Switching power supply device and applicable power driver

Abstract

The present application discloses a switching power supply device and a power driver applicable thereto, comprising: a self-power supply terminal for connecting a self-power supply; a reference voltage terminal for accessing a reference voltage and connecting a power conversion circuit; an input terminal for connecting a power supply bus; the switching power supply device encapsulates a circuit structure comprising: a switch unit, whose input end is connected to the input terminal; a line selection unit for outputting a second electrical signal in the switch unit from the reference voltage terminal or the self-power supply terminal in a controlled manner; a switch control unit for controlling the switch unit to be turned on, pre-off or turned off; a self-power supply detection unit for controlling the output end of the switch unit to be changed from being connected to the reference voltage terminal to being connected to the self-power supply terminal when it is determined that the self-power supply terminal is insufficiently powered during the startup phase of the switching power supply device. The present application can timely self-power supply when the power supply is insufficient during the startup phase to ensure the normal startup of the switching power supply device.

Description

Technical Field

[0001] The present application relates to the technical field of switching power supplies, and in particular to a switching power supply device and a power driver applicable thereto. Background Art

[0002] A switching power supply is a device used to convert electrical energy, converting the AC power provided by the power grid into various DC output voltages. It is widely used in electronic equipment adapters and other occasions because of its advantages such as fewer peripheral system components, low cost, simple structure, and low standby power consumption.

[0003] Figure 1 The structure block diagram of the existing switching power supply is shown. As shown in the figure, the switching power supply has an input terminal Vin, a feedback terminal FB, a power supply terminal VCC, a sampling terminal CS and a reference voltage terminal gnd, wherein the input terminal Vin is electrically connected to the power supply bus and is used to provide a starting current of the switching power supply through a resistor Ri and a capacitor Ci. The feedback terminal FB is used to obtain an output voltage Vout (i.e., a load power supply voltage) of a power conversion circuit composed of an inductor L0, a freewheeling diode D0 and an output capacitor C0 through voltage-dividing resistors R1 and R2 to generate a feedback signal. The sampling terminal CS is used to sample a current signal flowing through the inductor L0 through a sampling resistor Rs arranged in the power conversion circuit to generate a current detection signal. The switching power supply controls the on or off of the power switch tube inside it based on the feedback signal reflecting the output voltage Vout fed back by the feedback terminal FB and the current detection signal obtained by the sampling terminal CS, thereby changing the electrical signal in the power conversion circuit so that the power conversion circuit provides stable power supply to the load.

[0004] In this way, the switching power supply needs to set a sampling terminal CS to cooperate with the sampling resistor Rs to detect the peak current flowing through the power conversion circuit to determine the shutdown moment of the power switch tube in the switching power supply, which makes the integration level of the switching power supply low, the peripheral components are many and the wiring is cumbersome, which increases the hardware cost.

[0005] In addition, the switching power supply device supplies power to each internal module via the power supply terminal VCC. During the startup phase of the switching power supply device, only the capacitor Ci supplies power to the switching power supply device from the power supply terminal VCC. At this time, all modules in the switching power supply device need to be awakened and the switching power supply device may not be able to start smoothly due to insufficient power in the capacitor Ci. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the related art, the purpose of the present application is to provide a switching power supply device and a power driver suitable therefor.

[0007] To achieve the above-mentioned purpose and other related purposes, the first aspect of the present application discloses a switching power supply device, which is used to change the electrical signal in the power conversion circuit connected to the power supply bus so that the power conversion circuit provides stable power supply to the load, characterized in that the switching power supply device includes: a self-power supply terminal, which is used to connect a self-power supply; a reference voltage terminal, which is used to connect a reference voltage and connect the power conversion circuit; an input terminal, which is used to connect the power supply bus to obtain a second electrical signal from the power supply bus; wherein the switching power supply device encapsulates a circuit structure to output the second electrical signal in the power supply bus to the power conversion circuit by using the input terminal and the reference voltage terminal; wherein the circuit structure includes: a switch unit, whose input end is connected to the input terminal; a line selection unit, which is electrically connected to the output end of the switch unit, for being controlled outputs the second electrical signal in the switch unit from the reference voltage terminal or the self-power supply terminal; a switch control unit is connected to the self-power supply terminal and the control end of the switch unit and receives the first electrical signal of the self-power supply terminal, and is used to detect the first electrical signal, detect the second electrical signal, and control the switch unit to enter the on state, the pre-shutdown state or the off state based on the detection results; a self-power supply detection unit is connected to the self-power supply terminal, the line selection unit and the switch control unit, and is used to detect the first electrical signal during the period when the switch unit is in the pre-shutdown state; wherein, when the self-power supply detection unit determines based on the detection result that the self-power supply terminal is insufficiently powered during the startup phase of the switching power supply device, the line selection unit is controlled to change the output end of the switch unit from being connected to the reference voltage terminal to being connected to the self-power supply terminal.

[0008] In certain embodiments of the first aspect of the present application, the switch unit includes: a current-type switch module, which is arranged on the line between the input terminal and the line selection unit; and a driving power supply module, which is used to controllably output a driving signal to the control end of the current-type switch module.

[0009] In certain embodiments of the first aspect of the present application, the driving power supply module includes multiple driving power supplies, which are used to output a changing driving signal to the control end of the current-type switch module, and each driving power supply is independently controlled by the switch control unit; wherein, under the control of the switch control unit, a part of the driving power supplies performs a disconnection operation during the conduction period of the current-type switch module, and another part of the driving power supplies maintain the conduction state of the current-type switch module.

[0010] In certain embodiments of the first aspect of the present application, the other part of the driving power supply interrupts outputting the driving signal to the current-type switch module based on the pre-shutdown detection signal output by the switch control unit.

[0011] In certain embodiments of the first aspect of the present application, the line selection unit includes a second power tube connected between the output end of the switch unit and the reference voltage terminal; wherein the second power tube is in a linear region during the period when the switch unit and the reference voltage terminal are connected.

[0012] In certain embodiments of the first aspect of the present application, the self-powered detection unit includes: a comparison module, electrically connected to the self-powered terminal and the line selection unit, for comparing the first electrical signal with a self-powered reference signal, and outputting a self-powered detection signal to the line selection unit based on the comparison result.

[0013] In certain embodiments of the first aspect of the present application, the switching power supply device further includes: a start timing unit, electrically connected to the output end of the switch control unit, for timing the start-up duration of the switching power supply device based on the output of the switch control unit at the moment the switching power supply device is powered on.

[0014] In certain embodiments of the first aspect of the present application, the switch control unit includes: a conduction detection module, electrically connected to the self-power supply terminal, for detecting a first electrical signal of the self-power supply terminal and outputting a corresponding first indication signal; a pre-shutdown detection circuit, electrically connected between the output end of the switch unit and the line selection unit, for detecting the second electrical signal and outputting a pre-shutdown detection signal based on the detection result during the period when the line selection unit connects the output end of the switch unit with the reference voltage terminal; a shutdown timing circuit, electrically connected to the pre-shutdown detection circuit and the switch unit, for timing the duration of the switch unit in the pre-shutdown state based on the pre-shutdown detection signal, and outputting a second indication signal when the timing expires; a logic control module, electrically connected to the conduction detection module and the shutdown timing circuit, for controlling the switch unit to be in a conduction state, a pre-shutdown state or a shutdown state based on the control logic of the first indication signal and the second indication signal.

[0015] In certain embodiments of the first aspect of the present application, the shutdown timing circuit includes at least one of the following timing sub-circuit: a first timing sub-circuit, connected to the line selection unit, for comparing the sampling signal collected by the line selection unit with a preset first shutdown reference signal, and when the sampling signal reaches the first shutdown reference signal, the timing times out and outputs a first timing logic signal; a second timing sub-circuit including a timing capacitor, electrically connected to the pre-shutdown detection circuit, for controlling the timing capacitor to perform a timing operation based on the pre-shutdown detection signal, and when the voltage signal on one electrode side of the timing capacitor reaches the second shutdown reference signal, the timing times out and outputs a second timing logic signal; wherein the second indication signal is represented by the first timing logic signal or the second timing logic signal.

[0016] In certain embodiments of the first aspect of the present application, the shutdown timing circuit also includes: a timing logic sub-circuit, electrically connecting the first timing sub-circuit and the second timing sub-circuit, and used to output the second indication signal based on the timing logic of the first timing logic signal and the second timing logic signal.

