CN1972066A - Charging protection circuit - Google Patents

Abstract

The invention provides a charging protection circuit connected between a charging power supply and a battery, which is used for performing multiple protection of current limitation, overcurrent and overvoltage when the battery is charged. The charging protection circuit is provided with a fuse, an adapter and an overcurrent protector, wherein the fuse is used for transmitting current for charging the battery, the adapter can control the overcurrent protector according to the magnitude of the charging current, if the charging current is too large due to the short circuit of the battery, the adapter can start the overcurrent protector, and the overcurrent protector can conduct extra current on the fuse to accelerate the fuse to be melted down, so that the battery and a charging power supply can be quickly disconnected, and the overlarge charging current can not be fed into the battery. The charging protection circuit can realize current limiting and overvoltage protection by matching with related voltage limiters and current limiters.

Description

charging protection circuit

technical field

The invention relates to a charging protection circuit, in particular to a charging protection circuit capable of strengthening the overcurrent protection mechanism of a fuse with an electronic circuit.

Background technique

With the advancement of electrical and electronic technology, the volume and weight of many electronic devices have been greatly reduced to the extent that they can be carried around. Electronic devices such as mobile phones, personal digital assistants (PDAs, personal digital assistants), digital cameras, portable audio-visual playback devices (such as walkmans) and portable computers have been widely used by the public. In order to achieve portability, most of these portable electronic devices need to be powered by power storage components such as batteries; and to maintain continuous operation of these electronic devices, it is necessary to charge the batteries in the electronic devices. For example, mobile phones can often be equipped with a charging stand to charge the battery in the mobile phone; the charging stand can convert household AC power into DC charging power, and the charging current of this DC charging power can be transmitted to the mobile phone through the mobile phone battery, charge the battery.

However, in the process of charging the battery of an electronic device, the battery often fails and short-circuits due to various factors, and then leaks a large amount of charging current to the charging power source, and this excessive charging current can easily cause the battery to melt and burn. , or even explode; lightly damage the electronic device, and seriously injure the user. For example, the battery in a mobile phone may be short-circuited due to factors such as corrosion and moisture of the metal conductive part, the battery does not meet the specifications, the user incorrectly connects the battery polarity, and the internal circuit of the battery is damaged. Endangering the safety of mobile phones and users.

In the current prior art, fuses are used in the mobile phone to implement an over current protection (over current protection) mechanism during charging, so as to prevent the danger caused by the above-mentioned battery failure/short circuit. Under this prior art, a fuse is provided inside the mobile phone, and the fuse is electrically connected between the charging power source and the battery to transmit charging current to the battery during charging. When the charging current is too large (greater than the rated charging current), the fuse will gradually melt down; when the fuse is blown, the battery will be separated from the charging power source and the circuit will be broken.

Yet above-mentioned prior art also has shortcoming; One of main shortcoming is exactly that fuse melts down and needs considerable time, can't carry out quick response at once when charging current is too big, also just can't immediately connect battery with electric current too big. The charging power supply is disconnected. When the fuse starts to melt but is not blown, the battery will still conduct a large amount of current at the charging power source, and the danger caused by the short circuit of the battery cannot be completely avoided. In addition, in order to save power consumption, modern electronic devices operate at lower voltage/current, and the current they can withstand is also reduced accordingly, and the rated charging current for charging the electronic devices is also relatively low. In this case, a considerable charging current may have exceeded the rated charging current, but not enough to cause the fuse to start to blow; in this way, the overcurrent protection mechanism of the fuse cannot avoid the danger of shorting the battery. In other words, due to the lower rated charging current, the overcurrent protection mechanism should be more sensitive, and it is difficult to increase the sensitivity of the existing fuse overcurrent protection mechanism.

In addition, in the prior art, the protection mechanism during charging is also realized by software in the electronic device. For example, the processor in the mobile phone will receive the detection information of the charging current and voltage during charging, and execute specific software to judge whether the charging current and voltage are too large, so as to monitor the charging situation. However, the software protection mechanism involves various high-level operations (such as software execution), and relying solely on the software protection mechanism is not reliable enough, and may not be able to respond to overcurrent and overvoltage phenomena during charging in a timely manner.

