Switching power supply, control circuit, fault detection circuit and method

Abstract

The invention provides a switching power supply, a control circuit and a fault detection circuit and method.The fault detection circuit detects a control module, performs time-sharing detection on at least two of open circuit detection, short circuit detection and overvoltage detection of the output end of the switching power supply, and generates a corresponding second control signal under each detection; the voltage detection module generates a corresponding threshold voltage according to the second control signal under each item of detection and generates a corresponding detection signal according to the voltage of the output end of the switching power supply and the corresponding threshold voltage, and the detection control module generates a corresponding detection result signal according to the corresponding detection signal; the fault detection circuit obtains detection signals corresponding to at least two of open circuit detection, short circuit detection and overvoltage detection through the multiplexing voltage detection module. According to the invention, the same circuit is multiplexed in a time division manner to carry out open-circuit detection, short-circuit detection, overvoltage detection and undervoltage detection on the output end of the switching power supply, so that the safety and reliability of the switching power supply are improved, and the circuit structure is simplified.

Description

Technical Field

[0001] The present disclosure relates to the field of power electronics technology, and in particular to a switching power supply, a control circuit, a fault detection circuit and a method. Background Art

[0002] With the development and innovation of power electronics technology, switching power supply technology is also constantly innovating. At present, switching power supplies are widely used due to their small size, light weight and high efficiency. They are an indispensable power supply method for the rapid development of today's electronic information industry.

[0003] In practical applications, if the output of the switching power supply is open circuit, short circuit, voltage is too high, or voltage is too low, the load of the switching power supply cannot work properly, or even burns out. To meet the needs, the design of the switching power supply takes safety and reliability as the primary principles. Summary of the invention

[0004] In view of the above problems, an object of the present disclosure is to provide a switching power supply, a control circuit, a fault detection circuit and a method to improve the safety and reliability of the switching power supply.

[0005] According to a first aspect of the present disclosure, there is provided a fault detection circuit for a switching power supply control circuit, comprising:

[0006] a detection control module, used for performing time-sharing detection on at least two of the open circuit detection, short circuit detection and overvoltage detection of the output end of the switching power supply, and generating a corresponding second control signal under each detection; and

[0007] The voltage detection module generates a corresponding threshold voltage according to the second control signal under each detection, and generates a corresponding detection signal according to the voltage at the output end of the switching power supply and the corresponding threshold voltage, and the detection control module generates a corresponding detection result signal according to the corresponding detection signal,

[0008] The fault detection circuit obtains detection signals corresponding to at least two of open circuit detection, short circuit detection and overvoltage detection through a multiplexed voltage detection module.

[0009] Optionally, it includes: when the detection control module performs at least two detections on the output end of the switching power supply including an open circuit detection, it also generates a first control signal; the voltage detection module also determines whether to turn on an open circuit detection path based on the first control signal, and the open circuit detection path is connected between the power supply voltage and the output end of the switching power supply.

[0010] Optionally, the detection control module performs a first detection on the output end of the switching power supply according to the received power-on enable signal, and the first detection is an open circuit detection.

[0011] Optionally, the detection control module performs a first detection on the output end of the switching power supply according to the received power-on enable signal, and the first detection is a short circuit detection.

[0012] Optionally, the detection control module performs a first detection on the output end of the switching power supply, and the first detection is an open circuit detection, and the detection process includes:

[0013] The detection control module outputs a driving signal for shutting down the drive to the switching power supply;

[0014] The detection control module generates a third control signal to control the open circuit detection indication path to be turned on.

[0015] The detection control module outputs a first control signal and a second control signal to the voltage detection module, wherein the first control signal controls the open circuit detection path in the voltage detection module to be turned on so as to charge the output terminal of the switching power supply, and the second control signal controls the voltage detection module to generate an open circuit threshold voltage, and the voltage detection module generates the open circuit detection signal according to a comparison result between the voltage at the output terminal of the switching power supply and the open circuit threshold voltage;

[0016] The detection control module sets a first timing time, resets before starting timing, and after the timing reaches the first timing time, provides the open circuit detection signal generated by the voltage detection module to the input end of the open circuit detection indication path, and generates the open circuit detection result signal via the open circuit detection indication path;

[0017] The detection control module ends the fault detection when the open circuit detection result signal indicates that the switch power supply is in an open circuit state, and triggers itself to perform a second detection when the open circuit detection result signal indicates that the switch power supply is in a normal state.

[0018] Optionally, the second detection is a detection process of performing short circuit detection on the output terminal of the switching power supply, including:

[0019] The detection control module outputs a driving signal to the switching power supply to drive the switching circuit of the switching power supply to work;

[0020] The detection control module generates a third control signal to control the short-circuit detection indication path to be turned on;

[0021] The detection control module outputs a first control signal and a second control signal to the voltage detection module, wherein the first control signal controls the open circuit detection path in the voltage detection module to be turned off, and the second control signal controls the voltage detection module to generate a short circuit threshold voltage, and the voltage detection module generates the short circuit detection signal according to a comparison result between the voltage at the output end of the switching power supply and the short circuit threshold voltage;

[0022] The detection control module sets a second timing time, resets before starting timing, and after the timing reaches the second timing time, provides the short-circuit detection signal generated by the voltage detection module to the input end of the short-circuit detection indication path, and generates the short-circuit detection result signal via the short-circuit detection indication path;

[0023] The detection control module ends the fault detection when the short-circuit detection result signal indicates that the switch power supply is in a short-circuit state, and ends the fault detection or performs a third detection when the short-circuit detection result signal indicates that the switch power supply is in a normal state.

[0024] Optionally, the second detection is an overvoltage detection on the output end of the switching power supply.

[0025] Optionally, the third detection is an overvoltage detection on the output end of the switching power supply.

[0026] Optionally, the overvoltage detection process includes:

[0027] The detection control module outputs a driving signal to the switching power supply to drive the switching circuit of the switching power supply to work;

[0028] The detection control module generates a third control signal to control the overvoltage detection indication path to be turned on;

[0029] The detection control module outputs a first control signal and a second control signal to the voltage detection module, wherein the first control signal controls the open circuit detection path in the voltage detection module to be turned off, and the second control signal controls the voltage detection module to generate an overvoltage threshold voltage, and the voltage detection module generates the overvoltage detection signal according to a comparison result between the voltage at the output end of the switching power supply and the overvoltage threshold voltage;

[0030] The detection control module provides the overvoltage detection signal generated by the voltage detection module to the input end of the overvoltage detection indication path, and generates the overvoltage detection result signal via the overvoltage detection indication path;

[0031] The detection control module performs a fault protection action when the overvoltage detection result signal indicates that the switching power supply is in an overvoltage state, and continues to perform overvoltage detection when the overvoltage detection result signal indicates that the switching power supply is in a normal state.

[0032] Optionally, the performing a fault protection action includes:

[0033] The detection control module outputs an invalid state driving signal to the switching power supply to reduce the voltage at the output end of the switching power supply;

[0034] The detection control module generates a third control signal to control the undervoltage detection indication path to be turned on;

[0035] The detection control module outputs a first control signal and a second control signal to the voltage detection module, wherein the first control signal controls the open circuit detection path in the voltage detection module to be turned off, and the second control signal controls the voltage detection module to generate an undervoltage threshold voltage, and the voltage detection module generates the undervoltage detection signal according to a comparison result between the voltage at the output end of the switching power supply and the undervoltage threshold voltage;

[0036] The detection control module ends fault detection when the undervoltage detection result signal indicates that the voltage at the output end of the switching power supply drops below the undervoltage threshold, and continues undervoltage detection when the undervoltage detection result signal indicates that the voltage at the output end of the switching power supply does not drop below the undervoltage threshold.

[0037] Optionally, the detection control module performs a first detection on the output end of the switching power supply, and the first detection is a short circuit detection detection process including:

[0038] The detection control module outputs a driving signal to the switching power supply to drive the switching circuit of the switching power supply to work;

[0039] The detection control module generates a third control signal to control the short-circuit detection indication path to be turned on;

[0040] The detection control module outputs a second control signal to the voltage detection module, the second control signal controls the voltage detection module to generate a short-circuit threshold voltage, and the voltage detection module generates the short-circuit detection signal according to a comparison result between the voltage at the output end of the switching power supply and the short-circuit threshold voltage;

[0041] The detection control module sets a second timing time, resets before starting timing, and after the timing reaches the second timing time, provides the short-circuit detection signal generated by the voltage detection module to the input end of the short-circuit detection indication path, and generates the short-circuit detection result signal via the short-circuit detection indication path;

[0042] The detection control module ends the fault detection when the short-circuit detection result signal indicates that the switch power supply is in a short-circuit state, and ends the fault detection or performs a second detection when the short-circuit detection result signal indicates that the switch power supply is in a normal state.

[0043] Optionally, the second detection is a detection process of performing overvoltage detection on the output end of the switching power supply, including:

[0044] The detection control module outputs a driving signal to the switching power supply to drive the switching circuit of the switching power supply to work;

[0045] The detection control module generates a third control signal to control the overvoltage detection indication path to be turned on;

[0046] The detection control module outputs a second control signal to the voltage detection module, the second control signal controls the voltage detection module to generate an overvoltage threshold voltage, and the voltage detection module generates the overvoltage detection signal according to a comparison result between the voltage at the output end of the switching power supply and the overvoltage threshold voltage;

[0047] The detection control module provides the overvoltage detection signal generated by the voltage detection module to the input end of the overvoltage detection indication path, and generates the overvoltage detection result signal via the overvoltage detection indication path;

[0048] The detection control module performs a fault protection action when the overvoltage detection result signal indicates that the switching power supply is in an overvoltage state, and continues to perform overvoltage detection when the overvoltage detection result signal indicates that the switching power supply is in a normal state.

[0049] Optionally, the performing a fault protection action includes:

[0050] The detection control module outputs an invalid state driving signal to the switching power supply to reduce the voltage at the output end of the switching power supply;

[0051] The detection control module generates a third control signal to control the undervoltage detection indication path to be turned on;

[0052] The detection control module outputs a second control signal to the voltage detection module, the second control signal controls the voltage detection module to generate an undervoltage threshold voltage, and the voltage detection module generates the undervoltage detection signal according to a comparison result between the voltage at the output end of the switching power supply and the undervoltage threshold voltage;

[0053] The detection control module ends fault detection when the undervoltage detection result signal indicates that the voltage at the output end of the switching power supply drops below the undervoltage threshold, and continues undervoltage detection when the undervoltage detection result signal indicates that the voltage at the output end of the switching power supply does not drop below the undervoltage threshold.

[0054] Optionally, the ending fault detection includes:

[0055] The detection control module turns off the drive and enters a power-off state.

[0056] Optionally, the voltage detection module includes:

[0057] a current source, controlling whether to charge the output terminal of the switching power supply according to the first control signal;

[0058] A first capacitor, wherein a first end of the first capacitor is connected to the output end of the switching power supply and the current source, and a second end of the first capacitor is grounded;

[0059] a digital-to-analog converter, wherein an input terminal of the digital-to-analog converter receives the second control signal, and an output terminal of the digital-to-analog converter outputs a threshold voltage corresponding to the detection; and

[0060] A comparator, wherein a first input terminal of the comparator is connected to a first terminal of the first capacitor, a second input terminal of the comparator is connected to an output terminal of the digital-to-analog converter, and an output terminal of the comparator outputs a detection signal under corresponding detection.

[0061] Optionally, the voltage detection module includes:

[0062] A first capacitor, wherein a first end of the first capacitor is connected to the output end of the switching power supply, and a second end of the first capacitor is grounded;

[0063] a digital-to-analog converter, wherein an input terminal of the digital-to-analog converter receives the second control signal, and an output terminal of the digital-to-analog converter outputs a threshold voltage corresponding to the detection; and

[0064] A comparator, wherein a first input terminal of the comparator is connected to a first terminal of the first capacitor, a second input terminal of the comparator is connected to an output terminal of the digital-to-analog converter, and an output terminal of the comparator outputs a detection signal under corresponding detection.

[0065] Optionally, the detection control module includes:

[0066] A control unit receives a power-on enable signal, enters an open circuit detection according to the power-on enable signal, enters a short circuit detection or an undervoltage detection according to the open circuit detection result signal, enters an overvoltage detection according to the short circuit detection result signal, enters an undervoltage detection according to the overvoltage detection result signal, and outputs a corresponding first control signal and a second control signal to the voltage detection module under each detection, sets a first timing time and a second timing time, and provides a corresponding drive signal under the corresponding detection;

[0067] a timing unit connected to the control unit, generating a gating enable signal after entering the open circuit detection and a first timing time has passed, generating a gating enable signal after entering the short circuit detection and a second timing time has passed, and generating a gating enable signal when entering the overvoltage detection and entering the undervoltage detection; and

[0068] The gating unit is connected to the timing unit, the voltage detection module and the control unit, and generates corresponding detection result signals by passing different detection signals through corresponding detection indication paths according to the gating enable signal and the third control signal.