[0017] In certain embodiments of the first aspect of the present application, the switch control unit also includes: a first reference power supply, connected to the pre-shutdown detection circuit, for outputting a pre-shutdown reference signal for detecting the second electrical signal; a second reference power supply, connected to the pre-shutdown detection circuit, for outputting a second reference signal during the pre-shutdown state; wherein the pre-shutdown reference signal and the second reference signal are combined to obtain a first shutdown reference signal; a resistive circuit, electrically connected between a common output terminal of the first reference power supply and the second reference power supply and a reference voltage, for outputting the pre-shutdown reference signal or the first shutdown reference signal using a preset impedance; wherein the line selection unit and the resistive circuit have a preset resistance relationship, and the resistance relationship is determined based on the switch unit entering the pre-shutdown state.

[0018] In certain embodiments of the first aspect of the present application, the resistive circuit includes: a first power tube connected between the common output terminal and the reference voltage, which is in a linear region during the connection between the common output terminal and the reference voltage.

[0019] In certain embodiments of the first aspect of the present application, the pre-shutdown detection circuit includes: a comparison circuit, electrically connected to the resistive circuit and the line selection unit, for comparing a sampling signal sampled from the line selection unit and the pre-shutdown reference signal; a storage circuit, connected to the output end of the comparison circuit, for latching the comparison result of the comparison circuit and outputting the pre-shutdown detection signal.

[0020] In certain embodiments of the first aspect of the present application, the switch control unit further includes: an isolation module electrically connected between the line selection unit and the pre-shutdown detection circuit.

[0021] The second aspect of the present application discloses a power driver, comprising: a rectifier device, electrically connected to an external AC power supply, for rectifying an AC signal and transmitting it to a power supply bus; a switching power supply device as described in the embodiments disclosed in the first aspect of the present application, electrically connected to the power supply bus using an input terminal and connected to a reference voltage using a reference voltage terminal; a power conversion device, electrically connected to the power supply bus and the reference voltage terminal, for outputting stable power to a load under the on-off control of the switching power supply device; a power supply, electrically connected between the self-power supply terminal of the switching power supply device and the power supply bus, for providing power to the switching power supply device.

[0022] To sum up, the switching power supply device and the applicable power driver disclosed in the present application can promptly self-power when there is insufficient power supply during the startup phase to ensure the normal startup of the switching power supply device; in addition, the switching power supply device simplifies the external terminals and has a high degree of integration, which simplifies the wiring of peripheral components and reduces costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Shown is a structural block diagram of an existing switching power supply.

[0024] Figure 2 Shown is an external structure block diagram of a switching power supply device of the present application in one embodiment.

[0025] Figure 3 Shown is a schematic diagram of the peripheral circuit structure of the switching power supply device of the present application in one embodiment.

[0026] Figure 4 Shown is a schematic diagram of the internal circuit structure of the switching power supply device of the present application in one embodiment.

[0027] Figure 5 Shown is a schematic diagram of the circuit structure of a switch unit in an embodiment of the switching power supply device of the present application.

[0028] Figure 6 Shown is a schematic diagram of the circuit structure of a driving power module of the switching power supply device of the present application in one embodiment.

[0029] Figure 7 Shown is a structural block diagram of a switch control unit in an embodiment of the switching power supply device of the present application.

[0030] Figure 8 Shown is a structural block diagram of a disconnection detection module in an embodiment of the switching power supply device of the present application.

[0031] Fig. 9 Shown is a circuit structure schematic diagram of a circuit selection unit in an embodiment of the switching power supply device of the present application.

[0032] Fig.10 Shown is a schematic diagram of the circuit structure of a switch control unit in an embodiment of the switching power supply device of the present application.

[0033] Fig.11 Shown is a working waveform diagram of each unit of the switching power supply device of the present application in one embodiment.

[0034] Fig.12 Shown is a circuit structure diagram of a self-powered detection unit in an embodiment of the switching power supply device of the present application.

[0035] Fig.13Shown is a structural block diagram of a power driver of the present application in one embodiment. DETAILED DESCRIPTION

[0036] The following is an explanation of the implementation of the present application by means of specific embodiments. People familiar with the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification.

[0037] Although in some instances the terms first, second, etc. are used to describe various elements or parameters in this article, these elements or parameters should not be limited by these terms. These terms are only used to distinguish one or parameter from another or parameter. For example, the first indication signal can be referred to as the second indication signal, and similarly, the second indication signal can be referred to as the first indication signal without departing from the scope of the various described embodiments. The first indication signal and the second indication signal are both describing an indication signal, but unless the context clearly indicates otherwise, they are not the same indication signal. Similar situations also include a first electrical signal and a second electrical signal, or a first timing logic signal and a second timing logic signal.

[0038] Furthermore, as used in this article, the singular forms "one", "an" and "the" are intended to include plural forms as well, unless there is an indication to the contrary in the context. It should be further understood that the terms "comprise", "include" indicate the presence of the described features, steps, operations, elements, components, projects, kinds, and / or groups, but do not exclude the presence, occurrence or addition of one or more other features, steps, operations, elements, components, projects, kinds, and / or groups. The terms "or" and "and / or" used herein are interpreted as inclusive, or mean any one or any combination. Therefore, "A, B or C" or "A, B and / or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B and C". Exceptions to this definition will only occur when the combination of elements, functions, steps or operations is inherently mutually exclusive in some way.

[0039] A switching power supply is a device used to convert electric energy, which converts the AC power provided by the power grid into various DC output voltages. In various electronic devices and household appliances that require multiple power supplies with different voltages, switching power supplies can be used to provide output voltages such as 5V, 3.3V, 2.5V for digital circuits and ±12V, ±15V for analog circuits. Switching power supplies are widely used in electronic equipment adapters and other occasions because of their advantages such as fewer peripheral system components, low cost, simple structure, and low standby power consumption.

[0040] exist Figure 1In the switching power supply shown, the switching power supply has a feedback terminal FB and a sampling terminal CS, which are used to control the on or off of the power switch tube inside the switching power supply based on the feedback signal reflecting the output voltage Vout fed back by the feedback terminal FB and the current detection signal obtained by the sampling terminal CS, thereby changing the electrical signal in the power conversion circuit so that the power conversion circuit provides stable power supply to the load. In this way, the switching power supply needs to set the sampling terminal CS to cooperate with the sampling resistor Rs to detect the peak current flowing through the power conversion circuit to determine the turn-off moment of the power switch tube in the switching power supply, so that the integration degree of the switching power supply is low, the peripheral components are many, the wiring is complicated, and the hardware cost is increased.

[0041] In view of this, the present application discloses a switching power supply device, which is used to change the electrical signal in the power conversion circuit connected to the power supply bus so that the power conversion circuit provides stable power supply to the load. Figure 2 , which is a block diagram of the external structure of the switching power supply device of the present application in one embodiment. As shown in the figure, the switching power supply device 2 includes a self-power supply terminal 21, a reference voltage terminal 22, and an input terminal 20. The self-power supply terminal 21 is used to connect a self-power supply 3, the reference voltage terminal 22 is used to access a reference voltage gnd and connect the power conversion circuit 4, and the input terminal 20 is used to connect the power supply bus and obtain a second electrical signal from the power supply bus. The switching power supply device 2 encapsulates a circuit structure to output the second electrical signal in the power supply bus to the power conversion circuit 4 using the input terminal 20 and the reference voltage terminal 22.

[0042] In one embodiment, see Figure 3, which is a schematic diagram of the peripheral circuit structure of the switching power supply device of the present application in one embodiment. As shown in the figure, the self-powered power supply 3 includes a capacitor C2, one end of the capacitor C2 is electrically connected to the reference voltage terminal 22, and the other end is electrically connected to the self-powered terminal 21. At the same time, the other end of the capacitor C2 is also electrically connected to the power supply bus through the starting resistor R4, so as to maintain the power supply to the switching power supply device with the power provided by the power supply bus during the starting stage of the switching power supply. In this starting stage, the first electrical signal at the self-powered terminal 21 is the self-powered signal provided by the self-powered power supply 3. In order to avoid the power provided by the capacitor C2 being insufficient to support the smooth starting of the switching power supply device during the starting stage, in this embodiment, the self-powered signal of the self-powered terminal 21 is detected during the starting stage by the circuit structure encapsulated inside the switching power supply device. When the power supply is insufficient, the self-powered signal is supplemented by controlling the circuit structure to supplement the power supply of the self-powered terminal 21 so that the switching power supply device starts normally. After the switching power supply device is started, the power conversion circuit 4 has a stable output voltage Vout, so that the diode D2 is turned on, and the output voltage Vout supplies power to the switching power supply device. At this stage, the first electrical signal at the power supply terminal 21 is a bus power supply signal reflecting the load power supply. Figure 3 In the example shown, the starting resistor R4 is packaged inside the switching power supply device, and obtains the second electrical signal on the power supply bus through the input terminal 20 and transmits it to the capacitor C2. However, this is not limited to this, and the starting resistor R4 can also be set outside the switching power supply device and electrically connected between the power supply bus and the other end of the capacitor C2 through a wire.

