A startup and protection circuit and system for a boost converter

Abstract

The present invention discloses a start-up and protection circuit and system for a boost converter. The circuit includes: a selection circuit, a comparison circuit, a feedback circuit, and a protection circuit; the selection circuit is connected to the comparison circuit, and the selection circuit is used to output a start-up signal or a reference voltage signal according to a control 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; both the feedback circuit and the protection circuit are connected to the output end of the comparison circuit, the feedback circuit is used to output an enable feedback signal; the protection circuit is used to determine whether to output a feedback abnormal signal according to the start-up completion signal and the comparison signal, and the feedback abnormal signal is used to characterize that the feedback signal is abnormal. This ensures the smooth rise of the output voltage and the stable operation of the system. Through start-up signal control, feedback signal monitoring, and abnormal protection, the system reliability is improved, chip damage is avoided, and the influence of external interference is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of power management, and particularly to a start-up and protection circuit and system for a boost converter. Background Art

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

[0003] In the design of boost converters, the start-up process is a key link. Compared with buck converters, since the initial voltage at the output end of a boost converter is not 0, its soft-start design is more complex. Boost converters using an off-chip feedback mechanism are also subject to external factors, such as problems like poor soldering. Poor soldering may cause the feedback loop to fail, resulting in the boost converter being unable to operate properly and even potentially damaging the chip and subsequent circuits. Summary of the Invention

[0004] The present invention provides a start-up and protection circuit and system for a boost converter to solve the problems of unstable soft start and feedback loop failure of the boost converter.

[0005] According to one aspect of the present invention, a start-up and protection circuit for a boost converter is provided, including: a selection circuit, a comparison circuit, a feedback circuit, and a protection circuit;

[0006] The selection circuit is connected to the comparison circuit. The selection circuit is configured to output a start signal or a reference voltage signal according to an enable feedback signal. The comparison circuit is configured 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] Both the feedback circuit and the protection circuit are connected to the output end of the comparison circuit. The feedback circuit is further connected to the selection circuit. The feedback circuit is configured to output an enable feedback signal and output the enable feedback signal to the selection circuit;

[0008] The protection circuit is configured to determine whether to output a feedback anomaly signal according to a start completion signal and the comparison signal. The feedback anomaly 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. A first input end of the two-way selector inputs the start signal, a second input end of the two-way selector inputs the reference voltage signal, an enable input end of the two-way selector inputs the enable feedback signal, and an output end 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 an output terminal of the selection circuit. A feedback signal of an output terminal of the boost converter is input to a second input terminal of the comparator. An output terminal of the comparator is connected to a feedback circuit and the protection circuit.

[0011] Optionally, the feedback circuit includes a first D flip-flop. A power supply signal is input to a data input terminal of the first D flip-flop. The output terminal of the comparator is connected to a clock input terminal of the first D flip-flop. An enable control signal is input to an enable input terminal of the first D flip-flop. 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. A first input terminal of the AND gate is connected to the output terminal of the comparator. A start completion signal is input to a second input terminal of the AND gate. An output terminal of the AND gate is connected to a clock input terminal of the second D flip-flop. A power supply signal is input to a data input terminal of the second D flip-flop. The second D flip-flop outputs a feedback anomaly signal.

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

[0014] ;

[0015] wherein, represents 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, when the start signal is less than the feedback signal of the output terminal of the boost converter, the boost converter is in an off state.

[0018] Optionally, when the feedback signal of the output terminal of the boost converter is lower than a preset threshold, the output voltage is reduced to the input voltage level; the boost converter stops working, and the enable control signal and the start completion signal are reset 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, including the start and protection circuit of the boost converter, an inductor, a first switching transistor, a first diode, a second switching transistor, a second diode, a capacitor, a current source, a first resistor, and a second resistor according to any one of the above embodiments;

