Boost converter starting and protecting circuit and system

Abstract

The invention discloses a starting and protecting circuit and system of a boost converter. The circuit comprises a selection circuit, a comparison circuit, a feedback circuit and a protection circuit, the selection circuit is connected with the comparison circuit and is used for outputting the starting signal or the reference voltage signal according to the control signal; the comparison circuit is used for comparing a feedback signal of the output end of the boost converter with a signal output by the selection circuit and then outputting a comparison signal; the feedback circuit and the protection circuit are connected with the output end of the comparison circuit, and the feedback circuit is used for outputting an enabling feedback signal; the protection circuit is used for determining whether to output a feedback abnormal signal according to the starting completion signal and the comparison signal, and the feedback abnormal signal is used for representing that the feedback signal is abnormal. And stable rising of the output voltage and stable operation of the system are ensured. Through starting signal control, feedback signal monitoring and abnormity protection, system reliability is improved, chip damage is avoided, and external interference influence is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of power management, and in particular to a startup and protection circuit and system of a boost converter. Background Art

[0002] Boost converters are widely used in automotive electronics, power amplifiers, adaptive control systems, battery power management, consumer electronics and other fields. They can convert low voltage input into higher voltage output to meet the needs of different electronic devices for high voltage output.

[0003] In the design of boost converters, the startup process is a key link. Compared with buck converters, the boost converter's output initial voltage is not 0, which makes its soft start design more complicated. Boost converters using off-chip feedback mechanisms are also affected by external factors, such as cold soldering. Cold soldering may cause the feedback loop to fail, making the boost converter unable to work properly, and may even damage the chip and subsequent circuits. Summary of the invention

[0004] The present invention provides a starting and protection circuit and system for a boost converter, so as to solve the problems of unstable soft starting and failure of feedback loop of the boost converter.

[0005] According to one aspect of the present invention, there is provided a startup and protection circuit for a boost converter, comprising: a selection circuit, a comparison circuit, a feedback circuit and a protection circuit;

[0006] The selection circuit is connected to the comparison circuit, and the selection circuit is used to output the start signal or the reference voltage signal according to the enable feedback signal; the comparison circuit is used to compare the feedback signal at the output end of the boost converter with the signal output by the selection circuit and then output a comparison signal;

[0007] The feedback circuit and the protection circuit are both connected to the output end of the comparison circuit, the feedback circuit is also connected to the selection circuit, and the feedback circuit is used to output an enable feedback signal and output the enable feedback signal to the selection circuit;

[0008] The protection circuit is used to determine whether to output a feedback abnormality signal according to the startup completion signal and the comparison signal, and the feedback abnormality signal is used to indicate that the feedback signal at the output end of the boost converter is abnormal.

[0009] Optionally, the selection circuit includes a two-way selector, the start signal is input to the first input terminal of the two-way selector, the reference voltage signal is input to the second input terminal of the two-way selector, the enable feedback signal is input to the enable input terminal of the two-way selector, and the output terminal of the two-way selector is connected to the comparison circuit.

[0010] Optionally, the comparison circuit includes a comparator, a first input terminal of the comparator is connected to the output terminal of the selection circuit, a second input terminal of the comparator is connected to the feedback signal of the output terminal of the boost converter, and the output terminal of the comparator is connected to the feedback circuit and the protection circuit.

[0011] Optionally, the feedback circuit includes a first D flip-flop, a power supply signal is inputted into a data input terminal of the first D flip-flop, a clock input terminal of the first D flip-flop is connected to an output terminal of the comparator, an enable control signal is inputted into an enable input terminal of the first D flip-flop, and the first D flip-flop outputs an enable feedback signal.

[0012] Optionally, the protection circuit includes an AND gate and a second D flip-flop, the first input of the AND gate is connected to the output of the comparator, the second input of the AND gate inputs the start completion signal, the output of the AND gate is connected to the clock input of the second D flip-flop, the data input of the second D flip-flop inputs a power supply signal, and the second D flip-flop outputs a feedback abnormality signal.

[0013] Optionally, the conversion ratio between the input and output of the boost converter is:

[0014] ;

[0015] in, To represent the output voltage, represents the input voltage, and D represents the duty cycle of the control signal.

