Short-circuit protection circuit, fast charging protocol chip and electronic equipment

Abstract

The invention provides a short-circuit protection circuit, a fast charging protocol chip and electronic equipment. Comprising a short circuit detection circuit, an overcurrent protection circuit and a logic gate circuit. A preset threshold voltage is set in the overcurrent protection circuit; the short-circuit detection circuit is used for dividing a charging voltage accessed by a power supply terminal to obtain a first voltage, comparing the first voltage with a reference voltage, and outputting a first control voltage signal; the overcurrent protection circuit is used for collecting the difference voltage collected by the first sampling end and the second sampling end, comparing the difference voltage with the preset threshold voltage, and outputting a second control voltage signal; and the logic gate circuit is used for carrying out logic or operation on the first control voltage signal and the second control voltage signal, outputting a switch control signal and transmitting the switch control signal to a switch control end so as to control the first switch tube to be switched on or switched off. Therefore, the short-circuit protection circuit is simpler, the response speed is faster, and the logic gate circuit performs OR operation, so that the reliability is higher.

Description

Technical Field

[0001] The present application relates to the technical field of power management chips, and in particular to a short circuit protection circuit, a fast charging protocol chip and an electronic device. Background Art

[0002] In the mobile phone charging application scenario, the charging voltage is provided by the AC-DC (alternating current-direct current) module to charge the load (mobile phone). During the mobile phone charging process, a protection circuit is usually required on the mobile phone side or the adapter side to prevent damage to the mobile phone or the adapter in case of a short circuit.

[0003] See also Figure 1 , Figure 1 A structural diagram of a protection circuit provided for related technologies, such as Figure 1 As shown, during the charging process of the mobile phone, if an abnormal situation occurs, for example, a node in the path between the mobile phone and the AC-DC module is short-circuited to the ground, a large current will instantly pass through the switch tube and the mobile phone. The control end of the switch tube S1 is controlled by the protection circuit, so that the switch tube S1 can be immediately turned off when a short circuit occurs in the charging path, thereby disconnecting the AC-DC module and the mobile phone, thereby protecting the entire charging system. Summary of the invention

[0004] The present application provides a short circuit protection circuit, a fast charging protocol chip and an electronic device, which makes the short circuit protection circuit simpler, faster in response speed and more reliable. The specific technical solution is as follows:

[0005] In a first aspect, the present application provides a short-circuit protection circuit, the short-circuit protection circuit comprising: a short-circuit detection circuit, an overcurrent protection circuit and a logic gate circuit; the short-circuit detection circuit comprises a power supply terminal, the overcurrent protection circuit comprises a first sampling terminal and a second sampling terminal, the logic gate circuit comprises a switch control terminal, wherein the switch control terminal is electrically connected to the control terminal of the first switch tube, and a preset threshold voltage is set in the overcurrent protection circuit;

[0006] The short-circuit detection circuit is used to divide the charging voltage connected to the power terminal to obtain a first voltage, compare the first voltage with a reference voltage, output a first control voltage signal, and transmit the first control voltage signal to the logic gate circuit;

[0007] The overcurrent protection circuit is used to collect the difference voltage collected by the first sampling end and the second sampling end, compare the difference voltage with the preset threshold voltage, output a second control voltage signal, and transmit the second control voltage signal to the logic gate circuit, wherein the difference voltage is used to characterize the current flowing through the load;

[0008] The logic gate circuit is used to perform a logic OR operation on the first control voltage signal and the second control voltage signal, output a switch control signal, and transmit the switch control signal to the switch control end to control the first switch tube to be turned on or off.

[0009] In one possible design, the short circuit detection circuit includes: a voltage divider circuit and a comparison circuit;

[0010] The voltage dividing circuit is used to divide the charging voltage connected to the power terminal to obtain a first voltage;

[0011] The comparison circuit is used to compare the first voltage with a reference voltage and output a first control voltage signal.

