An overcurrent protection circuit, a linear voltage regulator, and an overcurrent protection method

Abstract

The application discloses an overcurrent protection circuit, a linear voltage stabilizer and an overcurrent protection method. The linear voltage stabilizer comprises a power tube, and the overcurrent protection circuit comprises a sampling module, a comparison module and a driving module. The sampling module collects an output end current of the linear voltage stabilizer and outputs a first current signal. The comparison module outputs a first voltage signal and a second voltage signal according to the first reference signal and the first current signal, wherein the first voltage signal and the second voltage signal are reverse signals. The driving module is connected to a loop circuit of the linear voltage stabilizer and is connected with the comparison module and a control electrode of the power tube. The driving module controls a driving voltage of the power tube according to the first voltage signal and clamps the driving voltage of the power tube at a first preset value according to the second voltage signal. The overcurrent protection circuit can ensure that the driving voltage of the power tube changes smoothly when the linear voltage stabilizer is protected, and effectively protects circuit elements.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit design, and in particular to an overcurrent protection circuit, a linear voltage regulator and an overcurrent protection method. Background Art

[0002] Linear regulators are widely used in various power supply scenarios due to their low cost, excellent output ripple suppression, and low quiescent current. Their reliability depends on the coordinated operation of various modules, of which overcurrent protection is a crucial feature. It limits chip power during output overload and short-circuit conditions, protecting the chip from overheating and damage.

[0003] Traditional overcurrent protection circuits will immediately shut down the power tube after detecting overcurrent. However, for loads that return to normal after a short overload, this current limiting protection circuit cannot achieve accurate return. At the same time, quickly shutting down the power tube may cause the current on the power tube to oscillate. The above reasons may cause the system to start repeatedly. Summary of the Invention

[0004] The present invention provides an overcurrent protection circuit, a linear voltage regulator and an overcurrent protection method to solve the problem in the prior art that the overcurrent protection circuit may cause repeated startup of the system.

[0005] According to one aspect of the present invention, a linear regulator overcurrent protection circuit is provided, wherein the linear regulator includes a power tube, a first electrode of the power tube is connected to an output end of the linear regulator, and the overcurrent protection circuit includes a sampling module, a comparison module, and a driving module;

[0006] The sampling module is connected to the power tube, and the sampling module is used to collect the output current of the linear regulator and output a first current signal;

[0007] The comparison module is connected to the sampling module, and the comparison module is used to output a first voltage signal and a second voltage signal according to the first reference signal and the first current signal, wherein the first voltage signal and the second voltage signal are inverse signals of each other;

[0008] The driving module is connected to the loop circuit of the linear regulator and is connected to the comparison module and the control electrode of the power tube. The driving module is used to control the driving voltage of the power tube according to the first voltage signal and clamp the driving voltage of the power tube at a first preset value according to the second voltage signal.

[0009] Optionally, the comparison module includes a first mirror unit, a second mirror unit, a charge storage unit and an inverting unit, the first mirror unit is connected to the first reference signal, the first mirror unit is used to mirror the first reference signal, the second mirror unit is connected to the first current signal, the second mirror unit is used to mirror the first current signal, the charge storage unit is connected to the first mirror unit and the second mirror unit, the charge storage unit is used to generate the first voltage signal based on the first reference signal and the first current signal, the inverting unit is connected to the charge storage unit, and the inverting unit is used to invert the first voltage signal and output the second voltage signal.

[0010] Optionally, the first mirror unit includes a first transistor and a second transistor, the first electrode of the first transistor is connected to the first reference signal, the second electrode of the first transistor is connected to the first power supply terminal, the control electrode of the first transistor is connected to the first electrode of the first transistor and the control electrode of the second transistor, the first electrode of the second transistor is connected to the output terminal of the first mirror unit, and the second electrode of the second transistor is connected to the first power supply terminal.

[0011] Optionally, the second mirror unit includes a third transistor and a fourth transistor, the first electrode of the third transistor is connected to the first current signal, the second electrode of the third transistor is grounded, the control electrode of the third transistor is connected to the first electrode of the third transistor and the control electrode of the fourth transistor, the first electrode of the fourth transistor is connected to the output end of the second mirror unit, and the second electrode of the fourth transistor is grounded.