Contents of the invention

Therefore, the main purpose of the present invention is to provide a charging protection circuit to assist the operation of the fuse, so as to realize a charging protection mechanism with fast response and high sensitivity at the hardware level, so as to overcome the shortcomings of the prior art. Perfectly maintain the safety of various electronic devices (such as mobile phones) and their users during charging.

The charging protection circuit of the present invention includes: a fuse, a current detector, a current limiter, a voltage limiter, an overcurrent protector, an adapter, a charging controller, an auxiliary adapter, an auxiliary Charge controller and an auxiliary fuse. One end of the fuse is used as an input end for receiving charging power from the charging power source, and the other end of the fuse is a shunt end, branching out into two circuit branches. An overcurrent protector and an auxiliary adapter are connected in series on one of the circuit branches. On another branch of the circuit, a current detector, an adapter and an auxiliary fuse are connected in series. After the auxiliary fuse is an output terminal of charging power, which can output the charging power to a battery. In other words, the circuit branch of the "current detector-adapter-auxiliary fuse" is the path for transmitting the charging power from the charging power supply to the battery, and is responsible for conducting the charging current. Among them, the current detector is used to detect the magnitude of the charging current, and reflect the detection result to the current limiter, and the current limiter further reflects the current detection result to the charge controller; The adapter actually controls the charging current conducted on this branch of the circuit by the adapter. In addition, the conduction control of the charging current by the adapter will be reflected to the overcurrent protector on another circuit branch.

When charging, when the charging current starts to increase and approaches or exceeds the rated charging current, the current detector will reflect the increase of the charging current to the adapter through the current limiter and the charging controller, so that the adapter Reduce the extent of its conduction and limit the size of the charging current; this also realizes the function of current limiting protection. If the charging current continues to increase, the adapter will strengthen the current limiting degree, and the enhanced current limiting situation will be reflected to the over-current protector; once the charging current is greater than a threshold current, the adapter will strengthen the current limiting degree It will cause the overcurrent protector on the other circuit branch to start to conduct an auxiliary current. Since the current on the fuse is mainly the sum of the branch currents of the two circuits, the conduction of an auxiliary current will make the total current on the fuse greater than the charging current, so as to quickly trigger the fuse to melt, so that the charging power supply and the battery can be quickly Open circuit, to achieve the purpose of overcurrent protection.

In other words, in the present invention, the overcurrent protector can be regarded as a controlled current source. Once the charging current is greater than the threshold current, the overcurrent protector will be activated under control to conduct an additional auxiliary current on the fuse , to accelerate the melting of the fuse. This makes the melting of the fuse no longer completely dependent on the size of the charging current; as long as the auxiliary current that makes the overcurrent protector conduct is larger, the fuse can be melted faster. Properly adjusting the start-up condition and the size of the auxiliary current of this overcurrent protector can realize an overcurrent protection mechanism with high sensitivity and fast response.

In addition to the fuse for receiving charging power, an auxiliary fuse can also be set in the charging protection circuit of the present invention as another line of defense for overcurrent protection. When the charging current on the circuit branch of "current detector-adapter-auxiliary fuse" is too large, the adapter itself will dissipate more heat due to current limitation, and the auxiliary fuse can be thermally coupled with the adapter. Use the heat of the adapter to accelerate the melting of this auxiliary fuse. Once the charging current increases to a maximum, the adapter itself may overheat due to current limiting, and the auxiliary fuse can be quickly melted and blown, disconnecting the charging power supply and the battery, and realizing another over-current protection mechanism.

In addition, in the charging protection circuit of the present invention, the voltage limiter is electrically connected to the shunt end to detect the voltage of the shunt end, and the detection result is reflected in the charging controller and the auxiliary charging controller. The charging controller and the auxiliary charging controller can respectively control the adapter and the auxiliary adapter according to the detection result of the voltage limiter. When the charging voltage provided by the charging power source is too large (greater than a threshold voltage), the voltage limiter will reflect this situation to the adapter and auxiliary adapter on the two circuit branches, so that both adapters stop Conduction, so that the excessive charging voltage will not be input to the battery. And this also realizes the function of overvoltage protection.

Because the charging protection circuit of the present invention can fully adjust the parameters of various protection mechanisms (such as threshold voltage, threshold current, and auxiliary current) in circuit design, it can be generally applied to various electronic devices that need to be charged. , to achieve perfect over-current, current-limiting and voltage-limiting protection in various electronic devices.