[0012] In a possible design, the voltage divider circuit includes: a first NOT gate, a second NOT gate, a second switch tube, a first resistor and a second resistor;

[0013] The first end of the first NOT gate is electrically connected to the enable end, and the second end of the first NOT gate is electrically connected to the first end of the second NOT gate;

[0014] The second end of the second NOT gate is electrically connected to the control end of the second switch tube;

[0015] A first end of the first resistor is electrically connected to the power supply terminal, and a second end of the first resistor is electrically connected to a first end of the second switch tube;

[0016] The second end of the second switch tube is electrically connected to the output end of the voltage divider circuit and the first end of the second resistor respectively;

[0017] A second terminal of the second resistor is grounded.

[0018] In one possible design, the comparison circuit includes: a first comparator;

[0019] The non-inverting input terminal of the first comparator is electrically connected to the reference voltage terminal, and the reference voltage terminal is used to access the reference voltage. The inverting input terminal of the first comparator is electrically connected to the output terminal of the voltage divider circuit. The output terminal of the first comparator is electrically connected to the output terminal of the comparison circuit, and is used to output a first control voltage signal.

[0020] In one possible design, the overcurrent protection circuit includes: a sampling resistor and a second comparator;

[0021] The first end of the sampling resistor is electrically connected to the first sampling end and the input end of the overcurrent protection circuit respectively, and the second end of the sampling resistor is grounded;

[0022] The non-inverting input terminal of the second comparator is electrically connected to the first sampling terminal, the inverting input terminal of the second comparator is electrically connected to the second sampling terminal, and the output terminal of the second comparator is electrically connected to the output terminal of the overcurrent protection circuit for outputting a second control voltage signal.

[0023] In one possible design, the logic gate circuit includes: an OR gate;

[0024] The first input end of the OR gate is electrically connected to the output end of the short-circuit detection circuit, the second output end of the OR gate is electrically connected to the output end of the overcurrent protection circuit, and the output end of the OR gate is electrically connected to the switch control end.

[0025] In a possible design, the first switch tube is an NMOS tube.

[0026] In a possible design, the resistance of the first resistor is twice the resistance of the second resistor, and the second switching tube is a high-voltage tube.

[0027] In a second aspect, the present application provides a fast charging protocol chip, including: the short-circuit protection circuit described in the first aspect above.

[0028] In a third aspect, the present application provides an electronic device, including: the fast charging protocol chip described in the second aspect above.

[0029] Beneficial effects of the embodiments of the present application:

[0030] In the embodiment of the present application, the short circuit of the power terminal VBUSP is detected by the short circuit detection circuit, and the first control voltage signal is output when the power terminal VBUSP is short-circuited; the current flowing through the load is detected by the overcurrent protection circuit, and the difference voltage is compared with the preset threshold voltage. When the charging path is short-circuited, the second control voltage signal is output; and the first control voltage signal and the second control voltage signal are logically or operated by the logic gate circuit, so that when the power terminal VBUSP is short-circuited or the current flowing through the load suddenly increases, a switch control signal is output to control the first switch tube to be turned off. Compared with the prior art, the overcurrent protection circuit in the present application compares the difference voltage directly with the preset threshold voltage by preset threshold voltage, outputs the second control voltage signal, and does not perform signal amplification processing, saves a comparator, makes the circuit simpler and responds faster; in addition, the first control voltage signal and the second control voltage signal are logically or operated by the logic gate circuit, and the first switch tube is turned off when either of the two short circuit situations occurs, and the reliability is higher.

[0031] The beneficial effects provided in the above-mentioned second aspect and various possible designs of the above-mentioned second aspect can refer to the beneficial effects brought about by the above-mentioned first aspect and various possible implementation methods of the first aspect, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other embodiments can also be obtained based on these drawings.

[0033] Figure 1 A structural schematic diagram of a protection circuit provided for related technology;

[0034] Figure 2 The first protection circuit provided in the related art;

[0035] Figure 3 The second protection circuit provided in the related art;

[0036] Figure 4 A schematic diagram of the structure of a short-circuit protection circuit provided in an embodiment of the present application;

[0037] Figure 5 A circuit diagram of a short-circuit protection circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0038] In this application, "at least one" means one or more, and "plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c alone can represent: a, b, c, a and b, a and c, or a, b, and c, where a, b, and c can be single or multiple. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0039] The directions or positional relationships indicated by terms such as "center", "longitudinal", "lateral", "up", "down", "left", "right", "front", and "back" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present application and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present application.

