only can control the electricity storage unit to no longer store the input electricity through the electricity storage control unit, but also set an electricity consumption unit on the electricity transmission path on which the electricity storage unit releases electricity, and use it to consume electricity stored in the electricity storage unit, thereby reducing the current flowing in the electronic module and achieving overcurrent protection. The electricity consumption unit set on the electricity transmission path may be a specifically set resistor, and may also be implemented by an electronic element already existing in the electronic module. 
         [0011]    By utilizing the overcurrent protection device of the present application, it is possible to effectively carry out overcurrent protection on the electronic module, rather than being limited by the operation state of the electronic module. For example, even if the output voltage in the boost converter is close to or less than the input voltage, the current in the boost converter can also be reduced effectively, thus implementing overcurrent protection. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    In order to more clearly explain the technical solution, drawings referenced in the description of embodiments or conventional technologies are briefly introduced below. The drawings described below are merely some embodiments of the present invention, a person of ordinary skill in the art can also obtain other drawings according to these drawings. Identical reference numerals typically indicate identical components throughout these drawings. 
           [0013]      FIG. 1  schematically illustrates a block diagram of the overcurrent protection device in the present application; 
           [0014]      FIG. 2  schematically illustrates an application example of the overcurrent protection device of the present application in an asynchronous boost converter; 
           [0015]      FIG. 3  schematically illustrates a circuit diagram of an overcurrent detection unit in the overcurrent protection device in  FIG. 2 ; 
           [0016]      FIG. 4  schematically illustrates an application example of overcurrent protection device of the present application in a synchronous boost converter; 
           [0017]      FIG. 5  illustrates a schematic diagram of the relationship between a gate-source voltage of the of triode and a drain current thereof in  FIG. 4 ; 
           [0018]      FIGS. 6( a ) and 6( b )  schematically illustrate a circuit diagram of a clamping unit in the overcurrent protection device shown in  FIG. 4 ; 
           [0019]      FIG. 7  schematically illustrates a circuit diagram of a second driving unit in the overcurrent protection device shown in  FIG. 4 ; 
           [0020]      FIG. 8  illustrates a schematic waveform of performing overcurrent protection by the overcurrent protection device in  FIG. 4  in the synchronous boost converter; and 
           [0021]      FIG. 9  illustrates a flowchart of an exemplary overcurrent protection method in the present application. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    The overcurrent protection device and the electronic module including the overcurrent protection device described herein can be realized in a variety of electronic apparatuses, which may include, but not are limited to, an electronic product, a portion of an electronic product, an electronic test equipment etc. The electronic product may include, but is not limited to, a smart phone, a TV, a tablet computer, a monitor, a personal digital assistant, a camera, an audio player, a memory etc. A portion of the consumer electronic product may include a multi-chip module, a power amplifier module, a voltage converter etc. 
         [0023]      FIG. 1  schematically illustrates a block diagram of the overcurrent protection device  100  in the present application. 
         [0024]    As shown in  FIG. 1 , an electronic module to which the overcurrent protection device  100  is applied may include: an electricity storage unit  10  for temporarily storing input electricity and being capable of releasing the stored electricity through an electricity transmission path; an electricity storage control unit  20  for controlling a storage and a release of electricity in the electricity storage unit  10 . The electronic module including the electricity storage unit  10  and the electricity storage control unit  20  for example is a boost converter, an amplifier etc. The power transmission path is a path on which the electricity of the electricity storage unit  10  is released. As an example, in the voltage converter, the power transmission path is a path between the electricity storage unit  10  and a port of outputting voltage, and the port of outputting voltage serves for supplying power to load of the voltage converter; in the amplifier, the electricity transmission path is a circuit path connected with an output of a charge pump. The boost converter, amplifier, etc. provided herein are merely examples of the electronic module to which the overcurrent protection device is applied, any electronic module including an electricity storage unit and an electricity storage control unit may adopt the overcurrent protection device in the present application. 