Description of drawings

FIG. 1 is a functional block diagram of the charging protection circuit of the present invention.

FIG. 2 is a schematic diagram of implementing the charging protection circuit in FIG. 1 with an electronic circuit.

FIG. 3 is a schematic diagram of overvoltage protection performed by the charging protection circuit of the present invention.

FIG. 4 is a schematic diagram of current limiting/overcurrent protection performed by the charging protection circuit of the present invention.

FIG. 5 is a schematic diagram of the charging protection circuit of the present invention applied to an electronic device.

Description of reference symbols

1, 5, 6, 14-15 (two-carrier junction) transistors

2 Zener diodes

3, 8, 9, 11-13, 16, 18, 19 resistors

4, 17 diodes

7 capacitance

21 fuse

22 auxiliary fuse

Q1-Q2 (Metal Oxide Semiconductor) Transistors

30 charging protection circuit 32 adapter

34 Auxiliary Adapter 36 Current Detector

38 current limiter 40 overcurrent protector

42 voltage limiter 46 charge controller

48 Auxiliary Charge Controller 50 Electronics

52 processing circuit 54 battery

56 charging power supply 201-207 path

Ic charging current Ioc auxiliary charging current

Na-Ne node Vin, Vout voltage

Detailed ways

Please refer to FIG. 1; FIG. 1 is a functional block diagram of the charging protection circuit 30 of the present invention. The charging protection circuit 30 is provided with a fuse 21, a current detector 36, an adapter 32, an auxiliary fuse 22, a current limiter 38, a charging controller 46, an auxiliary adapter 34, an overcurrent protection device 40, a voltage limiter 42 and an auxiliary charge controller 48. One end of the fuse 21 at the node Na is an input end, which is used to receive the charging power (that is, the input voltage Vin) from the charging power source; Separate two circuit branches. A current detector 36, an adapter 32, and an auxiliary fuse 22 are connected in series on the path 203; this path 203 is mainly used to conduct the charging current Ic, and the node Nc is used as the output terminal of the charging protection circuit 30 to charge the The current Ic (output voltage Vout) is output to the battery. On the path 203 , the adapter 32 is used to control the conduction degree of the path 203 , that is, the adapter 32 can control the magnitude of the charging current Ic. The current detector 36 is used to detect the magnitude of the charging current Ic, and the detection result is reflected to the current limiter 38 . The current limiter 38 further reflects the result of current detection to the charging controller 46, and the charging controller 46 controls the conduction degree of the adapter 32; equivalently, the charging controller 46 uses a current limiting signal to The conduction degree of the adapter 32 is controlled. Through the coordinated operation of the current detector 36 , the current limiter 38 , the charging controller 46 and the adapter 32 , the current limiting protection of the present invention can be realized.

When charging, when the current magnitude of the charging current Ic increases to approach or exceed the rated charging current, the current detector 36 will reflect the increase of the charging current to the current limiter 38, and the current limiter 38 will report the result of the current detection Reflected to the charge controller 46, and the charge controller 46 will control the adapter 32 to start limiting the current, that is, to reduce the conduction degree of the adapter 32, limit the current size of the charging current Ic, and make it no longer increase ; This also realizes the function of current limiting protection.

On the other hand, the auxiliary adapter 34 can control whether the path 205 is conducting, and the overcurrent protector 40 can decide whether to conduct an auxiliary current Ioc on the path 205 according to the degree of current limitation of the adapter 32; Equivalently speaking, the conduction degree of the adapter 32 (that is, the degree of its current limiting) forms an over-current signal to control whether the over-current protector 40 starts conducting the auxiliary current Ioc. During charging, when the current magnitude of the charging current Ic is still within the rated normal range, the overcurrent protector 40 will not conduct the auxiliary current Ioc; that is, the charging power input by the charging power source will be directly passed through the fuse 21 The path 203 is transmitted to the output terminal of the node Nc. However, as mentioned above, when the current magnitude of the charging current Ic (path 203) increases to approach or exceed the rated charging current, the adapter 32 will increase its limit according to the feedback from the current limiter 38 and the charge controller 46. The degree of current flow (that is, to reduce the degree of its conduction), for current limiting protection. If the charging power source continues to transmit higher current charging power on the path 203 (such as when the battery is short-circuited), the adapter 32 must further reduce its conduction level and continue to increase its current limiting degree; when the adapter 32 When the current limiting degree increases to a certain threshold value (that is, when the charging current Ic will exceed a threshold current), the overcurrent protector 40 will start to conduct the auxiliary current Ioc. It can be seen from FIG. 1 that once the overcurrent protector 40 starts conducting the auxiliary current Ioc at the node Nb, the current flowing through the fuse 21 will increase, not only conducting the charging current Ic, but also conducting the auxiliary current Ioc additionally. . When the current on the fuse 21 increases, its melting/blowing can be accelerated, so that the charging power supply and the battery can be disconnected quickly to prevent the battery from exploding due to excessive charging current; and this also realizes the process of the present invention stream protection.