[0043] like Figure 3 As shown, the power conversion circuit 4 includes an inductor L1, a freewheeling diode D1 and an output capacitor C1, wherein one end of the inductor L1 is electrically connected to the reference voltage terminal 22, and the other end is used as an output end, which is used to excite or demagnetize based on the electrical signal of the reference voltage terminal to provide stable power supply to the load, the cathode of the freewheeling diode D1 is electrically connected to the reference voltage terminal 22, and the anode is electrically connected to the power supply bus, which is used to freewheel during the demagnetization stage of the inductor L1, and the output capacitor C1 is electrically connected between the other end of the inductor L1 and the power supply bus, which is used to filter the output voltage Vout. However, this is not limited to this, and the power conversion circuit can also use a transformer, and it only needs to make adaptive adjustments to the connection method of the peripheral circuit.

[0044] See also Figure 4, which is a schematic diagram of the internal circuit structure of the switching power supply device of the present application in one embodiment. As shown in the figure, the circuit structure includes a switch unit 23, a switch control unit 24, a line selection unit 26, and a self-powered detection unit 25. Among them, the switch unit 23 is connected to the input terminal 20, the line selection unit 26 is electrically connected to the output end of the switch unit 23, and is used to controllably output the second electrical signal in the switch unit 23 from the reference voltage terminal 22 or the self-power supply terminal 21. The switch control unit 24 is connected to the self-power supply terminal 21 and the control end of the switch unit 23 and receives the first electrical signal at the self-power supply terminal 21, and is used to detect the first electrical signal, detect the second electrical signal, and control the switch unit 23 to enter the on state, the pre-shutdown state or the off state based on each detection result. The self-power supply detection unit 25 is connected to the self-power supply terminal 21, the line selection unit 26 and the switch control unit 24, and is used to detect the first electrical signal of the self-power supply terminal 21 during the period when the switch unit 23 is in the pre-shutdown state, and when it is determined based on the detection result that the self-power supply terminal 21 is insufficiently powered during the startup stage of the switching power supply device, the line selection unit 26 is controlled to change the output end of the switch unit 23 from being connected to the reference voltage terminal 22 to being connected to the self-power supply terminal 21.

[0045] The switch unit 23 is arranged on the line between the input terminal 20 and the line selection unit 26, so that the second electrical signal obtained by the input terminal 20 from the power supply bus is output to the reference voltage terminal 22 via the switch unit 23 for the power conversion circuit to perform energy conversion and provide stable power supply to the load, or when the self-power supply is insufficient during the startup phase of the switching power supply device, the second electrical signal obtained by the input terminal 20 from the power supply bus is output to the self-power supply terminal 21 via the switch unit 23 to supplement the power supply for the switching power supply device.

[0046] See also Figure 5 , which is a schematic diagram of the circuit structure of a switch unit in an embodiment of the switching power supply device of the present application. As shown in the figure, the switch unit 23 includes a current type switch module 230 and a driving power supply module 231.

[0047] The current-mode switch module 230 is arranged on the line between the input terminal 20 and the line selection unit 26. In one example, the current-mode switch module 230 includes a BJT power switch tube Q1. Here, the BJT power switch tube Q1 is a current-mode switch device, which can be used in a low-voltage environment where the output of the switching power supply device is 3.2 to 3.5V, for example, 3.3V. However, the gate drive voltage of the MOS field effect tube is generally above 4V, and the switching power supply device with a low voltage output can no longer drive the MOS field effect tube to work, and is not suitable for a low-voltage environment.

[0048] The driving power supply module 231 is used to output a driving signal to the control end of the current-type switch module 230 under control. Since the current-type switch module 230 needs to inject a large driving current into the control end when it is turned on, it will cause a large energy loss. In order to reduce the power consumption of the driving power supply module 231 while maintaining its high reliability, the driving power supply module 231 includes a plurality of driving power supplies, which are used to output a changing driving signal to the control end of the current-type switch module 230, and each driving power supply is independently controlled by the switch control unit 24. Among them, under the control of the switch control unit 24, a part of the driving power supply performs a disconnection operation during the conduction period of the current-type switch module 230, and another part of the driving power supply maintains the conduction state of the current-type switch module 230. For example, when the current-type switch module 230 is in the off state, the switch control unit 24 controls each driving power supply to supply power. At this time, each driving power supply outputs a control signal to the control end of the current-type switch module 230, that is, it simultaneously injects a driving current into the control end, so that the current-type switch module 230 is quickly turned on; after the current-type switch module 230 has been quickly turned on, a smaller driving current can maintain the conduction of the current-type switch module 230, and the switch control unit 24 controls a part of the driving power supply to perform a disconnection operation, and another part of the driving power supply maintains the conduction of the current-type switch module 230; when the switch control unit needs to control the switch unit to switch from the on state to the pre-off state, another part of the driving power supply interrupts the output of the driving signal to the current-type switch module 230 based on the pre-off detection signal output by the switch control unit 24, and at this time, all the driving power supplies no longer provide driving signals to the current-type switch module 230, so that the current-type switch module 230 is pre-off. The switch control unit 24 and the pre-off detection signal output by it will be described in detail later.

[0049] See also Figure 6, which is a schematic diagram of the circuit structure of the driving power module of the switching power device of the present application in one embodiment, as shown in the figure, the driving power module 231 includes a first driving power, a second driving power, and a switch device N3, the first driving power includes a first current source IB1 and a first switch S1, the first current source IB1 is electrically connected to the input end of the switch device N3 through the first switch S1, the second driving power includes a second current source IB2 and a second switch S2, the second current source IB2 is electrically connected to the input end of the switch device N3 through the second switch S2, the control end of the switch device N3 is electrically connected to the self-power supply terminal 21, and the output end is electrically connected to the current-type switch module 230, for outputting a driving signal to the current-type switch module 230. Wherein, the first switch S1 and the second switch S2 are controlled by the switch control unit. For example, the switch control unit controls the first switch S1 and the second switch S2 to perform a conduction operation during the off period of the current-type switch module 230 so that the current-type switch module 230 is quickly turned on; after the current-type switch module 230 has been quickly turned on, the switch control unit controls the first switch S1 to perform a disconnection operation during the on period of the current-type switch module 230, and the second switch S2 remains turned on to maintain the on state of the current-type switch module 230 to reduce power consumption, or the second switch S2 performs a disconnection operation during the on period of the current-type switch module 230, and the first switch S1 remains turned on. To maintain the on state of the current-source switch module 230; when the switch control unit needs to control the switch unit to switch from the on state to the pre-off state, corresponding to the states of the first switch S1 and the second switch S2 in the above, the second switch S2 interrupts the output of the drive signal to the current-source switch module 230 based on the pre-off detection signal output by the switch control unit to make the current-source switch module 230 pre-off, or the first switch S1 interrupts the output of the drive signal to the current-source switch module 230 based on the pre-off detection signal output by the switch control unit to make the current-source switch module 230 pre-off. It should be noted that the output end of the switch device N3 is also connected to the reference voltage gnd through the third switch S3, and the third switch S3 is also controlled by the switch control unit, and is used to be turned on based on the control logic output by the switch control unit to control the switch unit 23 to be disconnected so that the current-source switch module 230 is completely turned off. Among them, the switch control unit 24 and the pre-off detection signal output and the control logic of disconnection thereof will be described in detail later.

[0050] like Figure 4As shown, the switch control unit 24 is connected to the self-power supply terminal 21 and the control end of the switch unit 23 and receives the first electrical signal at the self-power supply terminal 21, and is used to detect the first electrical signal, detect the second electrical signal, and control the switch unit 23 to enter the on state, the pre-off state or the off state based on each detection result.

[0051] Combination Figure 3 As can be seen from the description, the output end of the power conversion circuit 4 is electrically connected to the self-power supply terminal 21. After the switching power supply is started, the output voltage Vout of the output end of the power conversion circuit 4 is output to the self-power supply terminal 21 to power the switching power supply device. The reference voltage terminal 22 is electrically connected to the input of the power conversion circuit 4. At this time, the first electrical signal of the self-power supply terminal 21 detected by the switch control unit 24 reflects the load power supply, and the second electrical signal detected reflects the electrical signal in the power conversion circuit 4, so as to adjust the timing for controlling the switch unit 23 to turn on, pre-turn off, or turn off according to the current load power supply demand. For example, the switch control unit 24 determines the turn-on timing of the switch unit 23 by detecting the voltage of the first electrical signal that changes with the load power supply to control the switch unit 23 to turn on. Synchronously with the detection of the first electrical signal, the switch control unit 24 determines the disconnection timing of the switch unit 23 by detecting the second electrical signal reflecting the electrical signal in the power conversion circuit 4 to control the switch unit 23 to pre-turn off or turn off.