[0020] The first end of the inductor is connected to the input voltage. The second end of the inductor is connected to the second pole of the first switching transistor. The first pole of the first switching transistor is grounded. The gate of the first switching transistor is connected to a first control signal. The anode of the first diode is connected to the first pole of the first switching transistor, and the cathode of the first diode is connected to the second pole of the first switching transistor. The gate of the second switching transistor is connected to a second control signal. The first pole of the second switching transistor is connected to the second end of the inductor. The second pole of the second switching transistor is connected to the first end of the capacitor. The anode of the second diode is connected to the first pole of the second switching transistor, and the cathode of the second diode is connected to the second pole of the second switching transistor. The second end of the capacitor is grounded. The first end of the current source is connected to the first end of the capacitor, and 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, and 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] In the technical solution of the embodiment of the present invention, through the collaborative work of the selection circuit, the comparison circuit, the feedback circuit, and the protection circuit, the selection circuit outputs a start signal or a reference voltage signal. The comparison circuit compares the feedback signal at the output end of the boost converter with the signal output by the selection circuit and outputs a comparison signal. The feedback circuit outputs an enable feedback signal according to the comparison signal to adjust 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, the voltage stabilization is achieved by using the feedback signal, and the protection circuit detects whether the feedback signal at the output end of the boost converter fails. After the start is completed, the system switches to the normal working state, solving the problems of unstable soft start and feedback loop failure of the boost converter and ensuring the reliability and stability of the boost converter. Through start signal control, monitoring of the feedback signal at the output end of the boost converter, and abnormal protection, the system reliability is improved, chip damage is avoided, and the influence of external interference is reduced. It should be understood that the content described in this part 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 easily understood 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 will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

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

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

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

[0026] Figure 4 It is a schematic circuit diagram of a boost converter provided according to an embodiment of the present invention. Specific Embodiments

[0027] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0028] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order different from those illustrated or described here. In addition, the terms "including" and "having" and their variants are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units does not have to be limited to those clearly listed steps or units, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0029] Figure 1 An embodiment of the present invention provides a schematic structural diagram of a start-up and protection circuit for a boost converter. This embodiment is applicable to the situation where the output voltage needs to be smoothly controlled during the start-up process of the boost converter. This circuit can be configured in fields such as automotive electronics, power amplifiers, battery power management, and consumer electronics. As Figure 1 shown, this 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 the enable feedback signal. The comparison circuit 102 is used to compare the feedback signal at the output terminal 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 terminal 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 abnormal signal according to the start completion signal and the comparison signal. The feedback abnormal signal is used to indicate that the feedback signal at the output terminal 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 terminal of the boost converter and the signal output by the selection circuit 101. The comparison circuit 102 can compare these 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 terminal of the comparison circuit 103 and can judge the start state of the system according to the start completion signal and the comparison signal and output a feedback abnormal signal. If the feedback signal at the output terminal of the boost converter is abnormal, for example, the feedback loop fails, the protection circuit 104 will output a feedback abnormal signal to activate the protection mechanism to reduce the output voltage to the input voltage level to protect the chip and the circuit from damage.

[0034] In the technical solution of the embodiment of the present invention, through the collaborative work of the selection circuit, the comparison circuit, the feedback circuit, and the protection circuit, the selection circuit outputs a start signal or a reference voltage signal. The comparison circuit compares the feedback signal at the output end of the boost converter with the signal output by the selection circuit and outputs a comparison signal. The feedback circuit outputs an enable feedback signal according to the comparison signal to adjust 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 protection circuit detects whether the feedback signal at the output end of the boost converter fails. After startup is completed, the system switches to the normal working state, solving the problems of unstable soft startup and feedback loop failure of the boost converter, and ensuring the reliability and stability of the boost converter. Through start signal control, monitoring of the feedback signal at the output end of the boost converter, and abnormal protection, the system reliability is improved, chip damage is avoided, and the influence of external interference is reduced.

[0035] Figure 2 For the sake of providing a schematic diagram of the startup and protection circuit of a boost converter according to an embodiment of the present invention, in some optional embodiments of the present invention, as Figure 2 shown, the selection circuit includes two multiplexers MXU. The first input terminals of the two multiplexers MXU input the start signal SS, the second input terminals of the two multiplexers MXU input the reference voltage signal V REF , the enable input terminals of the two multiplexers MXU input the enable feedback signal EN_EA, and the output terminals of the two multiplexers MXU are connected to the comparison circuit.