[0069] Optionally, the gating unit includes:

[0070] an open circuit detection indication path, wherein a control end of the open circuit detection indication path receives the third control signal, and an output end of the open circuit detection indication path outputs an open circuit detection result indication signal;

[0071] A short-circuit detection indication path, wherein a control end of the short-circuit detection indication path receives the third control signal, and an output end of the short-circuit detection indication path outputs a short-circuit detection result indication signal;

[0072] an overvoltage detection indication path, wherein a control end of the overvoltage detection indication path receives the third control signal, and an output end of the overvoltage detection indication path outputs an overvoltage detection result indication signal;

[0073] An undervoltage detection indication path, wherein a control end of the undervoltage detection indication path receives the third control signal, and an output end of the undervoltage detection indication path outputs an undervoltage detection result indication signal;

[0074] A first switch, wherein a control end of the first switch is connected to the timing unit to receive the enable signal, a first end of the first switch is connected to the voltage detection module to receive a detection signal, and a second end of the first switch is connected to an input end of the open circuit detection indication path, an input end of the short circuit detection indication path, an input end of the overvoltage detection indication path, and an input end of the undervoltage detection indication path.

[0075] Optionally, the open circuit detection indication path, the overvoltage detection indication path, and the undervoltage detection indication path are straight-through paths, and the short circuit detection indication path is an inverting path.

[0076] Optionally, the detection control module includes:

[0077] A control unit receives a power-on enable signal, enters short-circuit detection according to the power-on enable signal, enters overvoltage detection according to the short-circuit detection result signal, enters undervoltage detection according to the overvoltage detection result signal, and outputs a corresponding second control signal to the voltage detection module under each detection, sets a second timing time, and provides a corresponding drive signal under the corresponding detection;

[0078] a timing unit connected to the control unit, generating a gating enable signal after entering the short circuit detection and after a second timing time has passed, and generating a gating enable signal when entering the overvoltage detection and the undervoltage detection; and

[0079] The gating unit is connected to the timing unit, the voltage detection module and the control unit, and generates corresponding detection result signals by passing different detection signals through corresponding detection indication paths according to the gating enable signal and the third control signal.

[0080] Optionally, the gating unit includes:

[0081] A short-circuit detection indication path, wherein a control end of the short-circuit detection indication path receives the third control signal, and an output end of the short-circuit detection indication path outputs a short-circuit detection result indication signal;

[0082] an overvoltage detection indication path, wherein a control end of the overvoltage detection indication path receives the third control signal, and an output end of the overvoltage detection indication path outputs an overvoltage detection result indication signal;

[0083] An undervoltage detection indication path, wherein a control end of the undervoltage detection indication path receives the third control signal, and an output end of the undervoltage detection indication path outputs an undervoltage detection result indication signal;

[0084] A first switch, wherein a control end of the first switch is connected to the timing unit to receive the enable signal, a first end of the first switch is connected to the voltage detection module to receive a detection signal, and a second end of the first switch is connected to an input end of the short circuit detection indication path, an input end of the overvoltage detection indication path, and an input end of the undervoltage detection indication path.

[0085] Optionally, the detection control module is further used to perform one of open circuit detection, short circuit detection and overvoltage detection on the output end of the switching power supply.

[0086] According to a second aspect of the present disclosure, a control circuit of a switching power supply is provided, comprising the fault detection circuit as described above.

[0087] According to a third aspect of the present disclosure, a switching power supply is provided, comprising:

[0088] A control circuit including a fault detection circuit as described above;

[0089] a power-on enabling circuit, providing a power-on enabling signal to the fault detection circuit; and

[0090] The switch circuit converts the input voltage into an output voltage based on the control of the driving signal and provides it to the output end of the switching power supply.

[0091] Optionally, the switching power supply includes an AC-DC switching power supply or a DC-DC switching power supply.

[0092] Optionally, the power-on enabling circuit includes:

[0093] a resistor, wherein a first end of the resistor receives a second power supply voltage;

[0094] A second switch, wherein a control end of the second switch receives a fourth control signal, a first end of the second switch is connected to a second end of the resistor and provides the power-on enable signal, and a second end of the second switch is grounded.

[0095] According to a fourth aspect of the present disclosure, a fault detection method for a switching power supply control circuit is provided, comprising:

[0096] Perform time-sharing detection on at least two of the open circuit detection, short circuit detection, and overvoltage detection of the output terminal of the switching power supply, and generate a corresponding second control signal under each detection; and

[0097] Under each detection, a corresponding threshold voltage is generated according to the second control signal, and a corresponding detection signal is generated according to the voltage at the output end of the switching power supply and the corresponding threshold voltage, wherein detection signals corresponding to at least two of open circuit detection, short circuit detection, and overvoltage detection are obtained by multiplexing the voltage detection module; and

[0098] A corresponding detection result signal is generated according to the corresponding detection signal.

[0099] Optionally, when the at least two detections include an open circuit detection, a first control signal is further generated, and whether to conduct an open circuit detection path is determined according to the first control signal, wherein the open circuit detection path is connected between the power supply voltage and the output end of the switching power supply.

[0100] Optionally, it also includes:

[0101] A first detection is performed on the output end of the switching power supply according to the received power-on enable signal, wherein the first detection is an open circuit detection.

[0102] Optionally, it also includes:

[0103] A first detection is performed on the output end of the switching power supply according to the received power-on enable signal, wherein the first detection is a short circuit detection.

[0104] Optionally, the first detection is an open circuit detection detection process including:

[0105] Outputting a drive signal for shutting down the drive to the switching power supply;

[0106] generating a third control signal to control the open circuit detection indication path to be turned on,

[0107] Outputting a first control signal and a second control signal, wherein the first control signal controls the open circuit detection path to be turned on to charge the output terminal of the switching power supply, and the second control signal controls the generation of an open circuit threshold voltage, and generates the open circuit detection signal according to a comparison result between the voltage at the output terminal of the switching power supply and the open circuit threshold voltage;

[0108] Setting a first timing time, resetting before starting timing, and providing an open circuit detection signal to an input end of the open circuit detection indication path after the timing reaches the first timing time, and generating the open circuit detection result signal via the open circuit detection indication path;

[0109] The fault detection is ended when the open circuit detection result signal indicates that the switch power supply is in an open circuit state, and the second detection is triggered when the open circuit detection result signal indicates that the switch power supply is in a normal state.

[0110] Optionally, the second detection is a detection process of performing short circuit detection on the output terminal of the switching power supply, including:

[0111] Outputting a driving signal to the switching power supply to drive the switching circuit of the switching power supply to operate;

[0112] generating a third control signal to control the short-circuit detection indication path to be turned on;

[0113] Outputting a first control signal and a second control signal, wherein the first control signal controls the open circuit detection path to be turned off, and the second control signal controls the generation of a short circuit threshold voltage, and generating the short circuit detection signal according to a comparison result between the voltage at the output end of the switching power supply and the short circuit threshold voltage;

[0114] Setting a second timing time, resetting before starting timing, and providing a short circuit detection signal to an input end of the short circuit detection indication path after the timing reaches the second timing time, and generating the short circuit detection result signal via the short circuit detection indication path;

[0115] When the short-circuit detection result signal indicates that the switching power supply is in a short-circuit state, the fault detection is terminated; and when the short-circuit detection result signal indicates that the switching power supply is in a normal state, the fault detection is terminated or a third detection is performed.

[0116] Optionally, the second detection is an overvoltage detection on the output end of the switching power supply.

[0117] Optionally, the third detection is an overvoltage detection on the output end of the switching power supply.

[0118] Optionally, the overvoltage detection process includes:

[0119] Outputting a driving signal to the switching power supply to drive the switching circuit of the switching power supply to operate;

[0120] generating a third control signal to control the overvoltage detection indication path to be turned on;

[0121] Outputting a first control signal and a second control signal, wherein the first control signal controls the open circuit detection path to be turned off, and the second control signal controls the generation of an overvoltage threshold voltage, and generating the overvoltage detection signal according to a comparison result between the voltage at the output end of the switching power supply and the overvoltage threshold voltage;

[0122] Providing an overvoltage detection signal to an input end of the overvoltage detection indication path, and generating the overvoltage detection result signal via the overvoltage detection indication path;

[0123] When the overvoltage detection result signal indicates that the switching power supply is in an overvoltage state, a fault protection action is performed, and when the overvoltage detection result signal indicates that the switching power supply is in a normal state, overvoltage detection is continued.

[0124] Optionally, the performing a fault protection action includes:

[0125] Outputting an invalid state driving signal to the switching power supply to reduce the voltage at the output end of the switching power supply;

[0126] generating a third control signal to control the undervoltage detection indication path to be turned on;

[0127] Outputting a first control signal and a second control signal, wherein the first control signal controls the open circuit detection path to be turned off, and the second control signal controls the generation of an undervoltage threshold voltage, and generating the undervoltage detection signal according to a comparison result between the voltage at the output end of the switching power supply and the undervoltage threshold voltage;

[0128] The fault detection is ended when the undervoltage detection result signal indicates that the voltage at the output end of the switching power supply drops below the undervoltage threshold, and the undervoltage detection is continued when the undervoltage detection result signal indicates that the voltage at the output end of the switching power supply does not drop below the undervoltage threshold.

[0129] Optionally, the first detection is a detection process of short circuit detection, which includes:

[0130] Outputting a driving signal to the switching power supply to drive the switching circuit of the switching power supply to operate;

[0131] generating a third control signal to control the short-circuit detection indication path to be turned on;

[0132] Outputting a second control signal, wherein the second control signal controls the generation of a short-circuit threshold voltage, and generating the short-circuit detection signal according to a comparison result between the voltage at the output end of the switching power supply and the short-circuit threshold voltage;

[0133] Setting a second timing time, resetting before starting timing, and providing a short circuit detection signal to an input end of the short circuit detection indication path after the timing reaches the second timing time, and generating the short circuit detection result signal via the short circuit detection indication path;

[0134] When the short-circuit detection result signal indicates that the switching power supply is in a short-circuit state, the fault detection is terminated; and when the short-circuit detection result signal indicates that the switching power supply is in a normal state, the fault detection is terminated or a second detection is performed.

[0135] Optionally, the second detection is a detection process of performing overvoltage detection on the output end of the switching power supply, including:

[0136] Outputting a driving signal to the switching power supply to drive the switching circuit of the switching power supply to operate;

[0137] generating a third control signal to control the overvoltage detection indication path to be turned on;

[0138] Outputting a second control signal, wherein the second control signal controls the generation of an overvoltage threshold voltage, and the voltage detection module generates the overvoltage detection signal according to a comparison result between the voltage at the output end of the switching power supply and the overvoltage threshold voltage;

[0139] Providing an overvoltage detection signal to an input end of the overvoltage detection indication path, and generating the overvoltage detection result signal via the overvoltage detection indication path;

[0140] When the overvoltage detection result signal indicates that the switching power supply is in an overvoltage state, a fault protection action is performed, and when the overvoltage detection result signal indicates that the switching power supply is in a normal state, overvoltage detection is continued.

[0141] Optionally, the performing a fault protection action includes:

[0142] Outputting an invalid state driving signal to the switching power supply to reduce the voltage at the output end of the switching power supply;

[0143] generating a third control signal to control the undervoltage detection indication path to be turned on;

[0144] Outputting a second control signal, wherein the second control signal controls the generation of an undervoltage threshold voltage, and generating the undervoltage detection signal according to a comparison result between the voltage at the output end of the switching power supply and the undervoltage threshold voltage;

[0145] The fault detection is ended when the undervoltage detection result signal indicates that the voltage at the output end of the switching power supply drops below the undervoltage threshold, and the undervoltage detection is continued when the undervoltage detection result signal indicates that the voltage at the output end of the switching power supply does not drop below the undervoltage threshold.

[0146] The present invention provides a switching power supply, a control circuit, a fault detection circuit and a method. The present invention improves the safety and reliability of the switching power supply and simplifies the circuit structure by time-division multiplexing the same circuit to perform open circuit detection, short circuit detection, overvoltage detection and undervoltage detection on the output end of the switching power supply.