[0052] See also Figure 7 , which is a structural block diagram of a switch control unit of a switching power supply device of the present application in one embodiment. As shown in the figure, the switch control unit 24 includes a conduction detection module 240, a disconnection detection module 241 and a logic control module 242.

[0053] The conduction detection module 240 is electrically connected to the self-powered terminal 21, and is used to detect the first electrical signal of the self-powered terminal 21 and output a corresponding first indication signal. Since the first electrical signal of the self-powered terminal 21 reflects the power supply of the load after the switching power supply device is started, the conduction detection module 240 can select the time limit threshold of the corresponding load according to the voltage of the first electrical signal, and perform timing according to the selected time limit threshold, and output the first indication signal when the timing times out. For example, a logic circuit module including at least one comparator is used to detect the voltage of the first electrical signal and select the corresponding time limit threshold; a timing circuit module is used to perform timing, and a first indication signal is output when the timing is greater than the time limit threshold.

[0054] The disconnection detection module 241 is electrically connected to the output end of the switch unit 23 , and is used to detect the second electrical signal based on a preset first reference signal, and output a corresponding second indication signal.

[0055] Since the switch unit 23 includes a current-type switch module, and the current-type switch module has a storage effect at the control end, when the switch control unit 24 controls the switch unit 23 to be disconnected, a certain turn-off delay is caused, which, as the disconnection timing of the switch unit 23, will affect the accuracy and safety of the switching power supply device. In view of this, please refer to Figure 8 , which is a structural block diagram of a disconnection detection module in an embodiment of a switching power supply device of the present application. As shown in the figure, the disconnection detection module 241 includes a pre-shutdown detection circuit 2412 and a shutdown timing circuit 2413.

[0056] The pre-shutdown detection circuit 2412 is electrically connected to the line between the output end of the switch unit 23 and the line selection unit 26, and is used to detect the second electrical signal and output a pre-shutdown detection signal based on the detection result during the period when the line selection unit 26 connects the output end of the switch unit 23 and the reference voltage terminal 22.

[0057] The line selection unit includes a second power tube, which is connected between the output end of the switch unit and the reference voltage terminal, and is in a linear region (or triode region) during the period when the second power tube is connected to the switch unit and the reference voltage terminal. Fig. 9 , which is a schematic diagram of the circuit structure of the circuit selection unit of the switching power supply device of the present application in one embodiment. As shown in the figure, the circuit selection unit 26 includes a second power tube N2 and a diode D3. The second power tube N2 is connected in series between the output end of the switch unit 23 and the reference voltage terminal 22. The anode of the diode D3 is electrically connected to the output end of the switch unit 23, and the cathode is electrically connected to the self-power supply terminal 21. In one example, when the switching power supply device is sufficiently powered or the switching power supply device is started, the second power tube N2 is controlled to be turned on so that the output end of the switch unit 23 is connected to the reference voltage terminal 22, that is, the second electrical signal in the switch unit 23 is output to the power conversion circuit. At this time, the second power tube N2 has a certain resistance and is used to sample the second electrical signal to obtain a sampling signal reflecting the peak current in the power conversion circuit; in another example, when the switching power supply device is insufficiently powered in the startup stage, the second power tube N2 is controlled to be turned off so that the output end of the switch unit 23 is connected to the self-power supply terminal 21, and the second electrical signal in the switch unit 23 is output to the self-power supply terminal 21 through the diode D3 to realize self-power supply.

[0058] The switch control unit further includes a first reference power supply, which is used to provide a pre-shutdown reference signal for the pre-shutdown detection circuit 2412. For example, the first reference power supply may be a constant voltage source, in which case the pre-shutdown reference signal is a voltage signal of the constant voltage source. However, this is not limited to the above. Fig.10, which is a schematic diagram of the circuit structure of the switch control unit in an embodiment of the switch power supply device of the present application, as shown in the figure, the switch control unit also includes a first reference power supply 2411 and a resistive circuit 243, the first reference power supply 2411 includes a third current source IB3, the resistive circuit 243 is electrically connected between the third current source IB3 and the reference voltage terminal 22, and is used to output the pre-shutdown reference signal Pre_ref using a preset impedance, and here, the pre-shutdown reference signal Pre_ref is the voltage obtained when the third current source IB3 flows through the resistive circuit 243. It should be noted that the voltage value of the pre-shutdown reference signal Pre_ref has a certain proportional relationship with the voltage value obtained based on the resistance value of the second power tube N2 of the line selection unit 26 when connecting the output end of the switch unit 23 and the reference voltage terminal 22 and the preset peak current, and the proportional relationship can be adjusted with the current-type switch module in actual application, so as to determine the timing of pre-shutdown of the switch unit 23.

[0059] like Figure 8 and Fig.10 As shown, the pre-shutdown detection circuit 2412 is electrically connected between the output end of the switch unit 23 and the line selection unit 26 to detect the second electrical signal when the second power tube N2 of the line selection unit 26 is turned on (here, the second electrical signal reflects the peak current of the power conversion circuit and can also be called a sampling signal). The pre-shutdown detection circuit 2412 is also electrically connected to the node between the first reference power supply 2411 and the resistive circuit 243 to obtain the pre-shutdown reference signal Pre_ref, so that the pre-shutdown detection circuit 2412 obtains the sampling signal Sig_E based on the pre-shutdown reference signal Pre_ref, and outputs the corresponding pre-shutdown detection signal Pre_H. Fig.10In the illustrated embodiment, the pre-shutdown detection circuit 2412 includes a comparison circuit 2414 and a storage circuit 2415. The first input terminal of the comparison circuit 2414 is electrically connected to the resistive circuit 243 to obtain a pre-shutdown reference signal Pre_ref, and the second input terminal is connected to a node between the first reference power supply 2411 and the resistive circuit 243 to obtain a sampling signal Sig_E reflecting the peak current of the power conversion circuit. The comparison circuit 2414 compares the pre-shutdown reference signal Pre_ref and the sampling signal Sig_E, and outputs a comparison result based on the comparison result. The storage circuit 2415 is electrically connected to the output terminal of the comparison circuit 2414, and is used to latch the comparison result of the comparison circuit 2414 and output a pre-shutdown detection signal Pre_H. In one example, the value of the sampling signal Sig_E does not reach the value of the pre-shutdown reference signal Pre_ref, that is, the switch unit 23 does not reach the pre-shutdown timing, and the storage circuit 2415 does not output the pre-shutdown detection signal Pre_H based on the comparison result of the comparison circuit 2414; in another example, the value of the sampling signal Sig_E reaches the value of the pre-shutdown reference signal Pre_ref, that is, the switch unit 23 reaches the pre-shutdown timing, and the storage circuit 2415 outputs the pre-shutdown detection signal Pre_H based on the comparison result of the comparison circuit 2414. At this time, the switch control unit controls each driving power supply module to interrupt the output of the driving signal to the current type switch module based on the pre-shutdown detection signal Pre_H so that the current type switch module is in pre-shutdown.

[0060] It should be noted that the switch control unit 24 further includes an isolation module (not shown), which is electrically connected between the line selection unit 26 and the pre-shutdown detection circuit 2412 and is used to temporarily store the sampling signal Sig_E to output to the comparison circuit 2414. For example, the isolation module includes a buffer.

[0061] like Figure 8 As shown, the shutdown timing circuit 2413 is electrically connected to the pre-shutdown detection circuit 2412, and is used to time the pre-shutdown duration of the switch unit 23 based on the pre-shutdown detection signal, and output the second indication signal when the timing times out. The pre-shutdown duration is the duration of the shutdown delay caused by the storage effect of the current-type switch module at the control end. When the timing times out, it means that the electrons stored in the control end of the current-type switch module have also been released, and the second indication signal is output at this time. The second indication signal makes Figure 6 The third switch S3 in the switch unit 23 in the illustrated embodiment is controlled by the switch control unit to be turned on so that the current-source switch module is completely turned off.

[0062] In one embodiment, the shutdown timing circuit includes a first timing subcircuit, which is connected to the line selection unit and is used to compare the sampling signal with a preset first shutdown reference signal during the period when the line selection unit connects the output end of the switch unit and the reference voltage terminal, and when the sampling signal reaches the first shutdown reference signal, the timing times out and outputs a first timing logic signal. Here, the first timing logic signal is used to represent the second indication signal.