[0012] Optionally, the charge storage unit includes a first capacitor, a first end of the first capacitor is connected to an output end of the first mirror unit and an output end of the second mirror unit, and a second end of the first capacitor is grounded.

[0013] Optionally, the inverting unit includes a NOT logic gate circuit, an input end of the NOT logic gate circuit is connected to the charge storage unit, and an output end of the NOT logic gate circuit is connected to an output end of the inverting unit.

[0014] Optionally, the driving module includes a first current source, a second current source, a third current source, a fifth transistor, a sixth transistor, a seventh transistor and an eighth transistor, the positive electrode of the first current source is connected to the first power supply end, the negative electrode of the first current source is connected to the first electrode of the fifth transistor and the output end of the driving module, the control electrode of the fifth transistor is connected to the loop circuit of the linear regulator, the second electrode of the fifth transistor is connected to the positive electrode of the second current source, the positive electrode of the third current source and the control electrode of the sixth transistor, the negative electrode of the second current source is grounded, the negative electrode of the third current source is connected to the first electrode of the seventh transistor, the control electrode of the seventh transistor is connected to the second voltage signal, the second electrode of the seventh transistor is grounded, the first electrode of the sixth transistor is connected to the output end of the driving module, the second electrode of the sixth transistor is connected to the first electrode of the eighth transistor, the control electrode of the eighth transistor is connected to the first voltage signal, and the second electrode of the eighth transistor is grounded.

[0015] Optionally, the sampling module includes a ninth transistor, the control electrode of the ninth transistor is connected to the control electrode of the power tube, the second electrode of the ninth transistor is connected to the second electrode of the power tube, and the ninth transistor is used to copy the current of the first electrode of the power tube.

[0016] According to another aspect of the present invention, a linear regulator is provided, comprising a loop circuit and the overcurrent protection circuit; the loop circuit comprises an amplifying module and an output module, the output module comprises the power tube, and the driving module is connected between the amplifying module and the output module.

[0017] According to another aspect of the present invention, an overcurrent protection method is provided, which is performed by the overcurrent protection circuit, and the method includes:

[0018] The sampling module collects the current of the power tube and outputs a first current signal;

[0019] The comparison module compares the first current signal with the first reference signal and outputs the first voltage signal and the second voltage signal;

[0020] The driving module controls the driving voltage of the power tube according to the first voltage signal;

[0021] The driving module clamps the driving voltage of the power tube at the first preset value according to the second voltage signal.

[0022] According to the technical solution of the embodiment of the present invention, a sampling module is configured to collect the current at the output end of a linear regulator and output a first current signal; a comparison module is connected to the sampling module and configured to output a first voltage signal and a second voltage signal based on the input first reference signal and the first current signal, wherein the first voltage signal and the second voltage signal are inversely proportional to each other; a driving module is connected to the loop circuit of the linear regulator and to the comparison module and the control electrode of a power tube in the linear regulator. The driving module is configured to control the driving voltage of the power tube based on the first voltage signal and to clamp the driving voltage of the power tube to a first preset value based on the second voltage signal. The first voltage signal slowly decreases as the first current signal increases, ensuring that the driving voltage of the power tube changes slowly, gradually reducing the driving capability of the power tube and preventing repeated false triggering caused by current oscillation on the power tube due to rapid changes in the driving voltage of the power tube. At the same time, the second voltage signal is converted to a high-level signal when the first voltage signal decreases to a low level. The second voltage signal is a fast pulse signal that can fix the output of the driving circuit at a preset value, clamping the maximum output current of the power tube and implementing an overcurrent protection function, thereby solving the problem of repeated system startup caused by overcurrent protection circuits in the prior art.

[0023] 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 intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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.