[0147] Further, the fault detection circuit of the present disclosure performs an open circuit detection on the output end of the switching power supply according to the power-on enable signal, and performs a short circuit detection or ends the fault detection on the output end of the switching power supply according to the open circuit detection result signal after a first timing time, and performs an overvoltage detection or ends the fault detection on the output end of the switching power supply according to the short circuit detection result signal after a second timing time of performing a short circuit detection on the output end of the switching power supply, and performs an undervoltage detection or continues the overvoltage detection on the output end of the switching power supply according to the overvoltage detection result signal, and performs an undervoltage detection on the output end of the switching power supply and ends the fault detection or continues the undervoltage detection according to the undervoltage detection result signal. That is, the present disclosure improves the reliability and safety of the switching power supply through the above detection methods.

[0148] Furthermore, the fault detection circuit of the present disclosure performs short-circuit detection on the output end of the switching power supply according to the power-on enable signal, and performs overvoltage detection or ends fault detection on the output end of the switching power supply according to the short-circuit detection result signal after the second timing time, and performs overvoltage detection on the output end of the switching power supply and performs undervoltage detection or continues overvoltage detection on the output end of the switching power supply according to the overvoltage detection result signal, and performs undervoltage detection on the output end of the switching power supply and ends fault detection or continues undervoltage detection according to the undervoltage detection result signal. That is, the present disclosure improves the reliability and safety of the switching power supply through the above detection method.

[0149] Furthermore, the fault detection circuit of the present invention directly outputs the corresponding detection signal as a detection result indication signal without delaying the timing when performing overvoltage detection and undervoltage detection, thereby further improving the accuracy of fault detection.

[0150] Furthermore, the present disclosure implements multiple fault detection by providing a timing unit, a gating unit, and a control unit to time-share multiplex the same voltage detection circuit structure, thereby reducing the circuit structure of the switching power supply and saving circuit costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0151] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0152] Figure 1 A schematic diagram showing the structure of a switching power supply provided by an embodiment of the present disclosure is shown;

[0153] Figure 2 A structural schematic diagram of a fault detection circuit provided by an embodiment of the present disclosure is shown;

[0154] Figure 3 Show Figure 2A circuit diagram of a fault detection circuit;

[0155] Figure 4 A structural schematic diagram of another fault detection circuit provided by an embodiment of the present disclosure is shown;

[0156] Figure 5 Show Figure 4 A circuit diagram of a fault detection circuit;

[0157] Figure 6 A schematic diagram showing a flow chart of a fault detection method for a switching power supply provided by an embodiment of the present disclosure;

[0158] Figure 7 A schematic diagram showing a flow chart of an open circuit detection performed by a fault detection circuit provided by an embodiment of the present disclosure;

[0159] Figure 8 A schematic diagram showing a flow chart of a short circuit detection performed by a fault detection circuit provided by an embodiment of the present disclosure;

[0160] Fig. 9 A schematic diagram showing a flow chart of overvoltage detection performed by a fault detection circuit provided by an embodiment of the present disclosure;

[0161] Fig.10 A schematic diagram of a flow chart of undervoltage detection performed by a fault detection circuit provided in an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0162] Various embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. In each of the accompanying drawings, the same elements are represented by the same or similar reference numerals. For the sake of clarity, the various parts in the accompanying drawings are not drawn to scale.

[0163] In the prior art, a plurality of detection circuits are generally provided in the switching power supply to respectively detect whether the switching power supply is open circuit, short circuit, undervoltage, overvoltage, etc., which increases the complexity of the circuit structure of the switching power supply.

[0164] The specific implementation of the present disclosure is further described in detail below in conjunction with the drawings and examples.

[0165] Figure 1 A schematic diagram of the structure of a switching power supply provided in an embodiment of the present disclosure is shown. Figure 2 A structural schematic diagram of a fault detection circuit provided by an embodiment of the present disclosure is shown. Figure 3 Show Figure 2 Circuit schematic of the fault detection circuit.

[0166] like Figure 1As shown, the switching power supply includes a control circuit 1000, a switching circuit 3000, a power-on enabling circuit 2000, an output capacitor Co, and a load Rload. It should be noted that the switching power supply includes, for example, an AC-DC switching power supply and a DC-DC switching power supply. The control circuit 1000 is used to generate a switch control signal to control the switching circuit 3000 to be turned on or off. The control circuit 1000 includes a fault detection circuit 1100. When the fault detection circuit 1100 is started, the switching circuit 3000 is turned on or off by the drive signal pwm generated by the fault detection circuit 1100.

[0167] The fault detection circuit 1100 is used to perform at least one of open circuit detection, short circuit detection, overvoltage detection and undervoltage detection on the output end of the switching power supply.

[0168] Furthermore, if Figure 2 As shown, the fault detection circuit 1100 includes an enable terminal, a drive terminal, a detection terminal, a detection control module 1110 and a voltage detection module 1120. The detection control module 1110 is used to perform time-sharing detection on at least two of the open circuit detection, short circuit detection, and overvoltage detection of the output terminal of the switching power supply, and generate a corresponding first control signal ctrl1 and a second control signal ctrl2 under each detection. Under each detection, the voltage detection module 1120 determines whether to conduct the open circuit detection path according to the first control signal ctrl1, and generates a corresponding threshold voltage according to the second control signal ctrl2, and generates a corresponding detection signal cmp-flag according to the voltage of the output terminal VOUT of the switching power supply and the corresponding threshold voltage. Further, the detection control module 1100 also generates a corresponding detection result signal according to the corresponding detection signal cmp-flag. In this embodiment, the fault detection circuit 1100 obtains the detection signals corresponding to at least two of the open circuit detection, short circuit detection, and overvoltage detection by multiplexing the voltage detection module 1120.

[0169] In one embodiment, the detection control module 1110 is used to perform time-sharing detection on two of the open circuit detection, short circuit detection, and overvoltage detection at the output end of the switching power supply. Exemplarily, the detection control module performs a first detection, open circuit detection, on the output end of the switching power supply according to the received power-on enable signal, and ends the fault detection when the open circuit detection result signal indicates that the switching power supply is in an open circuit state, and triggers itself to perform a second detection, short circuit detection, when the open circuit detection result signal indicates that the switching power supply is in a normal state. Alternatively, the detection control module performs a first detection, open circuit detection, on the output end of the switching power supply according to the received power-on enable signal, and ends the fault detection when the open circuit detection result signal indicates that the switching power supply is in an open circuit state, and triggers itself to perform a second detection, undervoltage detection, when the open circuit detection result signal indicates that the switching power supply is in a normal state.

[0170] In one embodiment, the detection control module 1110 is used to perform time-sharing detection on three items of open circuit detection, short circuit detection, and overvoltage detection at the output end of the switching power supply. Exemplarily, the detection control module performs the first detection, open circuit detection, on the output end of the switching power supply according to the received power-on enable signal, and ends the fault detection when the open circuit detection result signal indicates that the switching power supply is in an open circuit state, triggers itself to perform the second detection, short circuit detection, when the open circuit detection result signal indicates that the switching power supply is in a normal state, and ends the fault detection when the short circuit detection result signal indicates that the switching power supply is in a short circuit state, and ends the fault detection when the short circuit detection result signal indicates that the switching power supply is in a normal state, and ends the fault detection or performs the third detection, overvoltage detection, when the short circuit detection result signal indicates that the switching power supply is in a normal state.

[0171] In other embodiments, the detection control module is further used to perform one of open circuit detection, short circuit detection and overvoltage detection on the output end of the switching power supply.

[0172] See also Figure 2 The detection control module 1110 includes a control unit 1111, a timing unit 1112, and a gating unit 1113.

[0173] The control unit 1111 receives a power-on enable signal enable provided by the enable terminal, to enter open circuit detection according to the power-on enable signal enable, and to enter short circuit detection or undervoltage detection according to the open circuit detection result signal, to enter overvoltage detection according to the short circuit detection result signal, to enter undervoltage detection according to the overvoltage detection result signal, and to output the corresponding first control signal ctrl1 and the second control signal ctrl2 to the voltage detection module 1120 under each detection, and to set the corresponding timing time t to the timing unit 1112 under each detection, and to output the third control signal mux-sel to the selection unit 1113 under each detection, and to provide the corresponding drive signal pwm under the corresponding detection.

[0174] The timing unit 1112 is connected to the control unit 1111, and generates a gate enable signal demux-en after entering the open circuit detection and the first timing time, generates a gate enable signal demux-en after entering the short circuit detection and the second timing time, and generates a gate enable signal demux-en when entering the overvoltage detection and the undervoltage detection. Further, that is, under each detection, the control unit 1111 provides a reset signal rest and a corresponding timing time t to the timing unit 1112, and the reset signal rest controls the timing unit 1112 to start timing from 0, and when the timing unit 1112 reaches the corresponding timing time t, the gate enable signal demux-en is generated and output to the gating unit 1113.

[0175] The gating unit 1113 is connected to the timing unit 1112, the voltage detection module 1120, and the control unit 1111, and according to the gating enable signal demux-en and the third control signal mux-sel, different detection signals cmp-flag are passed through the corresponding detection indication path to generate the corresponding detection result signal. Further, the gating unit 1113 controls the detection signal cmp-flag generated by the voltage detection module 1120 to be provided to the input end of each detection indication path according to the gating enable signal demux-en, and turns on the corresponding detection indication path according to the third control signal mux-sel, and then outputs the detection signal cmp-flag as the detection result indication signal under the corresponding detection from the output end of the turned-on detection indication path.

[0176] Exemplarily, the detection control module 1110 performs an open circuit detection on the output terminal VOUT of the switching power supply according to the received power-on enable signal enable, and performs a short circuit detection or ends the fault detection on the output terminal VOUT of the switching power supply according to the open circuit detection result signal oc-flag after the first timing time T1. And after the second timing time T2 of performing a short circuit detection on the output terminal VOUT of the switching power supply, the output terminal VOUT of the switching power supply is subjected to an overvoltage detection or ends the fault detection according to the short circuit detection result signal sc-flag. And after performing an overvoltage detection on the output terminal VOUT of the switching power supply, the output terminal VOUT of the switching power supply is subjected to an undervoltage detection or continues the overvoltage detection according to the overvoltage detection result signal ovp-flag. And after performing an undervoltage detection on the output terminal VOUT of the switching power supply, the fault detection is ended or continues the undervoltage detection according to the undervoltage detection result signal rvp-flag.

[0177] Furthermore, if Figure 3As shown. The control unit 1111 includes a microcontroller U1. The enable terminal ENABLE of the microcontroller U1 is connected to the enable terminal of the fault detection circuit 1100 to receive the power-on enable signal enable, the timing terminal TIME-SET of the microcontroller U1 is connected to the timing unit 1112 to set the corresponding timing time (including the first timing time T1 and the second timing time T2), the reset terminal REST of the microcontroller U1 provides the reset signal rest to the timing unit 1112, the first control terminal CTRL1 of the microcontroller U1 outputs the corresponding first control signal ctrl1 to the voltage detection module 1120, the second control terminal CTRL2 of the microcontroller U1 outputs the corresponding second control signal ctrl2 to the voltage detection module 1120, the driving terminal PWM of the microcontroller U1 is connected to the driving terminal of the fault detection circuit 1100 to provide the driving signal pwm to the switch circuit 3000 of the switching power supply, and the selection terminal SEL of the microcontroller U1 is connected to the selection unit 1113 to output the corresponding third control signal mux-sel. The first input terminal IN1 of the microcontroller U1 is connected to the gating unit 1113 to receive the open circuit detection result signal oc-flag, the second input terminal IN2 of the microcontroller U1 is connected to the gating unit 1113 to receive the short circuit detection result signal sc-flag, the third input terminal IN3 of the microcontroller U1 is connected to the gating unit 1113 to receive the overvoltage detection result signal ovp-flag, and the fourth input terminal IN4 of the microcontroller U1 is connected to the gating unit 1113 to receive the undervoltage detection result signal rvp-flag. Specifically, the control unit 1111 includes, for example, at least a circuit structure such as a digital logic circuit, a counter, and a register to perform a logic processing function and a timing processing function.

[0178] Furthermore, if Figure 3 The timing unit 1112 includes a counter U2, a timing terminal TIME-SET of the counter U2 is connected to a timing terminal TIME-SET of the microcontroller U1, a reset terminal REST of the counter U2 is connected to a reset terminal REST of the microcontroller U1, and an output terminal OUT of the counter U2 is connected to a strobe unit 1113 to output a strobe enable signal demux-en.