It can be seen from the above description that in the charging protection circuit 30 of the present invention, the auxiliary current that is additionally turned on by the overcurrent protector 40 can be used to accelerate the melting/blowing of the fuse 21 when necessary. This also enables the present invention to easily realize an overcurrent protection mechanism with high sensitivity and fast response. As long as the design parameters of the overcurrent protector are changed, the timing and conditions of its activation can be changed, thereby adjusting the sensitivity of the overcurrent protection mechanism. Changing the current size that the overcurrent protector 40 can conduct can adjust the reaction speed of the overcurrent protection mechanism; the higher the current that the overcurrent protector 40 can conduct after starting, the faster the fuse 21 can be burned. Break, to achieve a fast response over-current protection mechanism.

In addition, the charging protection circuit 30 of the present invention can also use another auxiliary fuse 22 to implement another redundant overcurrent protection. When actually implementing the charging protection circuit 30 , the auxiliary fuse 22 can be thermally coupled with the adapter 32 (for example, they are arranged in close positions). When the adapter 32 increases its current limiting degree, the adapter 32 itself will dissipate more heat or even burn out. At this time, the heat of the adapter 32 itself can cause the fuse 22 to melt and burn faster, forming a backup overcurrent protection mechanism.

In addition to the above-mentioned current limiting and overcurrent protection, in the charging protection circuit 30 of the present invention, the voltage limiter 42 can also be used for overvoltage protection. The voltage limiter 42 can detect the voltage of the node Nb, and reflect the detection result to the charging controller 46 and the auxiliary charging controller, and enable the charging controller 46 and the auxiliary charging controller 48 to use corresponding voltage limiting signals and auxiliary charging controllers respectively. The voltage limiting signal is used to control the adapter 32 and the auxiliary adapter 34 . When the voltage of node Nb exceeds a threshold voltage, the voltage limiter 42 will make the charging controller 46 turn off the adapter 32, and make the auxiliary charging controller 48 turn off the auxiliary adapter 34, so that the paths 203, 205 Both stop conduction, so that the excessive voltage will not be transmitted to the battery at the output end, and the purpose of overvoltage protection can also be achieved.

To further illustrate the actual implementation of the present invention with an electronic circuit, please refer to FIG. 2 (and refer to FIG. 1 together). FIG. 2 is an embodiment of the present invention implementing the charging protection circuit 30 in FIG. 1 with an actual circuit configuration. As shown in Figure 2, the current detector 36 can include one or more resistors connected in parallel (represented by three resistors 11-13 in Figure 2); On the path 203 , if the rated current that can be conducted by a single resistor is limited, resistors (with equal resistance values) can be connected in parallel as shown in FIG. 2 to increase the current that the current detector 36 itself can conduct. Two bicarrier junction transistors 5 and 6 can be arranged in the current limiter 38; the base-emitter cross voltage of the transistor 5 is controlled by each resistance in the current detector, and the collector current of the transistor 5 is It will be fed into the base of the transistor 6 , and the base current will be amplified by the transistor 6 into a larger current between the collector and the emitter, and transmitted to the charge controller 46 via the path 204 . A capacitor 7 and a resistor 9 can be installed in the charging controller 46; the voltage established at the node Nd can be regarded as a current-limiting signal/voltage-limiting signal. The adapter 32 can be realized by a power metal-oxide-semiconductor transistor Q1, its source and drain are connected in series to the path 203, and the gate is connected to the node Nd, so that according to the voltage of the charging controller 46 at the node Nd To adjust the degree of conduction between the drain and source. In addition, the transistor Q1 can be further thermally coupled with the fuse 22 (such as being placed in a close position).