         [0025]    The electricity storage control unit  20  controls the electricity storage unit  10  to receive input electricity from an input terminal Sin and temporarily store the input electricity in the electricity storage unit  10 , correspondingly, the current that flows through the electricity storage unit  10  increases gradually; thereafter, the electricity storage control unit  20  controls the electricity storage unit  10  to release the stored electricity through the electricity transmission path. Thus, when accumulation of electricity is excessive in the electricity storage unit  10 , the output current will be extremely large, which will destroy the electricity storage unit  10 , the electricity storage control unit  20 , and other electronic elements connected with the electricity storage unit  10  in the electricity transmission path. The electricity storage unit  10  for example is an inductor in the boost converter, a charge pump in the amplifier etc., and the electricity storage control unit  20  for example is a control switch in the boost converter, a control element for controlling the charge pump in the amplifier etc. 
         [0026]    In  FIG. 1 , only units or sections in the electronic module that are directly associated with overcurrent protection device  100  are illustrated. In practice, the electronic module may also include other units or sections, for example, the voltage converter may further include a feedback unit for performing feedback control based on an output voltage, a voltage stabilizing unit for stabilizing the output voltage, and a driving unit for driving the electricity storage control unit  20  etc. Units or sections included by an individual electronic module will vary depending on a different function of the electronic module. 
         [0027]    As shown in  FIG. 1 , the overcurrent protection device  100  of the present application may include: an overcurrent detection unit  110  for determining whether an overcurrent event occurs in the electronic module, outputting an overcurrent indication signal OCE indicative of whether an overcurrent event occurs, and supplying the overcurrent indication signal OCE to the electricity storage control unit  20  so as to control the electricity storage unit  10  to release electricity when an overcurrent event occurs; an electricity consumption unit  120  removably connected in the electricity transmission path and consuming electricity that passes through the electricity transmission path while being connected in the electricity transmission path; an overcurrent control unit  130  for controlling connection of the electricity consumption unit  120  in the electricity transmission path based on the overcurrent indication signal OCE. 
         [0028]    The overcurrent detection unit  110  can for example detect a current output from the electricity storage unit  10  of the electronic module, and determine whether an overcurrent event occurs in the electronic module by comparing the current output from the electricity storage unit  10  with a preset current threshold. Typically, when the current output from the electricity storage unit  10  is greater than or equal to the preset current threshold, it is determined that an overcurrent event occurs in the electronic module; when the current output from the electricity storage unit  10  is less than the preset current threshold, it is determined that no overcurrent event occurs in the electronic module. Alternatively, the overcurrent detection unit  110  can also detect voltage in the electricity transmission path, and determine whether an overcurrent event occurs in the electronic module by comparing the detected voltage with a preset voltage threshold. Various ways may be adopted for different electronic modules to determine whether an overcurrent event occurs therein, specific determination ways do not constitute a limitation to the embodiments of the present application. 
         [0029]    The electricity consumption unit  120  can be outside the electricity transmission path when no overcurrent event occurs, and be connected in the electricity transmission path to consume electricity when an overcurrent event occurs. As an example, the electricity consumption unit may be a resistor, a load that consumes electricity, and so on. Any element that consumes electricity may be used as the electricity consumption unit  120 . 
         [0030]    When the overcurrent indication signal OCE output by overcurrent detection unit  110  indicates that an overcurrent event occurs, the overcurrent detection unit  110  supplies the overcurrent indication signal OCE to the electricity storage control unit  20  to control the electricity storage unit  10  to release electricity and no longer receive more electricity from the input terminal Sin. 
         [0031]    When the overcurrent indication signal OCE output by overcurrent detection unit  110  indicates that an overcurrent event occurs, the overcurrent control unit  130  controls to connect the electricity consumption unit  120  in the electricity transmission path in order to consume electricity and thereby avoid a continued increase of the current output by the electricity storage unit, and accordingly protect the electricity storage unit  10  and the electricity storage control unit  20  and electronic elements in the electricity release path from being destroyed. For example, the overcurrent control unit  130  may control to attach the electricity consumption unit  120  in the electricity transmission path as a bypass unit, such that when no overcurrent event occurs, current of the electricity storage unit  10  directly passes through the electricity transmission path without passing through the electricity consumption unit  120 , and when an overcurrent event occurs, the electricity consumption unit  120  is made to reside in the electricity transmission path to consume electricity. 
