Protection circuit for external power tube, implementation method and charging chip

Abstract

According to the protection circuit for the external power tube, the implementation method and the charging chip provided by the invention, whether the input pin VBUS is short-circuited or not is detected before the ACDRV driving circuit is started, and if the detection result shows that the input pin VBUS is short-circuited, the ACDRV driving circuit is not opened. Only when the detection result is normal, the ACDRV drive circuit is started, and then the input pin VBUS can be normally electrified and started. By means of the method, the external power tube is effectively protected, the reliability of the charging system is improved, and the problems that the VAC is powered on repeatedly all the time and the external power tube is likely to be damaged can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of charging systems, and in particular to a protection circuit, an implementation method and a charging chip for an external power tube. Background Art

[0002] In the charging system, the adapter's output pin VAC is connected to an external protection power tube (generally composed of ACFET and QBFET, which respectively improve the withstand voltage and reverse blocking protection), and then connected to the input pin VBUS of the charging chip. When the chip detects that VAC is connected, a high-voltage drive signal will be generated and output inside the chip, turning on the external protection power tube, and VBUS will be powered on normally. If VBUS is in a short-circuit state, there will be a large current and voltage when it is turned on, which is likely to burn out the external protection power tube.

[0003] In order to solve the above technical problems, the indirect solution of external power tube protection is usually adopted in the prior art as follows: when VAC is detected to be valid, the chip starts to turn on ACDRV, and the VBUS voltage starts to rise. If VBUS is in a short-circuit state, the current flowing through the external power tube is very large. When the overcurrent protection of the power supply in the Adapter is triggered, the VAC voltage begins to drop. After the drop continues for a period of time, the VAC_UVLO protection is triggered, and the chip will turn off ACDRV. At this time, the VAC voltage will start to rise again, and then turn on ACDRV again. This situation will repeat until the short-circuit source of VBUS is removed to return to normal.

[0004] It can be seen that the indirect solution of using external power tube protection on the market is mainly achieved by triggering the OCP protection of the built-in power chip of the adapter to cause VAC to drop. The continuous drop of VAC will further cause VAC_UVLO to become high and turn off ACDRV. When ACDRV is turned off, the path between VAC and VBUS will be disconnected, so the VAC voltage will rise again, causing VAC_UVLO to become low, and then turn on ACDRV, and this process will continue to repeat. Due to the long response time of the above process, if the external power tube has abnormal high voltage and high current, this will increase the risk of ACFET and QBFET being burned. Summary of the invention

[0005] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a protection circuit, implementation method and charging chip for an external power tube, which is used to solve the technical problem that if the external power tube has abnormal high voltage and high current, this will increase the risk of the external protection power tube being burned out.

[0006] In order to achieve the above-mentioned purpose and other related purposes, the present invention provides a protection circuit for an external power tube, the circuit comprising: a power adapter, an external protection power tube and a charging chip; wherein the charging chip is provided with an input pin VAC, an input pin VBUS, a control pin ACDRV, a VBUS short-circuit detection circuit connected to the input pin VBUS and an ACDRV drive circuit connected to the control pin ACDRV; the VBUS short-circuit detection circuit is connected to the ACDRV drive circuit; the output pin of the power adapter is connected to the input pin VAC and the external protection power tube; the external protection power tube is connected to the input pin VBUS And control pin ACDRV; the charging chip is powered and started by the power adapter when it is detected that the input pin VAC is connected to the power adapter, and when the power-on is completed and the power supply signal of the power adapter is detected to be normal, the VBUS short-circuit detection circuit is controlled to perform short-circuit detection on the input pin VBUS; when the input pin VBUS is detected to be not short-circuited, the ACDRV drive circuit is turned on, and the ACDRV signal is output by controlling the pin ACDRV to turn on the external protection power tube, and the input pin VBUS is powered on; when the input pin VBUS is detected to be short-circuited, the ACDRV drive circuit is not started.