[0179] Furthermore, if Figure 3As shown. The gating unit 1113 includes an open circuit detection indication path, a short circuit detection indication path, an overvoltage detection indication path, an undervoltage detection indication path, and a first switch K1. The control end of the open circuit detection indication path receives the third control signal mux-sel output by the microcontroller U1, and the output end of the open circuit detection indication path outputs an open circuit detection result indication signal oc-flag. The control end of the short circuit detection indication path receives the third control signal mux-sel output by the microcontroller U1, and the output end of the short circuit detection indication path outputs a short circuit detection result indication signal sc-flag. The control end of the overvoltage detection indication path receives the third control signal mux-sel output by the microcontroller U1, and the output end of the overvoltage detection indication path outputs an overvoltage detection result indication signal ovp-flag. The control end of the undervoltage detection indication path receives the third control signal mux-sel output by the microcontroller U1, and the output end of the undervoltage detection indication path outputs an undervoltage detection result indication signal rvp-flag. The control end of the first switch K1 is connected to the counter U2 of the timing unit 1112 to receive the strobe enable signal demux-en, the first end of the first switch K1 is connected to the voltage detection module 1120 to receive the detection signal cmp-flag, and the second end of the first switch K1 is connected to the input end of the open circuit detection indication path, the input end of the short circuit detection indication path, the input end of the overvoltage detection indication path, and the input end of the undervoltage detection indication path. Exemplarily, the open circuit detection indication path, the overvoltage detection indication path, and the undervoltage detection indication path are straight-through paths, and the short circuit detection indication path is an inverting path. Among them, the third control signal mux-sel is, for example, a 4-bit signal, and exemplarily, the third control signal mux-sel is 0001 to indicate that the open circuit detection indication path is turned on.

[0180] Furthermore, if Figure 3 As shown. The voltage detection module 1120 includes a current source I1, a first capacitor Cs, a comparator U3, and a digital-to-analog converter U4. The current source I1 controls whether to charge the output terminal VOUT of the switching power supply according to the first control signal ctrl1. The first end of the first capacitor Cs is connected to the output terminal VOUT of the switching power supply and the current source I1, and the second end of the first capacitor Cs is grounded. The input end of the digital-to-analog converter U4 receives the second control signal ctrl2, and the output end of the digital-to-analog converter U4 outputs the threshold voltage under the corresponding detection. The first input end (for example, the positive input end) of the comparator U3 is connected to the first end of the first capacitor Cs, the second input end of the comparator U3 is connected to the output end of the digital-to-analog converter U4, and the output end of the comparator U3 outputs the detection signal cmp-flag under the corresponding detection. Among them, the first power supply voltage VCC1 and the current source I1 constitute an open circuit detection path, and are connected to the output terminal VOUT of the switching power supply via the current source I1.

[0181] Furthermore, the enable terminal of the fault detection circuit 1100 is connected to, for example, an external controller pin, and is further controlled by high and low levels.

[0182] Furthermore, when the detection control module 1110 detects an open circuit, the control unit 1111 outputs a first control signal ctrl1 and a second control signal ctrl2 to the voltage detection module 1120, sets a first timing time T1, and turns off the PWM drive (does not provide a drive signal pwm to the switch circuit 1200 of the switching power supply), and generates a third control signal mux-sel to control the open circuit detection indication path to be turned on. The voltage detection module 1120 turns on the open circuit detection path according to the first control signal ctrl1 to provide a charging current to the first end of the first capacitor Cs to charge the output end of the switching power supply, generates an open circuit threshold voltage according to the second control signal ctrl2, and generates an open circuit detection signal according to a comparison result between the voltage at the output end VOUT of the switching power supply and the open circuit threshold voltage. Then, the timing unit 1112 is used to perform timing so as to provide the open circuit detection signal generated by the voltage detection module 1120 to the input end of the open circuit detection indication path of the selection unit 1113 after the first timing time T1, and the open circuit detection result signal oc-flag is output from the output end of the open circuit detection indication path, and the fault detection is terminated when the switch power supply is in an open circuit state or the short circuit detection is entered when the switch power supply is in a normal state according to the open circuit detection result signal oc-flag. After the control unit receives the open circuit detection result signal oc-flag indicating an open circuit, the control unit enters a protection power-off state, and no subsequent detection steps are performed, and it is no longer powered on, thereby terminating the fault detection. After the control unit receives the open circuit detection result signal oc-flag indicating that the circuit is not open, the control unit performs short circuit detection or undervoltage detection in sequence according to its own timing processing function.

[0183] Furthermore, when the detection control module 1110 detects a short circuit, the control unit 1111 outputs a first control signal ctrl1 and a second control signal ctrl2 to the voltage detection module 1120, sets a second timing time T2, provides a driving signal pwm to the switching power supply to drive the switch circuit 1200 of the switching power supply to power on, and generates a third control signal mux-sel to control the short circuit detection indication path to be turned on. The voltage detection module 1120 turns off the short circuit detection path (the current source I1 is turned off) according to the first control signal ctrl1, generates a short circuit threshold voltage according to the second control signal ctrl2, and generates a short circuit detection signal according to the comparison result of the voltage at the output terminal VOUT of the switching power supply and the short circuit threshold voltage. Then, the timing unit 1112 is used to perform timing so as to provide the short-circuit detection signal generated by the voltage detection module 1120 to the input end of the short-circuit detection indication path of the selection unit 1113 after the second timing time T2, and the short-circuit detection result signal sc-flag is output from the output end of the short-circuit detection indication path, and according to the short-circuit detection result signal sc-flag, the fault detection is ended when the switching power supply is in the short-circuit state or the overvoltage detection is entered when the switching power supply is in the normal state.

[0184] Furthermore, when the detection control module 1110 detects overvoltage, the control unit 1111 outputs the first control signal ctrl1 and the second control signal ctrl2 to the voltage detection module 1120, sets the third timing time T3, provides the driving signal pwm to the switching power supply to drive the switch circuit 1200 of the switching power supply to work normally, and generates the third control signal mux-sel to control the overvoltage detection indication path to be turned on. The voltage detection module 1120 turns off the open circuit detection path according to the first control signal ctrl1, generates the overvoltage threshold voltage according to the second control signal ctrl2, and generates the short circuit detection signal according to the comparison result of the voltage at the output terminal VOUT of the switching power supply and the overvoltage threshold voltage. Then, the timing unit 1112 is used to perform timing so as to provide the overvoltage detection signal generated by the voltage detection module 1120 to the input end of the overvoltage detection indication path of the selection unit 1113 after a third timing time (preferably 0), and the overvoltage detection result signal ovp-flag is outputted from the output end of the overvoltage detection indication path, and according to the overvoltage detection result signal ovp-flag, a driving signal pwm is provided to the switching power supply when the switching power supply is in an overvoltage state so as to reduce the voltage at the output end VOUT of the switching power supply and execute a fault protection action to enter undervoltage detection, or the overvoltage detection is continued when the switching power supply is in a normal state.

[0185] Further, when the detection control module 1110 detects undervoltage, the control unit 1111 outputs the first control signal ctrl1 and the second control signal ctrl2 to the voltage detection module 1120, sets the fourth timing time T4, provides the driving signal pwm to the switching power supply to reduce the voltage of the output terminal VOUT of the switching power supply, and generates the third control signal mux-sel to control the undervoltage detection indication path to be turned on. The voltage detection module 1120 turns off the disconnection detection path according to the first control signal ctrl1, generates the undervoltage threshold voltage according to the second control signal ctrl2, and generates the undervoltage detection signal according to the comparison result of the voltage of the output terminal VOUT of the switching power supply and the undervoltage threshold voltage. Then, the timing unit 1112 is used to perform timing so as to provide the undervoltage detection signal generated by the voltage detection module 1120 to the input end of the undervoltage detection indication path of the selection unit 1113 after a fourth timing time (preferably 0), and the undervoltage detection result signal rvp-flag is output from the output end of the undervoltage detection indication path, and according to the undervoltage detection result signal rvp-flag, the fault detection is ended when the switching power supply is in an undervoltage state, or the undervoltage detection is continued when the switching power supply is in a normal state or an overvoltage state.

[0186] Furthermore, the short-circuit threshold voltage is smaller than the overvoltage threshold voltage, the overvoltage threshold voltage is smaller than the open-circuit threshold voltage, and the undervoltage threshold voltage is smaller than the overvoltage threshold voltage.

[0187] The input end of the switch circuit 1200 receives the input voltage vin and the drive signal PWM (or the switch control signal provided by the control circuit), and the output end of the switch circuit 1200 outputs the voltage VOUT. The switch circuit 1200 can adopt any DC / DC or AC / DC conversion topology, such as a synchronous or asynchronous boost, buck converter, and a forward, flyback converter, etc. Exemplarily, the switch circuit 1200 includes a power tube and an inductor, the power tube and the inductor are connected in series between the input voltage vin and the output end of the switching power supply, and the control end of the power tube is connected to the control circuit and the driving end of the fault detection circuit 1100. The output capacitor Co is connected in parallel with the load Rload, the first end of the output capacitor Co is connected to the output end VOUT of the switching power supply, and the second end of the output capacitor Co is grounded.

[0188] In an alternative embodiment, the switch circuit 3000 may include, for example, two power tubes and an inductor, wherein the two power tubes are connected between the input voltage vin and the ground. The inductor is connected between the middle connection node of the two power tubes and the output end of the switch power supply, wherein the control end of one of the power tubes is connected to the driving end of the control circuit and the fault detection circuit 1100, and the control end of the other power tube receives an inverted signal of the signal received by the control end of the power tube.

[0189] The power-on enabling circuit 2000 is used to provide a power-on enabling signal enable to the enabling terminal. The power-on enabling circuit 2000 includes a resistor R1 and a second switch K2. The first end of the resistor R1 receives a second power supply voltage VCC2. The control end of the second switch K2 receives a fourth control signal, the first end of the second switch K2 is connected to the second end of the resistor R1 and provides the power-on enabling signal enable, and the second end of the second switch K2 is grounded. Wherein, when the switch K2 is a mechanical switch, it is turned on or off by manual control.

[0190] It should be noted that the open circuit detection is to detect whether the first end of the capacitor Cs and the detection end of the fault detection circuit 1100 are open circuited. The short circuit detection is to detect whether the detection end is short-circuited to the ground. The overvoltage detection is to detect whether the output voltage Vout received by the detection end is overvoltage.

[0191] Figure 4 A structural schematic diagram of another fault detection circuit provided by an embodiment of the present disclosure is shown.

[0192] Figure 5 Show Figure 4 Circuit schematic of the fault detection circuit.

[0193] The difference between this embodiment and the above embodiments is that the fault detection circuit 4100 does not perform open circuit detection on the output end of the switching power supply.

[0194] In this embodiment, the detection control module performs a first detection on the output end of the switching power supply according to the received power-on enable signal, and the first detection is a short circuit detection. The detection process of the short circuit detection includes:

[0195] The detection control module outputs a driving signal to the switching power supply to drive the switching circuit of the switching power supply to work;

[0196] The detection control module generates a third control signal to control the short-circuit detection indication path to be turned on;

[0197] The detection control module outputs a second control signal to the voltage detection module, the second control signal controls the voltage detection module to generate a short-circuit threshold voltage, and the voltage detection module generates a short-circuit detection signal according to a comparison result between the voltage at the output end of the switching power supply and the short-circuit threshold voltage;

[0198] The detection control module sets a second timing time, resets before starting the timing, and after the timing reaches the second timing time, provides the short-circuit detection signal generated by the voltage detection module to the input end of the short-circuit detection indication path, and generates a short-circuit detection result signal via the short-circuit detection indication path;

[0199] The detection control module ends the fault detection when the short-circuit detection result signal indicates that the switching power supply is in a short-circuit state, and ends the fault detection or performs a second detection when the short-circuit detection result signal indicates that the switching power supply is in a normal state.

[0200] The second test is to detect overvoltage at the output of the switching power supply:

[0201] The detection control module outputs a driving signal to the switching power supply to drive the switching circuit of the switching power supply to work;

[0202] The detection control module generates a third control signal to control the overvoltage detection indication path to be turned on;

[0203] The detection control module outputs a second control signal to the voltage detection module, the second control signal controls the voltage detection module to generate an overvoltage threshold voltage, and the voltage detection module generates an overvoltage detection signal according to a comparison result between the voltage at the output end of the switching power supply and the overvoltage threshold voltage;

[0204] The detection control module provides the overvoltage detection signal generated by the voltage detection module to the input end of the overvoltage detection indication path, and generates an overvoltage detection result signal via the overvoltage detection indication path;

[0205] The detection control module performs a fault protection action when the overvoltage detection result signal indicates that the switching power supply is in an overvoltage state, and continues to perform overvoltage detection when the overvoltage detection result signal indicates that the switching power supply is in a normal state.

[0206] Executing fault protection actions include:

[0207] The detection control module outputs an invalid state driving signal to the switching power supply to reduce the voltage at the output end of the switching power supply;

[0208] The detection control module generates a third control signal to control the undervoltage detection indication path to be turned on;

[0209] The detection control module outputs a second control signal to the voltage detection module, the second control signal controls the voltage detection module to generate an undervoltage threshold voltage, and the voltage detection module generates an undervoltage detection signal according to a comparison result between the voltage at the output end of the switching power supply and the undervoltage threshold voltage;

[0210] The detection control module ends fault detection when the undervoltage detection result signal indicates that the voltage at the output end of the switching power supply drops below the undervoltage threshold, and continues undervoltage detection when the undervoltage detection result signal indicates that the voltage at the output end of the switching power supply does not drop below the undervoltage threshold.