         [0032]    In the overcurrent protection device  100  described in conjunction with  FIG. 1 , when an overcurrent event occurs, as compared with a configuration where only the electricity storage unit  10  no longer stores the input electricity in the conventional technology, the electricity consumption unit is further provided on the electricity transmission path where the electricity storage unit  10  releases electricity, and electricity stored in the electricity storage unit  10  is consumed by using the electricity consumption unit, which gradually reduces the current flowing in the electronic module and thereby achieves overcurrent protection. 
         [0033]      FIG. 2  schematically illustrates an application example of the overcurrent protection device  200  of the present application in an asynchronous boost converter.  FIG. 2  shows the overcurrent protection device  200  in the present application and a device in the asynchronous boost converter and connected with the overcurrent protection device  200 . 
         [0034]    As shown in  FIG. 2 , the electricity storage unit  10  in  FIG. 1  is formed by using an inductor L connected to a port that inputs voltage Vin. A triode T N  and a first driving unit for the triode T N  are used as an electricity storage control unit  20  for controlling the inductor L. The electricity transmission path having a diode D thereon is formed between the inductor L and a port that outputs voltage Vout. Further, the asynchronous boost converter further includes a capacitor C used for stably outputting the output voltage Vout. 
         [0035]    During a charging process, the triode T N  is turned on under control of the first driving unit, i.e., a short circuit is formed between the inductor L and the ground to produce current. The diode D is turned off because voltage at its input is lower than voltage at its output, i.e., an open circuit is formed between a connection point (i.e., point SW in  FIG. 2 ) of the inductor L and the triode T N  and the port that outputs voltage, and the capacitor C is prevented from discharging to ground. Since the input voltage Vin is a direct current, induction current in the inductor L increases at a constant rate, and as the induction current increases, electricity is stored in the inductor L. 
         [0036]    During a discharging process, the triode T N  is turned off under control of the first driving unit, i.e., an open path is formed between the inductor L and the ground; the diode D is turned on because the voltage at its input is higher than voltage at its output, i.e., a short circuit is formed between the point SW in  FIG. 2  and the port that outputs voltage. Because of a holding characteristic of the induction current, the current that passes through the inductor L will slowly decrease from a value when the charging is completed, until a next charging process starts or the current value drops to zero. The voltage between two ends of the capacitor C increases, and boosting conversion is achieved. 
         [0037]    A resistor R and a switch S of the overcurrent protection device  200  in  FIG. 2  correspond to the electricity consumption unit  120  and the overcurrent control unit  130  of the overcurrent protection device  100  in  FIG. 1 , respectively. That is to say, the electricity consumption unit  120  and the overcurrent control unit  130  in  FIG. 1  are implemented by using the resistor R and the switch S, respectively. 
         [0038]    As shown  FIG. 2 , the overcurrent protection device  200  comprises: an overcurrent detection unit  110  for determining whether an overcurrent event occurs in the electronic module based on the current in the inductor L (e.g., current at the point SW in  FIG. 2 ), outputting an overcurrent indication signal OCE indicating whether an overcurrent event occurs, and supplying the overcurrent indication signal OCE to the first driving unit to control the inductor L to discharge via the triode T N ; a resistor R removably connected in the electricity transmission path and consuming electricity that passes through the electricity transmission path while being connected in the electricity transmission path; a switch S for opening when the overcurrent indication signal OCE indicates that an overcurrent event occurs, and connecting the resistor R in the electricity transmission path to consume electricity. Further, when the overcurrent indication signal OCE indicates that no overcurrent event occurs, the switch S is closed, and a short circuit is formed thereby excluding the resistor R from the electricity transmission path. 