[0007] In one embodiment of the present invention, the charging chip detects whether the power supply signal of the power adapter is normal after power-on is completed, and outputs a detection signal to the VBUS short-circuit detection circuit.

[0008] In one embodiment of the present invention, the VBUS short-circuit detection circuit is activated when a detection signal corresponding to detecting that the power supply signal of the power adapter is normal is input.

[0009] In one embodiment of the present invention, the VBUS short-circuit detection circuit includes: a current source, a switch and a voltage comparator; wherein one end of the switch is connected to the current source and the non-inverting input end of the voltage comparator, and the other end is connected to the current source connected to the input pin VBUS; the negative input end of the voltage comparator is connected to the reference voltage, and the output end is connected to the ACDRV drive circuit.

[0010] In one embodiment of the present invention, when the VBUS short-circuit detection circuit inputs a detection signal corresponding to a detection signal indicating that the power supply signal of the power adapter is normal, the control switch is closed, the current source is activated, and the current flows to the input pin VBUS through the switch; the voltage comparator compares the sensed voltage on the input pin VBUS with the reference voltage and outputs a short-circuit detection signal; if the short-circuit detection signal corresponds to a signal indicating that the input pin VBUS is detected as short-circuited, the ACDRV drive circuit is not turned on; if the short-circuit detection signal corresponds to a signal indicating that the corresponding input pin VBUS is detected as not short-circuited, the ACDRV drive circuit is turned on.

[0011] In one embodiment of the present invention, the voltage comparator compares the sensed voltage on the input pin VBUS with a reference voltage. If the sensed voltage is lower than the reference voltage, the input pin VBUS is detected as short-circuited, and the voltage comparator outputs a low-level signal; if the sensed voltage is higher than or equal to the reference voltage, the input pin VBUS is detected as not short-circuited, and the voltage comparator outputs a high-level signal.

[0012] In one embodiment of the present invention, after the short circuit detection is completed, the current source, the switch and the voltage comparator are controlled to be turned off.

[0013] To achieve the above-mentioned purpose and other related purposes, the present invention provides a method for realizing a protection circuit for an external power tube, which is applied to a charging chip, connected to a power adapter and an external protection power tube, and includes: an input pin VAC, an input pin VBUS, a control pin ACDRV, a VBUS short-circuit detection circuit connected to the input pin VBUS, and an ACDRV drive circuit connected to the control pin ACDRV. The method includes: when it is detected that the input pin VAC is connected to the power adapter, the power adapter supplies power and starts; when the power-on is completed and the power supply signal of the power adapter is detected to be normal, the VBUS short-circuit detection circuit is controlled to perform a short-circuit detection on the input pin VBUS; when the input pin VBUS is detected to be not short-circuited, the ACDRV drive circuit is turned on, and an ACDRV signal is output through the control pin ACDRV to turn on the external protection power tube, and the input pin VBUS is powered on; when the input pin VBUS is detected to be short-circuited, the ACDRV drive circuit is not started.

[0014] To achieve the above-mentioned purpose and other related purposes, the present invention provides a charging chip, including: an input pin VAC, an input pin VBUS, a control pin ACDRV, a VBUS short-circuit detection circuit connected to the input pin VBUS, and an ACDRV drive circuit connected to the control pin ACDRV; wherein the input pin VAC is connected to the output pin of a power adapter; the input pin VBUS and the control pin ACDRV are connected to the external protection power tube; the charging chip is powered and started by the power adapter when it is detected that the input pin VAC is connected to the power adapter, and when the power-on is completed and the power supply signal of the power adapter is detected to be normal, the VBUS short-circuit detection circuit is controlled to perform short-circuit detection on the input pin VBUS; when the input pin VBUS is detected to be not short-circuited, the ACDRV drive circuit is turned on, the ACDRV signal is output through the control pin ACDRV, the external protection power tube is turned on, and the input pin VBUS is powered on; when the input pin VBUS is detected to be short-circuited, the ACDRV drive circuit is not started.