[0036] Among them, the two multiplexers MXU, also known as 1-of-2 multiplexers, 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 at the first input terminal is output; when the selection control signal is 1, the output is equal to the second input, that is, the signal at the second input terminal is output. Specifically, the two multiplexers MXU can determine whether to output the start signal SS or the reference voltage signal V REF according to the enable feedback signal EN_EA. 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 is selected as the output.

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

[0038] Among them, 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 the positive input terminal, and the second input terminal of the comparator CMP can be the negative input terminal. The selection circuit selects to output the start signal SS or the reference voltage signal V REF , so the positive input terminal of the comparator CMP receives the start signal SS or the reference voltage signal V REF . The negative input terminal of the comparator CMP receives the feedback signal V from the output terminal of the boost converter FB . The feedback signal V at the output terminal of the boost converter FB is the feedback information of the output voltage, representing the output voltage of the boost converter. The comparator CMP generates a comparison signal according to the comparison between the output signal of the selection circuit and the feedback signal V at the output terminal of the boost converter FB . The comparison signal 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 according to the output signal of the comparator CMP and the startup completion signal SS-done

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

[0040] Among them, the D flip-flop is a sequential circuit that can store data and output according to the change of the clock signal. When the clock signal arrives, the D flip-flop stores the power supply signal at the data input terminal inside it and outputs it to the output terminal of the flip-flop. The enable input terminal of the first D flip-flop D1 inputs the enable control signal EN_CTRL. Only when the enable control signal EN_CTRL is valid can the first D flip-flop D1 store and output data according to the clock signal. The power supply signal VDD can be a fixed control signal or a status signal, for example, it can be 1. According to the input power supply signal VDD, the output signal of the comparator, and the enable control signal EN_CTRL, the first D flip-flop D1 can generate the 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 alternative 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, and the startup process ends. At the same time, the output end of the comparator CMP is connected to the protection circuit, and the logic of the AND gate AND ensures normal operation only when the soft startup 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 at the same time, the output of the AND gate AND is 1. At this time, the second D flip-flop D2 will store the data at the data input terminal, which can be 1, and the output feedback abnormal signal FB_erro is also 1. At this time, the boost converter stops working, and the enable control signal EN_CTRL and the startup completion signal SS_done are reset until the fault is eliminated and the boost converter is restarted.

[0044] In some alternative embodiments of the present invention, the conversion ratio of the input to the output of the boost converter is:

[0045] ;

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

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

[0048] Among them, the ramp signal is a signal that changes linearly with time, usually showing a smooth rising or falling trend, and its shape is like a ramp. It can be used to control the input of the system to generate a gradually changing voltage or current. By applying a ramp signal, the voltage can be gradually increased to avoid sudden current surges 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 up, the voltage does not immediately jump to the preset high value, but can be gradually increased through the ramp signal. It can effectively control the output voltage of the boost converter and make it smoothly rise from a low voltage to the required operating voltage.

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

[0050] Among them, due to the existence of the body diode in the traditional boost converter, the output voltage is not 0 before startup, that is, the feedback signal V at the output end of the boost converter FB is not 0. During the startup process, the startup signal SS and the feedback signal V at the output end of the boost converterFB is compared. If the value of the start signal SS is less than the value of the feedback signal V at the output end of the boost converter, the boost converter will not start the boost conversion. It can prevent the system from working prematurely when the voltage is unstable or the start signal does not reach the predetermined condition, avoiding system damage. By comparing the start signal SS and the feedback signal V at the output end of the boost converter FB to ensure that the boost converter can only start after the voltage reaches the condition, and when the feedback signal V at the output end of the boost converter FB rises to the expected target, the start completion signal SS_done is 1 at this moment. At the same time, enabling the feedback signal EN_EA can control the selection of the start signal SS. FB rises to the expected target, the start completion signal SS_done is 1 at this moment. At the same time, enabling the feedback signal EN_EA can control the selection of the start signal SS.

[0051] In some alternative 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 completion signal until the fault is eliminated and the boost converter restarts.