[0211] Ending the fault detection includes shutting down the drive of the detection control module and entering a power-off state.

[0212] like Figure 4As shown, the detection control module 4110 includes a control unit 4111 , a timing unit 1112 , and a gating unit 4113 .

[0213] The control unit 4111 receives a power-on enable signal enable provided by the enable terminal, to enter short-circuit detection according to the power-on enable signal enable, to enter overvoltage detection according to the short-circuit detection result signal, to enter undervoltage detection according to the overvoltage detection result signal, and to output the corresponding second control signal ctrl2 to the voltage detection module 4120 under each detection, and to set the second timing time T2 to the timing unit 1112 under short-circuit detection, and to output the third control signal mux-sel to the selection unit 4113 under each detection, and to provide the corresponding drive signal pwm under the corresponding detection.

[0214] The timing unit 1112 is connected to the control unit 4111, and generates a gate enable signal demux-en after entering the short circuit detection and the second timing time, and generates a gate enable signal demux-en when entering the overvoltage detection and the undervoltage detection. Further, the control unit 4111 provides a reset signal rest and a corresponding timing time t to the timing unit 1112 under each detection, and the reset signal rest controls the timing unit 1112 to start timing from 0, and when the timing unit 1112 reaches the corresponding timing time t, the gate enable signal demux-en is generated and output to the gate unit 4113.

[0215] The gating unit 4113 is connected to the timing unit 1112, the voltage detection module 4120, and the control unit 4111, and according to the gating enable signal demux-en and the third control signal mux-sel, different detection signals cmp-flag are passed through the corresponding detection indication path to generate the corresponding detection result signal. Further, the gating unit 4113 controls the detection signal cmp-flag generated by the voltage detection module 4120 to be provided to the input end of each detection indication path according to the gating enable signal demux-en, and turns on the corresponding detection indication path according to the third control signal mux-sel, and then outputs the detection signal cmp-flag as the detection result indication signal under the corresponding detection from the output end of the turned-on detection indication path.

[0216] Further, the detection control module 4110 performs short-circuit detection on the output terminal VOUT of the switching power supply according to the received power-on enable signal enable, and performs overvoltage detection or ends fault detection on the output terminal VOUT of the switching power supply according to the short-circuit detection result signal sc-flag after the second timing time T2. Also, overvoltage detection is performed on the output terminal VOUT of the switching power supply and undervoltage detection or continues overvoltage detection is performed on the output terminal VOUT of the switching power supply according to the overvoltage detection result signal ovp-flag. Also, undervoltage detection is performed on the output terminal VOUT of the switching power supply and fault detection ends or continues undervoltage detection according to the undervoltage detection result signal rvp-flag.

[0217] Furthermore, if Figure 5 As shown. The control unit 4111 includes a microcontroller U1. The enable terminal ENABLE of the microcontroller U1 is connected to the enable terminal of the fault detection circuit 4100 to receive the power-on enable signal enable, the timing terminal TIME-SET of the microcontroller U1 is connected to the timing unit 1112 to set the corresponding timing time (including the second timing time T2), the reset terminal REST of the microcontroller U1 provides a reset signal rest to the timing unit 1112, the second control terminal CTRL2 of the microcontroller U1 outputs the corresponding second control signal ctrl2 to the voltage detection module 4120, the driving terminal PWM of the microcontroller U1 is connected to the driving terminal of the fault detection circuit 4100 to provide the driving signal pwm to the switching circuit 3000 of the switching power supply, and the selection terminal SEL of the microcontroller U1 is connected to the selection unit 4113 to output the corresponding third control signal mux-sel. The second input terminal IN2 of the microcontroller U1 is connected to the gating unit 4113 to receive the short circuit detection result signal sc-flag, the third input terminal IN3 of the microcontroller U1 is connected to the gating unit 4113 to receive the overvoltage detection result signal ovp-flag, and the fourth input terminal IN4 of the microcontroller U1 is connected to the gating unit 4113 to receive the undervoltage detection result signal rvp-flag. Specifically, the control unit 4111 includes, for example, at least a digital logic circuit, a counter, a register and other circuit structures to perform logic processing functions and timing processing functions.

[0218] Furthermore, if Figure 5 The timing unit 1112 includes a counter U2, a timing terminal TIME-SET of the counter U2 is connected to a timing terminal TIME-SET of the microcontroller U1, a reset terminal REST of the counter U2 is connected to a reset terminal REST of the microcontroller U1, and an output terminal OUT of the counter U2 is connected to the strobe unit 4113 to output a strobe enable signal demux-en.

[0219] Furthermore, if Figure 5As shown. The gating unit 4113 includes a short-circuit detection indication path, an overvoltage detection indication path, an undervoltage detection indication path, and a first switch K1. The control end of the short-circuit detection indication path receives the third control signal mux-sel output by the microcontroller U1, and the output end of the short-circuit detection indication path outputs a short-circuit detection result indication signal sc-flag. The control end of the overvoltage detection indication path receives the third control signal mux-sel output by the microcontroller U1, and the output end of the overvoltage detection indication path outputs an overvoltage detection result indication signal ovp-flag. The control end of the undervoltage detection indication path receives the third control signal mux-sel output by the microcontroller U1, and the output end of the undervoltage detection indication path outputs an undervoltage detection result indication signal rvp-flag. The control end of the first switch K1 is connected to the counter U2 of the timing unit 1112 to receive the strobe enable signal demux-en, the first end of the first switch K1 is connected to the voltage detection module 4120 to receive the detection signal cmp-flag, and the second end of the first switch K1 is connected to the input end of the short circuit detection indication path, the input end of the overvoltage detection indication path, and the input end of the undervoltage detection indication path. Exemplarily, the overvoltage detection indication path and the undervoltage detection indication path are straight-through paths, and the short circuit detection indication path is an inverting path. Among them, the third control signal mux-sel is, for example, a 4-bit signal, and exemplarily, the third control signal mux-sel is 0001 to indicate that the short circuit detection indication path is turned on.

[0220] Furthermore, if Figure 5 As shown. The voltage detection module 4120 includes a first capacitor Cs, a comparator U3, and a digital-to-analog converter U4. The first end of the first capacitor Cs is connected to the output end VOUT of the switching power supply, and the second end of the first capacitor Cs is grounded. The input end of the digital-to-analog converter U4 receives the second control signal ctrl2, and the output end of the digital-to-analog converter U4 outputs the threshold voltage under the corresponding detection. The first input end (for example, the positive input end) of the comparator U3 is connected to the first end of the first capacitor Cs, the second input end of the comparator U3 is connected to the output end of the digital-to-analog converter U4, and the output end of the comparator U3 outputs the detection signal cmp-flag under the corresponding detection.

[0221] Figure 6 A schematic flow chart of a method for detecting a fault of a switching power supply provided in an embodiment of the present disclosure is shown. Figure 7 A schematic diagram of a flow chart of open circuit detection performed by a fault detection circuit provided in an embodiment of the present disclosure is shown. Figure 8 A schematic diagram of a process of performing short circuit detection by a fault detection circuit provided in an embodiment of the present disclosure is shown. Fig. 9 A schematic diagram of a flow chart of overvoltage detection performed by a fault detection circuit provided in an embodiment of the present disclosure is shown. Fig.10A schematic diagram of a flow chart of undervoltage detection performed by a fault detection circuit provided in an embodiment of the present disclosure is shown.

[0222] like Figure 6 As shown, the fault detection method of the switching power supply includes the following steps:

[0223] Step S110: performing time-sharing detection on at least two of the open circuit detection, short circuit detection, overvoltage detection, and undervoltage detection of the output terminal of the switching power supply.

[0224] Step S120: generating a corresponding second control signal under each detection.

[0225] Step S130: generating a corresponding threshold voltage according to the second control signal under each detection, and generating a corresponding detection signal according to the voltage at the output end of the switching power supply and the corresponding threshold voltage.

[0226] Step S140: generating a corresponding detection result signal according to the corresponding detection signal.

[0227] An implementation method of the fault detection circuit 1100 of the present disclosure to implement time-division multiplexing detection will be described below with reference to the accompanying drawings.

[0228] Furthermore, step S110 of the switching power supply fault detection method includes:

[0229] Performing an open circuit detection on the output end of the switching power supply according to the received power-on enable signal, and performing a short circuit detection on the output end of the switching power supply or ending the fault detection according to the open circuit detection result signal after a first timing period;

[0230] After a second timing period of short-circuit detection on the output end of the switching power supply, an overvoltage detection is performed on the output end of the switching power supply or a fault detection is terminated according to a short-circuit detection result signal;

[0231] Performing overvoltage detection on the output end of the switching power supply and performing fault protection on the output end of the switching power supply according to the overvoltage detection result signal to enter undervoltage detection or continue overvoltage detection; and

[0232] An undervoltage detection is performed on the output end of the switching power supply and the fault detection is ended or the undervoltage detection is continued according to the undervoltage detection result signal.

[0233] For example, Figure 7 As shown, the open circuit detection of the switching power supply includes the following steps:

[0234] Step S210: Receive a power-on enable signal to enter open circuit detection. Figure 3As shown, the second switch K2 of the power-on enable circuit 2000 is turned on to provide a power-on enable signal enable to the enable terminal of the fault detection circuit 1100. Exemplarily, when the microcontroller U1 detects that the enable terminal ENABLE is at a high level, it enters the open circuit detection mode.

[0235] Step S220: output a first control signal to conduct the open circuit detection path, output a second control signal to generate an open circuit threshold voltage, output a third control signal to conduct the open circuit detection indication path, set a first timing time, and turn off the PWM drive. Figure 3 As shown, the microprocessor U1 outputs a first control signal ctrl1 and a second control signal ctrl2 to the voltage detection module 1120, and the voltage detection module 1120 turns on the open circuit detection path according to the first control signal ctrl1 to charge the output terminal VOUT of the switching power supply to control the open circuit detection indication path to be turned on. An open circuit threshold voltage is generated according to the second control signal ctrl2, and an open circuit detection signal is generated according to the comparison result of the voltage at the output terminal VOUT of the switching power supply and the open circuit threshold voltage. And the microprocessor U1 sets the first timing time T1 to provide it to the counter U2, and when entering the open circuit detection, provides a reset signal rest to the counter U2 before starting counting. And the microprocessor U1 turns off the PWM drive (does not provide the drive signal pwm to the switch circuit 1200 of the switching power supply). And the microprocessor U1 also generates a third control signal mux-sel to the gating unit 1113 to control the conduction of the open circuit detection indication path.

[0236] Step S230: After counting the first timing time, the open circuit detection signal is output as the open circuit detection result signal. Figure 3 As shown, the counter U2 performs timing to provide a selection enable signal demux-en to the control end of the first switch K1 of the selection unit 1113 after the first timing time T1 to turn on the first switch K1, and then provide the open circuit detection signal generated by the voltage detection module 1120 to the input end of the open circuit detection indication path of the selection unit 1113 through the first switch K1, and the open circuit detection result signal oc-flag is output from the output end of the open circuit detection indication path.

[0237] Step S240: Determine whether the open circuit detection result signal indicates an open circuit. If the circuit is open, execute step S250: control power off. If the circuit is normal (no open circuit), execute step S260: enter short circuit detection. Figure 2 As shown, the microprocessor U1 controls power-off to end fault detection when the open circuit detection result signal oc-flag is at a first level, and enters short circuit detection when the open circuit detection result signal oc-flag is at a second level.

[0238] Furthermore, during the open circuit detection, the open circuit detection path is turned on. If the connection between the output capacitor Co in the switching power supply and the output terminal is open, the current will charge the first capacitor Cs to a very high voltage. If it is not open, the current can only charge the first capacitor Cs to a very low voltage in a short time. Then, after the first timing time T1, if the circuit is open, the voltage of the output terminal VOUT is greater than the open circuit threshold voltage, the comparator U3 outputs a high-level open circuit detection signal, the gating unit 1113 outputs a set signal (oc-flag=1) of the open circuit detection result signal oc-flag, indicating an open circuit, and the microprocessor U1 enters the protection power-down state to end the fault detection. If the circuit is not open, the voltage of the output terminal VOUT is less than the open circuit threshold voltage, the comparator U3 outputs a low-level open circuit detection signal, and the gating unit 1113 outputs a reset signal (oc-flag=0) of the open circuit detection result signal oc-flag, indicating that the circuit is not open, and the microprocessor U1 enters the short circuit detection.