[0025] Figure 1 This is a circuit diagram of a related art circuit in which an overcurrent protection circuit is connected to a linear regulator loop circuit;

[0026] Figure 2 It is an overcurrent protection working waveform diagram of a traditional overcurrent protection circuit in the related art;

[0027] Figure 3 1 is a schematic structural diagram of an overcurrent protection circuit for a linear regulator provided by an embodiment of the present invention;

[0028] Figure 4 1 is a schematic structural diagram of another linear regulator overcurrent protection circuit provided by an embodiment of the present invention;

[0029] Figure 5 is a circuit diagram of a comparison module provided by an embodiment of the present invention;

[0030] Figure 6 is a circuit diagram of a driving module provided by an embodiment of the present invention;

[0031] Figure 7 is a circuit diagram of the driving module in a first driving state;

[0032] Figure 8 is a circuit diagram of the driving module in a second driving state;

[0033] Figure 9 is a circuit diagram of the driving module in a third driving state;

[0034] Figure 10 is a curve diagram showing changes in current and output voltage on a power tube according to an embodiment of the present invention;

[0035] Figure 11 This is a flow chart of an overcurrent protection method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the solutions 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 drawings in the embodiments of the present invention. Obviously, the embodiments described 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 making creative efforts should fall within the scope of protection of the present invention.

[0037] 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 are not necessarily used to describe a specific order or sequence. It should be understood that the numbers 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 any variations thereof 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.

[0038] Linear regulators are widely used in various power supply scenarios. The overcurrent protection circuit in a linear regulator limits the output power of the power transistor in the linear regulator, preventing the power transistor from being damaged due to excessive temperature when the linear regulator output is overloaded or short-circuited. Figure 1 This is a circuit diagram of an overcurrent protection circuit connected to a linear regulator loop circuit in the related art. Figure 2This is the overcurrent protection working waveform of the traditional overcurrent protection circuit in the related technology. Figure 1 As shown, the linear regulator loop circuit 101 is connected to the traditional overcurrent protection circuit 102. For high-speed and high-current applications, the linear regulator needs to have a faster slew rate. Therefore, this type of linear regulator usually has a driver stage BUF. The linear regulator loop circuit 101 also includes an amplifier AMP, a power tube Mp, a first protection resistor Rb1, a second protection resistor Rb2, a filter capacitor CL and a load resistor RL. The source of the power tube Mp is connected to the regulator power supply terminal V IN , the gate voltage of the power tube Mp is V G , the drain voltage of the power tube Mp is the output voltage V of the linear regulator OUT The voltage at the connection point between the first protection resistor Rb1 and the second protection resistor Rb2 is used as the feedback voltage V of the linear regulator loop circuit. FB , the amplifier AMP is based on the feedback voltage V at the input FB and reference voltage V REF Output voltage signal to the driver BUF. The traditional current limiting protection circuit 102 is a traditional current limiting protection circuit, the sampling MOS tube M P1 The current is sampled in proportion to the current of the power tube Mp, and after the current mirror is combined with the reference current source I LIMIT The current I LIMIT In comparison, the current mirrors are M N1 and M N2 The first current mirror and M P3 and M P4 The second current mirror is formed. When the reference current I LIMIT When the current is greater than the sampling current, the current limiting control voltage V CON It is high level and controls the PMOS tube M in reverse phase. P2 The gate of the PMOS tube is high, P2 Turn off; on the contrary, when the reference current I LIMIT When the current is less than the sampling current, the current limiting control voltage V CON Lowering the PMOS tube M P2 Open to limit the gate voltage V of the power tube Mp G The voltage drops to achieve the purpose of current limiting.

[0039] like Figure 2 As shown, when the load current I LOAD At the reference current I LIMIT When the current limiting circuit is near t2, the current limiting circuit is triggered in the t2 period. In the traditional current limiting circuit, the current limiting circuit and the linear regulator loop circuit will work alternately. The reason is that the slew capability of the linear regulator loop circuit is strong at this time, and the current I flowing through the power tube Mp is D Oscillations will occur beyond the normal load range I OUT,nom , VOUT,nom The output voltage of the power tube Mp will cause the power of the power tube Mp to be too high and it will be difficult to accurately return to normal working state. In particular, for a load that returns to normal after a short overload, the current limiting protection circuit cannot achieve accurate return. At the same time, the traditional overcurrent protection circuit will immediately shut down the power tube after detecting an overcurrent. The rapid shutdown of the power tube may cause the current on the power tube to oscillate. The above reasons may cause the system to start repeatedly.