[0016] Optionally, the start signal includes a ramp signal.

[0017] Optionally, the boost converter is configured to be in a closed state when the start signal is smaller than a feedback signal at an output end of the boost converter.

[0018] Optionally, the boost converter is used to reduce the output voltage to the input voltage level when the feedback signal at the output end of the boost converter is lower than a preset threshold; the boost converter stops working and resets the enable control signal and the start-up completion signal until the fault is eliminated and the boost converter is restarted.

[0019] According to another aspect of the present invention, a boost converter system is provided, comprising the startup and protection circuit of the boost converter according to any one of the above embodiments, an inductor, a first switch tube, a first diode, a second switch tube, a second diode, a capacitor, a current source, a first resistor and a second resistor;

[0020] The first end of the inductor is connected to the input voltage, the second end of the inductor is connected to the second electrode of the first switch tube, the first electrode of the first switch tube is grounded, the gate of the first switch tube is connected to the first control signal, the anode of the first diode is connected to the first electrode of the first switch tube, the cathode of the first diode is connected to the second electrode of the first switch tube, the gate of the second switch tube is connected to the second control signal, the first electrode of the second switch tube is connected to the second end of the inductor, the second electrode of the second switch tube is connected to the first end of the capacitor, the anode of the second diode is connected to the first electrode of the second switch tube, the cathode of the second diode is connected to the second electrode of the second switch tube, the second end of the capacitor is grounded, the first end of the current source is connected to the first end of the capacitor, the second end of the current source is grounded, the first end of the first resistor is connected to the first end of the current source, the second end of the first resistor is connected to the first end of the second resistor, the first end of the second resistor outputs a feedback signal, the first end of the second resistor is connected to the comparison circuit, and the second end of the second resistor is grounded.

[0021] The technical solution of the embodiment of the present invention is that the selection circuit, the comparison circuit, the feedback circuit and the protection circuit work together, the selection circuit outputs a start signal or a reference voltage signal, and the feedback signal at the output end of the boost converter is compared with the signal output by the selection circuit through the comparison circuit, and a comparison signal is output. The feedback circuit outputs an enable feedback signal according to the comparison signal, adjusts the working state of the boost converter, and makes its output voltage consistent with the expected value. The output voltage is controlled by the start signal, the voltage is stabilized by the feedback signal, and the feedback signal at the output end of the boost converter is detected by the protection circuit to see if it is invalid. After the start is completed, the system switches to a normal working state, solves the problem of unstable soft start of the boost converter and failure of the feedback loop, and ensures the reliability and stability of the boost converter. Through the control of the start signal, the feedback signal monitoring and abnormal protection at the output end of the boost converter, the system reliability is improved, the chip damage is avoided, and the influence of external interference is reduced. It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easy to understand through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1is a schematic structural diagram of a startup and protection circuit of a boost converter provided according to an embodiment of the present invention;

[0024] Figure 2 is a schematic diagram of a startup and protection circuit of a boost converter provided according to an embodiment of the present invention;

[0025] Figure 3 is a schematic diagram of a startup process of a boost converter provided according to an embodiment of the present invention;

[0026] Figure 4 is a schematic diagram of a boost converter provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0028] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0029] Figure 1 The present invention provides a schematic diagram of the structure of a boost converter startup and protection circuit. This embodiment is applicable to the case where the boost converter needs to smoothly control the output voltage rise during startup. The circuit can be configured in the fields of automotive electronics, power amplifiers, battery power management, consumer electronics, etc. Figure 1 As shown, the circuit includes: a selection circuit 101, a comparison circuit 102, a feedback circuit 103 and a protection circuit 104;

[0030] The selection circuit 101 is connected to the comparison circuit 102. The selection circuit 101 is used to output a start signal or a reference voltage signal according to an enable feedback signal. The comparison circuit 102 is used to compare the feedback signal at the output end of the boost converter with the signal output by the selection circuit 101 and then output a comparison signal.

[0031] The feedback circuit 103 and the protection circuit 104 are both connected to the output end of the comparison circuit 102. The feedback circuit is also connected to the selection circuit. The feedback circuit 103 is used to output an enable feedback signal and output the enable feedback signal to the selection circuit.