[0015] In one embodiment of the present invention, the VBUS short-circuit detection circuit includes: a current source, a switch and a voltage comparator; wherein one end of the switch is connected to the current source and the non-inverting input end of the voltage comparator, and the other end is connected to the current source connected to the input pin VBUS; the negative input end of the voltage comparator is connected to the reference voltage, and the output end is connected to the ACDRV drive circuit.

[0016] As described above, the present invention is a protection circuit, implementation method and charging chip for an external power tube, which has the following beneficial effects: before starting the ACDRV drive circuit, the present invention first detects whether the input pin VBUS is short-circuited. If the detection result finds a short circuit, the ACDRV drive circuit will not be turned on. Only when the detection result is normal will the ACDRV drive circuit be turned on, and then the input pin VBUS can be powered on and started normally. In this way, the external power tube is effectively protected, the reliability of the charging system is improved, and the problem of VAC being repeatedly powered on and the external power tube being damaged can be solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of a flow chart of a protection circuit for an external power tube in one embodiment of the present invention.

[0018] Figure 2 FIG. 4 is a schematic diagram showing the structure of a VBUS short-circuit detection circuit in an embodiment of the present invention.

[0019] Figure 3 It is a flow chart of a method for implementing a protection circuit for an external power tube in one embodiment of the present invention.

[0020] Figure 4 Shown is a schematic diagram of the structure of a charging chip in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0022] It should be noted that in the following description, reference is made to the accompanying drawings, which describe several embodiments of the present invention. It should be understood that other embodiments may also be used, and that mechanical composition, structural, electrical and operational changes may be made without departing from the spirit and scope of the present invention. The following detailed description should not be considered restrictive, and the scope of the embodiments of the present invention is limited only by the claims of the published patents. The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. Spatially related terms, such as "upper", "lower", "left", "right", "below", "below", "lower", "above", "upper", etc., may be used in the text to facilitate the description of the relationship between an element or feature shown in the figure and another element or feature.

[0023] Throughout the specification, when a part is said to be "connected" to another part, this includes not only the case of "direct connection" but also the case of "indirect connection" by placing other elements therebetween. In addition, when a part is said to "include" a certain constituent element, unless otherwise stated, it does not exclude other constituent elements, but means that other constituent elements may be included.

[0024] The terms first, second and third mentioned herein are used to describe various parts, components, regions, layers and / or segments, but are not limited thereto. These terms are only used to distinguish a certain part, component, region, layer or segment from other parts, components, regions, layers or segments. Therefore, the first part, component, region, layer or segment described below may refer to the second part, component, region, layer or segment within the scope of the present invention.

[0025] Furthermore, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless there is an indication to the contrary in the context. It should be further understood that the terms "comprise", "include" indicate the presence of the described features, operations, elements, components, items, kinds, and / or groups, but do not exclude the presence, occurrence or addition of one or more other features, operations, elements, components, items, kinds, and / or groups. The terms "or" and "and / or" used herein are interpreted as inclusive, or mean any one or any combination. Therefore, "A, B or C" or "A, B and / or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B and C". Exceptions to this definition will only occur when the combination of elements, functions or operations is inherently mutually exclusive in some way.

[0026] The present invention provides a protection circuit for an external power tube. Before starting the ACDRV drive circuit, it first detects whether the input pin VBUS is short-circuited. If the detection result finds a short circuit, the ACDRV drive circuit will not be turned on. Only when the detection result is normal will the ACDRV drive circuit be turned on, and then the input pin VBUS can be powered on and started normally. Through this method, the external power tube is effectively protected, the reliability of the charging system is improved, and the problem that the VAC is repeatedly powered on and the external power tube may be damaged can be solved.

[0027] At the same time, in order to make the purpose, technical solution and advantages of the present invention more clear, the technical solution in the embodiment of the present invention is further described in detail through the following embodiments and in combination with the accompanying drawings. It should be understood that the specific embodiments described here are only used to explain the present invention and are not used to limit the invention.