[0040] The terms "connected" and "connected" should be understood in a broad sense. For example, the "connected" or "connected" of a circuit structure can refer to not only physical connection, but also electrical connection or signal connection. For example, it can be directly connected, that is, physically connected, or indirectly connected through at least one intermediate element, as long as the circuit is connected, or it can be the internal connection of two elements; signal connection can refer to signal connection through a circuit or through a media medium, such as radio waves. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] For related technologies such as Figure 1 A protection circuit is provided. In practical applications, there are usually two specific circuit implementation methods. The first method is referred to Figure 2 , Figure 2 The first protection circuit provided in the related art is as follows: Figure 2 As shown, the working principle of the protection circuit is as follows: the current on the charging path is detected by the resistor R, and the voltage difference collected at both ends of the resistor R is amplified by the SNS module to obtain the amplified voltage, and the amplified voltage is compared with the reference voltage REF_1. When the amplified voltage is higher than the reference voltage REF_1, an OCP_STAT (Over-current Protection) signal is generated, and the over-current protection signal is transmitted to the bend NDRV_1. The bend NDRV_1 is electrically connected to the control end of the switch tube S1, and can control the conduction or shutdown of the switch tube S1. When a short circuit occurs in the charging path, the current flowing through the load will increase instantly, and the voltage difference across the resistor R will also increase. When the amplified voltage is higher than the reference voltage REF_1, an OCP_STAT signal is generated, and the switch tube S1 is immediately shut down by controlling the bend NDRV_1 to disconnect the AC-DC module and the mobile phone, thereby protecting the entire charging system.

[0042] Figure 2 The protection circuit in the circuit is generally set on the low voltage side, and the high voltage tube can be avoided in the circuit, such as Figure 2As shown, the circuit uses two comparators, one comparator is used to amplify the voltage difference across the resistor R, and the other comparator is used to compare the amplified voltage with the reference voltage REF_1. The circuit structure is relatively complex. In addition, due to the use of two comparators, the response speed of the circuit is slow. When a node on the charging path is short-circuited, due to the slow response speed of the circuit, the switch tube S1 is not turned off in time, and the current in the charging path is too large, which will cause the protection circuit to burn out and damage the mobile phone.

[0043] The second method see Figure 3 , Figure 3 The second protection circuit provided in the related art is as follows: Figure 3 As shown, the working principle of the protection circuit is: detect the voltage of either the bend pin VBUSP_2 or the bend pin VBUSM_2, VBUSP_2 and VBUSM_2 are electrically connected to the first end and the second end of the switch tube S1 respectively, and the voltage relationship between the bend pin VBUSP_2 and the bend pin VBUSM_2 is: VBUSP_2 = VBUSM_2 + I*Rdson, where I is the current flowing through the switch tube S1, and Rdson is the equivalent resistance value of the switch tube S1. The bend pin NDRV_2 is electrically connected to the control end of the switch tube S1, and can control the on or off of the switch tube S1. When a short circuit occurs in the charging path, VBUSP_2 will drop to a very low voltage value. When the voltage value is lower than the reference voltage REF_2, a VBUS_SHT signal is generated. The VBUS_SHT signal controls the switch tube S1 to be immediately turned off through the bend pin NDRV_2, disconnecting the AC-DC module and the mobile phone, thereby protecting the entire charging system.

[0044] Figure 3 The protection circuit in the charging circuit can only detect whether the voltage of the VBUSP_2 pin is powered off. It is a voltage detection and cannot directly reflect the current situation in the charging path. When the charging path is short-circuited, it is necessary to control the switch tube S1 to turn off. It is necessary to accurately calculate the relationship between the current threshold to be protected and the voltage of the VBUSP_2 pin. If a short circuit occurs, the current in the charging path is too large but the voltage of the VBUSP_2 pin is not lower than the reference voltage REF_2, then the switch tube cannot be controlled to turn off. Therefore, Figure 3 The protection circuit in the circuit is not very reliable.