[0032] The protection circuit 104 is used to determine whether to output a feedback abnormality signal according to the startup completion signal and the comparison signal, and the feedback abnormality signal is used to indicate that the feedback signal at the output end of the boost converter is abnormal.

[0033] Among them, the selection circuit 101 can decide whether to output a start signal or a reference voltage signal according to the input of the enable feedback signal. The start signal can be used to control the start process of the boost converter, and the start signal can be a ramp signal. The reference voltage signal provides a reference voltage for the boost converter. The comparison circuit 102 receives the feedback signal from the output end of the boost converter and the signal from the output of the selection circuit 101. The comparison circuit 102 can compare the two signals and output a comparison signal. The feedback circuit 103 can output an enable feedback signal according to the comparison signal output by the comparison circuit 102. The enable feedback signal can be used to adjust the working state of the boost converter so that its output voltage is consistent with the expected value. The protection circuit 104 is also connected to the output end of the comparison circuit 103, and can judge the startup state of the system according to the startup completion signal and the comparison signal, and output a feedback abnormality signal. If the feedback signal at the output end of the boost converter is abnormal, for example, the feedback loop fails, the protection circuit 104 will output a feedback abnormality signal, activate the protection mechanism to reduce the output voltage to the input voltage level, and protect the chip and circuit from damage.

[0034] The technical solution of the embodiment of the present invention is that the selection circuit, the comparison circuit, the feedback circuit and the protection circuit work together, the selection circuit outputs a start signal or a reference voltage signal, and the feedback signal at the output end of the boost converter is compared with the signal output by the selection circuit through the comparison circuit, and a comparison signal is output. The feedback circuit outputs an enable feedback signal according to the comparison signal, and adjusts the working state of the boost converter so that its output voltage is consistent with the expected value. The rise of the output voltage is controlled by the start signal, and the feedback signal at the output end of the boost converter is detected by the protection circuit to see whether it is invalid. After the start is completed, the system switches to a normal working state, which solves the problem of unstable soft start of the boost converter and failure of the feedback loop, and ensures the reliability and stability of the boost converter. Through the control of the start signal, the feedback signal monitoring and abnormal protection at the output end of the boost converter, the system reliability is improved, chip damage is avoided, and the influence of external interference is reduced.

[0035] Figure 2 A schematic diagram of a startup and protection circuit of a boost converter is provided according to an embodiment of the present invention. In some optional embodiments of the present invention, for example, Figure 2 As shown, the selection circuit includes a two-way selector MXU, a first input terminal of the two-way selector MXU inputs a start signal SS, and a second input terminal of the two-way selector MXU inputs a reference voltage signal V REF , an enable feedback signal EN_EA is input to an enable input terminal of the two-way selector MXU, and an output terminal of the two-way selector MXU is connected to the comparison circuit.

[0036] Among them, the two-way selector MXU, also known as a 2-to-1 multiplexer, can select one output from two input signals. The selected output signal can be determined by the selection control signal. When the selection control signal is 0, the output is equal to the first input, that is, the signal of the first input end is output; when the selection control signal is 1, the output is equal to the second input, that is, the signal of the second input end is output. Specifically, the two-way selector MXU can decide whether to output the start signal SS or the reference voltage signal V according to the enable feedback signal EN_EA. REF When the enable feedback signal EN_EA is 0, the start signal SS is selected as the output; when the enable feedback signal EN_EA is 1, the reference voltage signal V REF as output.

[0037] In some optional embodiments of the present invention, continue to refer to Figure 2 The comparison circuit includes a comparator CMP, a first input terminal of the comparator CMP is connected to the output terminal of the selection circuit, and a second input terminal of the comparator CMP is connected to the feedback signal V of the output terminal of the boost converter. FB , the output end of the comparator CMP is connected to the feedback circuit and the protection circuit.