[0063] In practical applications, such as Fig.10 As shown, the first timing sub-circuit includes a first comparison circuit 2416, the first input end of the first comparison circuit 2416 is electrically connected to the line selection unit to obtain the sampling signal Sig_E, and the second input end is used to obtain the first shutdown reference signal Shutd_ref. The first comparison circuit 2416 compares the sampling signal Sig_E with the first shutdown reference signal Shutd_ref, and outputs the first timing logic signal Shutd_H1 when the sampling signal Sig_E reaches the first shutdown reference signal Shutd_ref. For example, the first shutdown reference signal can be provided by a constant voltage source. In this case, the first shutdown reference signal is the voltage signal of the constant voltage source. However, this is not limited to this. Fig.10 As shown in the example, the switch control unit also includes a second reference power supply 244 connected to the pre-shutdown detection circuit 2412. Here, the resistive circuit 243 is electrically connected between the common output terminal of the first reference power supply 2411 and the second reference power supply 244 and the reference voltage terminal 22. As described above, the resistive circuit 243 cooperates with the first reference power supply 2411 to generate and output a pre-shutdown reference signal Pre_ref using a preset impedance so that the pre-shutdown detection circuit 2412 electrically outputs a corresponding pre-shutdown detection signal Pre_H. At this time, the second reference power supply 244 is used to output a second reference signal based on the pre-shutdown detection signal Pre_H, and the first shut-down reference signal Shutd_ref is generated by the resistive circuit 243 using a preset impedance to cooperate with the common output of the first reference power supply 2411 and the second reference power supply 244. It should be noted that the voltage value of the first shut-down reference signal Shutd_ref is equal to the voltage value obtained based on the resistance value of the second power tube N2 of the line selection unit 26 and the preset peak current, so as to determine the timing of the complete shut-down of the switch unit.

[0064] Further, the second reference power source 244 includes a fourth current source IB4 and a fourth switch S4, wherein the fourth current source IB4 is electrically connected to the resistive circuit 243 via the fourth switch S4, wherein the fourth switch S4 is controlled by the pre-shutdown detection circuit 2412 and the shutdown timing circuit 2413. In one example, the pre-shutdown detection circuit 2412 outputs a pre-shutdown detection signal Pre_H, and the fourth switch S4 performs a turn-on operation during a turn-off period based on the pre-shutdown detection signal Pre_H so that the fourth current source IB4 outputs a second reference signal; in another example, the shutdown timing circuit 2413 outputs a second indication signal, and the fourth switch S4 performs a turn-off operation during a turn-on period based on the second indication signal to reset the second reference power source 244 so that the electrical loop of the fourth current source IB4 is disconnected.

[0065] Furthermore, the resistive circuit 243 includes a first power tube N1, which is connected in series between the common output end of the first reference power supply 2411 and the second reference power supply 244 and the reference voltage terminal 22 in a conducting state, and has a certain resistance. The first reference power supply 2411 and the second reference power supply 244 can be sampled by a preset resistance value to output the pre-shutdown reference signal Pre_ref or the first shut-down reference signal Shutd_ref. There is a preset resistance relationship between the first power tube N1 and the second power tube N2 in the line selection unit 26, so that the specifications of the required third current source IB3 and the fourth current source IB4 can be determined. For example, the first power tube N1 and the second power tube N2 are both NMOS tubes, and the NMOS tube working in the linear region (or triode region) is similar to the role of a resistor. Here, the resistance relationship between the first power tube N1 and the second power tube N2 is reflected by the width-to-length Miller ratio.

[0066] In another embodiment, the shutdown timing circuit includes a second timing sub-circuit, the second timing sub-circuit includes a timing capacitor, the second timing sub-circuit is electrically connected to the pre-shutdown detection circuit, and is used to control the timing capacitor to perform a timing operation based on the pre-shutdown detection signal, and when the voltage signal on an electrode side of the timing capacitor reaches a second shutdown reference signal, the timing times out and outputs a second timing logic signal, wherein the second timing logic signal is used to represent a second indication signal.

[0067] In one example, if Fig.10As shown, the second timing sub-circuit also includes a charging circuit 2417, a discharging circuit 2418 and a second comparison circuit 2419. The charging circuit 2417 and the discharging circuit 2418 are both electrically connected to one end of the timing capacitor C3, and the other end of the timing capacitor C3 is connected to a reference voltage gnd. The first input end of the second comparison circuit 2419 is electrically connected to one end of the timing capacitor C3, and is used to obtain a voltage signal on an electrode side of the timing capacitor C3. The second input end of the second comparison circuit 2419 is used to obtain a second shutdown reference signal V0. The second shutdown reference signal V0 can be provided by a constant voltage source, or provided by a constant voltage source and a voltage divider resistor after voltage division, or provided by a sampling voltage obtained by a constant current source and a sampling resistor. The charging circuit 2417 is composed of a fifth current source IB5 and a fifth switch S2 connected in series between the self-power supply terminal 21 and the timing capacitor C3. The fifth switch S5 is controlled by the conduction detection module and the pre-shutdown detection circuit 2412, and is used to perform a conduction operation during the disconnection period based on the first indication signal output by the conduction detection module to charge the timing capacitor C3 so that the voltage signal on one electrode side of the timing capacitor C3 continues to increase. The fifth switch S5 also performs a disconnection operation during the conduction period based on the pre-shutdown detection signal Pre_H output by the pre-shutdown detection circuit 2412 to interrupt the charging of the timing capacitor C3. The discharge circuit 2418 is composed of a sixth current source IB6 and a sixth switch S6 connected in series between the timing capacitor C3 and the terminal connected to the reference voltage gnd. The sixth switch S6 is controlled by the pre-shutdown detection circuit 2412, and is used to perform a conduction operation during the shutdown period based on the pre-shutdown detection signal Pre_H output by the pre-shutdown detection circuit 2412 to discharge the timing capacitor C3, so that the voltage signal on one electrode side of the timing capacitor C3 continues to decrease. When the voltage signal on one electrode side of the timing capacitor C3 decreases to the second shutdown reference signal V0, the second comparison circuit 2419 outputs a second timing logic signal Shutd_H2.

[0068] It should be noted that the initial value of the timing capacitor C3 at the start of charging is equal to the voltage value of the second shutdown reference signal V0 so that the charging and discharging amounts of the timing capacitor C3 are consistent. Thus, the charging and discharging time ratio of the timing capacitor C3 is equal to the current ratio of the fifth current source IB5 and the sixth current source IB6. In practical applications, the design can be made according to the actual duration of the pre-shutdown to determine the timing of the complete shutdown of the switch unit. In one example, Fig.10As shown, one end of the timing capacitor C3 is also electrically connected to a constant voltage source via a seventh switch S7, and the voltage provided by the constant voltage source is equal to the voltage value of the second shutdown reference signal. The seventh switch S7 is controlled by the second timing sub-circuit and the conduction detection module, and is used to perform a conduction operation during the disconnection period based on the second timing logic signal Shutd_H2 output by the second timing sub-circuit so that the initial value of the timing capacitor C3 at the start of charging is equal to the voltage value of the second shutdown reference signal V0. The seventh switch S7 also performs a disconnection operation during the conduction period based on the first indication signal output by the conduction detection module so as not to affect the subsequent charging and discharging of the timing capacitor C3.

[0069] In another embodiment, the shutdown timing circuit includes both the first timing sub-circuit and the second timing sub-circuit. The circuit structures and working processes of the first timing sub-circuit and the second timing sub-circuit are as described above and are not described in detail here. Fig.10 As shown, the shutdown timing circuit further includes a timing logic subcircuit 24130, the timing logic subcircuit 24130 is electrically connected to the first timing subcircuit and the second timing subcircuit, and is used to output the second indication signal Shutd_H based on the timing logic of the first timing logic signal Shutd_H1 and the second timing logic signal Shutd_H2. In practical applications, the timing logic subcircuit includes but is not limited to a trigger, a timer, a selector, an AND gate, an OR gate, a NAND gate, a NOT gate, etc. according to the control logic.

[0070] like Figure 7 As shown, the logic control module 242 is electrically connected to the shutdown timing circuit (not shown) of the conduction detection module 240 and the disconnection detection module 241, and is used to control the switch unit 23 to be in the conduction state, pre-shutdown state or shutdown state based on the control logic of the first indication signal and the second indication signal. Among them, the circuit structure and controlled process of the switch unit 23 can be found in the Figure 4 , Figure 5 and Figure 6 As described above, the logic control module 242 includes but is not limited to a trigger, a timer, a selector, an AND gate, an OR gate, a NAND gate, a NOT gate, etc. according to the control logic.

[0071] In actual applications, the switching power supply device supplies power to each internal module via the self-power supply terminal, and during the startup phase of the switching power supply device, the switching power supply device is powered only by the self-power supply electrically connected to the self-power supply terminal. At this time, all modules in the switching power supply device need to be awakened and the switching power supply device may not be able to start smoothly due to insufficient power of the self-power supply.

[0072] like Figure 4As shown, the self-power supply detection unit 25 is connected to the self-power supply terminal 21, the line selection unit 26 and the switch control unit 24, and is used to detect the first electrical signal during the period when the switch unit 23 is in the pre-shutdown state, and when it is determined based on the detection result that the self-power supply terminal 21 is underpowered during the startup phase of the switching power supply device, the line selection unit 26 is controlled to change the output end of the switch unit 23 from being connected to the reference voltage terminal 22 to being connected to the self-power supply terminal 21.