On the other hand, on the path 205 , the overcurrent protector 40 can be realized by one or more groups of controlled current sources; as in FIG. 2 , the overcurrent protector 40 is provided with two groups of controlled current sources. One group is formed by BCJT 14 and resistor 18 (path 206 ), and the other group is formed by BCJT 15 and resistor 19 (path 207 ). In each group of controlled current sources, the auxiliary current Ioc of the overcurrent protector 40 can be formed by summing up the current conducted between the emitter and the collector of each bicarrier junction transistor. In the controlled current source, the bases of the bicarrier junction transistors can be connected to the drain of the transistor Q1 through the diode 17 and the resistor 16, and the drain voltage of the transistor Q1 is used as an overcurrent signal to control each receiving transistor. Controls whether the current source should start conducting. The auxiliary adapter 34 on the path 205 can be realized by a metal oxide semiconductor transistor Q2; the source and collector of the transistor Q2 control the conduction of the path 205, and the gate voltage of the transistor Q2 is controlled by the resistor 8. The resistor 8 is also the auxiliary charging controller 48 ; the voltage established by the resistor 8 at the node Ne can be regarded as an auxiliary voltage limiting signal to the auxiliary adapter 34 .

The voltage limiter 42 of the charging protection circuit of the present invention can be realized by a metal oxide semiconductor transistor 1 , a Zener diode 2 and a resistor 3 . The Zener diode 2 and the resistor 3 are connected in series to the base of the transistor 1, the emitter of the transistor 1 is connected to the node Nb, and the collector is connected to the resistor 8 of the auxiliary charge controller 48 at the node Ne on the one hand to establish an auxiliary voltage limiting signal, On the other hand, the node Nd is connected to the charging controller 46 via a diode 4 to establish a voltage limiting signal at the node Nd. Since the current limiter 38 will also establish a current limit signal at the node Nd, the diode 4 can prevent the current of the current limiter 38 on the path 204 from flowing back to the voltage limiter 42 through the path 201 .

The cooperative operation of the various circuits in FIG. 2 can be described as follows. The charging current Ic on the path 203 will establish a voltage on each resistor of the current detector 36, thereby controlling the base-emitter cross voltage of the transistor 5, which is equivalent to controlling the conduction of the transistor 5 according to the magnitude of the charging current Ic degree. The current conducted between the collector and the emitter of the transistor 5 will be amplified by the transistor 6 and injected into the charging controller 46 so as to establish a voltage at the node Nd as a current limiting signal to control the conduction of the adapter 32 (transistor Q1). pass level. That is to say, when charging, when the charging current Ic increases, the cross-voltage of each resistor in the current detector 36 also increases thereupon, which also increases the conduction degree of the transistor 5 (that is, increases its conduction current), and the transistor 6 will inject a larger current into the charge controller 46, so that the voltage of the node Nd rises rapidly, so that the source-gate cross voltage of the transistor Q1 is reduced, and the transistor Q1 The degree of conduction is reduced, so that the charging current Ic can be reduced by reverse control. In other words, through the negative feedback operation of the current detector 36 , the current limiter 38 , the charging controller 46 and the adapter 32 , the charging current Ic on the path 203 is limited to a certain current value. This also realizes the current limiting function of the present invention.

When charging, when the charging power provided by the charging power source is still within the normal condition of the rated value, the collector voltage (reflecting the voltage of the node Nc) and the emitter voltage (reflecting the voltage of the node Nb) of the transistors 14 and 15 are not much different. Large, so that the transistors 14 and 15 are not turned on; the charging power is mainly transmitted from the path 203 . When the transistor Q1 in the adapter 32 is limiting the current, the voltage across the collector-source will reflect the degree of current limiting. As the charging current Ic on the path 203 increases, the conduction degree of the transistors 5 and 6 also increases, so that the voltage of the node Nd increases, and the cross-voltage between the gate and the source of the transistor Q1 decreases to reduce its conduction degree; Correspondingly, the drain-source cross voltage of the transistor Q1 will increase accordingly, and the drain voltage of the transistor Q1 at the node Nc will decrease. In this way, the base voltages of the transistors 14 and 15 are also dropped. When the power transmitted by the charging power source through the path 203 greatly increases beyond the rated value, the transistor Q1 is bound to perform a strong voltage limit, which will cause the drain voltage of the transistor Q1 to drop to a certain threshold value, which will cause the transistor Q1 The base voltage of 14, 15 drops, so that the voltage across the emitter-collector of transistors 14, 15 increases to the extent that transistors 14, 15 can be turned on. In this way, the transistors 14 and 15 will quickly conduct currents on the paths 206 and 207 respectively; at this time, the overcurrent protector 40 will start to conduct an additional auxiliary current Ioc on the path 205 . The additional turned-on auxiliary current Ioc will quickly melt/blow the fuse 21 together with the charging current Ic at a high summed current, so as to realize the overcurrent protection mechanism of the present invention. When charging, when the charging power source provides too much charging power and the transistor Q1 starts to limit the current, the transistor Q1 will consume the excess charging power to keep the current on the path 203 constant; if the charging power is really large, The transistor Q1 may be melted down, and at this time, the heat dissipated by the transistor Q1 will cause the fuse 22 to blow out rapidly, thereby implementing a backup overcurrent protection mechanism.