[0040] In order to solve the above problems, an embodiment of the present invention provides an overcurrent protection circuit for a linear regulator. Figure 3 FIG. 1 is a schematic diagram of a linear regulator overcurrent protection circuit according to an embodiment of the present invention. Figure 3 As shown, the linear regulator includes a power tube Mp, a first electrode of the power tube Mp is connected to the output end of the linear regulator, and the overcurrent protection circuit includes a sampling module 110, a comparison module 120 and a driving module 130; the sampling module 110 is connected to the power tube Mp, and the sampling module 110 is used to collect the output current of the linear regulator and output a first current signal; the comparison module 120 is connected to the sampling module 110, and the comparison module 120 is used to output a first voltage signal and a second voltage signal based on the input first reference signal and the first current signal, wherein the first voltage signal and the second voltage signal are inverse signals to each other; the driving module 130 is connected to the loop circuit of the linear regulator, and is connected to the comparison module 120 and the control electrode of the power tube Mp. The driving module 130 is used to control the driving voltage of the power tube Mp according to the first voltage signal, and clamp the driving voltage of the power tube Mp to a first preset value according to the second voltage signal.

[0041] In the embodiment of the present invention, the power tube Mp can be a P-type MOS tube or an N-type MOS tube. Taking the P-type MOS tube as an example, the first electrode of the power tube Mp is a drain, the second electrode of the power tube Mp is a source, and the control electrode of the power tube Mp is a gate. The first electrode of the power tube Mp serves as the output end of the linear regulator, and the second electrode of the power tube Mp is connected to the regulator power supply end V IN The control electrode voltage of the power tube Mp is the driving voltage of the power tube Mp. The sampling module 110 is a module for collecting the current of the first electrode of the power tube Mp (the output current of the linear regulator). The first current signal I SENSE is proportional to the current of the power tube Mp. For example, the sampling module 110 includes a ninth transistor Q9. Figure 4 FIG. 1 is a schematic diagram of another linear regulator overcurrent protection circuit provided by an embodiment of the present invention. Figure 4As shown, the control electrode of the ninth transistor Q9 is connected to the control electrode of the power tube Mp, the second electrode of the ninth transistor Q9 is connected to the second electrode of the power tube Mp, the first electrode of the ninth transistor Q9 is proportional to the current of the first electrode of the power tube Mp, and the ninth transistor Q9 is used to copy the current of the power tube Mp. The comparison module 120 is formed by comparing the first current signal I SENSE With the first reference signal I LIMIT , output the first voltage signal V CMP_PRE and the second voltage signal V CMP The driving module 130 is a module for controlling the driving voltage of the power tube Mp.

[0042] In the embodiment of the present invention, the sampling module 110 collects the output current of the linear regulator and outputs a first current signal I SENSE The comparison module 120 converts the first current signal I SENSE With the first reference signal I LIMIT Compare and output the first voltage signal V CMP_PRE and the second voltage signal V CMP , the driving module 130 is based on the first voltage signal V CMP_PRE Control the driving voltage V of the power tube Mp G , and according to the second voltage signal V CMP The driving voltage V of the power tube Mp G Clamped at the first preset value. For example, when the first current signal I SENSE Less than the first reference signal I LIMIT When the first voltage signal V CMP_PRE is a high level signal, the second voltage signal V CMP = is a low level signal, the driving module 130 drives the power tube Mp normally. SENSE Slowly increases and is less than or equal to the first reference signal I LIMIT When the first voltage signal V CMP_PRE Slowly decrease (intermediate voltage), the second voltage signal V CMP When the first current signal I SENSE Greater than the first reference signal I LIMIT When the first voltage signal V CMP_PRE is a low level signal, the second voltage signal V CMP When the signal is a high level, the driving module 130 clamps the driving voltage of the power tube Mp at a first preset value to implement an overcurrent protection function.

[0043] The technical solution of this embodiment provides an overcurrent protection circuit for a linear regulator. A sampling module is configured to collect the current at the output of the linear regulator and output a first current signal. A comparison module is connected to the sampling module and configured to output a first voltage signal and a second voltage signal based on a first reference signal and a first current signal. The first voltage signal and the second voltage signal are inversely proportional to each other. A driving module is connected to the loop circuit of the linear regulator and to the comparison module and a control electrode of a power transistor in the linear regulator. The driving module is configured to control the driving voltage of the power transistor based on the first voltage signal and to clamp the driving voltage of the power transistor to a first preset value based on the second voltage signal. The first voltage signal slowly decreases as the first current signal increases, ensuring that the driving voltage of the power transistor changes slowly, gradually reducing the driving capability of the power transistor and preventing repeated false triggering caused by current oscillation on the power transistor due to rapid changes in the driving voltage of the power transistor. Simultaneously, the second voltage signal is converted to a high-level signal when the first voltage signal decreases to a low level. The second voltage signal is a fast pulse signal that can fix the output of the driving circuit at a preset value, clamping the maximum output current of the power transistor and implementing an overcurrent protection function. This solves the problem of repeated system startup caused by overcurrent protection circuits in the prior art.