[0052] Among them, the preset threshold refers to a preset reference voltage. When the feedback signal at the output end of the boost converter is lower than the preset threshold, it indicates that there may be a problem with the output feedback resistor. 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 an abnormal feedback signal at the output end of the boost converter is detected, 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 fault of the system is eliminated or repaired. After the fault is eliminated, the boost converter can restart to resume normal operation. The boost converter can receive the start signal again and resume the boost process to start voltage conversion.

[0053] Figure 4 is a schematic diagram of a boost converter provided by an embodiment of the present invention, as Figure 4 shown. The system includes: the start and protection circuit of the boost converter in any of the above embodiments, an inductor L1, a first switching transistor S1, a first diode D1, a second switching transistor S2, a second diode D2, a capacitor C1, a current source I1, a first resistor R1, and a second resistor R2;

[0054] The first end of the inductor L1 is connected to the input voltage V IN, the second terminal of the inductor L1 is connected to the second pole of the first switching transistor S1. The first pole of the first switching transistor S1 is grounded. The gate of the first switching transistor S1 is connected to the first control signal. The anode of the first diode S2 is connected to the first pole of the first switching transistor S1. The cathode of the first diode D1 is connected to the second pole of the first switching transistor S1. The gate of the second switching transistor S2 is connected to the second control signal. The first pole of the second switching transistor S2 is connected to the second terminal of the inductor L1. The second pole of the second switching transistor S2 is connected to the first terminal of the capacitor C1. The anode of the second diode D2 is connected to the first pole of the second switching transistor S2. The cathode of the second diode D2 is connected to the second pole of the second switching transistor S2. The second terminal of the capacitor C1 is grounded. The first terminal of the current source I1 is connected to the first terminal of the capacitor C1. The second terminal of the current source I1 is grounded. The first terminal of the first resistor R1 is connected to the first terminal of the current source I1. The second terminal of the first resistor R1 is connected to the first terminal of the second resistor R2. The first terminal of the second resistor R2 outputs the feedback signal V FB , the first terminal of the second resistor is connected to the comparison circuit, and the second terminal of the second resistor R2 is grounded.

[0055] Among them, 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 determined according to the feedback signal V at the output end of the boost converter. By generating the first control signal and the second control signal to adjust the conduction time of the first switching transistor S1 and the second switching transistor S2 to control the output voltage V FB . And the output voltage is stabilized through the feedback circuit. The input voltage V out is the power input of the circuit, providing the DC input power supply of the circuit. The inductor L1 is used to store energy in the circuit. When the second switching transistor S2 is conducting, the inductor stores energy. When the second switching transistor S1 is off, the inductor releases energy and delivers the current to the output terminal through the second diode D2 to boost the output voltage. The first switching transistor S1 can control the conduction and disconnection of the circuit. The second switching transistor S2 can be used for the protection of the output voltage V IN . When the overvoltage or the feedback signal is abnormal, it can help the output voltage V OUT drop to a safe level. The first poles of the first switching transistor S1 and the second switching transistor S2 can be the source electrodes, and the second poles can be the drain electrodes. The second diode D2 can prevent the current from flowing back, ensuring that when the first switching transistor S1 is off, the energy released by the inductor flows to the load instead of returning to the input. The capacitor C1 is used to smooth the output voltage, reduce the ripple generated by the switching, and ensure the stability of the output voltage. The current source I1 provides a constant load current to simulate the actual load behavior. The combination of the first resistor R1 and the second resistor R2 can be used as a voltage divider, which can be used to sample the output voltage and convert it into the feedback signal V at the output end of the boost converter OUT . The feedback signal V at the output end of the boost converter FB ​FB It can be used to monitor the output voltage and ensure that the output voltage is stabilized at the target value.

[0056] Specifically, the working principle of the boost converter system is as follows: When the first switch tube S1 is closed, the current passes through the input power supply V IN , inductor L1, and the first switch tube S1 to form a closed loop. At this time, the inductor L1 stores energy, and the current in the inductor L1 gradually increases. At this time, the second diode D2 is in the reverse bias state, and the output voltage is provided by the capacitor C1 to ensure the stability of the load current. The output terminal is supplied with energy by the capacitor C1 to maintain the load power supply. After the first switch tube S1 is turned off, the energy stored in the inductor L1 will be released to the output terminal through the second diode D2 to supply energy to the load and the capacitor C1, thereby boosting the output voltage. The inductor current drops rapidly, and at the same time, the inductor energy is converted into voltage and superimposed on the input voltage V IN to output energy higher than the input voltage V IN . The output voltage V OUT is detected by the first resistor R1 and the second resistor R2 and provides feedback through the feedback signal V FB at the output terminal of the boost converter. The conduction time of the first switch tube S1 and the second switch tube S2 can be adjusted according to the feedback signal V FB at the output terminal of the boost converter to achieve stable control of the output voltage.