[0045] In response to the problems of complex circuits, slow response speed and low reliability in protection circuits in the prior art, the present application provides a short-circuit protection circuit, a fast charging protocol chip and an electronic device.

[0046] The short-circuit protection circuit may be a chip or a circuit module.

[0047] Among them, the fast charging protocol chip may include a short circuit protection circuit.

[0048] In this application, electronic devices may include, but are not limited to: adapters, chargers, tablet computers, smart home devices, vehicles, and wearable devices.

[0049] See also Figure 4 , Figure 4 A short circuit protection circuit 1000 provided in an embodiment of the present application is as follows: Figure 4 As shown, the short-circuit protection circuit 1000 includes: a short-circuit detection circuit 100, an overcurrent protection circuit 200 and a logic gate circuit 300; the short-circuit detection circuit 100 includes a power supply terminal VBUSP, the overcurrent protection circuit 200 includes a first sampling terminal CSP and a second sampling terminal CSN, and the logic gate circuit 300 includes a switch control terminal NDRV, wherein the switch control terminal NDRV is electrically connected to the control terminal of the first switch tube Q1, and a preset threshold voltage is set in the overcurrent protection circuit 200.

[0050] The short circuit detection circuit 100 is used to divide the charging voltage connected to the power terminal VBUSP to obtain a first voltage, compare the first voltage with a reference voltage, output a first control voltage signal VBUSP_SHT_STAT, and transmit the first control voltage signal VBUSP_SHT_STAT to the logic gate circuit 300.

[0051] The overcurrent protection circuit 200 is used to collect the difference voltage collected by the first sampling terminal CSP and the second sampling terminal CSN, compare the difference voltage with a preset threshold voltage, output a second control voltage signal IBUS_OCP, and transmit the second control voltage signal IBUS_OCP to the logic gate circuit 300, wherein the difference voltage is used to characterize the current flowing through the load.

[0052] The logic gate circuit 300 is used to perform a logic OR operation on the first control voltage signal VBUSP_SHT_STAT and the second control voltage signal IBUS_OCP, output a switch control signal VBUSP_SHORT, and transmit the switch control signal VBUSP_SHORT to the switch control terminal NDRV to control the first switch tube Q1 to be turned on or off.

[0053] The fast charging protocol chip is an indispensable part of modern smartphones and other portable electronic devices. It is mainly responsible for managing and optimizing the fast charging process of the power supply. The fast charging protocol chip can adjust the voltage and current according to the needs of the mobile phone, determine the protocol that the fast charging charger can support, and provide a series of necessary protection functions.

[0054] The short-circuit protection circuit in the present application is a partial circuit in the fast charging protocol chip, and the fast charging protocol chip may include: a power terminal VBUSP, a first sampling terminal CSP, a second sampling terminal CSN, and a switch control terminal NDRV. Among them, the power terminal VBUSP is used to access the charging voltage output by the AC-DC module. The first sampling terminal CSP and the second sampling terminal CSN collect the difference voltage through a resistor connected in series between the load and the ground. The difference voltage can characterize the current flowing through the load. When a short circuit occurs in the charging path, the current flowing through the load will increase instantly, that is, by detecting the difference voltage, it is possible to detect whether a short circuit occurs in the charging path. The switch control terminal NDRV is electrically connected to the control end of the first switch tube Q1, and is used to control the switch tube to turn off the first switch tube Q1 when a short circuit occurs in the charging path.

[0055] The reference voltage can be set as required, and since the first voltage is compared with the reference voltage to output the first control voltage signal, the reference voltage value needs to be based on the first voltage and can be set as required by the design.