         [0039]      FIG. 3  schematically illustrates a circuit diagram of an overcurrent detection unit  110  in the overcurrent protection device  200  in  FIG. 2 . As shown in  FIG. 3 , current at the point SW in  FIG. 2  is sensed by a current sensor, and converted to a sensed voltage Vsense to be output. The sensed voltage Vsense is compared with a preset reference voltage Vref by a comparator CMP, and then logical operations are performed on a comparison result of the comparator CMP and a clock signal CLK by using three “NOR” gates NOR 1 , NOR 2 , NOR 3 , so as to obtain the overcurrent indication signal OCE. When the sensed voltage Vsense is less than the reference voltage Vref, an overcurrent signal OCE which is a high signal is output when the clock signal CLK is at a rising edge to indicate that no overcurrent event occurs; when the sensed voltage Vsense is greater than or equal to the reference voltage Vref, an overcurrent indication signal OCE which is a low signal is output when the clock signal CLK is at a rising edge to indicate that an overcurrent event occurs. As described above, different modes may be adopted for different electronic modules to determine whether an overcurrent event occurs therein, and specific determination ways do not constitute a limitation to the embodiments of the present application. 
         [0040]    When the overcurrent indication signal OCE output by overcurrent detection unit  110  indicates that an overcurrent event occurs, the overcurrent indication signal OCE is supplied to the first driving unit, which drives the triode T N  to control the inductor L to release electricity and no longer receive more electricity from the input terminal, and to control the switch S to open and connect the resistor R in the electricity transmission path in order to consume electricity and thereby avoid a continued increase of the current output by the inductor L, and accordingly protect the inductor L, the triode T N , the diode D, and the load powered by the output voltage \Tout from being destroyed. Here, the resistor R is only schematic, a light emitting element or the like may also be employed as the electricity consumption unit, thus prompting occurrence of an overcurrent event while consuming electricity. 
         [0041]    When the overcurrent indication signal OCE output by overcurrent detection unit  110  indicates that no overcurrent event occurs, the first driving unit normally drives the triode T N  to control the inductor L to discharge or charge, the switch S is in a closed state, and correspondingly the two ends of the resistor R is made a short circuit, so that the resistor R is excluded from the electricity transmission path in the boost converter, and the normal operation of the boost converter will not be affected. 
         [0042]    In the overcurrent protection device  200  described in conjunction with  FIG. 2 , when an overcurrent event occurs, as compared with a configuration where only the inductor L is controlled to no longer store the input electricity in the conventional technology, the resistor R is further provided on the electricity transmission path where the inductor L releases electricity, and electricity stored in the electricity storage unit  10  is also consumed by the resistor R. In this case, even if the output voltage in the boost converter is dose to or less than the input voltage, the resistor R can also be used to effectively reduce the current in the boost converter and achieve overcurrent protection. 
         [0043]      FIG. 4  schematically illustrates an application example of overcurrent protection device of the present application in a synchronous boost converter.  FIG. 4  shows the overcurrent protection device  400  in the present application and an element in the synchronous boost converter which is connected to the overcurrent protection device  400 . 
         [0044]    The inductor L, the triode T N , the first driving unit for the triode T N , and the capacitor C in the synchronous boost converter in  FIG. 4  are the same as the inductor L, the triode T N , the first driving unit for the triode T N , and the capacitor C in the asynchronous booster converter in  FIG. 2 , respectively. The synchronous boost converter in  FIG. 4  differs from the asynchronous boost converter in  FIG. 2  in that: the diode D in  FIG. 2  is replaced with the triode T p  in  FIG. 4 , and the triode T p  is driven by a second driving unit, which serves for generating a high signal or a low signal to cause the triode T N  to turn on or turn off. In addition, the overcurrent protection device  400  in  FIG. 4  also differs in operation as described herein from the overcurrent protection device  200  in  FIG. 2 . 
         [0045]    The charging process and the discharging process of the synchronous boost converter in  FIG. 4  are similar to those of the asynchronous boost converter in  FIG. 2 , respectively, which are briefly described below. 
         [0046]    During a charging process, the triode T N  is turned on under control of the first driving unit, i.e., a short circuit is formed between the inductor L and the ground to produce induction current, and the triode T p  is turned off under driving of the second driving unit to yield an open path formed between the inductor L and a port that outputs the voltage Vout. Since the input voltage Vin is a direct current, induction current in the inductor L increases at a constant rate, and as the induction current increases, electricity is stored in the inductor L. 