[0038] The comparator CMP can be used to compare the magnitudes of two input signals and output a binary signal, usually a high level or a low level, according to the comparison result. The first input terminal of the comparator CMP can be a positive input terminal, and the second input terminal of the comparator CMP can be a negative input terminal. The selection circuit selects to output the start signal SS or the reference voltage signal V REF Therefore, the positive input terminal of the comparator CMP receives the start signal SS or the reference voltage signal V REF The negative input of the comparator CMP receives the feedback signal V from the output of the boost converter. FB The feedback signal V at the output of the boost converter FB It is the feedback information of the output voltage, which represents the output voltage of the boost converter. The comparator CMP selects the output signal of the circuit and the feedback signal V at the output of the boost converter. FB The comparison generates a comparison signal. It is transmitted to the feedback circuit and the protection circuit at the same time. The feedback circuit adjusts the feedback loop according to the output signal of the comparator CMP to ensure that the output voltage is consistent with the expected target. The protection circuit determines whether the system is in a normal startup state based on the output signal of the comparator CMP and the startup completion signal SS-done.

[0039] In some optional embodiments of the present invention, continue to refer to Figure 2 The feedback circuit includes a first D flip-flop D1, a data input terminal Q1 of the first D flip-flop D1 inputs a power signal VDD, a clock input terminal of the first D flip-flop D1 is connected to the output terminal of the comparator, an enable input terminal of the first D flip-flop D1 inputs an enable control signal EN_CTRL, and the first D flip-flop D1 outputs an enable feedback signal EN_EA.

[0040] Among them, the D flip-flop is a timing circuit that can store and output data according to the change of the clock signal. When the clock signal arrives, the D flip-flop will store the power signal at the data input end inside it and output it to the output end of the flip-flop. The enable input end of the first D flip-flop D1 inputs the enable control signal EN_CTRL. Only when the enable control signal EN_CTRL is valid, the first D flip-flop D1 can store and output data according to the clock signal. The power signal VDD can be a fixed control signal or state signal, for example, it can be 1. According to the input power signal VDD, the output signal of the comparator and the enable control signal EN_CTRL, the first D flip-flop D1 can generate an enable feedback signal EN_EA. The first D flip-flop D1 can output the enable feedback signal EN_EA according to the output of the comparator CMP and the enable control signal EN_CTRL to ensure the normal operation of the boost converter.

[0041] In some optional embodiments of the present invention, continue to refer to Figure 2The protection circuit includes an AND gate AND and a second D flip-flop D2, a first input end of the AND gate AND is connected to the output end of the comparator CMP, a second input end of the AND gate AND is input with a start completion signal SS_done, an output end of the AND gate AND is connected with a clock input end of the second D flip-flop D2, a data input end Q2 of the second D flip-flop D2 is input with a power supply signal VDD, and the second D flip-flop D2 outputs a feedback abnormality signal FB_erro.

[0042] Among them, the AND gate AND can be used to perform logical operations on signals, and the D flip-flop is used to store and output signals. The first input end of the AND gate AND is connected to the output end of the comparator CMP. The second input end of the AND gate AND receives the startup completion signal SS_done. The output signal of the AND gate AND will be input as a clock signal to the clock input end of the second D flip-flop D2. The data input end of the second D flip-flop D2 is connected to the power signal VDD. When the clock signal is triggered, the power signal VDD can be stored by the second D flip-flop D2. The output end of the second D flip-flop D2 can output a feedback abnormality signal FB_erro according to the state stored internally. The feedback abnormality signal FB_erro can determine whether there is a feedback abnormality. If the feedback signal at the output end of the boost converter is abnormal, for example, the feedback loop fails, the protection circuit will output a feedback abnormality signal, and the protection circuit can respond to the abnormality in time. The feedback signal and the startup process of the output end of the boost converter can be monitored by the protection circuit to ensure the stability and reliability of the system.