The principle of implementing the overvoltage protection mechanism with the circuit in FIG. 2 can be described as follows. In the voltage limiter 42, the zener diode 2/resistor 3 can establish a reference voltage; when the voltage of the node Nb is within the rated normal range, the cross voltage between the emitter and the base of the transistor 1 is not large, and the transistor 1 does not conduct By turning on, the resistor 8 of the auxiliary charge controller 48 will not build up the voltage, so that the transistor Q2 is turned on normally, and the voltage of the charge controller 46 at the node Nd is controlled by the current limiter 46 . When the voltage of node Nb increases beyond the normal range, the emitter-base cross voltage of transistor 1 will increase and transistor 1 will start to conduct; the current conducted by transistor 1 will be injected into the auxiliary charge controller 48 and charge controller 46. The current injected into the auxiliary charge controller 48 builds up a voltage across the resistor 8, which increases the gate voltage of the transistor Q2 and reduces the source-gate voltage, turning off the transistor Q2. Likewise, the voltage injected into the charge controller 46 will increase the gate voltage of the transistor Q1, which in turn will reduce the source-gate cross voltage of the transistor Q1, turning off the transistor Q1. In this way, the high voltage of the node Nb cannot be conducted to the output terminal via the paths 203 and 205 , thus realizing the voltage limiting protection function.

It can be seen from Fig. 2 that the present invention can simply adjust the starting conditions and response speed of the current limiting, overcurrent and overvoltage protection mechanisms by changing the circuit parameters, so that the charging protection circuit of the present invention can be widely used in various charging devices that require charging. electronic device. For example, by adjusting the resistance of the resistor 3 and selecting Zener diodes 2 with different breakdown voltages, the activation condition and sensitivity of the voltage limiting protection mechanism can be adjusted. Adjusting the resistance value of the resistors 11-13 or the driving capabilities of the transistors 5 and 6 can adjust the operation and response speed of the current limiter. By changing the resistance value of the resistor 16 and selecting different diodes 17, the conditions under which the overcurrent protection mechanism will be activated can be adjusted. To increase the response speed of the overcurrent protection mechanism, transistors 14 and 15 with better current driving capability can be selected, or more groups of controlled current sources can be added in the overcurrent protector 40 . It should be emphasized here that FIG. 2 is only a schematic diagram of an embodiment of the present invention, and the charging protection circuit shown in FIG. 1 of the present invention can also be implemented with other types of circuit configurations. For example, in FIG. 2 , the controlled current source in the overcurrent protector 40 can be realized by using other types of controlled current sources/current mirrors instead. The voltage limiter 42 can be realized by a comparator and a controlled current source; wherein, the comparator is used to compare whether the voltage of the node Nb is greater than a normal value, and controls the controlled current source to reflect the comparison result to the charging controller 46 in the form of current (In the example of Figure 2, transistor 1 integrates the functions of a comparator and a controlled current source). The current limiter 38 itself is also a controlled current source, and other types of circuit designs can also be used; for example, the current limiter 38 can be realized by using a controlled current source in the overcurrent protector 40, and the overcurrent protector 40 can also be realized by using the controlled current source in the current limiter 38.