         [0047]    During a discharging process, the triode T N  is turned off under control of the first driving unit, i.e., an open path is formed between the inductor L and the ground, and the triode T p  is turned on under driving of the second driving unit, i.e., a short circuit is formed between the inductor L and a port that outputs the voltage Vout. Because of the holding characteristic of the induction current, the current that passes through the inductor L will slowly decrease from a value when the charging is completed, and the voltage between two ends of the capacitor C increases correspondingly, that is, boosting conversion is achieved. 
         [0048]    A clamping unit  131  of the overcurrent protection device  400  in  FIG. 4  corresponds to the overcurrent control unit  130  of the overcurrent protection device  100  in  FIG. 1 . In addition, in  FIG. 4 , the electricity consumption unit  120  is not specifically set in the overcurrent protection device  400 . Instead the triode T p  in the synchronous boost converter is used for consuming electricity in the electricity transmission path when an overcurrent event occurs. That is to say, the electricity consumption unit  120  and the overcurrent control unit  130  in  FIG. 1  correspond to the triode T p  and the clamping unit  131  in the overcurrent protection device  400  of  FIG. 4 , respectively. In  FIG. 4 , the triode T N  is an N-type triode, the triode T p  is a P-type triode, which are just examples. Other types of triode may be used as the triodes T N  and T p , the specific type of each triode does not constitute a limitation to the embodiments of the present application. 
         [0049]    As shown in  FIG. 4 , the overcurrent protection device  400  may include: an overcurrent detection unit  110  for determining whether an overcurrent event occurs in the synchronous boost converter based on the current in the inductor L (e.g., current at point SW in  FIG. 4 ), outputting an overcurrent indication signal OCE indicating whether an overcurrent event occurs, and supplying the overcurrent indication signal OCE to the first driving unit to control the inductor L to discharge via the triode T N ; a triode T p  whose source and drain are connected in the electricity transmission path, and whose gate is connected to a second driving unit; a clamping unit  131  for clamping the gate of the triode T p  at a predetermined voltage when the overcurrent indication signal OCE indicates that an overcurrent event occurs and thereby increasing a resistance value of the triode T p  so as to consume the electricity in the electricity transmission path. The predetermined voltage may be the input voltage Vin, or a predetermined value smaller than the input voltage Vin. When the overcurrent indication signal OCE indicates that no overcurrent event occurs, the clamping unit  131  does not clamp the gate of the triode T p , and the triode T p  operates normally as a triode in the synchronous boost converter. The overcurrent detection unit  110  in  FIG. 4  is the same as that described in the above in conjunction with  FIGS. 1-3 , an thus no details are repeated here. 
         [0050]    Principle of clamping the gate of the triode T p  at the predetermined voltage to increase the resistance value of the triode T p  will be described below in conjunction with  FIG. 5 .  FIG. 5  illustrates a schematic diagram of the relationship between a gate-source voltage Vsg of the triode T p  and a drain current Id thereof in  FIG. 4 . 
         [0051]    In  FIG. 5 , horizontal axis represents the source-gate voltage Vsg of the triode T p , longitudinal axis represents the drain current Id thereof. Curves  1  and  2  in  FIG. 5  show the source-gate voltage Vsg and the drain current Id when the source-drain voltage Vsd are at Vsd 1  and Vsd 2  (Vsd 1  is greater than Vsd 2 ), respectively. When the gate of the triode T p  is clamped at the predetermined voltage, the gate voltage of the transistor is promoted, the source-gate voltage Vsg decreases, the source-drain voltage Vsd at the same drain current Id increases, and correspondingly, the resistance value of the triode T p  increases. 
         [0052]    It can be seen from the illustration of  FIG. 5  that, when the predetermined voltage at which the gate (i.e., point Pgate in  FIG. 4 ) of the triode T p  is clamped varies, i.e. the clamping voltage varies, the resistance value of the triode T p  changes correspondingly. The higher the clamping voltage is, the greater the resistance value of the triode T p  is; the lower the clamping voltage is, the smaller the resistance value of the triode T p  is. When the resistance value of the triode T p  s large, overcurrent protection can be achieved quickly. 
         [0053]    In order to facilitate the achievement, the gate of the triode T p  may be clamped at the input voltage Vin of the synchronous boost converter, and in such a configuration, it is not necessary to provide other supply voltages to the synchronous boost converter. In addition, the gate of the triode T p  may be clamped at a preset voltage lower than the input voltage Vin. 