[0043] Specifically, refer to Figure 2 The working principle of the startup and protection circuit of the boost converter is as follows: When the enable feedback signal EN_EA is 0, the two-way selector MXU selects the startup signal SS as the output, and the startup signal SS is input to the positive input terminal of the comparator CMP. The startup signal SS is connected to the feedback signal V at the output terminal of the boost converter. FB By comparison, the start signal SS is a ramp signal, which can control the output voltage to rise gradually to avoid damage to the circuit due to instantaneous large current shock. FB When the comparator CMP outputs 1, the boost converter starts to work. The first D flip-flop D1 receives the high level output by the comparator CMP, and the first D flip-flop D1 stores the data at the data input end, which can be 1, and the output enable feedback signal EN_EA is also 1. At this time, the two-way selector MXU selects the reference voltage signal V REF As an output, the comparator CMP can convert the reference voltage signal V REF The feedback signal V FB For comparison, the boost converter output feedback signal V FBWhen it is consistent with the expected target, the startup completion signal SS_done is 1, the startup process ends, and the output of the comparator CMP is connected to the protection circuit. The logic of the AND gate AND ensures that normal operation can only be performed when the soft start is completed and there is no feedback error. When the comparison signal output by the comparator CMP and the startup completion signal SS_done are both 1, the AND gate AND output is 1. At this time, the second D flip-flop D2 will store the data at the data input end, which can be 1, and the output feedback abnormality signal FB_erro is also 1. At this time, the boost converter stops working and resets the enable control signal EN_CTRL and the startup completion signal SS_done until the fault is eliminated and the boost converter restarts.

[0044] In some optional embodiments of the present invention, the conversion ratio between the input and output of the boost converter is:

[0045] ;

[0046] in, To represent the output voltage, represents the input voltage, and D represents the duty cycle of the control signal.

[0047] In some optional embodiments of the present invention, the start signal includes a ramp signal.

[0048] Among them, the ramp signal is a signal that changes linearly over time, usually showing a smooth upward or downward trend and a ramp shape. It can be used to control the input of the system to produce a gradually changing voltage or current. The voltage can be gradually increased by applying a ramp signal to avoid sudden current shocks and protect circuit components, especially during the startup process of power systems such as boost converters and buck converters. The ramp signal can help alleviate circuit instability or damage caused by sudden voltage changes. When the system starts, the voltage does not immediately jump to the preset high value, and can be gradually increased by the ramp signal. The output voltage of the boost converter can be effectively controlled so that it rises smoothly from a low voltage to the required operating voltage.

[0049] Figure 3 is a schematic diagram of a startup process of a boost converter provided according to an embodiment of the present invention. In some optional embodiments of the present invention, Figure 3 As shown, the boost converter is used when the start signal SS is less than the feedback signal V at the output of the boost converter. FB The boost converter is in the off state.

[0050] Among them, due to the presence of the body diode, the output voltage of the traditional boost converter is not 0 before startup, that is, the feedback signal V at the output end of the boost converter FB During the startup process, the startup signal SS and the feedback signal V at the output of the boost converter areFB If the value of the start signal SS is less than the feedback signal V at the output of the boost converter, FB The boost converter will not start to perform boost conversion if the voltage is unstable or the start signal does not meet the predetermined conditions. This can prevent the system from working prematurely and avoid system damage. By comparing the start signal SS and the feedback signal V at the output of the boost converter FB , ensuring that the boost converter can only start after the voltage reaches the condition, and the feedback signal V at the output of the boost converter FB After rising to the expected target, the start completion signal SS_done is 1 at this moment. At the same time, the enable feedback signal EN_EA can control the selection of the start signal SS.

[0051] In some optional embodiments of the present invention, the boost converter is used to reduce the output voltage to the input voltage level when the feedback signal at the output end of the boost converter is lower than a preset threshold; the boost converter stops working and resets the enable control signal and the start-up completion signal until the fault is eliminated and the boost converter is restarted.

[0052] Among them, the preset threshold refers to a preset reference voltage. When the feedback signal at the output of the boost converter is lower than the preset threshold, it indicates that there may be a problem with the output feedback resistor. In order to protect the system and avoid damage, the boost converter can reduce the output voltage to the input voltage level, thereby preventing the output voltage from being too high or unstable. Once the feedback signal at the output of the boost converter is detected to be abnormal, the boost converter will stop working, that is, stop the boost operation. At the same time, the enable control signal and the start completion signal can be reset so that the boost converter no longer accepts the start command until the system fault is eliminated or repaired. After the fault is eliminated, the boost converter can resume normal operation by restarting. The boost converter can receive the start signal again, resume the boost process, and start voltage conversion.