[0028] Before further describing the present invention in detail, the nouns and terms involved in the embodiments of the present invention are explained. The nouns and terms involved in the embodiments of the present invention are applicable to the following interpretations:

[0029] <1> VAC (Voltage Alternating Current), in a charging system, VAC usually refers to the AC voltage output by a power adapter, which is converted into a DC voltage (DC) for use by the device after rectification and filtering. The input pin VAC mentioned in the present invention refers to the pin connected to VAC.

[0030] <2> VBUS (Voltage BUS, bus voltage), in the charging system, the VBUS pin is used to connect the charging device (such as a mobile phone, tablet computer, etc.) and the charger or power adapter. The input pin VBUS mentioned in the present invention refers to the bus voltage pin.

[0031] <3> ACDRV (AC Drive), the control pin ACDRV and the ACDRV drive circuit mentioned in the present invention are an AC drive control pin and a drive circuit, which are used to drive an external protection power tube.

[0032] The following is a detailed description of the embodiments of the present invention with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. The present invention can be embodied in many different forms and is not limited to the embodiments described herein.

[0033] like Figure 1 A schematic structural diagram of a protection circuit for an external power tube in an embodiment of the present invention is shown.

[0034] The protection circuit for the external power tube includes: a power adapter 1, an external protection power tube 2 and a charging chip 3;

[0035] The charging chip 3 is provided with an input pin VAC, an input pin VBUS, a control pin ACDRV, a VBUS short-circuit detection circuit and the ACDRV drive circuit; the VBUS short-circuit detection circuit is integrated inside the charging chip 3 and is used to monitor the state of the input pin VBUS in real time to determine whether there is a short circuit. The circuit is closely connected with the ACDRV drive circuit so as to control the ACDRV drive circuit to be turned off when a short circuit is detected. The ACDRV drive circuit controls the ACDRV signal to be output from the control pin ACDRV to the external protection power tube 2 according to the result of the VBUS short-circuit detection circuit, thereby controlling the switching state of the external protection power tube 2. The input pin VAC receives the input voltage from the power adapter 1 as the power supply source of the charging chip 3; the input pin VBUS is connected to the external protection power tube 2; the control pin ACDRV is used to control the on and off of the external protection power tube 2 by outputting the ACDRV signal.

[0036] The output pin of the power adapter 1 is directly connected to the input pin VAC of the charging chip 3, and is also connected to the external protection power tube 2. The power adapter 1 is responsible for providing stable voltage and current to meet the energy requirements during the charging process.

[0037] The external protection power tube 2 is usually composed of an ACFET with enhanced voltage resistance and a QBFET with reverse blocking protection; one end of the external protection power tube 2 is connected to the input pin VBUS of the charging chip 3, and the other end is connected to the power adapter 1. At the same time, the external protection power tube 3 is also connected to the control pin ACDRV, receiving the control signal from the charging chip 3 to achieve on-off control.

[0038] The specific workflow is as follows:

[0039] When the power adapter 1 is connected to the input pin VAC of the charging chip 1 , the charging chip 1 starts to power on and start.

[0040] Once the power-on is completed and the power supply signal of the power adapter 1 is detected to be normal, the charging chip 3 immediately starts the VBUS short-circuit detection circuit to perform a short-circuit detection on the input pin VBUS.

[0041] If the input pin VBUS is detected as not being in a short-circuit state, the charging chip 3 will turn on the ACDRV driving circuit and output an ACDRV signal through the control pin ACDRV, thereby turning on the external protection power tube 2 and allowing the input pin VBUS to be powered on normally.

[0042] If the input pin VBUS is detected to be in a short-circuit state, the charging chip 3 will not start the ACDRV driving circuit and keep the external protection power tube 2 in a closed state to prevent the short-circuit current from damaging the circuit.