         [0054]      FIGS. 6( a ) and 6( b )  schematically illustrate a circuit diagram of the clamping unit  131  in the overcurrent protection device shown in  FIG. 4 . 
         [0055]    In  FIG. 6( a ) , the clamping unit  131  includes series-connected triodes T 1  and T 2 , wherein the source of the triode T 1  is connected to the input voltage Vin, the gate of the triode T 1  is connected to its drain, and connected to the source of the triode T 2 , the drain of the triode T 2  is connected to the gate (point Pgate in  FIG. 4 ) of the triode T p , i.e., drain voltage of the triode T 2  is equal to gate voltage Vg of the triode T p , and the gate of the triode T 2  is turned on or turned off under the driving of the overcurrent indication signal OCE. When the overcurrent indication signal OCE is enabled, the triode T 2  is turned on, the source-gate voltage Vsg of the triode T 1  is equal to its source-drain voltage Vsd, the gate voltage Vg of the triode T p  is equal to the input voltage Vin minus the source-gate voltage Vsg of triode T 1 . When the overcurrent indication signal OCE is disabled, the triode T 2  is turned off, an open circuit is formed between the gate of the triode T p  and the input voltage Vin, so as to not clamp the gate voltage of the triode T. 
         [0056]    In  FIG. 6( b ) , the clamping unit  131  includes a triode T 3 , whose source is connected to the input voltage Vin and whose drain is connected to the gate of the triode T p , the gate of the triode T 3  can be turned on or turned off under the driving of the overcurrent indication signal OCE. When the overcurrent indication signal OCE is enabled, the triode T 3  is turned on, the drain voltage of the triode T 3  is equal to the input voltage Vin, i.e., the gate voltage Vg of the triode T p  is clamped at the input voltage Vin. When the overcurrent indication signal OCE is disabled, the triode T 3  is turned off, an open path is formed between the gate of the triode T p  and the input voltage Vin, so as to not clamp the gate voltage of the triode T p . 
         [0057]    The second driving unit may be made to output a high level consistently while the clamping unit  131  clamps the gate voltage of the triode T p , in this case, the clamping voltage of the gate of the triode T p  will be affected by the high level output by the second driving unit. Alternatively, the second driving unit may be made to disconnect the gate of the triode T p , so as to clamp the gate voltage Vg of the triode T p  at a desired voltage. 
         [0058]    As an example of disconnecting the second driving unit with the gate of triode T p , it is possible to set a switch driven by using the overcurrent indication signal OCE between the traditional second driving unit and the gate of the triode T p . When the overcurrent OCE signal indicates that no overcurrent event occurs, the switch is in a closed state, the second driving unit drives the triode T p  to turn on or turn off in the traditional way; when the overcurrent indication signal OCE indicates an overcurrent event occurs, the OCE overcurrent indication signal drives the switch to open, so that an open path is formed between the second driving unit and the gate of the triode T p . Alternatively, the second driving unit may be also made to present a high impedance with respect to the gate of the second triode when the overcurrent indication signal OCE indicates that an overcurrent event occurs, which will be described in conjunction with  FIG. 7 . 
         [0059]      FIG. 7  schematically illustrates a circuit diagram of a second driving unit in the overcurrent protection device shown in  FIG. 4 . In  FIG. 7 , the second driving unit receives the overcurrent indication signal OCE and a control signal Sc for instructing the triode T p  to turn on or turn off. Inverters (INV 1 -INV 7 ), “NOR” gates (NOR 4 , NOR 5 ), AND gates (AND 1 , AND 2 ) are used for performing logic operations on the overcurrent indication signal OCE and the control signal Sc, and a driving signal is output through a triode T 4  and a triode T 5 .  FIG. 7  shows specific example of a connection relationship. When the overcurrent indication signal OCE indicates that no overcurrent event occurs, the triode T 4  and the triode T 5  in  FIG. 7  output  0  or  1  under control of the control signal Sc, for example, when the triode T 4  turns off and the triode T 5  turns on under action of the control signal Sc, the second driving unit in  FIG. 7  outputs a driving signal “ 0 ” to cause the triode T p  to turn off; when the triode T 4  turns on and the triode T 5  turns off under action of the control signal Sc, the second driving unit in  FIG. 7  outputs a driving signal “ 1 ” to turn on the triode T p . When the overcurrent indication signal OCE indicates that an overcurrent event occurs, both the triode T 4  and triode T 5  in  FIG. 7  turn off under action of the overcurrent indication signal OCE, output of the second driving unit is a high impedance, which does not affect the clamping voltage at the gate of triode T p . 