[0053] Figure 4 A schematic diagram of a boost converter provided by an embodiment of the present invention, such as Figure 4 As shown, the system includes: a startup and protection circuit of the boost converter of any of the above embodiments, an inductor L 1 , the first switch tube S 1 , the first diode D 1 , the second switch tube S 2 , the second diode D 2 , capacitor C 1 , current source I 1 , the first resistor R 1 and the second resistor R 2 ;

[0054] Inductance L 1 The first end is connected to the input voltage VIN , inductance L 1 The second end of the first switch tube S 1 The second pole of the first switch tube S 1 The first electrode of the first switch tube S is grounded. 1 The gate of the first diode S is connected to the first control signal. 2 The positive electrode and the first switch tube S 1 The first electrode of the first diode D 1 The negative electrode of the first switch tube S 1 The second electrode of the second switch tube S 2 The gate of the second switch tube S is connected to the second control signal. 2 The first pole and the inductor L 1 The second end of the second switch tube S 2 The second electrode and capacitor C 1 The first end of the second diode D 2 The positive electrode and the second switch tube S 2 The first electrode is connected to the second diode D 2 The negative electrode of the second switch tube S 2 The second electrode of the capacitor C 1 The second end of the current source I 1 The first end of the capacitor C 1 The first end is connected to the current source I 1 The second end of the first resistor R 1 The first terminal is connected to the current source I 1 The first end is connected to the first resistor R 1 The second end of the second resistor R 2 The first end of the second resistor R 2 The first end outputs the feedback signal V FB , the first end of the second resistor is connected to the comparison circuit, the second resistor R 2 The second end is grounded.

[0055] The boost converter system includes a boost converter and a boost converter startup and protection circuit. The boost converter has feedback control. The startup and protection circuit of the boost converter can be based on the feedback signal V at the output end of the boost converter. FB By generating a first control signal and a second control signal, the first switch tube S is adjusted 1 and the second switch tube S 2 The on-time controls the output voltage V out The output voltage is stabilized by the feedback circuit. IN It is the power input of the circuit, providing the DC input power of the circuit. 1 It is used to store energy in the circuit.2 When the inductor is turned on, it stores energy. 1 When disconnected, the inductor releases energy and passes through the second diode D 2 The current is delivered to the output terminal to increase the output voltage. 1 The second switch tube S 2 Can be used for output voltage V OUT Protection, overvoltage or feedback signal abnormality, can help output voltage V OUT The first switch tube S 1 and the second switch tube S 2 The first electrode of can be a source electrode, and the second electrode can be a drain electrode. The second diode D 2 It can prevent the current from flowing back and ensure that when the first switch tube S 1 When disconnected, the energy released by the inductor flows to the load instead of returning to the input. 1 Used to smooth the output voltage, reduce the ripple generated by the switch, and ensure the stability of the output voltage. 1 Provides a constant load current to simulate actual load behavior. The first resistor R 1 and the second resistor R 2 The combination can be used as a voltage divider to sample the output voltage and convert it into a feedback signal V at the output of the boost converter. FB The feedback signal V at the output of the boost converter FB It can be used to monitor the output voltage and ensure that the output voltage is stable at the target value.

[0056] Specifically, the working principle of the boost converter system is as follows: the first switch tube S 1 When closed, current flows through the input power supply V IN 、Inductance L 1 , and the first switch tube S 1 A closed loop is formed. At this time, the inductor L 1 Energy storage, inductor L 1 The current in the second diode D 2 In the reverse bias state, the output voltage is controlled by the capacitor C 1 Provided to ensure the stability of the load current. The output end is connected by capacitor C 1 Provide energy to keep the load powered. 1 After disconnection, the inductor L 1 The energy stored in the diode will pass through the second diode D 2 Released to the output terminal, to the load and capacitor C 1 Provide energy to increase the output voltage. The inductor current drops rapidly, and at the same time, the inductor energy is converted into voltage, which is superimposed on the input voltage V INThe output voltage is higher than the input voltage V IN Energy. Output voltage V OUT The first resistor R 1 and the second resistor R 2 The feedback signal V at the output of the boost converter is detected and FB Provide feedback. The feedback signal V at the output of the boost converter can be FB Adjust the first switch tube S 1 and the second switch tube S 2 The on-time of the output voltage can be controlled stably.