[0044] Figure 5 is a circuit diagram of a comparison module provided by an embodiment of the present invention, such as Figure 5 As shown, the comparison module 120 includes a first mirror unit, a second mirror unit, a charge storage unit and an inverting unit, and the first mirror unit is connected to the first reference signal I LIMIT The first mirror unit is used to LIMIT Mirror image, the second mirror image unit is connected to the first current signal I SENSE The second mirror unit is used to SENSE Mirror, the charge storage unit is connected to the first mirror unit and the second mirror unit, the charge storage unit is used to LIMIT and the first current signal I SENSE Generate a first voltage signal V CMP_PRE The reverse unit is connected to the charge storage unit, and the reverse unit is used to CMP_PRE Invert and output the second voltage signal V CMP .

[0045] In the embodiment of the present invention, the first mirror unit is a first reference signal I LIMIT The mirror processing unit, the second mirror unit is a first current signal I SENSE The current mirror can provide a stable current source in the circuit to ensure the normal operation of the circuit. At the same time, the current mirror has a high input impedance, which can play a role in circuit isolation and prevent signal interference. The charge storage unit is based on the first reference signal ILIMIT and the first current signal I SENSE A charge storage unit, for example, when the first current signal I SENSE Slowly increases and is less than the first reference signal I LIMIT When the first voltage signal V CMP_PRE is a high level signal, the charge storage unit is connected to the first voltage signal V CMP_PRE Store charge. Since the accumulation of charge is a slow process, the first voltage signal V CMP_PRE The reverse unit is a first voltage signal V CMP_PRE The reverse processing unit outputs a second voltage signal V CMP With the first voltage signal V CMP_PRE In reverse, the second voltage signal V CMP is a fast pulse signal, the driving module 130 is based on the second voltage signal V CMP The driving voltage of the power tube Mp is clamped to a first preset value.

[0046] Specifically, the first mirror unit includes a first transistor Q1 and a second transistor Q2, and the first electrode of the first transistor Q1 is connected to the first reference signal I LIMIT The second electrode of the first transistor Q1 is connected to the first power supply terminal V1, the control electrode of the first transistor Q1 is connected to the first electrode of the first transistor Q1 and the control electrode of the second transistor Q2, the first electrode of the second transistor Q2 is connected to the output terminal of the first mirror unit, and the second electrode of the second transistor Q2 is connected to the first power supply terminal V1. The second mirror unit includes a third transistor Q3 and a fourth transistor Q4. The first electrode of the third transistor Q3 is connected to the first current signal I SENSE The second electrode of the third transistor Q3 is grounded, the control electrode of the third transistor Q3 is connected to the first electrode of the third transistor Q3 and the control electrode of the fourth transistor Q4, the first electrode of the fourth transistor Q4 is connected to the output end of the second mirror unit, and the second electrode of the fourth transistor Q4 is grounded.

[0047] In the embodiment of the present invention, the first reference signal I LIMIT The first current signal I is output to the output end of the first mirror unit formed by the first transistor Q1 and the second transistor Q2. SENSE The voltage of the connection node between the output end of the first mirror unit and the output end of the second mirror unit is the first voltage signal V CMP_PRE , referring to the above embodiment, when the first reference signal I LIMIT Greater than or equal to the first current signal I SENSE When the first voltage signal V CMP_PRE is a high level signal, when the first reference signal ILIMIT Less than the first current signal I SENSE When the first voltage signal V CMP_PRE It is a low level signal.

[0048] Continue to refer Figure 5 The charge storage unit includes a first capacitor C1, a first end of which is connected to the output of the first mirror unit and the output of the second mirror unit, and a second end of which is grounded. The inverting unit includes a NOT logic gate circuit U1, an input end of which is connected to the charge storage unit, and an output end of which is connected to the output end of the inverting unit.