         [0060]    In addition, the synchronous boost converter may also adopt the structure of the overcurrent protection device  200  shown in  FIG. 2 . In this case, the second driving unit drives the triode T p  in a conventional manner, the overcurrent detection unit  110  supplies the overcurrent indication signal OCE to the switch S to control whether to consume electricity on the electricity transmission path by the resistor R. 
         [0061]      FIG. 8  illustrates a schematic waveform of performing overcurrent protection by the overcurrent protection device in  FIG. 4  in the synchronous boost converter. In  FIG. 8 , horizontal axis represents time, longitudinal axis in  FIG. 8( a )  represents voltage, and  FIG. 8( a )  shows curves of the input voltage Yin and the output voltage \Tout; longitudinal axis in FIG.  8 ( b ) represents current, and  FIG. 8( b )  shows a curve of current of a load supplied by the output voltage Vout; longitudinal axis of  FIG. 8( c )  represents voltage of the overcurrent indication signal OCE output by the overcurrent detection unit  110 , wherein when the overcurrent indication signal OCE appears as a low value, it indicates that an overcurrent event occurs; longitudinal axis of  FIG. 8( d )  represents voltage, and  FIG. 8( d )  shows a curve of voltage at the point SW in  FIG. 4 , which reflects a switching frequency of the synchronous boost converter. As can be seen, when an overcurrent event occurs as the input voltage Vin is close to the output voltage Vout, the output voltage Vout and load current can be reduced effectively by the overcurrent protection device of the present application, thus overcurrent protection is achieved (as shown by the ellipse blocks in  FIGS. 8( a ) and 8( b ) ). 
         [0062]    From the description provided above with reference to  FIGS. 4-8  it can be known that, when an overcurrent event occurs, as compared with a configuration where only the inductor L is controlled to no longer store the input electricity in the conventional technology, an existing triode of the synchronous boost converter is also used for forming an electricity consumption element to consume electricity stored in the inductor L in the electricity transmission path. Even if the output voltage in the synchronous boost converter is close to or less than the input voltage, the electricity consumption element formed by the triode can also be used for effectively reducing the current in the boost converter and achieve overcurrent protection. 
         [0063]      FIG. 9  illustrates a flowchart of an example overcurrent protection method  900  in the present application. The overcurrent protection method  900  may be used for the electronic module as follows and electronic apparatus including the electronic module. The electronic module may include: an electricity storage unit for temporarily storing input electricity and capable of releasing the stored electricity through an electricity transmission path; and an electricity storage control unit for controlling storage and release of electricity in the electricity storage unit. The electronic module for example is a voltage converter, an amplifier, a monitor, etc., and any electronic module including the electricity storage unit and the electricity storage control unit may adopt the overcurrent protection device of the present application. In addition, the electronic module may also include other units or sections, for example, the voltage converter may further include a feedback unit for performing feedback control based on an output signal, a voltage stabilizing unit for stabilizing an output voltage, and a driving unit for driving the electricity storage control unit etc. 
         [0064]    As shown in  FIG. 9 , the overcurrent protection method  900  for the electronic module may comprise: determining whether an overcurrent event occurs in the electronic module, and generating an overcurrent indication signal OCE indicative of whether the overcurrent event occurs (S 910 ); supplying the overcurrent indication signal OCE to the electricity storage control unit for controlling the electricity storage unit to release electricity when the overcurrent event occurs (S 920 ); setting an electricity consumption unit removably connected in the electricity transmission path and capable of consuming electricity that passes through the electricity transmission path while being connected in the electricity transmission path (S 930 ); and controlling connection of the electricity consumption unit in the electricity transmission path based on the overcurrent indication signal OCE (S 940 ). 