[0057] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0058] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A startup and protection circuit for a boost converter, characterized in that: include: Selection circuit, comparison circuit, feedback circuit and protection circuit; The selection circuit is connected to the comparison circuit, and the selection circuit is used to output the start signal or the reference voltage signal according to the enable feedback signal; the comparison circuit is used to compare the feedback signal at the output end of the boost converter with the signal output by the selection circuit and then output a comparison signal; The feedback circuit and the protection circuit are both connected to the output end of the comparison circuit, the feedback circuit is also connected to the selection circuit, and the feedback circuit is used to output an enable feedback signal and output the enable feedback signal to the selection circuit; The protection circuit is used to determine whether to output a feedback abnormality signal according to the startup completion signal and the comparison signal, and the feedback abnormality signal is used to indicate that the feedback signal at the output end of the boost converter is abnormal.

2. The circuit according to claim 1, characterized in that The selection circuit includes a two-way selector, the start signal is input into the first input end of the two-way selector, the reference voltage signal is input into the second input end of the two-way selector, the enable feedback signal is input into the enable input end of the two-way selector, and the output end of the two-way selector is connected to the comparison circuit.

3. The circuit according to claim 1, characterized in that The comparison circuit includes a comparator, a first input end of the comparator is connected to the output end of the selection circuit, a second input end of the comparator is connected to the feedback signal of the output end of the boost converter, and an output end of the comparator is connected to the feedback circuit and the protection circuit.

4. The circuit according to claim 3, characterized in that The feedback circuit includes a first D flip-flop, a power supply signal is input into a data input terminal of the first D flip-flop, a clock input terminal of the first D flip-flop is connected to an output terminal of the comparator, an enable control signal is input into an enable input terminal of the first D flip-flop, and the first D flip-flop outputs an enable feedback signal.

5. The circuit according to claim 3, characterized in that The protection circuit includes an AND gate and a second D flip-flop, wherein the first input terminal of the AND gate is connected to the output terminal of the comparator, the second input terminal of the AND gate inputs the startup completion signal, the output terminal of the AND gate is connected to the clock input terminal of the second D flip-flop, the data input terminal of the second D flip-flop inputs the power supply signal, and the second D flip-flop outputs a feedback abnormality signal.

6. The circuit according to claim 1, characterized in that The conversion ratio of the boost converter input to output is: ； in, To represent the output voltage, represents the input voltage, and D represents the duty cycle of the control signal.

7. The circuit according to claim 1, characterized in that The start signal includes a ramp signal.

8. The circuit according to claim 1, characterized in that The boost converter is configured to be in a closed state when the start signal is smaller than a feedback signal at an output end of the boost converter.

9. The circuit according to claim 1, characterized in that The boost converter is used to reduce the output voltage to the input voltage level when the feedback signal at the output end of the boost converter is lower than a preset threshold; the boost converter stops working and resets the enable control signal and the start-up completion signal until the fault is eliminated and the boost converter is restarted.

10. A boost converter system, characterized in that: A startup and protection circuit of a boost converter comprising the boost converter according to any one of claims 1 to 9, an inductor, a first switch tube, a first diode, a second switch tube, a second diode, a capacitor, a current source, a first resistor and a second resistor; The first end of the inductor is connected to the input voltage, the second end of the inductor is connected to the second electrode of the first switch tube, the first electrode of the first switch tube is grounded, the gate of the first switch tube is connected to the first control signal, the anode of the first diode is connected to the first electrode of the first switch tube, the cathode of the first diode is connected to the second electrode of the first switch tube, the gate of the second switch tube is connected to the second control signal, the first electrode of the second switch tube is connected to the second end of the inductor, the second electrode of the second switch tube is connected to the first end of the capacitor, the anode of the second diode is connected to the first electrode of the second switch tube, the cathode of the second diode is connected to the drain of the second switch tube, the second end of the capacitor is grounded, the first end of the current source is connected to the first end of the capacitor, the second end of the current source is grounded, the first end of the first resistor is connected to the first end of the current source, the second end of the first resistor is connected to the first end of the second resistor, the first end of the second resistor outputs a feedback signal, the first end of the second resistor is connected to the comparison circuit, and the second end of the second resistor is grounded.

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