[0239] For example, Figure 8 As shown, short circuit detection of the switching power supply includes the following steps:

[0240] Step S310: Enter short circuit detection according to the open circuit detection result signal. Figure 3 As shown, the selection unit 1113 outputs a reset signal (oc-flag=0) of the open circuit detection result signal oc-flag, indicating that there is no open circuit, and the microprocessor U1 enters the short circuit detection mode.

[0241] Step S320: output a first control signal to turn off the open circuit detection path, output a second control signal to generate a short circuit threshold voltage, output a third control signal to turn on the short circuit detection indication path, set a second timing time, and provide a drive signal to drive the switch power supply to power on. Figure 3As shown, the microprocessor U1 outputs a first control signal ctrl1 and a second control signal ctrl2 to the voltage detection module 1120, and the voltage detection module 1120 turns off the open circuit detection path according to the first control signal ctrl1. And the microprocessor U1 sets the second timing time T2 to provide to the counter U2, and when entering the short circuit detection, provides a reset signal rest to the counter U2 before starting counting. And the microprocessor U1 provides a drive signal pwm to the switching power supply to control the switch 1000 to power on. The switching power supply power-on means that the microprocessor U1 first makes the drive signal pwm output a high level, so that the voltage of the output terminal VOUT of the switching power supply starts to rise, and then the MCU controls the drive signal pwm to output high and low levels to drive the power tube in the switch circuit 1200 of the switching power supply, so that the voltage of the output terminal VOUT of the switching power supply rises according to the designed slope. And the microprocessor U1 also generates a third control signal mux-sel to the gating unit 1113 to control the conduction short circuit detection indication path. In addition, the microprocessor U1 generates a short-circuit threshold voltage according to the second control signal ctrl2, and generates an open-circuit detection signal according to a comparison result between the voltage at the output terminal VOUT of the switching power supply and the short-circuit threshold voltage.

[0242] Step S330: After timing the second timing time, the short circuit detection signal is output as a short circuit detection result signal. Figure 3 As shown, the counter U2 performs timing to provide a selection enable signal demux-en to the control end of the first switch K1 of the selection unit 1113 after the second timing time T2 to turn on the first switch K1, and then provide the short-circuit detection signal generated by the voltage detection module 1120 to the input end of the short-circuit detection indication path of the selection unit 1113 through the first switch K1, and the short-circuit detection result signal sc-flag is output from the output end of the short-circuit detection indication path.

[0243] Step S340: Determine whether the short circuit detection result signal indicates a short circuit. In the case of a short circuit, execute step S350: control power off. In the normal case (no short circuit), execute step S360: enter overvoltage detection. Figure 2 As shown, the microprocessor U1 controls power-off to end fault detection when the short-circuit detection result signal sc-flag is at a first level, and enters overvoltage detection when the short-circuit detection result signal sc-flag is at a second level.

[0244] Furthermore, during short-circuit detection, the open-circuit detection path is disconnected. If a short-circuit fault occurs, the comparator U3 outputs a low level, and the short-circuit detection indication path is reversed. The short-circuit detection result signal sc_flag is a high level, indicating that a short-circuit fault has occurred, and the microprocessor U1 enters the protection power-off state to end the fault detection. Conversely, the comparator U3 outputs a high level, and the short-circuit detection indication path (reverse path) is reversed. The short-circuit detection result signal sc_flag is a low level, indicating that there is no short-circuit fault, and the microprocessor U1 enters the overvoltage detection.

[0245] For example, Fig. 9 As shown, the overvoltage detection of the switching power supply includes the following steps:

[0246] Step S410: Enter overvoltage detection according to the short circuit detection result signal. Figure 3 As shown, the gating unit 1113 outputs a reset signal (sc-flag=0) of the short-circuit detection result signal sc-flag, indicating that there is no short circuit, and the microprocessor U1 enters the overvoltage detection mode.

[0247] Step S420: output a first control signal to shut down the open circuit detection path, output a second control signal to generate an overvoltage threshold voltage, output a third control signal to conduct the overvoltage detection indication path, set a third timing time, and provide a drive signal to drive the switch power supply to work. Figure 3 As shown, the microprocessor U1 outputs a first control signal ctrl1 and a second control signal ctrl2 to the voltage detection module 1120, and the voltage detection module 1120 turns off the disconnection detection path according to the first control signal ctrl1 (the current source I1 is not turned on). And the microprocessor U1 sets a third timing time to provide to the counter U2, preferably, the third timing time is 0. And the drive signal pwm provided by the microprocessor U1 to the switching power supply outputs high and low levels to drive the power tube in the switching circuit 1200 of the switching power supply, so that the switching power supply works normally. And the microprocessor U1 also generates a third control signal mux-sel to the gating unit 1113 to control the conduction of the overvoltage detection indication path. And the microprocessor U1 also generates an overvoltage threshold voltage according to the second control signal ctrl2, and generates an overvoltage detection signal according to the comparison result of the voltage at the output terminal VOUT of the switching power supply and the overvoltage threshold voltage.

[0248] Step S430: Output the overvoltage detection signal as an overvoltage detection result signal. Figure 3As shown, when entering overvoltage detection, the control end of the first switch K1 of the gating unit 1113 provides a gating enable signal demux-en to turn on the first switch K1, and then the overvoltage detection signal generated by the voltage detection module 1120 is provided to the input end of the overvoltage detection indication path of the gating unit 1113 through the first switch K1, and the overvoltage detection result signal ovp-flag is outputted from the output end of the overvoltage detection indication path.

[0249] Step S440: Determine whether the overvoltage detection result signal indicates overvoltage. In the case of overvoltage, step S450 is executed: perform fault protection action. In normal case (no overvoltage), step S460 is executed: continue overvoltage detection. Figure 3 As shown, when the overvoltage detection result signal ovp-flag is at a first level, the microprocessor U1 provides a low-level driving signal pwm to the switching power supply to reduce the output voltage of the switching power supply and enter undervoltage detection, and continues the overvoltage detection when the overvoltage detection result signal ovp-flag is at a second level.

[0250] Furthermore, after entering the overvoltage detection, the counter U2 always outputs a high-level strobe enable signal demux-en. Once the voltage at the output terminal VOUT exceeds the overvoltage threshold voltage during the operation of the switching power supply, the overvoltage detection result signal ovp_flag is immediately set high, indicating that an output overvoltage fault has occurred, and the microprocessor U1 will control the output overvoltage protection state and control the voltage at the output terminal VOUT to drop. At the same time, the microprocessor U1 will control the undervoltage detection mode to control the power-off to end the fault detection when the voltage at the output terminal VOUT drops to the target value (undervoltage threshold voltage), and turn off the PWM drive at the same time.

[0251] For example, Fig.10 As shown, executing the fault protection action refers to performing undervoltage detection on the switching power supply, which includes the following steps:

[0252] Step S510: Enter undervoltage detection according to the overvoltage detection result signal. Figure 3 As shown, the selection unit 1113 outputs a setting signal (ovp-flag=1) of the overvoltage detection result signal ovp-flag, indicating overvoltage, and the microprocessor U1 enters the undervoltage detection mode.

[0253] Step S520: output a first control signal to turn off the open circuit detection path, output a second control signal to generate an undervoltage threshold voltage, output a third control signal to turn on the undervoltage detection indication path, set a fourth timing time, and provide a drive signal to reduce the voltage at the output end of the switching power supply. Figure 3As shown, the microprocessor U1 outputs a first control signal ctrl1 and a second control signal ctrl2 to the voltage detection module 1120, and the voltage detection module 1120 turns off the disconnection detection path according to the first control signal ctrl1. And the microprocessor U1 sets a fourth timing time to provide to the counter U2, preferably, the fourth timing time is 0. And the drive signal pwm provided by the microprocessor U1 to the switching power supply outputs a low level to reduce the voltage of the output terminal VOUT of the switching power supply. And the microprocessor U1 also generates a third control signal mux-sel to the gating unit 1113 to control the conduction of the undervoltage detection indication path. And the microprocessor U1 also generates an undervoltage threshold voltage according to the second control signal ctrl2, and generates an undervoltage detection signal according to the comparison result of the voltage at the output terminal VOUT of the switching power supply and the undervoltage threshold voltage.

[0254] Step S530: Output the undervoltage detection signal as an undervoltage detection result signal. Figure 3 As shown, when entering under-voltage detection, the control end of the first switch K1 of the gating unit 1113 provides a gating enable signal demux-en to turn on the first switch K1, and then the under-voltage detection signal generated by the voltage detection module 1120 is provided to the input end of the under-voltage detection indication path of the gating unit 1113 through the first switch K1, and the under-voltage detection result signal rvp-flag is outputted from the output end of the under-voltage detection indication path.

[0255] Step S540: Determine whether the undervoltage detection result signal indicates undervoltage. In the case of undervoltage, execute step S550: end fault detection. In normal case (no undervoltage), execute step S460: continue undervoltage detection. Figure 2 As shown, the microprocessor U1 controls power-off to end fault detection when the undervoltage detection result signal rvp-flag is at a first level, and continues undervoltage detection when the undervoltage detection result signal rvp-flag is at a second level.

[0256] Furthermore, after entering the undervoltage detection, the counter U2 always outputs a high-level gate enable signal demux-en. Once the voltage at the output terminal VOUT exceeds the undervoltage threshold voltage during the operation of the switching power supply, the undervoltage detection result signal rvp_flag is immediately set high, indicating that after the overvoltage fault, the output voltage has been reduced to below the target value by controlling PWM to maintain a low level), and the microprocessor U1 controls the power-off to end the fault detection. Otherwise, the undervoltage detection will continue until the voltage at the output terminal VOUT of the switching power supply drops to the target value.

[0257] In other embodiments, step S110 of the switching power supply fault detection method further includes:

[0258] An open circuit detection is performed on the output end of the switching power supply according to the received power-on enable signal, and a short circuit detection is performed on the output end of the switching power supply or fault detection is terminated according to the open circuit detection result signal after a first timing period.

[0259] In other embodiments, step S110 of the switching power supply fault detection method further includes:

[0260] Performing an open circuit detection on the output end of the switching power supply according to the received power-on enable signal, and performing an overvoltage detection or ending fault detection on the output end of the switching power supply according to the open circuit detection result signal after a first timing period;

[0261] Performing overvoltage detection on the output end of the switching power supply and performing fault protection on the output end of the switching power supply according to the overvoltage detection result signal to enter undervoltage detection or continue overvoltage detection; and

[0262] An undervoltage detection is performed on the output end of the switching power supply and the fault detection is ended or the undervoltage detection is continued according to the undervoltage detection result signal.

[0263] The present disclosure also provides a fault detection method performed by a fault detection circuit 4100, comprising:

[0264] The first detection is performed on the output end of the switching power supply according to the received power-on enable signal. The first detection is a short circuit detection. The detection process of the short circuit detection includes:

[0265] Outputting a driving signal to the switching power supply to drive the switching circuit of the switching power supply to work;

[0266] generating a third control signal to control the short-circuit detection indication path to be turned on;

[0267] Outputting a second control signal, the second control signal controls the generation of a short-circuit threshold voltage, and generating a short-circuit detection signal according to a comparison result between the voltage at the output end of the switching power supply and the short-circuit threshold voltage;

[0268] Setting a second timing time, resetting before starting timing, and providing a short circuit detection signal to an input end of a short circuit detection indication path after timing reaches the second timing time, and generating a short circuit detection result signal via the short circuit detection indication path;

[0269] When the short-circuit detection result signal indicates that the switching power supply is in a short-circuit state, the fault detection is terminated, and when the short-circuit detection result signal indicates that the switching power supply is in a normal state, the fault detection is terminated or a second detection is performed.

[0270] The second test is to detect overvoltage at the output of the switching power supply:

[0271] Outputting a driving signal to the switching power supply to drive the switching circuit of the switching power supply to work;

[0272] generating a third control signal to control the overvoltage detection indication path to be turned on;

[0273] Output a second control signal, the second control signal controls the generation of an overvoltage threshold voltage, and the voltage detection module generates an overvoltage detection signal according to a comparison result between the voltage at the output end of the switching power supply and the overvoltage threshold voltage;

[0274] Providing an overvoltage detection signal to an input end of an overvoltage detection indication path, and generating an overvoltage detection result signal via the overvoltage detection indication path;

[0275] When the overvoltage detection result signal indicates that the switching power supply is in an overvoltage state, a fault protection action is performed, and when the overvoltage detection result signal indicates that the switching power supply is in a normal state, overvoltage detection is continued.