         [0065]    When the overcurrent indication signal OCE generated in S 910  indicates that an overcurrent event occurs, the electricity storage control unit controls the electricity storage unit to release electricity and no longer receive more electricity in S 920 , the power consumption unit is connected in the electricity transmission path in S 930  and S 940  in order to consume electricity, thereby avoiding a continued increase of the current output by the electricity storage unit, and accordingly protect the electricity storage unit and the electricity storage control unit and electronic elements in the electricity release path from being destroyed. 
         [0066]    In S 930  a resistor may be provided in the electricity transmission path as the electricity consumption unit, with a switch connected in parallel with the resistor being set therein, change of the operating state of the switch can cause the resistor to reside in the electricity transmission path or be excluded from the electricity transmission path. In particular, when the overcurrent indication signal OCE indicates that an overcurrent event occurs, the switch connected in parallel with the resistor is opened in S 940 , correspondingly, the resistor resides in the electricity transmission path to consume electricity; when the overcurrent indication signal OCE indicates that no overcurrent event occurs, the switch in parallel with the resistor is closed in S 940  to form a short circuit, the resistor is excluded from the power transmission path. 
         [0067]    Further, in the case that there is a triode (e.g., the triode T p  in  FIG. 4 ) in the electricity transmission path, the electricity consumption unit may be implemented by using the triode in S 930 , without the need to set an electricity consumption unit specifically. Accordingly, in S 940 , the gate of the triode in the electricity transmission path is clamped at a high voltage, so that the triode presents resistive properties, and consumes electricity in the electricity transmission path. The high voltage may be the input voltage in the boost converter or a predetermined voltage lower than the input voltage. For more flexibility clamping the gate of the triode at a desired high voltage, the gate of the triode may be disconnected with its driving signal when an overcurrent event occurs. Disconnection of the gate of the triode and its driving signal may be implemented via a switch, or may also be implemented by causing the driving unit for generating the driving signal to generate a high output impedance. 
         [0068]    In the overcurrent protection method of the present application, when an overcurrent event occurs, the electricity consumption unit is further provided on the electricity transmission path where the electricity storage unit releases electricity, and electricity stored in the electricity storage unit is also consumed by the electricity consumption unit, thus reducing the current flowing through the circuit module and achieving overcurrent protection. Even if the output voltage in the boost converter is close to or less than the input voltage, the electricity consumption unit can also be used for effectively reducing the current in the boost converter and achieving efficient overcurrent protection. 
         [0069]    In the various examples described herein, references are made to triodes. It will be understood that such triodes can include transistors such as field-effect transistors (FETs). Such FETs can include, for example, MOSFET devices and/or transistors implemented in other process technologies. Other types of transistors can be utilized to implement one or more features of the present disclosure. 
         [0070]    Those skilled in the art can understand, for convenience and simplicity of the description, as for specific implementations of the method embodiments described above, corresponding process in the preceding product embodiments can be implemented. 
         [0071]    Those with ordinary skill in the art can appreciate that, devices and algorithm steps described with reference to the embodiments disclosed in this document may be implemented through electronic hardware, or a combination of the electronic hardware and software,. As for each specific application, a person skilled in the art can use different methods to implement the described functions, but such implementations should not be construed as being beyond the scope of the present invention. 
         [0072]    Principles and advantages of technical solutions described above are applicable to any system and module that require overcurrent protection. The system and module having the overcurrent protection can be realized in a variety of electronic apparatuses, which may include, but not are limited to, an electronic product, a portion of an electronic product, an electronic test equipment etc. The consumer electronic product may include, but is not limited to, a smart phone, a TV, a tablet computer, a monitor, a personal digital assistant, a camera, an audio player, a memory etc. A portion of the consumer electronic product may include a multi-chip module, a power amplifier module, a voltage converter etc. 
         [0073]    The above described are only specific implementations of the present technical solution, but the scope of the present technical solution is not limited thereto, and any alternatives and equivalents that can be conceivable by a person skilled in the art should be encompassed within the scope of protection of the present technical solution.