Please refer to Figure 3 and Figure 4 (and refer to Figure 2 together). Fig. 3, Fig. 4 illustrate the operation situation of the charging protection circuit of the present invention with the actual embodiment of Fig. 2 circuit configuration; in amperes). First, Figure 3 shows the implementation of the overvoltage protection mechanism; when the voltage Vin (Figure 2) input by the charging power source exceeds a threshold voltage (for example, 6.8 volts), transistors 1 and 2 (that is, the adapter , Auxiliary Adapter) will stop conduction, disconnect the battery from the charging power supply, and provide voltage limiting protection. What Fig. 4 shows is then the situation of current limiting/overcurrent protection of the present invention; At the point Pa of Fig. 4, the charging power provided by the charging power source begins to increase to approach/exceed the rated normal value (for example, 460 microamperes), and The current limiter 38 ( FIG. 2 ) will start to reduce the conduction degree of the transistor Q1 via the charging controller 46 , so that the charging current is maintained at a constant value, and plays the role of current limiting protection. At point Pb in Figure 4, the charging power provided by the charging power source increases significantly. At this time, the overcurrent protection circuit will start to accelerate the melting/blowing of the fuse 21 with the auxiliary current that is additionally turned on, so that the battery and the charging power source can be connected quickly. Ground open circuit, to achieve the purpose of over-current protection.

Please refer to Figure 5 (and refer to Figure 1 and Figure 2 together). FIG. 5 is a schematic diagram of applying the charging protection circuit 30 of the present invention to an electronic device 50 . The processing circuit 52 in the electronic device 50 is used to control the operation of the electronic device 50, the battery 54 (or power storage device) is used to supply the power required by the processing circuit 52, and the charging protection circuit 30 of the present invention can be arranged on the battery When the electronic device 50 is connected to a charging power source 56 to be charged, the charging protection circuit 30 of the present invention can control the transmission path of the charging power between the charging power source 56 and the battery 54 supplied by the power supply, and play a limited role. Current, overcurrent and overvoltage protection functions. The electronic device 50 can be a mobile phone, and the processing circuit 52 can include an antenna, a wireless communication line, a microphone, a speaker, a man-machine interface (man-machine interface, such as a keyboard, a screen), a mobile phone processor, a storage device, and the like. Of course, the electronic device 50 can also be a digital camera (the processing circuit includes a lens drive circuit, a processor, a storage device, an optical control circuit, etc.), a personal assistant or a portable computer (the processing circuit includes a central processing unit, a random memory memory, non-volatile storage devices, hard disks, CDs, keyboards, screens, etc.) and portable video playback devices (processing circuits include video processing and playback circuits) and the like.

In general, compared with the prior art, the present invention can use electronic circuits to assist the overcurrent protection mechanism of the fuse at the hardware level, so as to realize a charging protection mechanism with high sensitivity, fast response and wide application. Provide perfect current limiting/overcurrent and overvoltage protection mechanisms for electronic devices and users during charging.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the claims of the present invention shall fall within the scope of the present invention.

Claims (16)

1. charge protector, it includes:

One fuse, its two ends are respectively an input and a shunting end; This fuse receives an electric current of power supply supply via this input, and this electric current is shunted end by this export;

One output is electrically connected in this shunting end, receives a charging current also with this charging current output with this shunting termination of cause; And

One overcurrent protector, electric coupling are connected in this shunting end; When this charging current was not higher than a threshold current, this overcurrent protector can the conducting electric current; And when this charging current was higher than this threshold current, this current foldback circuit can be in extra conducting one auxiliary current of this shunting end, made excessive and this fuse that melts down of electric current between these fuse two ends.

2. charge protector as claimed in claim 1, it also includes:

One adapter is electrically connected between this output and this shunting end; This adapter can transmit this charging current, and can produce the overcurrent signal of a correspondence according to the size of this charging current; And this overcurrent protector promptly judges whether to want this auxiliary current of conducting according to this overcurrent signal.

3. charge protector as claimed in claim 2; wherein this adapter includes a metal oxide semiconductor transistor; the source electrode of this metal oxide semiconductor transistor is electrically connected in this shunting end; the drain electrode of this metal oxide semiconductor transistor is electrically connected in this output, and the drain voltage of this metal oxide semiconductor transistor is this overcurrent signal.

4. charge protector as claimed in claim 3; wherein this overcurrent protector includes at least one double carriers junction transistor; the base voltage of each double carriers junction transistor is controlled by the drain voltage of this metal oxide semiconductor transistor, so that judge whether according to this overcurrent signal will be in the emitter and the inter-collector conducting electric current of each double carriers junction transistor.