[0056] The preset threshold voltage is pre-set in the overcurrent protection circuit, and the size of the preset threshold voltage can be adjusted according to design requirements. It is used to compare with the difference voltage to output a second control voltage signal. By setting the preset threshold voltage in the overcurrent protection circuit, it is possible to avoid the process in the related art of first amplifying the voltage difference through a comparator and then comparing the amplified voltage with the reference voltage REF_1 through another comparator. The present application sets the preset threshold voltage and directly compares the difference voltage with the preset threshold voltage, so as to determine whether the current in the charging path exceeds the preset threshold point. Compared with the prior art, the response speed of the method in the present application is significantly improved.

[0057] The short-circuit detection circuit can detect the short-circuit of the power terminal VBUSP, and output the first control voltage signal when the power terminal VBUSP is short-circuited; the overcurrent protection circuit can detect the current flowing through the load, and when it is detected that the current flowing through the load suddenly increases, it is considered that the charging path is short-circuited, and the second control voltage signal is output. The logic gate circuit performs a logical OR operation on the first control voltage signal and the second control voltage signal, so that when either of the two situations occurs, the power terminal VBUSP is short-circuited or the current flowing through the load suddenly increases, a switch control signal is output to control the first switch tube to turn off, disconnect the AC-DC module and the load (mobile phone), thereby cutting off the path from the charging voltage to the ground, and protecting the entire charging system.

[0058] In the embodiment of the present application, the short circuit of the power terminal VBUSP is detected by the short circuit detection circuit, and the first control voltage signal is output when the power terminal VBUSP is short-circuited; the current flowing through the load is detected by the overcurrent protection circuit, and the difference voltage is compared with the preset threshold voltage. When the charging path is short-circuited, the second control voltage signal is output; and the first control voltage signal and the second control voltage signal are logically or operated by the logic gate circuit, so that when the power terminal VBUSP is short-circuited or the current flowing through the load suddenly increases, a switch control signal is output to control the first switch tube to be turned off. Compared with the prior art, the overcurrent protection circuit in the present application compares the difference voltage directly with the preset threshold voltage by preset threshold voltage, outputs the second control voltage signal, and does not perform signal amplification processing, saves a comparator, makes the circuit simpler and responds faster; in addition, the first control voltage signal and the second control voltage signal are logically or operated by the logic gate circuit, and the first switch tube is turned off when either of the two short circuit situations occurs, and the reliability is higher.

[0059] In one possible embodiment, see Figure 5 , Figure 5 A circuit diagram of a short circuit protection circuit provided in an embodiment of the present application, such as Figure 5 As shown, the short circuit detection circuit 100 includes: a voltage divider circuit 101 and a comparison circuit 102 .

[0060] The voltage dividing circuit 101 is used for dividing the charging voltage connected to the power terminal VBUSP to obtain a first voltage VFB.

[0061] The comparison circuit 102 is used for comparing the first voltage VFB with the reference voltage Ref, and outputting a first control voltage signal VBUSP_SHT_STAT.

[0062] In one possible embodiment, see Figure 5 ,like Figure 5 As shown, the voltage divider circuit 101 includes: a first NOT gate D1, a second NOT gate D2, a second switch tube MN1, a first resistor R1 and a second resistor R2.

[0063] A first end of the first NOT gate D1 is electrically connected to the enable end EN, and a second end of the first NOT gate D1 is electrically connected to a first end of the second NOT gate D2 .

[0064] The second end of the second NOT gate D2 is electrically connected to the control end of the second switch tube MN1 .

[0065] A first end of the first resistor R1 is electrically connected to the power terminal VBUSP, and a second end of the first resistor R1 is electrically connected to a first end of the second switch tube MN1.

[0066] The second end of the second switch tube MN1 is electrically connected to the output end of the voltage divider circuit 101 and the first end of the second resistor R2 respectively;

[0067] A second end of the second resistor R2 is grounded.

[0068] In a possible embodiment, the second switch tube MN1 is an NMOS tube, the first end of the second switch tube MN1 is a drain, the second end of the second switch tube MN1 is a source, and the control end of the second switch tube MN1 is a gate.

[0069] In one possible embodiment, see Figure 5 ,like Figure 5 As shown, the comparison circuit 102 includes: a first comparator U1.