[0073] See also Fig.12 Combined with Fig.10 , Fig.12 The circuit structure diagram of the self-powered detection unit of the switching power supply device of the present application in one embodiment is shown. As shown in the figure, the self-powered detection unit includes a comparison module 250, which is electrically connected to the self-powered terminal 21 and the line selection unit 26, and is used to compare the first electrical signal with a self-powered reference signal Vref, and output a self-powered detection signal Sig_V to the line selection unit 26 based on the comparison result. When the first electrical signal is higher than the self-powered reference signal Vref, that is, the self-powered terminal 21 is powered normally, the comparison module 250 does not output the self-powered detection signal Sig_V based on the comparison result, or the output self-powered detection signal Sig_V is an invalid value; when the first electrical signal does not reach the self-powered reference signal Vref, that is, the self-powered terminal 21 is underpowered, the comparison module 250 outputs a valid self-powered detection signal Sig_V based on the comparison result. The self-powered reference signal Vref may be provided by a constant voltage source, or provided by a constant voltage source and a voltage divider resistor, or provided by a sampling voltage obtained by a constant current source and a sampling resistor, and this application does not limit this.

[0074] The startup phase of the switching power supply device is the period from when the switching power supply device is powered on to when the power conversion circuit provides stable power to the load. In view of this, the switching power supply device further includes a startup control unit (not shown), which is electrically connected to the output end of the switch control unit and is used to time the startup phase of the switching power supply device.

[0075] In one embodiment, the startup timing unit counts the startup phase based on a preset fixed duration. Here, the startup timing unit includes a controller and a timer electrically connected to the controller, the controller is connected to the output end of the switch control unit, and is used to detect the output of the switch control unit and control the timer to start timing when an electrical signal is detected at the output end of the switch control unit (i.e., the moment when the switching power supply device is powered on) and enable the self-powered detection unit at the same time, so that the line selection unit connects the output end of the switch unit to the self-powered terminal based on the self-powered detection signal output by the self-powered detection unit, so that the second electrical signal in the switch circuit is output to the self-powered terminal; when the timer counts to the preset duration, the controller disables the automatic electrical detection unit, so that the self-powered detection unit no longer detects, and the line selection unit maintains the connection of the output of the switch unit to the reference voltage terminal, so that the second electrical signal in the switch circuit is output to the power conversion circuit connected to the reference voltage terminal. The preset duration of the timer timing is the duration of the startup phase of the switching power supply device. For example, the preset duration is 15 to 28 ms, and in actual applications, it can be set to 24 ms.

[0076] In another embodiment, the start timing unit counts the start phase based on the number of pulses output by the switch control unit. Here, the drive timing unit includes a controller and a counter electrically connected to the controller, the controller is connected to the output end of the switch control unit, and is used to detect the output of the switch control unit and control the counter to start counting the number of pulses output by the switch control unit when an electrical signal is detected at the output end of the switch control unit (i.e., the moment the switch power supply device is powered on) and enable the self-powered detection unit, so that the line selection unit connects the output end of the switch unit to the self-powered terminal based on the self-powered detection signal output by the self-powered detection unit, so that the second electrical signal in the switch circuit is output to the self-powered terminal; when the timer counts to a preset number of pulses, the controller disables the automatic power detection unit, so that the self-powered detection unit no longer performs detection, and the line selection unit maintains the connection of the output of the switch unit to the reference voltage terminal, so that the second electrical signal in the switch circuit is output to the power conversion circuit connected to the reference voltage terminal. Here, the preset number of pulses counted by the counter corresponds to the duration of the start phase of the switch power supply device. For example, the preset number of pulses is 150 to 280, and in actual applications, it can be set to 240.

[0077] In this way, each time after the switching power supply device is started, the self-power supply detection unit will no longer work, thereby ensuring that when the power conversion circuit connected to the switching power supply device causes insufficient power supply to the self-power supply terminal under the condition of short-circuit protection, the self-power supply detection unit will not malfunction based on the detection result, that is, the self-power supply detection unit will not mistakenly identify the short-circuit protection as insufficient power supply to the self-power supply terminal and supply power to the self-power supply terminal so that the switching power supply device continues to work.

[0078] However, it is not limited to this. In order to achieve the purpose of short-circuit protection, in another embodiment, the start timing unit includes a timer and a controller. The timer is electrically connected between the output end of the switch control unit and the controller, and is used to start timing based on the output of an electrical signal from the switch control unit (i.e., the moment when the switching power supply device is powered on), and output a start signal to the controller when the timing reaches a preset duration. The controller is also electrically connected to the output end of the self-powered detection unit. When the timer does not send a start signal, the controller controls the line selection unit based on the self-powered detection signal output by the self-powered detection unit to connect the output end of the switch unit to the self-powered terminal so that the second electrical signal is output from the self-powered terminal for self-powering; after the timer sends a start signal, the controller controls the switch unit to disconnect based on the self-powered detection signal and the start signal at the output end of the self-powered unit, thereby achieving short-circuit protection. Here, the preset duration of the timer timing is the duration of the startup phase of the switching power supply device. For example, the preset duration is 15 to 28 ms, and in actual applications, it can be set to 24 ms.

[0079] In another embodiment, the start timing unit includes a counter and a controller, the counter is electrically connected between the output end of the switch control unit and the controller, and is used to count the number of pulses output by the switch control unit based on the output of an electrical signal by the switch control unit (i.e., the moment when the switch power supply device is powered on), and output a start signal to the controller when the counted number of pulses reaches a preset number of pulses. The controller is also electrically connected to the output end of the self-powered detection unit. When the counter does not send a start signal, the controller controls the line selection unit to connect the output end of the switch unit to the self-powered terminal based on the self-powered detection signal output by the self-powered detection unit so that the second electrical signal is output from the self-powered terminal for self-powered supply; after the counter sends a start signal, the controller controls the switch unit to disconnect based on the self-powered detection signal and the start signal at the output end of the self-powered unit, thereby realizing short-circuit protection. Here, the preset number of pulses counted by the counter corresponds to the duration of the startup phase of the switch power supply device. For example, the preset number of pulses is 150 to 280, and in actual applications, it can be set to 240.

[0080] In this way, during the startup phase of the switching power supply device, once the self-power supply detection unit detects that the self-power supply terminal is insufficiently powered, the controller will promptly control the line selection unit to switch the output end of the switching unit from being connected to the reference voltage terminal to being connected to the self-power supply terminal for self-power supply; and after the startup phase, during the normal operation of the switching power supply device, once the self-power supply detection unit detects that the self-power supply terminal is insufficiently powered, that is, there is a risk of short circuit in the external circuit connected to the switching power supply device, the controller will control the switching unit to disconnect for short-circuit protection.

[0081] In fact, in order to reduce power consumption, in the above embodiment, when the second electrical signal in the switch unit is switched from the reference voltage terminal to the self-power supply terminal output by the power tube in the second resistive circuit, the power tube in the first resistive circuit is also controlled to be disconnected.

[0082] It should be noted that, combined with Fig.10 As shown, in the startup phase of the switching power supply device, when the self-power supply terminal 21 is insufficiently powered and needs self-power supply, the second power tube N2 in the line selection unit 26 is controlled to be disconnected. At this time, the sampling signal Sig_E obtained by the second power tube N2 in the line selection unit 26 can no longer reflect the peak current in the power conversion circuit 4. Similarly, in order to reduce power, the first power tube N1 of the resistive circuit 243 is also controlled to be disconnected, and the first shutdown reference signal Shutd_ref generated by the resistive circuit 243 using a preset impedance in conjunction with the common output of the first reference power supply 2411 and the second reference power supply 244 can no longer be used as a reference signal reflecting that the BJT power switch tube Q1 is completely turned off. Fig.10 The first timing logic signal Shutd_H1 output by the first timing subcircuit cannot be used as the second indication signal. In this case, the switching power supply device may only include the second timing subcircuit, and the second timing logic signal Shutd_H2 output by the second timing subcircuit is used as the second indication signal. However, this is not limited to the above. The switching power supply device may also include Fig.10 The first timing sub-circuit and the second timing sub-circuit shown, at this time, the timing logic sub-circuit 24130 is controlled by the self-power supply detection signal Sig_V to shield the first timing logic signal Shutd_H2 output by the first timing sub-circuit when the self-power supply terminal 21 is insufficiently powered.

[0083] See also Fig.11 , showing the working waveform of each unit of the switching power supply device of the present application in one embodiment, the following is combined with Figures 1 to 12 The operation process of the switching power supply device in the above embodiments is described.