[0276] Executing fault protection actions include:

[0277] Outputting an invalid state driving signal to the switching power supply to reduce the voltage at the output end of the switching power supply;

[0278] generating a third control signal to control the undervoltage detection indication path to be turned on;

[0279] Outputting a second control signal, the second control signal controls the generation of an undervoltage threshold voltage, and generating an undervoltage detection signal according to a comparison result between the voltage at the output end of the switching power supply and the undervoltage threshold voltage;

[0280] The fault detection is ended when the undervoltage detection result signal indicates that the voltage at the output end of the switching power supply drops below the undervoltage threshold, and the undervoltage detection is continued when the undervoltage detection result signal indicates that the voltage at the output end of the switching power supply does not drop below the undervoltage threshold.

[0281] The present invention provides a switching power supply, a control circuit, a fault detection circuit and a method. The present invention improves the safety and reliability of the switching power supply and simplifies the circuit structure by time-division multiplexing the same circuit to perform open circuit detection, short circuit detection, overvoltage detection and undervoltage detection on the output end of the switching power supply.

[0282] Further, the fault detection circuit of the present disclosure performs an open circuit detection on the output end of the switching power supply according to the power-on enable signal, and performs a short circuit detection or ends the fault detection on the output end of the switching power supply according to the open circuit detection result signal after a first timing time, and performs an overvoltage detection or ends the fault detection on the output end of the switching power supply according to the short circuit detection result signal after a second timing time of performing a short circuit detection on the output end of the switching power supply, and performs an undervoltage detection or continues the overvoltage detection on the output end of the switching power supply according to the overvoltage detection result signal, and performs an undervoltage detection on the output end of the switching power supply and ends the fault detection or continues the undervoltage detection according to the undervoltage detection result signal. That is, the present disclosure improves the reliability and safety of the switching power supply through the above detection methods.

[0283] Furthermore, the fault detection circuit of the present disclosure performs short-circuit detection on the output end of the switching power supply according to the power-on enable signal, and performs overvoltage detection or ends fault detection on the output end of the switching power supply according to the short-circuit detection result signal after the second timing time, and performs overvoltage detection on the output end of the switching power supply and performs undervoltage detection or continues overvoltage detection on the output end of the switching power supply according to the overvoltage detection result signal, and performs undervoltage detection on the output end of the switching power supply and ends fault detection or continues undervoltage detection according to the undervoltage detection result signal. That is, the present disclosure improves the reliability and safety of the switching power supply through the above detection method.

[0284] Furthermore, the fault detection circuit of the present invention directly outputs the corresponding detection signal as a detection result indication signal without delaying the timing when performing overvoltage detection and undervoltage detection, thereby further improving the accuracy of fault detection.

[0285] Furthermore, the present disclosure implements multiple fault detection by providing a timing unit, a gating unit, and a control unit to time-share multiplex the same voltage detection circuit structure, thereby reducing the circuit structure of the switching power supply and saving circuit costs.

[0286] According to the embodiments of the present invention as described above, these embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and changes can be made based on the above description. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can make good use of the present invention and the modified use based on the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A fault detection circuit for a switching power supply control circuit, wherein: include: A detection control module, used for performing time-sharing detection on at least two of the open circuit detection, short circuit detection and overvoltage detection of the output end of the switching power supply, and generating a corresponding second control signal under each detection; as well as The voltage detection module generates a corresponding threshold voltage according to the second control signal under each detection, and generates a corresponding detection signal according to the voltage at the output end of the switching power supply and the corresponding threshold voltage, and the detection control module generates a corresponding detection result signal according to the corresponding detection signal, The fault detection circuit obtains detection signals corresponding to at least two of open circuit detection, short circuit detection and overvoltage detection through a multiplexed voltage detection module.

2. The fault detection circuit according to claim 1, wherein: include: The detection control module also generates a first control signal when the at least two detections performed on the output end of the switching power supply include an open circuit detection. The voltage detection module also determines whether to turn on an open circuit detection path based on the first control signal. The open circuit detection path is connected between the power supply voltage and the output end of the switching power supply.

3. The fault detection circuit according to claim 2, wherein: The detection control module performs a first detection on the output end of the switching power supply according to the received power-on enable signal, wherein the first detection is an open circuit detection.

4. The fault detection circuit according to claim 1, wherein: The detection control module performs a first detection on the output end of the switching power supply according to the received power-on enable signal, wherein the first detection is a short circuit detection.

5. The fault detection circuit according to claim 3, wherein: The first detection is an open circuit detection detection process including: The detection control module outputs a driving signal for shutting down the drive to the switching power supply; The detection control module generates a third control signal to control the open circuit detection indication path to be turned on. The detection control module outputs a first control signal and a second control signal to the voltage detection module, wherein the first control signal controls the open circuit detection path in the voltage detection module to be turned on so as to charge the output terminal of the switching power supply, and the second control signal controls the voltage detection module to generate an open circuit threshold voltage, and the voltage detection module generates the open circuit detection signal according to a comparison result between the voltage at the output terminal of the switching power supply and the open circuit threshold voltage; The detection control module sets a first timing time, resets before starting timing, and after the timing reaches the first timing time, provides the open circuit detection signal generated by the voltage detection module to the input end of the open circuit detection indication path, and generates the open circuit detection result signal via the open circuit detection indication path; The detection control module ends the fault detection when the open circuit detection result signal indicates that the switch power supply is in an open circuit state, and triggers itself to perform a second detection when the open circuit detection result signal indicates that the switch power supply is in a normal state.

6. The fault detection circuit according to claim 5, wherein: The second detection is a detection process of short-circuit detection on the output end of the switching power supply, including: The detection control module outputs a driving signal to the switching power supply to drive the switching circuit of the switching power supply to work; The detection control module generates a third control signal to control the short-circuit detection indication path to be turned on; The detection control module outputs a first control signal and a second control signal to the voltage detection module, wherein the first control signal controls the open circuit detection path in the voltage detection module to be turned off, and the second control signal controls the voltage detection module to generate a short circuit threshold voltage, and the voltage detection module generates the short circuit detection signal according to a comparison result between the voltage at the output end of the switching power supply and the short circuit threshold voltage; The detection control module sets a second timing time, resets before starting timing, and after the timing reaches the second timing time, provides the short-circuit detection signal generated by the voltage detection module to the input end of the short-circuit detection indication path, and generates the short-circuit detection result signal via the short-circuit detection indication path; The detection control module ends the fault detection when the short-circuit detection result signal indicates that the switch power supply is in a short-circuit state, and ends the fault detection or performs a third detection when the short-circuit detection result signal indicates that the switch power supply is in a normal state.

7. The fault detection circuit according to claim 5, wherein: The second detection is to perform overvoltage detection on the output end of the switching power supply.

8. The fault detection circuit according to claim 6, wherein: The third detection is to perform overvoltage detection on the output end of the switching power supply.

9. The fault detection circuit according to claim 7 or 8, wherein: The overvoltage detection process includes: The detection control module outputs a driving signal to the switching power supply to drive the switching circuit of the switching power supply to work; The detection control module generates a third control signal to control the overvoltage detection indication path to be turned on; The detection control module outputs a first control signal and a second control signal to the voltage detection module, wherein the first control signal controls the open circuit detection path in the voltage detection module to be turned off, and the second control signal controls the voltage detection module to generate an overvoltage threshold voltage, and the voltage detection module generates the overvoltage detection signal according to a comparison result between the voltage at the output end of the switching power supply and the overvoltage threshold voltage; The detection control module provides the overvoltage detection signal generated by the voltage detection module to the input end of the overvoltage detection indication path, and generates the overvoltage detection result signal via the overvoltage detection indication path; The detection control module performs a fault protection action when the overvoltage detection result signal indicates that the switching power supply is in an overvoltage state, and continues to perform overvoltage detection when the overvoltage detection result signal indicates that the switching power supply is in a normal state.

10. The fault detection circuit according to claim 9, wherein: The execution of the fault protection action comprises: The detection control module outputs an invalid state driving signal to the switching power supply to reduce the voltage at the output end of the switching power supply; The detection control module generates a third control signal to control the undervoltage detection indication path to be turned on; The detection control module outputs a first control signal and a second control signal to the voltage detection module, wherein the first control signal controls the open circuit detection path in the voltage detection module to be turned off, and the second control signal controls the voltage detection module to generate an undervoltage threshold voltage, and the voltage detection module generates the undervoltage detection signal according to a comparison result between the voltage at the output end of the switching power supply and the undervoltage threshold voltage; The detection control module ends fault detection when the undervoltage detection result signal indicates that the voltage at the output end of the switching power supply drops below the undervoltage threshold, and continues undervoltage detection when the undervoltage detection result signal indicates that the voltage at the output end of the switching power supply does not drop below the undervoltage threshold.

11. The fault detection circuit according to claim 4, wherein: The first detection is a short circuit detection detection process including: The detection control module outputs a driving signal to the switching power supply to drive the switching circuit of the switching power supply to work; The detection control module generates a third control signal to control the short-circuit detection indication path to be turned on; The detection control module outputs a second control signal to the voltage detection module, the second control signal controls the voltage detection module to generate a short-circuit threshold voltage, and the voltage detection module generates the short-circuit detection signal according to a comparison result between the voltage at the output end of the switching power supply and the short-circuit threshold voltage; The detection control module sets a second timing time, resets before starting timing, and after the timing reaches the second timing time, provides the short-circuit detection signal generated by the voltage detection module to the input end of the short-circuit detection indication path, and generates the short-circuit detection result signal via the short-circuit detection indication path; The detection control module ends the fault detection when the short-circuit detection result signal indicates that the switch power supply is in a short-circuit state, and ends the fault detection or performs a second detection when the short-circuit detection result signal indicates that the switch power supply is in a normal state.

12. The fault detection circuit according to claim 11, wherein: The second detection is a detection process of performing overvoltage detection on the output end of the switching power supply, including: The detection control module outputs a driving signal to the switching power supply to drive the switching circuit of the switching power supply to work; The detection control module generates a third control signal to control the overvoltage detection indication path to be turned on; The detection control module outputs a second control signal to the voltage detection module, the second control signal controls the voltage detection module to generate an overvoltage threshold voltage, and the voltage detection module generates the overvoltage detection signal according to a comparison result between the voltage at the output end of the switching power supply and the overvoltage threshold voltage; The detection control module provides the overvoltage detection signal generated by the voltage detection module to the input end of the overvoltage detection indication path, and generates the overvoltage detection result signal via the overvoltage detection indication path; The detection control module performs a fault protection action when the overvoltage detection result signal indicates that the switching power supply is in an overvoltage state, and continues to perform overvoltage detection when the overvoltage detection result signal indicates that the switching power supply is in a normal state.

13. The fault detection circuit according to claim 12, wherein: The execution of the fault protection action comprises: The detection control module outputs an invalid state driving signal to the switching power supply to reduce the voltage at the output end of the switching power supply; The detection control module generates a third control signal to control the undervoltage detection indication path to be turned on; The detection control module outputs a second control signal to the voltage detection module, the second control signal controls the voltage detection module to generate an undervoltage threshold voltage, and the voltage detection module generates the undervoltage detection signal according to a comparison result between the voltage at the output end of the switching power supply and the undervoltage threshold voltage; The detection control module ends fault detection when the undervoltage detection result signal indicates that the voltage at the output end of the switching power supply drops below the undervoltage threshold, and continues undervoltage detection when the undervoltage detection result signal indicates that the voltage at the output end of the switching power supply does not drop below the undervoltage threshold.

14. The fault detection circuit according to any one of claims 5, 6, 10, 11, and 13, wherein: The end of the fault detection comprises: The detection control module turns off the drive and enters a power-off state.

15. The fault detection circuit according to claim 2, wherein: The voltage detection module comprises: a current source, controlling whether to charge the output terminal of the switching power supply according to the first control signal; A first capacitor, wherein a first end of the first capacitor is connected to the output end of the switching power supply and the current source, and a second end of the first capacitor is grounded; a digital-to-analog converter, wherein an input terminal of the digital-to-analog converter receives the second control signal, and an output terminal of the digital-to-analog converter outputs a threshold voltage corresponding to the detection; and A comparator, wherein a first input terminal of the comparator is connected to a first terminal of the first capacitor, a second input terminal of the comparator is connected to an output terminal of the digital-to-analog converter, and an output terminal of the comparator outputs a detection signal under corresponding detection.

16. The fault detection circuit according to claim 1, wherein: The voltage detection module comprises: A first capacitor, wherein a first end of the first capacitor is connected to the output end of the switching power supply, and a second end of the first capacitor is grounded; a digital-to-analog converter, wherein an input terminal of the digital-to-analog converter receives the second control signal, and an output terminal of the digital-to-analog converter outputs a threshold voltage corresponding to the detection; and A comparator, wherein a first input terminal of the comparator is connected to a first terminal of the first capacitor, a second input terminal of the comparator is connected to an output terminal of the digital-to-analog converter, and an output terminal of the comparator outputs a detection signal under corresponding detection.