[0070] The non-inverting input terminal of the first comparator U1 is electrically connected to the reference voltage terminal, and the reference voltage terminal is used to access the reference voltage Ref. The inverting input terminal of the first comparator U1 is electrically connected to the output terminal of the voltage divider circuit 101. The output terminal of the first comparator U1 is electrically connected to the output terminal of the comparison circuit 102, and is used to output the first control voltage signal VBUSP_SHT_STAT.

[0071] In a possible embodiment, the resistance of the first resistor R1 is twice the resistance of the second resistor R2, and the second switch tube MN1 is a high-voltage tube.

[0072] The short-circuit detection circuit is used to detect the charging voltage connected to the power terminal VBUSP, and detect whether the charging voltage is connected to the ground, and whether a short-circuit fault occurs. The charging voltage connected to the power terminal VBUSP can reach up to 20V, so MN1 uses a high-voltage tube as a switch of the voltage-dividing resistor (R1, R2), and the enable signal connected to the enable terminal EN is the power supply voltage of the chip, usually 3.3V or 5V.

[0073] The non-inverting input terminal of the first comparator U1 is electrically connected to the reference voltage terminal, and the reference voltage terminal is used to access the reference voltage Ref. In an example, the reference voltage Ref is 1.1V. Since the resistance of the first resistor R1 is twice the resistance of the second resistor R2, that is, R1=2R2, at this time, when the charging voltage connected to the power terminal VBUSP is about 3.3V, the first comparator U1 will flip, and the second switch tube MN1 can be turned on normally. When the charging voltage connected to the power terminal VBUSP is very high, for example, the charging voltage connected to VBUSP is 20V, the switch impedance of the second switch tube MN1 is relatively large. Due to the influence of the second switch tube MN1, the voltage value of the first voltage VFB is not the voltage value obtained by the voltage division of the first resistor R1 and the second resistor R2. The first voltage VFB is about 6V, but at this time, because the first voltage VFB is much higher than the reference voltage Ref (1.1V), the first comparator U1 outputs the first control voltage signal VBUSP_SHT_STAT which is always at a low level, and the subsequent logic gate circuit will not turn off the first switch Q1 after performing an OR operation.

[0074] Through the above analysis, it can be concluded that: when the charging voltage connected to the power terminal VBUSP of the short-circuit detection circuit is very high, the first comparator U1 outputs the first control voltage signal VBUSP_SHT_STAT which is always at a low level, and the logic gate circuit of the subsequent stage will not turn off the first switch Q1 after the OR operation; when the charging voltage connected to the power terminal VBUSP is about 3.3V, the first comparator U1 will flip, and the second switch tube MN1 can be turned on normally, and the impedance of the second switch tube MN1 is very small at this time. When the charging voltage connected to the power terminal VBUSP is connected to the ground and a short circuit occurs, the first comparator U1 outputs the first control voltage signal VBUSP_SHT_STAT which is at a high level, so that the logic gate circuit of the subsequent stage turns off the first switch Q1 after the OR operation.

[0075] In an embodiment of the present application, the charging voltage connected to the power terminal VBUSP is detected by a short-circuit detection circuit. When it is detected that the charging voltage is connected to the ground, the output first control voltage signal VBUSP_SHT_STAT is at a high level, so that the logic gate circuit of the subsequent stage turns off the first switch Q1 after performing an OR operation, disconnects the AC-DC module and the load (mobile phone), thereby cutting off the path from the charging voltage to the ground, thereby protecting the entire charging system.

[0076] In one possible embodiment, see Figure 5 ,like Figure 5 As shown, the overcurrent protection circuit 200 includes: a sampling resistor RSNS and a second comparator U2.

[0077] A first end of the sampling resistor RSNS is electrically connected to the first sampling terminal CSP and the input terminal of the overcurrent protection circuit 200 , respectively, and a second end of the sampling resistor RSNS is grounded.

[0078] The non-inverting input terminal of the second comparator U2 is electrically connected to the first sampling terminal CSP, the inverting input terminal of the second comparator U2 is electrically connected to the second sampling terminal CSN, and the output terminal of the second comparator U2 is electrically connected to the output terminal of the overcurrent protection circuit 200 for outputting the second control voltage signal IBUS_OCP.