[0049] In the embodiment of the present invention, the first end of the first capacitor C1 is connected to the connection node of the output end of the first mirror unit and the output end of the second mirror unit, and the first end of the first capacitor C1 is connected to the first voltage signal V CMP_PRE , referring to the above embodiment, when the first current signal I SENSE Slowly increases and is less than the first reference signal I LIMIT When the first voltage signal V CMP_PRE is a high level signal, the first capacitor C1 is connected to the first voltage signal V CMP_PRE Store charge, so that the first voltage signal V CMP_PRE After the NOT logic gate circuit U1 negates the input signal, it outputs a signal that is the opposite of the input signal. The second voltage signal V CMP With the first voltage signal V CMP_PRE In reverse, the second voltage signal V CMP It is a fast pulse signal, which is a first voltage signal V that changes slowly. CMP_PRE Based on the above, the driving module 130 is guaranteed to be slowly disabled, and the driving voltage V output by the driving module 130 is G is slowly changing, the second voltage signal V CMP It is used to control the driving module 130 to be disabled and fix the output voltage of the driving module to a first preset value.

[0050] Figure 6 is a circuit diagram of a driving module provided by an embodiment of the present invention, such as Figure 6 As shown, the driving module 130 includes a first current source I BIAS1 , the second current source I BIAS2 , the third current source I BIAS3 , a fifth transistor Q5, a sixth transistor Q6, a seventh transistor Q7 and an eighth transistor Q8, a first current source I BIAS1 The positive electrode is connected to the first power supply terminal V1, the first current source I BIAS1The negative electrode of the fifth transistor Q5 is connected to the first electrode of the fifth transistor Q5 and the output end of the driving module 130, the control electrode of the fifth transistor Q5 is connected to the loop circuit of the linear regulator, and the second electrode of the fifth transistor Q5 is connected to the second current source I BIAS2 The positive electrode of the third current source I BIAS3 The positive electrode and the control electrode of the sixth transistor Q6, the second current source I BIAS2 The negative electrode of the third current source I BIAS3 The negative electrode of the seventh transistor Q7 is connected to the first electrode, and the control electrode of the seventh transistor Q7 is connected to the second voltage signal V CMP The second electrode of the seventh transistor Q7 is grounded, the first electrode of the sixth transistor Q6 is connected to the output end of the driving module 130, the second electrode of the sixth transistor Q6 is connected to the first electrode of the eighth transistor Q8, and the control electrode of the eighth transistor Q8 is connected to the first voltage signal V CMP_PRE , the second electrode of the eighth transistor Q8 is grounded.

[0051] Referring to the above embodiment, when the first current signal I SENSE Less than the first reference signal I LIMIT When the first voltage signal V CMP_PRE is a high level signal, the second voltage signal V CMP is a low-level signal, the seventh transistor Q7 is turned off, the eighth transistor Q8 is turned on (equivalent to a small resistor), and the driving module 130 drives the power tube Mp normally (the first driving state). Figure 7 This is a circuit diagram of the driving module in the first driving state. SENSE Gradually approaching and exceeding the first reference signal I LIMIT During the process, the first voltage signal V CMP_PRE The conduction capability of the eighth transistor Q8 gradually decreases (equivalent to the resistance gradually increasing), and a large resistor is connected in series to the source (i.e., the second electrode) of the sixth transistor Q6, so that the driving capability of the driving module 130 gradually decreases (the second driving state). At this time, the second voltage signal V CMP is low level, the seventh transistor Q7 is still in the off state, Figure 8 This is a circuit diagram of the driving module in the second driving state. SENSE Completely beyond the first reference signal I LIMIT , the first voltage signal V CMP_PRE is a low level signal, the second voltage signal V CMP = is a high level signal, the eighth transistor Q8 is completely turned off, the seventh transistor Q7 is turned on (equivalent to a small resistor), and the third current source I BIAS3 The bias current generated is introduced to drive the output voltage of the module (i.e. the driving voltage V G) is clamped at a fixed value (i.e., the first preset value), the driving module 130 completely loses its driving capability (the third driving state), Figure 9 : is a circuit diagram of the driving module in the third driving state. The first current signal I SENSE Return to normal state (less than the first reference signal I LIMIT ), the output voltage of the driving module 130 slowly recovers, and the driving module returns to the normal driving state. Figure 10 is a curve diagram showing the change of the current and output voltage on the power tube in the embodiment of the present invention, I LOAD is the load current, I LIMIT is the reference current (first reference current), V OUT,nom is the output voltage of the power tube Mp, I D is the current flowing through the power tube Mp, I OUT,nom is a normal load current, a, b, and c represent the first driving state, the second driving state, and the third driving state, respectively. It can be seen that the overcurrent protection circuit of this embodiment will not trigger the power tube multiple times, and the switching from the normal state to the overcurrent state, or from the overcurrent state to the normal state is smooth.