5. charge protector as claimed in claim 2, it also includes:

One charge controller is electrically connected in this adapter; This charge controller can produce the current limliting signal of a correspondence according to the size of this charging current, and this adapter also can be controlled the size of its charging current of transmitting according to this current limliting signal; When this current limliting signal showed that this charging current increases, this adapter can reduce the charging current of its conducting.

6. charge protector as claimed in claim 5, it also includes:

One current detector is electrically connected between this shunting end and this output, is used for detecting the size of this charging current; And

One flow restricter is electrically connected between this current detector and this charge controller, and this flow restricter can be reflected into the testing result of this current detector this charge controller, makes this charge controller can produce this current limliting signal accordingly.

7. charge protector as claimed in claim 6; wherein this adapter includes a metal oxide semiconductor transistor; the source electrode of this metal oxide semiconductor transistor is electrically connected in this shunting end; the drain electrode of this metal oxide semiconductor transistor is electrically connected in this output; the grid of this metal oxide semiconductor transistor is electrically connected in this charge controller, and the drain voltage of this metal oxide semiconductor transistor is this overcurrent signal.

8. charge protector as claimed in claim 7, wherein this current detector includes at least one resistance, is electrically connected between this shunting end and this output; And this flow restricter includes at least one double carriers junction transistor, the base stage of this double carriers junction transistor and emitter cross-over connection be in the two ends of the resistance of this current detector, makes the electric current of conducting between this two-carrier emitter and the collector electrode can reflect size of current between this shunting end and this output

9. charge protector as claimed in claim 7; wherein this charge controller includes resistance and an electric capacity; this flow restricter can produce the electric current of a correspondence and transfer to this charge controller according to the testing result of this current detector; setting up cross-pressure on the resistance of this charge controller and electric capacity, and this cross-pressure is the current limliting signal that this charge controller produces.

10. charge protector as claimed in claim 2, it also includes:

One voltage limiter is electrically connected in this shunting end, is used for detecting the voltage of this shunting end; And

One charge controller is electrically connected in this voltage limiter and this adapter, and this charge controller can produce the pressure limiting signal of a correspondence according to the testing result of this voltage limiter, and this pressure limiting signal is transferred to this adapter; The voltage that shows this shunting end when this pressure limiting signal is during greater than a voltage threshold value, this adapter can stop at that this shunting is held and this output between transmission current.

11. charge protector as claimed in claim 10, it also includes:

One auxiliary adapter is electrically connected between this shunting end and this overcurrent protector, is used for controlling being electrically connected between this shunting end and this overcurrent protector; And

One auxiliary charging controller is electrically connected in this voltage limiter; This auxiliary charging controller can produce the auxiliary pressure limiting signal of a correspondence according to the testing result of this voltage limiter, and should assist the pressure limiting signal to transfer to this auxiliary adapter; The voltage that shows this shunting end when this auxiliary pressure limiting signal is during greater than a limit voltage, and this auxiliary adapter can stop being electrically connected between this shunting end and this overcurrent guarantor auxiliary guards device.

12. charge protector as claimed in claim 11 wherein should include a metal oxide semiconductor transistor by auxiliary adapter, the source electrode of this metal oxide semiconductor transistor and drain electrode are electrically connected in respectively between this shunting end and this overcurrent protector; Include a resistance in this auxiliary charging controller; This voltage limiter can be according to the voltage of this shunting end and with the current delivery of correspondence to this auxiliary charging device, so that set up a cross-pressure on the resistance of this auxiliary charging controller as should auxiliary pressure limiting signal; And the grid that should assist metal oxide semiconductor transistor in the adapter promptly is controlled by the resistance cross-pressure of auxiliary charging controller.

13. charge protector as claimed in claim 2, it also includes:

One auxiliary fuse is electrically connected between this adapter and this output.

14. charge protector as claimed in claim 13 wherein should be thermally coupled in this adapter by auxiliary fuse, made that the temperature that this adapter raises can be quickened the meltdown of this auxiliary fuse when the charging current of this adapter conducting raises.

15. charge protector as claimed in claim 1, its input be with cause one charge power supply received current, and this output is used for exporting this charging current with to this battery charge to a battery.

16. charge protector as claimed in claim 13, it is built in the electronic installation, and this battery promptly is used to provide the required electric power of this electronic installation running.

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