[0043] The present invention uses a VBUS short-circuit detection circuit to detect whether the input pin VBUS is short-circuited before starting the ACDRV drive circuit. If the detection result finds a short circuit, the ACDRV drive circuit will not be turned on, and the external power tube will not be turned on. Only when the detection result is normal will the ACDRV drive circuit be turned on, and then the input pin VBUS can be powered on and started normally. This can avoid the high voltage and high current situation on the VBUS pin for a certain period of time, reduce the risk of damage to the external power tube, and improve system reliability.

[0044] In one embodiment, after the charging chip 3 is connected to the power adapter 1 and completes the power-on process, it will further perform voltage detection on the power supply signal of the power adapter 1, and the detection signal is VAC_OK, which is used to control the VBUS short-circuit detection circuit. Once it is detected that the voltage value of the power supply signal reaches or exceeds the preset target threshold (i.e., meets the requirements), the charging chip 3 will output a detection signal corresponding to a normal signal, i.e., VAC_OK=1, which is output to the VBUS short-circuit detection circuit to control the VBUS short-circuit detection circuit to start; otherwise, it will output a detection signal corresponding to an abnormal signal, i.e., VAC_OK=0, which is output to the VBUS short-circuit detection circuit to control the VBUS short-circuit detection circuit not to start.

[0045] In a specific embodiment, the VBUS short circuit detection circuit is activated when a detection signal corresponding to detecting that the power supply signal of the power adapter 1 is normal is input. For example, the VBUS short circuit detection circuit is activated when a detection signal VAC_OK=1 is inputted therein.

[0046] In one embodiment, if Figure 2 , the VBUS short circuit detection circuit includes: a current source U2, a switch U4 and a voltage comparator U3;

[0047] Among them, one end of the switch U4 is connected to the current source U2 and the non-inverting input end of the voltage comparator U3, and the other end is connected to the current source U2 and the input pin VBUS; the switch U4 also inputs the detection signal VAC_OK; the negative input end of the voltage comparator U3 is connected to the reference voltage VREF, and the output end is connected to the ACDRV drive circuit.

[0048] In a specific embodiment, when the VBUS short-circuit detection circuit inputs a detection signal corresponding to the detection that the power supply signal of the power adapter 1 is normal, the control switch U4 is closed, the current source U2 is activated, and the current flows to the input pin VBUS through the switch U4, and the sensing voltage VBUS_SNS is generated on the input pin VBUS; the sensing voltage VBUS_SNS generated on the input pin VBUS is input to the non-inverting input end of the voltage comparator U3, and at the same time, a reference voltage VREF is connected to the negative input end of the voltage comparator U3, and the voltage comparator U3 compares the two voltage values ​​in real time and outputs a short-circuit detection signal VBUS_OK according to the comparison result. If the short-circuit detection signal corresponds to a signal that the input pin VBUS is detected as short-circuited, the ACDRV drive circuit is not turned on; if the short-circuit detection signal corresponds to a signal that the corresponding input pin VBUS is detected as non-short-circuited, the ACDRV drive circuit is turned on.

[0049] In a specific embodiment, the voltage comparator U3 compares the sensed voltage VBUS_SNS on the input pin VBUS with a reference voltage VREF;

[0050] If the sense voltage VBUS_SNS is lower than the reference voltage VREF, this usually means that the voltage on the input pin VBUS drops abnormally, which may be caused by a short circuit. At this time, the voltage comparator U3 will determine that the input pin VBUS is in a short circuit state and output a low-level signal, VBUS_OK = 0. After outputting a low-level signal (indicating a short circuit), the ACDRV drive circuit will be prevented from turning on, and the external protection power tube (ACFET + QBFET) will be kept off to prevent the short-circuit current from damaging the circuit.

[0051] If the sense voltage VBUS_SNS is higher than or equal to the reference voltage VREF, it means that the voltage on the input pin VBUS is within the normal range and no short circuit occurs. At this time, the voltage comparator U3 will determine that the input pin VBUS is not in a short circuit state and output a high level signal, VBUS_OK = 1. After outputting a high level signal (indicating no short circuit), the ACDRV drive circuit will be controlled to turn on, and the ACDRV signal will be output through the control pin ACDRV to turn on the external protection power tube (ACFET + QBFET) to power on the VBUS pin.