[0052] An embodiment of the present invention also provides a linear regulator, including a loop circuit and an overcurrent protection circuit provided by any of the above embodiments, the loop circuit includes an amplification module and an output module, the output module includes a power tube Mp, a first protection resistor Rb1, a second protection resistor Rb2, a filter capacitor CL and a load resistor RL, and the driving module 130 is connected between the amplification module and the output module.

[0053] In an embodiment of the present invention, an overcurrent protection circuit is configured to compare a first current signal with a first reference signal by providing a comparison module, and then output a first voltage signal and a second voltage signal. The first voltage signal slowly decreases as the first current signal increases, and the second voltage signal transforms to a high-level signal when the first voltage signal drops to a low level. The second voltage signal is a rapid pulse signal. A driver module is provided to slowly change the drive voltage of a power transistor based on the first voltage signal, thereby gradually reducing the drive capability of the power transistor and preventing repeated false triggering caused by current oscillations in the power transistor caused by rapid changes in the drive voltage. The driver module fixes the output voltage at a first preset value based on the second voltage signal, clamping the maximum output current of the power transistor and implementing an overcurrent protection function. Applying the overcurrent protection circuit to a linear regulator can promptly and accurately restore normal circuit operation to normal for loads that return to a normal output range after a short overload, avoiding repeated system restarts. Furthermore, the current limit value is unaffected by changes in the output voltage, achieving a low current limit threshold and ensuring safe operation of the linear regulator.

[0054] An embodiment of the present invention further provides an overcurrent protection method, which can be applied to the overcurrent protection circuit provided by any embodiment of the present invention. Figure 11 FIG. 1 is a flow chart of an overcurrent protection method provided by an embodiment of the present invention. Figure 11 As shown, the overcurrent protection methods include:

[0055] S10: The sampling module collects the current of the power tube and outputs a first current signal.

[0056] S20 , the comparison module compares the first current signal with the first reference signal, and outputs a first voltage signal and a second voltage signal.

[0057] S30: The driving module controls the driving voltage of the power tube according to the first voltage signal.

[0058] S40 , the driving module clamps the driving voltage of the power tube to a first preset value according to the second voltage signal.

[0059] An overcurrent protection method provided by an embodiment of the present invention is implemented by the overcurrent protection circuit of any of the above embodiments. The overcurrent protection circuit samples a proportional small current of a power tube through a sampling module, outputs a first voltage signal that slowly decreases as the first current signal increases, and a second voltage signal that rapidly flips through a comparison module, and slowly reduces the driving capability of the power tube through a driving module to prevent repeated false touches caused by current oscillations on the power tube due to rapid changes in the power tube driving voltage. The overcurrent protection circuit also fixes the output voltage at a first preset value, clamping the maximum output current of the power tube to implement an overcurrent protection function, thereby preventing repeated system startup and effectively improving the safety of the linear regulator.

[0060] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present invention can be performed 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.

[0061] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A linear regulator overcurrent protection circuit, characterized in that: The linear regulator includes a power tube, a first electrode of the power tube is connected to the output end of the linear regulator, and the overcurrent protection circuit includes a sampling module, a comparison module and a driving module; The sampling module is connected to the power tube, and the sampling module is used to collect the output current of the linear regulator and output a first current signal; The comparison module is connected to the sampling module, and the comparison module is used to output a first voltage signal and a second voltage signal according to the first reference signal and the first current signal, wherein the first voltage signal and the second voltage signal are inverse signals of each other; The driving module is connected to the loop circuit of the linear regulator and is connected to the comparison module and the control electrode of the power tube. The driving module is used to control the driving voltage of the power tube according to the first voltage signal and clamp the driving voltage of the power tube at a first preset value according to the second voltage signal.