[0079] The sampling resistor RSNS is used to detect the current flowing through the load. Since the current flowing through the load is usually large, the value of the sampling resistor RSNS is usually small. In an example, the resistance value of the sampling resistor RSNS is 5 mΩ or 10 mΩ.

[0080] The first sampling terminal CSP and the second sampling terminal CSN are used to collect the voltage difference between the two ends of the sampling resistor RSNS, that is, the difference voltage. During the normal charging process of the mobile phone, the current Iloop flowing through the load is 0A~12A. At this time, the difference voltage (that is, the voltage collected by the first sampling terminal CSP minus the voltage collected by the second sampling terminal CSN) is up to 60mV. A preset threshold voltage is set in the overcurrent protection circuit. When the preset threshold voltage (offset) is 100mV, the difference voltage is lower than the preset threshold voltage, and the second control voltage signal IBUS_OCP is always low. When the charging voltage connected to the power terminal VBUSP is connected to the ground and a short circuit occurs, the current Iloop flowing through the load may suddenly increase. When Iloop exceeds 20A, the difference voltage exceeds 100mV, the second comparator U2 will flip, and the second control voltage signal IBUS_OCP is high, so that the logic gate circuit of the subsequent stage turns off the first switch Q1 after performing an OR operation.

[0081] In the embodiment of the present application, by detecting the voltage difference across the sampling resistor RSNS, when it is detected that the current Iloop flowing through the load suddenly increases, the output second control voltage signal IBUS_OCP is at a high level, so that the logic gate circuit of the subsequent stage turns off the first switch Q1 after performing an OR operation, disconnects the AC-DC module and the load (mobile phone), thereby cutting off the path from the charging voltage to the ground, thereby protecting the entire charging system.

[0082] In one possible embodiment, see Figure 5 ,like Figure 5 As shown, the logic gate circuit 300 includes: an OR gate U3.

[0083] The first input terminal of the OR gate U3 is electrically connected to the output terminal of the short-circuit detection circuit, the second output terminal of the OR gate is electrically connected to the output terminal of the overcurrent protection circuit, and the output terminal of the OR gate is electrically connected to the switch control terminal.

[0084] The first input terminal and the second input terminal of the OR gate are respectively connected to the first control voltage signal VBUSP_SHT_STAT and the second control voltage signal IBUS_OCP. When either of the first control voltage signal VBUSP_SHT_STAT and the second control voltage signal IBUS_OCP is at a high level, the OR gate U3 will output the switch control signal VBUSP_SHORT to control the first switch tube Q1 to turn off.

[0085] In an embodiment of the present application, a logic gate circuit is used to perform a logical OR operation on the first control voltage signal and the second control voltage signal, so that when a short circuit occurs at the power terminal VBUSP or the current flowing through the load suddenly increases, it is considered that a short circuit overcurrent event has occurred in the charging path, and a control voltage signal VBUSP_SHT_STAT and a second control voltage signal IBUS_OCP are ORed, and a switch control signal is output to control the first switch tube to turn off, disconnect the AC-DC module and the load (mobile phone), thereby cutting off the path from the charging voltage to the ground, thereby protecting the entire charging system.

[0086] In a possible embodiment, the first switch tube is an NMOS tube.

[0087] Due to the low impedance characteristics of NMOS tubes, the first switch tube is usually selected as an NMOS tube in the application of the charging system. In one embodiment, the drain of the first switch tube Q1 is electrically connected to the AC-DC module, the source of the first switch tube Q1 is electrically connected to the load (mobile phone), and the control end of the first switch tube Q1 is the gate.

[0088] An embodiment of the present application also provides a fast charging protocol chip, including: the above-mentioned short-circuit protection circuit.

[0089] An embodiment of the present application also provides an electronic device, including: the above-mentioned fast charging protocol chip.