[0084] When the switching power supply device 2 is connected to the power supply bus, the self-power supply unit 3 obtains the second electrical signal on the power supply bus through the input terminal 20 via the starting resistor R4, and supplies power to the circuit structure in the switching power supply device 2 through the self-power supply terminal 21. The switch control unit 24 starts to output a control signal to control the switch unit 23 to be turned on, pre-shutdown or shut down. At the same time, the start timing unit starts to count the startup duration of the switching power supply device 2 based on the output of the switch control unit 24.

[0085] During the startup time of the startup timing unit of the switching power supply device 2, when the switch unit 23 is in the pre-shutdown state, once the self-power supply detection unit 25 detects that the self-power supply terminal 21 is insufficiently powered, the line selection unit 26 is controlled to switch the output end of the switch unit from being connected to the reference voltage terminal 22 to being connected to the self-power supply terminal 21 for self-power supply. When insufficient power supply to the self-power supply terminal 21 is not detected, the output end of the switch unit 23 is maintained connected to the reference voltage terminal 22.

[0086] When the startup time of the startup timing unit of the switching power supply device 2 exceeds the startup time, that is, after the startup of the switching power supply device 2 is completed, the switch control unit 24 still controls the switch unit 23 to be turned on, pre-shutdown or shut down, and the line selection unit 26 always maintains the output end of the switch unit 23 connected to the reference voltage terminal 22. In one example, the self-power detection unit 25 no longer performs self-power detection when the startup timing unit times out; in another example, once the self-power detection unit 25 detects that the self-power terminal 21 is insufficiently powered when the startup timing unit times out, it controls the switch unit 23 to be disconnected to achieve short-circuit protection.

[0087] The switching power supply device 2 controls the switch unit 23 to turn on, pre-turn off or turn off as follows: the switch control unit 24 controls the first switch S1 and the second switch S2 to turn on and controls the third switch S3 to turn off based on the first indication signal output by the conduction detection module 240, so that the output of the first current source IB1 and the second current source IB2 forms a driving current Ib=IB1+IB2 to drive the BJT power switch tube Q1 through the switch device N3 to quickly turn on the BJT power switch tube Q1. After the preset time Δt, in order to reduce power consumption, the switch control unit 24 controls the first switch S1 and the second switch S2 to turn on and turn off the third switch S3. The control unit 24 controls the first switch S1 to be disconnected, and only the second current source IB2 provides the driving current Ib=IB2 for the BJT power switch tube Q1 so that the BJT power switch tube Q1 is maintained in the on state, and the second electrical signal on the power supply bus flows into the power conversion circuit 4 through the BJT power switch tube Q1 so that the inductor L1 in the power conversion circuit 4 is in the excitation stage, and the line selection unit 26 is arranged between the BJT power switch tube Q1 and the reference voltage terminal 22, and the sampled signal Sig_E collected by it reflects the change of the electrical signal on the inductor L1. The pre-shutdown detection circuit 2412 detects the sampled signal Sig_E based on the pre-shutdown reference signal Pre_ref, and outputs the corresponding pre-shutdown detection signal Pre_H when the sampled signal Sig_E reaches the pre-shutdown reference signal Pre_ref.

[0088] Taking the shutdown timing circuit 2413 including the first timing sub-circuit as an example, the switch control unit 24 controls the second switch S2 to be disconnected based on the pre-shutdown detection signal Pre_H to interrupt the output drive current Ib, thereby making the BJT power switch tube Q1 enter the pre-shutdown state. In view of the storage effect of the control end of the BJT power switch tube Q1, at this time, the second electrical signal still flows into the power conversion circuit 4 through the sampling circuit. Synchronously with this, the switch control unit 24 also controls the fourth switch S4 to be turned on based on the pre-shutdown detection signal Pre_H so that the first resistive circuit 243 uses a preset impedance to cooperate with the common output of the first reference power supply 2411 and the second reference power supply 244 to generate a first shutdown reference signal Shutd_ref. The first timing sub-circuit compares the first shutdown reference signal Shutd_ref and the sampling signal Sig_E. When the sampling signal Sig_E reaches the first shutdown reference signal Shutd_ref, it outputs a first timing logic signal Shutd_H1. At this time, the first timing logic signal Shutd_H1 is the second indication signal Shutd_H. The switch control unit 24 controls the fourth switch S4 to be turned off and the third switch S3 to be turned on based on the second indication signal Shutd_H, so that the BJT power switch tube Q1 is completely turned off.

[0089] Taking the shutdown timing circuit 2413 including the second timing sub-circuit as an example, the switch control unit 24 controls the fifth switch S5 to be turned on based on the first indication signal output by the above-mentioned conduction detection module, so that the charging circuit 2417 charges the timing capacitor C3 and the voltage signal on one electrode side of the timing capacitor C3 continues to increase. When the pre-shutdown detection circuit 2412 outputs the corresponding pre-shutdown detection signal Pre_H, the switch control unit 24 controls the fifth switch S5 to be disconnected and controls the sixth switch S6 to be turned on based on the pre-shutdown detection signal Pre_H, so that the timing capacitor C3 is discharged through the discharge circuit 2418, so that the voltage signal on one electrode side of the timing capacitor C3 is continuously reduced. When the voltage signal on one electrode side of the timing capacitor C3 is reduced to the second shutdown reference signal V0, the second timing sub-circuit outputs the second timing logic signal Shutd_H2. Here, the second timing logic signal Shutd_H2 is the second indication signal Shutd_H. The switch control unit 24 controls the sixth switch S6 to be disconnected and the third switch S3 to be turned on based on the second indication signal Shutd_H, so that the BJT power switch tube Q1 is completely turned off.

[0090] Taking the example that the shutdown timing circuit 2413 includes both the first timing subcircuit and the second timing subcircuit, the working process of the first timing subcircuit and the second timing subcircuit is as described above and will not be described in detail here. At this time, the shutdown timing circuit 2413 also includes a timing logic subcircuit 24130, the timing logic subcircuit 24130 is electrically connected to the first timing subcircuit and the second timing subcircuit, and based on the timing logic of the first timing logic signal Shutd_H1 and the second timing logic signal Shutd_H2, outputs the second indication signal Shutd_H, and the switch control unit 24 controls the fourth switch S4 and the sixth switch S6 to be disconnected and the third switch S3 to be turned on based on the second indication signal Shutd_H, so that the BJT power switch tube Q1 is completely turned off.

[0091] In summary, the switching power supply device disclosed in the present application can promptly self-power when there is insufficient power supply during the startup phase to ensure the normal startup of the switching power supply device, and at the same time achieve short-circuit protection; in addition, the switching power supply device simplifies the external terminals and has a high degree of integration, which simplifies the wiring of peripheral components and reduces costs; and internally takes into account the existence of pre-shutdown of the switching unit, and obtains the disconnection timing of the switching unit through the pre-shutdown detection circuit and the shutdown timing circuit, thereby making the switching power supply device highly accurate and reliable.

[0092] This application also discloses a power driver, see Fig.13, which is a structural block diagram of a power driver of the present application in one embodiment. As shown in the figure, the power driver includes a rectifier device 50, a switching power supply device 51, a power conversion device 53, and a power supply 52.

[0093] The rectifier 50 is electrically connected to an external AC power source and is used to rectify the AC signal and transmit it to the power supply bus.

[0094] The switching power supply device 51 includes a self-power supply terminal 511, a reference voltage terminal 512, and an input terminal 510. The input terminal 510 is used to electrically connect the power supply bus and the reference voltage terminal 512 is used to connect the reference voltage gnd. The switching power supply device 51 encapsulates a circuit structure to output the electrical signal in the power supply bus to the power conversion circuit 53 using the input terminal 510 and the reference voltage terminal 512. The circuit structure encapsulated in the switching power supply device 51 is as described above. Figures 1 to 12 As shown in the description, no further elaboration is given here.

[0095] The power conversion device 53 is electrically connected to the power supply bus and the reference voltage terminal 512, and is used to output stable power to the load under the on-off control of the switching power supply device 51. In an embodiment, the circuit structure of the power conversion device 53 may include: Figure 3 The power conversion circuit 4 shown, here, that is, the power conversion device 53 includes an inductor L1, a freewheeling diode D1 and an output capacitor C1, wherein one end of the inductor L1 is electrically connected to the reference voltage terminal 512, and the other end is used as an output end, which is used to excite or demagnetize based on the electrical signal of the reference voltage terminal to provide stable power supply to the load, the cathode of the freewheeling diode D1 is electrically connected to the reference voltage terminal 512, and the anode is electrically connected to the power supply bus, which is used for freewheeling during the demagnetization stage of the inductor L1, and the output capacitor C1 is electrically connected between the other end of the inductor L1 and the power supply bus, which is used to filter the output voltage Vout. However, this is not limited to this, and the power conversion circuit can also use a transformer, and it only needs to make adaptive adjustments to the connection method of the peripheral circuit.