[0052] In one embodiment, after the short circuit detection is completed, the current source U2, the switch U4 and the voltage comparator U3 are controlled to be turned off to achieve the purpose of reducing power consumption.

[0053] Similar to the principle of the above embodiment, the present invention provides a method for implementing a protection circuit for an external power tube.

[0054] The following provides specific embodiments in conjunction with the accompanying drawings:

[0055] like Figure 3 A flow chart showing a method for implementing a protection circuit for an external power tube in an embodiment of the present invention.

[0056] Applied to a charging chip, connected to a power adapter and an external protection power tube, including: an input pin VAC, an input pin VBUS, a control pin ACDRV, a VBUS short-circuit detection circuit connected to the input pin VBUS, and an ACDRV drive circuit connected to the control pin ACDRV, wherein the input pin VAC is connected to the output pin of the power adapter; the input pin VBUS and the control pin ACDRV are connected to the external protection power tube,

[0057] The method comprises:

[0058] Step S1: When it is detected that the input pin VAC is connected to the power adapter, the power adapter is powered and started.

[0059] Step S2: When the power-on is completed and the power supply signal of the power adapter is detected to be normal, the VBUS short-circuit detection circuit is controlled to perform a short-circuit detection on the input pin VBUS.

[0060] In one embodiment, after power-on is completed, it is detected whether the power supply signal of the power adapter is normal, and a detection signal is output to the VBUS short-circuit detection circuit.

[0061] In one embodiment, the VBUS short circuit detection circuit is activated when a detection signal corresponding to detecting that the power supply signal of the power adapter is normal is input.

[0062] In one embodiment, the VBUS short circuit detection circuit includes: a current source, a switch and a voltage comparator; wherein one end of the switch is connected to the current source and the non-inverting input end of the voltage comparator, and the other end is connected to the current source connected to the input pin VBUS; the negative input end of the voltage comparator is connected to the reference voltage, and the output end is connected to the ACDRV drive circuit.

[0063] In one embodiment, when the VBUS short-circuit detection circuit inputs a detection signal corresponding to a detection signal indicating that the power supply signal of the power adapter is normal, the control switch is closed, the current source is activated, and the current flows to the input pin VBUS through the switch; the voltage comparator compares the sensed voltage on the input pin VBUS with the reference voltage and outputs a short-circuit detection signal.

[0064] In one embodiment, the voltage comparator compares the sensed voltage on the input pin VBUS with a reference voltage. If the sensed voltage is lower than the reference voltage, the input pin VBUS is detected as short-circuited, and the voltage comparator outputs a low-level signal; if the sensed voltage is higher than or equal to the reference voltage, the input pin VBUS is detected as not short-circuited, and the voltage comparator outputs a high-level signal.

[0065] Step S3: When the input pin VBUS is detected as not short-circuited, the ACDRV driving circuit is turned on, and an ACDRV signal is output through the control pin ACDRV to turn on the external protection power tube, and the input pin VBUS is powered on.

[0066] In one embodiment, if the short circuit detection signal corresponds to a signal that the corresponding input pin VBUS is detected as not short circuited, the ACDRV driving circuit is turned on, and the ACDRV signal is output through the control pin ACDRV to turn on the external protection power tube and power on the input pin VBUS.

[0067] In one embodiment, if the voltage comparator outputs a high level signal, the ACDRV driving circuit is turned on, and an ACDRV signal is output through the control pin ACDRV to turn on the external protection power tube, and the input pin VBUS is powered on.

[0068] Step S4: When the input pin VBUS is detected as short-circuited, the ACDRV driving circuit is not started.

[0069] In one embodiment, if the short-circuit detection signal corresponds to a signal indicating that the input pin VBUS is short-circuited, the ACDRV driving circuit is not turned on.

[0070] In one embodiment, if the voltage comparator outputs a low level signal, the ACDRV driving circuit is not started.