2. The linear regulator overcurrent protection circuit according to claim 1, characterized in that: The comparison module includes a first mirror unit, a second mirror unit, a charge storage unit and an inverting unit. The first mirror unit is connected to the first reference signal and is used to mirror the first reference signal. The second mirror unit is connected to the first current signal and is used to mirror the first current signal. The charge storage unit is connected to the first mirror unit and the second mirror unit and is used to generate the first voltage signal based on the first reference signal and the first current signal. The inverting unit is connected to the charge storage unit and is used to invert the first voltage signal and output the second voltage signal.

3. The linear regulator overcurrent protection circuit according to claim 2, wherein: The first mirror unit includes a first transistor and a second transistor, the first electrode of the first transistor is connected to the first reference signal, the second electrode of the first transistor is connected to the first power supply terminal, the control electrode of the first transistor is connected to the first electrode of the first transistor and the control electrode of the second transistor, the first electrode of the second transistor is connected to the output terminal of the first mirror unit, and the second electrode of the second transistor is connected to the first power supply terminal.

4. The linear regulator overcurrent protection circuit according to claim 3, wherein: The second mirror unit includes a third transistor and a fourth transistor, a first electrode of the third transistor is connected to the first current signal, a second electrode of the third transistor is grounded, a control electrode of the third transistor is connected to the first electrode of the third transistor and the control electrode of the fourth transistor, a first electrode of the fourth transistor is connected to the output end of the second mirror unit, and a second electrode of the fourth transistor is grounded.

5. The linear regulator overcurrent protection circuit according to claim 4, characterized in that: The charge storage unit includes a first capacitor, a first end of the first capacitor is connected to the output end of the first mirror unit and the output end of the second mirror unit, and a second end of the first capacitor is grounded.

6. The linear regulator overcurrent protection circuit according to claim 2, wherein: The inverting unit includes a NOT logic gate circuit, an input end of the NOT logic gate circuit is connected to the charge storage unit, and an output end of the NOT logic gate circuit is connected to an output end of the inverting unit.

7. The linear regulator overcurrent protection circuit according to claim 1, wherein: The driving module includes a first current source, a second current source, a third current source, a fifth transistor, a sixth transistor, a seventh transistor and an eighth transistor. The positive electrode of the first current source is connected to the first power supply end, the negative electrode of the first current source is connected to the first electrode of the fifth transistor and the output end of the driving module, the control electrode of the fifth transistor is connected to the loop circuit of the linear regulator, the second electrode of the fifth transistor is connected to the positive electrode of the second current source, the positive electrode of the third current source and the control electrode of the sixth transistor, the negative electrode of the second current source is grounded, the negative electrode of the third current source is connected to the first electrode of the seventh transistor, the control electrode of the seventh transistor is connected to the second voltage signal, the second electrode of the seventh transistor is grounded, the first electrode of the sixth transistor is connected to the output end of the driving module, the second electrode of the sixth transistor is connected to the first electrode of the eighth transistor, the control electrode of the eighth transistor is connected to the first voltage signal, and the second electrode of the eighth transistor is grounded.

8. The linear regulator overcurrent protection circuit according to claim 1, wherein: The sampling module includes a ninth transistor, a control electrode of the ninth transistor is connected to the control electrode of the power tube, a second electrode of the ninth transistor is connected to the second electrode of the power tube, and the ninth transistor is used to replicate the current of the first electrode of the power tube.

9. A linear voltage regulator, characterized in that: It comprises a loop circuit and the overcurrent protection circuit according to any one of claims 1 to 8; the loop circuit comprises an amplification module and an output module, the output module comprises the power tube, and the driving module is connected between the amplification module and the output module.

10. An overcurrent protection method, characterized in that: The method is performed by the overcurrent protection circuit according to any one of claims 1 to 8, comprising: The sampling module collects the current of the power tube and outputs a first current signal; The comparison module compares the first current signal with the first reference signal and outputs the first voltage signal and the second voltage signal; The driving module controls the driving voltage of the power tube according to the first voltage signal; The driving module clamps the driving voltage of the power tube at the first preset value according to the second voltage signal.

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