17. The fault detection circuit according to claim 3, wherein: The detection control module comprises: A control unit receives a power-on enable signal, enters an open circuit detection according to the power-on enable signal, enters a short circuit detection or an undervoltage detection according to the open circuit detection result signal, enters an overvoltage detection according to the short circuit detection result signal, enters an undervoltage detection according to the overvoltage detection result signal, and outputs a corresponding first control signal and a second control signal to the voltage detection module under each detection, sets a first timing time and a second timing time, and provides a corresponding drive signal under the corresponding detection; a timing unit connected to the control unit, generating a gating enable signal after entering the open circuit detection and a first timing time has passed, generating a gating enable signal after entering the short circuit detection and a second timing time has passed, and generating a gating enable signal when entering the overvoltage detection and entering the undervoltage detection; and The gating unit is connected to the timing unit, the voltage detection module and the control unit, and generates corresponding detection result signals by passing different detection signals through corresponding detection indication paths according to the gating enable signal and the third control signal.

18. The fault detection circuit according to claim 17, wherein: The gating unit comprises: an open circuit detection indication path, wherein a control end of the open circuit detection indication path receives the third control signal, and an output end of the open circuit detection indication path outputs an open circuit detection result indication signal; A short-circuit detection indication path, wherein a control end of the short-circuit detection indication path receives the third control signal, and an output end of the short-circuit detection indication path outputs a short-circuit detection result indication signal; an overvoltage detection indication path, wherein a control end of the overvoltage detection indication path receives the third control signal, and an output end of the overvoltage detection indication path outputs an overvoltage detection result indication signal; An undervoltage detection indication path, wherein a control end of the undervoltage detection indication path receives the third control signal, and an output end of the undervoltage detection indication path outputs an undervoltage detection result indication signal; A first switch, wherein a control end of the first switch is connected to the timing unit to receive the enable signal, a first end of the first switch is connected to the voltage detection module to receive a detection signal, and a second end of the first switch is connected to an input end of the open circuit detection indication path, an input end of the short circuit detection indication path, an input end of the overvoltage detection indication path, and an input end of the undervoltage detection indication path.

19. The fault detection circuit of the switching power supply according to claim 18, wherein: The open circuit detection indication path, the overvoltage detection indication path, and the undervoltage detection indication path are straight-through paths, and the short circuit detection indication path is an inverting path.

20. The fault detection circuit according to claim 4, wherein: The detection control module comprises: A control unit receives a power-on enable signal, enters short-circuit detection according to the power-on enable signal, enters overvoltage detection according to the short-circuit detection result signal, enters undervoltage detection according to the overvoltage detection result signal, and outputs a corresponding second control signal to the voltage detection module under each detection, sets a second timing time, and provides a corresponding drive signal under the corresponding detection; a timing unit connected to the control unit, generating a gating enable signal after entering the short circuit detection and after a second timing time has passed, and generating a gating enable signal when entering the overvoltage detection and the undervoltage detection; and The gating unit is connected to the timing unit, the voltage detection module and the control unit, and generates corresponding detection result signals by passing different detection signals through corresponding detection indication paths according to the gating enable signal and the third control signal.

21. The fault detection circuit according to claim 20, wherein: The gating unit comprises: A short-circuit detection indication path, wherein a control end of the short-circuit detection indication path receives the third control signal, and an output end of the short-circuit detection indication path outputs a short-circuit detection result indication signal; an overvoltage detection indication path, wherein a control end of the overvoltage detection indication path receives the third control signal, and an output end of the overvoltage detection indication path outputs an overvoltage detection result indication signal; An undervoltage detection indication path, wherein a control end of the undervoltage detection indication path receives the third control signal, and an output end of the undervoltage detection indication path outputs an undervoltage detection result indication signal; A first switch, wherein a control end of the first switch is connected to the timing unit to receive the enable signal, a first end of the first switch is connected to the voltage detection module to receive a detection signal, and a second end of the first switch is connected to an input end of the short circuit detection indication path, an input end of the overvoltage detection indication path, and an input end of the undervoltage detection indication path.

22. The fault detection circuit according to claim 1, wherein: The detection control module is also used to perform one of open circuit detection, short circuit detection and overvoltage detection on the output end of the switching power supply.

23. A control circuit for a switching power supply, wherein: Comprising a fault detection circuit as described in any one of claims 1-22.

24. A switching power supply, wherein: include: A control circuit comprising a fault detection circuit as described in any one of claims 1 to 22 above; A power-on enabling circuit, providing a power-on enabling signal to the fault detection circuit; as well as The switch circuit converts the input voltage into an output voltage based on the control of the driving signal and provides it to the output end of the switching power supply.

25. The switching power supply according to claim 24, wherein: The switching power supply includes an AC-DC switching power supply and a DC-DC switching power supply.

26. The switching power supply according to claim 24, wherein: The power-on enabling circuit comprises: a resistor, wherein a first end of the resistor receives a second power supply voltage; A second switch, wherein a control end of the second switch receives a fourth control signal, a first end of the second switch is connected to a second end of the resistor and provides the power-on enable signal, and a second end of the second switch is grounded.

27. A fault detection method for a switching power supply control circuit, wherein: include: Perform time-sharing detection on at least two of the open circuit detection, short circuit detection, and overvoltage detection of the output terminal of the switching power supply, and generate a corresponding second control signal under each detection; as well as Under each detection, a corresponding threshold voltage is generated according to the second control signal, and a corresponding detection signal is generated according to the voltage at the output end of the switching power supply and the corresponding threshold voltage, wherein detection signals corresponding to at least two of open circuit detection, short circuit detection, and overvoltage detection are obtained by multiplexing the voltage detection module; as well as A corresponding detection result signal is generated according to the corresponding detection signal.

28. The fault detection method according to claim 27, wherein: When the at least two detections include an open circuit detection, a first control signal is further generated, and whether to conduct an open circuit detection path is determined according to the first control signal, wherein the open circuit detection path is connected between the power supply voltage and the output end of the switching power supply.

29. The fault detection method according to claim 28, wherein: Also includes: A first detection is performed on the output end of the switching power supply according to the received power-on enable signal, wherein the first detection is an open circuit detection.

30. The fault detection method according to claim 27, wherein: Also includes: A first detection is performed on the output end of the switching power supply according to the received power-on enable signal, wherein the first detection is a short circuit detection.

31. The fault detection method according to claim 29, wherein: The first detection is an open circuit detection detection process including: Outputting a drive signal for shutting down the drive to the switching power supply; generating a third control signal to control the open circuit detection indication path to be turned on, Outputting a first control signal and a second control signal, wherein the first control signal controls the open circuit detection path to be turned on to charge the output terminal of the switching power supply, and the second control signal controls the generation of an open circuit threshold voltage, and generates the open circuit detection signal according to a comparison result between the voltage at the output terminal of the switching power supply and the open circuit threshold voltage; Setting a first timing time, resetting before starting timing, and providing an open circuit detection signal to an input end of the open circuit detection indication path after the timing reaches the first timing time, and generating the open circuit detection result signal via the open circuit detection indication path; The fault detection is ended when the open circuit detection result signal indicates that the switch power supply is in an open circuit state, and the second detection is triggered when the open circuit detection result signal indicates that the switch power supply is in a normal state.

32. The fault detection method according to claim 31, wherein: The second detection is a detection process of short-circuit detection on the output end of the switching power supply, including: Outputting a driving signal to the switching power supply to drive the switching circuit of the switching power supply to operate; generating a third control signal to control the short-circuit detection indication path to be turned on; Outputting a first control signal and a second control signal, wherein the first control signal controls the open circuit detection path to be turned off, and the second control signal controls the generation of a short circuit threshold voltage, and generating the short circuit detection signal according to a comparison result between the voltage at the output end of the switching power supply and the short circuit threshold voltage; Setting a second timing time, resetting before starting timing, and providing a short circuit detection signal to an input end of the short circuit detection indication path after the timing reaches the second timing time, and generating the short circuit detection result signal via the short circuit detection indication path; When the short-circuit detection result signal indicates that the switching power supply is in a short-circuit state, the fault detection is terminated; and when the short-circuit detection result signal indicates that the switching power supply is in a normal state, the fault detection is terminated or a third detection is performed.

33. The fault detection method according to claim 31, wherein: The second detection is to perform overvoltage detection on the output end of the switching power supply.

34. The fault detection method according to claim 32, wherein: The third detection is to perform overvoltage detection on the output end of the switching power supply.

35. The fault detection method according to claim 33 or 34, wherein: The overvoltage detection process includes: Outputting a driving signal to the switching power supply to drive the switching circuit of the switching power supply to operate; generating a third control signal to control the overvoltage detection indication path to be turned on; Outputting a first control signal and a second control signal, wherein the first control signal controls the open circuit detection path to be turned off, and the second control signal controls the generation of an overvoltage threshold voltage, and generating the overvoltage detection signal according to a comparison result between the voltage at the output end of the switching power supply and the overvoltage threshold voltage; Providing an overvoltage detection signal to an input end of the overvoltage detection indication path, and generating the overvoltage detection result signal via the overvoltage detection indication path; When the overvoltage detection result signal indicates that the switching power supply is in an overvoltage state, a fault protection action is performed, and when the overvoltage detection result signal indicates that the switching power supply is in a normal state, overvoltage detection is continued.

36. The fault detection method according to claim 35, wherein: The execution of the fault protection action comprises: Outputting an invalid state driving signal to the switching power supply to reduce the voltage at the output end of the switching power supply; generating a third control signal to control the undervoltage detection indication path to be turned on; Outputting a first control signal and a second control signal, wherein the first control signal controls the open circuit detection path to be turned off, and the second control signal controls the generation of an undervoltage threshold voltage, and generating the undervoltage detection signal according to a comparison result between the voltage at the output end of the switching power supply and the undervoltage threshold voltage; The fault detection is ended when the undervoltage detection result signal indicates that the voltage at the output end of the switching power supply drops below the undervoltage threshold, and the undervoltage detection is continued when the undervoltage detection result signal indicates that the voltage at the output end of the switching power supply does not drop below the undervoltage threshold.

37. The fault detection method according to claim 30, wherein: The first detection is a short circuit detection detection process including: Outputting a driving signal to the switching power supply to drive the switching circuit of the switching power supply to operate; generating a third control signal to control the short-circuit detection indication path to be turned on; Outputting a second control signal, wherein the second control signal controls the generation of a short-circuit threshold voltage, and generating the short-circuit detection signal according to a comparison result between the voltage at the output end of the switching power supply and the short-circuit threshold voltage; Setting a second timing time, resetting before starting timing, and providing a short circuit detection signal to an input end of the short circuit detection indication path after the timing reaches the second timing time, and generating the short circuit detection result signal via the short circuit detection indication path; When the short-circuit detection result signal indicates that the switching power supply is in a short-circuit state, the fault detection is terminated; and when the short-circuit detection result signal indicates that the switching power supply is in a normal state, the fault detection is terminated or a second detection is performed.

38. The fault detection method according to claim 37, wherein: The second detection is a detection process of performing overvoltage detection on the output end of the switching power supply, including: Outputting a driving signal to the switching power supply to drive the switching circuit of the switching power supply to operate; generating a third control signal to control the overvoltage detection indication path to be turned on; Outputting a second control signal, wherein the second control signal controls the generation of an overvoltage threshold voltage, and the voltage detection module generates the overvoltage detection signal according to a comparison result between the voltage at the output end of the switching power supply and the overvoltage threshold voltage; Providing an overvoltage detection signal to an input end of the overvoltage detection indication path, and generating the overvoltage detection result signal via the overvoltage detection indication path; When the overvoltage detection result signal indicates that the switching power supply is in an overvoltage state, a fault protection action is performed, and when the overvoltage detection result signal indicates that the switching power supply is in a normal state, overvoltage detection is continued.

39. The fault detection method according to claim 38, wherein: The execution of the fault protection action comprises: Outputting an invalid state driving signal to the switching power supply to reduce the voltage at the output end of the switching power supply; generating a third control signal to control the undervoltage detection indication path to be turned on; Outputting a second control signal, wherein the second control signal controls the generation of an undervoltage threshold voltage, and generating the undervoltage detection signal according to a comparison result between the voltage at the output end of the switching power supply and the undervoltage threshold voltage; The fault detection is ended when the undervoltage detection result signal indicates that the voltage at the output end of the switching power supply drops below the undervoltage threshold, and the undervoltage detection is continued when the undervoltage detection result signal indicates that the voltage at the output end of the switching power supply does not drop below the undervoltage threshold.

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