[0071] Since the principle of the implementation method of the protection circuit for the external power tube has been described in the above-mentioned embodiment, it will not be repeated here.

[0072] like Figure 3 A schematic structural diagram of a charging chip in an embodiment of the present invention is shown.

[0073] The charging chip comprises: an input pin VAC, an input pin VBUS, a control pin ACDRV, a VBUS short circuit detection circuit connected to the input pin VBUS, and an ACDRV driving circuit connected to the control pin ACDRV;

[0074] Wherein, the input pin VAC is connected to the output pin of the power adapter; the input pin VBUS and the control pin ACDRV are connected to the external protection power tube;

[0075] The charging chip is powered and started by the power adapter when it detects that the input pin VAC is connected to the power adapter. When the power-on is completed and the power supply signal of the power adapter is detected to be normal, the VBUS short-circuit detection circuit is controlled to perform a short-circuit detection on the input pin VBUS; when the input pin VBUS is detected to be not short-circuited, the ACDRV drive circuit is turned on, the ACDRV signal is output through the control pin ACDRV, the external protection power tube is turned on, and the input pin VBUS is powered on; when the input pin VBUS is detected to be short-circuited, the ACDRV drive circuit is not started.

[0076] In one embodiment, the VBUS short circuit detection circuit includes: a current source, a switch and a voltage comparator; wherein one end of the switch is connected to the current source and the non-inverting input end of the voltage comparator, and the other end is connected to the current source connected to the input pin VBUS; the negative input end of the voltage comparator is connected to the reference voltage, and the output end is connected to the ACDRV drive circuit.

[0077] Since the implementation principle of the charging chip has been described in the above embodiments, it will not be repeated here.

[0078] In summary, the protection circuit, implementation method and charging chip for the external power tube of the present invention detect whether the input pin VBUS is short-circuited before starting the ACDRV drive circuit. If the detection result finds a short circuit, the ACDRV drive circuit will not be turned on. Only when the detection result is normal will the ACDRV drive circuit be turned on, and then the input pin VBUS can be powered on and started normally. Through this method, the external power tube is effectively protected, the reliability of the charging system is improved, and the problem of VAC being repeatedly powered on and the external power tube being damaged can be solved. Therefore, the present invention effectively overcomes the various shortcomings in the prior art and has a high industrial utilization value.

[0079] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A protection circuit for an external power tube, characterized in that: The circuit includes: a power adapter, an external protection power tube and a charging chip; The charging chip is provided with an input pin VAC, an input pin VBUS, a control pin ACDRV, a VBUS short-circuit detection circuit connected to the input pin VBUS, and an ACDRV drive circuit connected to the control pin ACDRV; the VBUS short-circuit detection circuit is connected to the ACDRV drive circuit; the output pin of the power adapter is connected to the input pin VAC and an external protection power tube; the external protection power tube is connected to the input pin VBUS and the control pin ACDRV; When the charging chip detects that the input pin VAC is connected to the power adapter, it is powered and started by the power adapter. When the power-on is completed and the power supply signal of the power adapter is detected to be normal, the VBUS short-circuit detection circuit is controlled to perform a short-circuit detection on the input pin VBUS; when the input pin VBUS is detected to be not short-circuited, the ACDRV drive circuit is turned on, and the ACDRV signal is output by controlling the pin ACDRV to turn on the external protection power tube, and the input pin VBUS is powered on; when the input pin VBUS is detected to be short-circuited, the ACDRV drive circuit is not started.

2. The protection circuit for an external power tube according to claim 1, characterized in that: After the charging chip is powered on, it detects whether the power supply signal of the power adapter is normal, and outputs a detection signal to the VBUS short-circuit detection circuit.

3. The protection circuit for an external power tube according to claim 2, characterized in that: The VBUS short-circuit detection circuit is activated when a detection signal corresponding to detecting that the power supply signal of the power adapter is normal is input.