[0096] The power supply 52 is electrically connected between the self-power supply terminal 511 of the switching power supply device 51 and the power supply bus, and is used to provide power to the switching power supply device 51. In an embodiment, the power supply 52 includes Figure 3The self-powered power supply 3 shown, here, that is, the power supply 52 includes a capacitor C2, one end of the capacitor C2 is electrically connected to the reference voltage terminal 512, and the other end is electrically connected to the self-powered terminal 511. At the same time, the other end of the capacitor C2 is also electrically connected to the power supply bus through the starting resistor R4, so as to maintain the power supply to the switching power supply device 51 with the power provided by the power supply bus during the starting stage of the switching power supply. After the switching power supply is started, the power conversion circuit 4 has a stable output voltage Vout, so that the diode D2 is turned on, and the output voltage Vout supplies power to the switching power supply device 51. Among them, the starting resistor R4 can be encapsulated inside the switching power supply device 51, and the second electrical signal on the power supply bus is obtained through the input terminal 510 and transmitted to the capacitor C2. However, it is not limited to this. The starting resistor R4 can also be set outside the switching power supply device and electrically connected between the power supply bus and the other end of the capacitor C2 through a wire.

[0097] The power driver disclosed in the present application can be self-powered to ensure normal startup of the power driver, and at the same time achieve the short-circuit protection function.

[0098] The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed in the present application shall still be covered by the claims of the present application.

Claims

1. A switching power supply device, used for changing an electrical signal in a power conversion circuit connected to a power supply bus so that the power conversion circuit provides stable power to a load, characterized in that: The switching power supply device comprises: Self-powered terminal, used to connect a self-powered power source; A reference voltage terminal, used for receiving a reference voltage and connecting to the power conversion circuit; An input terminal, used for connecting to the power supply bus to obtain a second electrical signal from the power supply bus; Wherein, the switching power supply device encapsulates a circuit structure to output the second electrical signal in the power supply bus to the power conversion circuit by using the input terminal and the reference voltage terminal; Wherein, the circuit structure includes: a switch unit, an input end of which is connected to the input terminal; a line selection unit, electrically connected to the output end of the switch unit, and used for outputting the second electrical signal in the switch unit from the reference voltage terminal or the self-power supply terminal in a controlled manner; A switch control unit is connected to the self-powered terminal and the control end of the switch unit and receives a first electrical signal from the self-powered terminal, and is used to detect the first electrical signal, detect the second electrical signal, and control the switch unit to enter a conducting state, a pre-shutdown state, or a shutoff state based on each detection result; the switch control unit includes a conduction detection module, a pre-shutdown detection circuit, a shutoff timing circuit, and a logic control module; the conduction detection module is electrically connected to the self-powered terminal, and is used to detect the first electrical signal and output a corresponding first indication signal; the pre-shutdown detection circuit is electrically connected to the output end of the switch unit and the line selection The circuit selection unit is used to detect the second electrical signal and output a pre-shutdown detection signal based on the detection result during the period when the output end of the switch unit is connected to the reference voltage terminal by the line selection unit; the shutdown timing circuit is electrically connected to the pre-shutdown detection circuit and the switch unit, and is used to time the duration of the switch unit being in the pre-shutdown state based on the pre-shutdown detection signal, and output a second indication signal when the timing times out; the logic control module is electrically connected to the conduction detection module and the shutdown timing circuit, and is used to control the switch unit to be in the conduction state, the pre-shutdown state or the shutdown state based on the control logic of the first indication signal and the second indication signal; A self-powered detection unit, connected to the self-powered terminal, the line selection unit and the switch control unit, and configured to detect the first electrical signal during a period in which the switch unit is in a pre-shutdown state; When the self-power supply detection unit determines based on the detection result that the self-power supply terminal is insufficiently powered during the startup phase of the switching power supply device, the line selection unit is controlled to change the output end of the switching unit from being connected to the reference voltage terminal to being connected to the self-power supply terminal.

2. The switching power supply device according to claim 1, characterized in that: The switch unit comprises: A current-type switch module is arranged on the line between the input terminal and the line selection unit; The driving power supply module is used to output a driving signal to the control end of the current-type switch module under control.

3. The switching power supply device according to claim 2, characterized in that: The driving power supply module includes a plurality of driving power supplies, which are used to output a changing driving signal to the control end of the current-type switch module; Each driving power supply is independently controlled by the switch control unit; wherein, under the control of the switch control unit, a part of the driving power supply performs a shutdown operation during the conduction period of the current-type switch module, and another part of the driving power supply maintains the conduction state of the current-type switch module.

4. The switching power supply device according to claim 3, characterized in that: The other part of the driving power supply stops outputting the driving signal to the current-source switching module when the switching unit turns into the pre-shutdown state.

5. The switching power supply device according to claim 1, characterized in that: The line selection unit includes a second power tube connected between the output end of the switch unit and the reference voltage terminal; wherein the second power tube is in a linear region during the period of connecting the switch unit and the reference voltage terminal.

6. The switching power supply device according to claim 1, characterized in that: The self-powered detection unit includes: a comparison module electrically connected to the self-powered terminal and the line selection unit, used for comparing the first electrical signal with a self-powered reference signal, and outputting a self-powered detection signal to the line selection unit based on the comparison result.

7. The switching power supply device according to claim 6, characterized in that: The switching power supply device further includes: a startup timing unit electrically connected to the output end of the switch control unit, and used to time the startup duration of the switching power supply device based on the output of the switch control unit when the switching power supply device is powered on.

8. The switching power supply device according to claim 1, characterized in that: The shutdown timing circuit includes at least one of the following timing sub-circuit: A first timing subcircuit, connected to the line selection unit, for comparing the sampling signal collected by the line selection unit with a preset first shutdown reference signal, timing times out when the sampling signal reaches the first shutdown reference signal, and outputting a first timing logic signal; A second timing sub-circuit including a timing capacitor, electrically connected to the pre-shutdown detection circuit, and configured to control the timing capacitor to perform a timing operation based on the pre-shutdown detection signal, and when a voltage signal on an electrode side of the timing capacitor reaches a second shutoff reference signal, the timing times out and outputs a second timing logic signal; The second indication signal is represented by the first timing logic signal or the second timing logic signal.

9. The switching power supply device according to claim 8, characterized in that: The shutdown timing circuit also includes: The timing logic sub-circuit is electrically connected to the first timing sub-circuit and the second timing sub-circuit, and is used to output the second indication signal based on the timing logic of the first timing logic signal and the second timing logic signal.

10. The switching power supply device according to claim 1, characterized in that: The switch control unit also includes: A first reference power supply, connected to the pre-shutdown detection circuit, and configured to output a pre-shutdown reference signal for detecting the second electrical signal; A second reference power supply is connected to the pre-shutdown detection circuit and is used to output a second reference signal during the pre-shutdown state; wherein the pre-shutdown reference signal and the second reference signal are combined to obtain a first shutdown reference signal; A resistive circuit is electrically connected between a common output terminal of the first reference power supply and the second reference power supply and a reference voltage, and is used to output the pre-shutdown reference signal or the first shutdown reference signal using a preset impedance; wherein the line selection unit and the resistive circuit have a preset resistance relationship, and the resistance relationship is determined based on the switch unit entering a pre-shutdown state.

11. The switching power supply device according to claim 10, characterized in that: The resistive circuit includes: a first power tube connected between the common output terminal and the reference voltage, and in a linear region when the common output terminal and the reference voltage are connected.

12. The switching power supply device according to claim 10, characterized in that: The pre-shutdown detection circuit comprises: A comparison circuit, electrically connected to the resistive circuit and the line selection unit, for comparing a sampling signal sampled from the line selection unit with the pre-shutdown reference signal; The storage circuit is connected to the output end of the comparison circuit and is used for latching the comparison result of the comparison circuit and outputting the pre-shutdown detection signal.

13. The switching power supply device according to claim 1, characterized in that: The switch control unit further includes: an isolation module electrically connected between the line selection unit and the pre-shutdown detection circuit.

14. A power driver, characterized in that: include: A rectifier device, electrically connected to an external AC power source, for rectifying the AC signal and transmitting it to the power supply bus; The switching power supply device according to any one of claims 1 to 13, wherein the input terminal is electrically connected to the power supply bus and the reference voltage terminal is connected to the reference voltage; A power conversion device, electrically connected to the power supply bus and the reference voltage terminal, for outputting stable power to a load under the on-off control of the switching power supply device; A power supply is electrically connected between the self-power supply terminal of the switching power supply device and the power supply bus, and is used to provide power to the switching power supply device.

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