[0090] Finally, it should be noted that the above embodiments are only specific implementation methods of the present application, but the protection scope of the present application is not limited thereto, and any changes or substitutions within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A short circuit protection circuit, characterized in that: The short-circuit protection circuit comprises: a short-circuit detection circuit, an overcurrent protection circuit and a logic gate circuit; the short-circuit detection circuit comprises a power connection terminal, the overcurrent protection circuit comprises a first sampling terminal and a second sampling terminal, the logic gate circuit comprises a switch control terminal, wherein the switch control terminal is electrically connected to the control terminal of the first switch tube, and a preset threshold voltage is set in the overcurrent protection circuit; The short-circuit detection circuit is used to divide the charging voltage connected to the power terminal to obtain a first voltage, compare the first voltage with a reference voltage, output a first control voltage signal, and transmit the first control voltage signal to the logic gate circuit; The overcurrent protection circuit is used to collect the difference voltage collected by the first sampling end and the second sampling end, compare the difference voltage with the preset threshold voltage, output a second control voltage signal, and transmit the second control voltage signal to the logic gate circuit, wherein the difference voltage is used to characterize the current flowing through the load; The logic gate circuit is used to perform a logic OR operation on the first control voltage signal and the second control voltage signal, output a switch control signal, and transmit the switch control signal to the switch control end to control the first switch tube to be turned on or off.

2. The short circuit protection circuit according to claim 1, characterized in that: The short circuit detection circuit comprises: a voltage dividing circuit and a comparison circuit; The voltage dividing circuit is used to divide the charging voltage connected to the power terminal to obtain a first voltage; The comparison circuit is used to compare the first voltage with a reference voltage and output a first control voltage signal.

3. The short circuit protection circuit according to claim 2, characterized in that: The voltage divider circuit includes: a first NOT gate, a second NOT gate, a second switch tube, a first resistor and a second resistor; The first end of the first NOT gate is electrically connected to the enable end, and the second end of the first NOT gate is electrically connected to the first end of the second NOT gate; The second end of the second NOT gate is electrically connected to the control end of the second switch tube; A first end of the first resistor is electrically connected to the power supply terminal, and a second end of the first resistor is electrically connected to a first end of the second switch tube; The second end of the second switch tube is electrically connected to the output end of the voltage divider circuit and the first end of the second resistor respectively; A second terminal of the second resistor is grounded.

4. The short circuit protection circuit according to claim 2, characterized in that: The comparison circuit comprises: a first comparator; The non-inverting input terminal of the first comparator is electrically connected to the reference voltage terminal, and the reference voltage terminal is used to access the reference voltage. The inverting input terminal of the first comparator is electrically connected to the output terminal of the voltage divider circuit. The output terminal of the first comparator is electrically connected to the output terminal of the comparison circuit, and is used to output a first control voltage signal.

5. The short circuit protection circuit according to claim 1, characterized in that: The overcurrent protection circuit comprises: a sampling resistor and a second comparator; The first end of the sampling resistor is electrically connected to the first sampling end and the input end of the overcurrent protection circuit respectively, and the second end of the sampling resistor is grounded; The non-inverting input terminal of the second comparator is electrically connected to the first sampling terminal, the inverting input terminal of the second comparator is electrically connected to the second sampling terminal, and the output terminal of the second comparator is electrically connected to the output terminal of the overcurrent protection circuit for outputting a second control voltage signal.

6. The short circuit protection circuit according to claim 1, characterized in that: The logic gate circuit comprises: an OR gate; The first input end of the OR gate is electrically connected to the output end of the short-circuit detection circuit, the second output end of the OR gate is electrically connected to the output end of the overcurrent protection circuit, and the output end of the OR gate is electrically connected to the switch control end.

7. The short circuit protection circuit according to claim 1, characterized in that: The first switch tube is an NMOS tube.

8. The short circuit protection circuit according to claim 3, characterized in that: The resistance value of the first resistor is twice the resistance value of the second resistor, and the second switch tube is a high-voltage tube.

9. A fast charging protocol chip, characterized in that: include: A short circuit protection circuit as claimed in any one of claims 1 to 8.

10. An electronic device, characterized in that: include: The fast charging protocol chip as claimed in claim 9.

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