4. The protection circuit for an external power tube according to claim 1 or 3, characterized in that: The VBUS short circuit detection circuit comprises: a current source, a switch and a voltage comparator; Among them, one end of the switch is connected to the current source and the non-inverting input end of the voltage comparator, and the other end is connected to the current source connected to the input pin VBUS; the negative input end of the voltage comparator is connected to the reference voltage, and the output end is connected to the ACDRV drive circuit.

5. The protection circuit for an external power tube according to claim 4, characterized in that: When the VBUS short-circuit detection circuit inputs a detection signal corresponding to a detection signal indicating that the power supply signal of the power adapter is normal, the control switch is closed, the current source is activated, and the current flows to the input pin VBUS through the switch; the voltage comparator compares the sensed voltage on the input pin VBUS with the reference voltage and outputs a short-circuit detection signal; if the short-circuit detection signal corresponds to a signal indicating that the input pin VBUS is detected to be short-circuited, the ACDRV drive circuit is not turned on; if the short-circuit detection signal corresponds to a signal indicating that the corresponding input pin VBUS is detected to be non-short-circuited, the ACDRV drive circuit is turned on.

6. The protection circuit for an external power tube according to claim 5, characterized in that: The voltage comparator compares the sensed voltage on the input pin VBUS with a reference voltage. If the sensed voltage is lower than the reference voltage, the input pin VBUS is detected as short-circuited, and the voltage comparator outputs a low-level signal; if the sensed voltage is higher than or equal to the reference voltage, the input pin VBUS is detected as not short-circuited, and the voltage comparator outputs a high-level signal.

7. The protection circuit for an external power tube according to claim 4, characterized in that: After the short-circuit detection is completed, the control current source, switch and voltage comparator are turned off.

8. A method for implementing a protection circuit for an external power tube, characterized in that: Applied to a charging chip, connected to a power adapter and an external protection power tube, including: an input pin VAC, an input pin VBUS, a control pin ACDRV, a VBUS short-circuit detection circuit connected to the input pin VBUS, and an ACDRV drive circuit connected to the control pin ACDRV, the method includes: When it is detected that the input pin VAC is connected to the power adapter, the power adapter is used to supply power and start the system; When power-on is completed and the power supply signal of the power adapter is detected to be normal, the VBUS short-circuit detection circuit is controlled to perform short-circuit detection on the input pin VBUS; When the input pin VBUS is detected as not short-circuited, the ACDRV drive circuit is turned on, and the ACDRV signal is output through the control pin ACDRV to turn on the external protection power tube, and the input pin VBUS is powered on; When the input pin VBUS is detected as short-circuited, the ACDRV drive circuit is not started.

9. A charging chip, characterized in that: include: An input pin VAC, an input pin VBUS, a control pin ACDRV, a VBUS short-circuit detection circuit connected to the input pin VBUS, and an ACDRV drive circuit connected to the control pin ACDRV; Wherein, the input pin VAC is connected to the output pin of the power adapter; the input pin VBUS and the control pin ACDRV are connected to the external protection power tube; The charging chip is powered and started by the power adapter when it detects that the input pin VAC is connected to the power adapter. When the power-on is completed and the power supply signal of the power adapter is detected to be normal, the VBUS short-circuit detection circuit is controlled to perform a short-circuit detection on the input pin VBUS; when the input pin VBUS is detected to be not short-circuited, the ACDRV drive circuit is turned on, the ACDRV signal is output through the control pin ACDRV, the external protection power tube is turned on, and the input pin VBUS is powered on; when the input pin VBUS is detected to be short-circuited, the ACDRV drive circuit is not started.

10. The charging chip according to claim 9, characterized in that: The VBUS short-circuit detection circuit includes: a current source, a switch and a voltage comparator; wherein one end of the switch is connected to the current source and the non-inverting input end of the voltage comparator, and the other end is connected to the current source connected to the input pin VBUS; the negative input end of the voltage comparator is connected to the reference voltage, and the output end is connected to the ACDRV drive circuit.

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