[0057] It should be understood that various forms of the processes shown above can be used, and the steps can be reordered, added, or deleted. For example, the steps described in the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved. This is not limited herein.

[0058] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A start-up and protection circuit for a boost converter, characterized in that, Comprising: A selection circuit, a comparison circuit, a feedback circuit, and a protection circuit; The selection circuit is connected to the comparison circuit. The selection circuit is configured to output a start signal or a reference voltage signal according to an enabling feedback signal. The comparison circuit is configured to compare the feedback signal at the output terminal of the boost converter with the signal output by the selection circuit and then output a comparison signal; Both the feedback circuit and the protection circuit are connected to the output terminal of the comparison circuit. The feedback circuit is further connected to the selection circuit. The feedback circuit is configured to output an enabling feedback signal and output the enabling feedback signal to the selection circuit; The protection circuit is configured to determine whether to output a feedback abnormal signal according to a start completion signal and the comparison signal. The feedback abnormal signal is used to indicate that the feedback signal at the output terminal of the boost converter is abnormal.

2. The circuit according to claim 1, wherein The selection circuit includes two multiplexers. The first input terminals of the two multiplexers receive the start signal. The second input terminals of the two multiplexers receive the reference voltage signal. The enabling input terminals of the two multiplexers receive the enabling feedback signal. The output terminals of the two multiplexers are connected to the comparison circuit.

3. The circuit according to claim 1, wherein The comparison circuit includes a comparator. The first input terminal of the comparator is connected to the output terminal of the selection circuit. The second input terminal of the comparator receives the feedback signal at the output terminal of the boost converter. The output terminal of the comparator is connected to the feedback circuit and the protection circuit.

4. The circuit according to claim 3, wherein The feedback circuit includes a first D flip-flop. The data input terminal of the first D flip-flop receives a power supply signal. The clock input terminal of the first D flip-flop is connected to the output terminal of the comparator. The enabling input terminal of the first D flip-flop receives an enabling control signal. The first D flip-flop outputs an enabling 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. 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 receives the start 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 receives a power supply signal. The second D flip-flop outputs a feedback abnormal signal.

6. The circuit according to claim 1, wherein The conversion ratio of the input and output of the boost converter is: ； Among them, is used 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, wherein The start signal includes a ramp signal.

8. The circuit according to claim 1, characterized in that, When the start signal is less than the feedback signal at the output terminal of the boost converter, the boost converter is in an off state.

9. The circuit according to claim 1, characterized in that, When the feedback signal at the output terminal of the boost converter is lower than a preset threshold, the boost converter reduces the output voltage to the input voltage level. The boost converter stops working and resets the enabling control signal and the start completion signal until the fault is eliminated and the boost converter restarts.

10. A boost converter system, characterized in that, Including the start and protection circuit of the boost converter according to any one of claims 1-9, an inductor, a first switching transistor, a first diode, a second switching transistor, 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 pole of the first switching transistor. The first pole of the first switching transistor is grounded. The gate of the first switching transistor is connected to the first control signal. The anode of the first diode is connected to the first pole of the first switching transistor, and the cathode of the first diode is connected to the second pole of the first switching transistor. The gate of the second switching transistor is connected to the second control signal. The first pole of the second switching transistor is connected to the second end of the inductor. The second pole of the second switching transistor is connected to the first end of the capacitor. The anode of the second diode is connected to the first pole of the second switching transistor, and the cathode of the second diode is connected to the second pole of the second switching transistor. The second end of the capacitor is grounded. The first end of the current source is connected to the first end of the capacitor, and 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, and 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, and the first end of the second resistor is connected to the comparison circuit. The second end of the second resistor is grounded.

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