Low-temperature-drift current-limiting protection circuit applied to linear voltage regulator

Abstract

The invention relates to the technical field of semiconductor integrated circuits, in particular to a low-temperature drift current-limiting protection circuit applied to a linear voltage regulator, which comprises a two-way current sampling unit circuit, a transistor threshold offset unit circuit, a sampling resistance offset unit circuit, a current-limiting control unit circuit and a bias unit circuit. A traditional current-limiting protection circuit is improved, a two-way current sampling circuit is adopted to sample load current, and a sampling resistor offset circuit and a transistor threshold offset circuit are adopted to eliminate two factors influencing a current-limiting threshold in a temperature zone range, so that the current-limiting threshold is only related to two resistors of the same type; in actual use, accurate over-current operation of the linear voltage regulator can be achieved, over-current threshold drift in a temperature zone range can be reduced, and high-power device damage caused by the fact that the high-temperature lower limit current value is too high is avoided. The current regulator is widely applied to the field of heavy-load current linear voltage regulators.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor integrated circuits, and specifically to a low-temperature-drift current-limiting protection circuit applied to a linear voltage regulator. Background Art

[0002] As a device that achieves a certain precision voltage regulation within a certain range of voltage, load, and temperature changes, a linear voltage regulator is favored in scenarios that require providing a large load current due to its low noise, high precision, and simple use. However, in the event of an overcurrent situation, the device will draw a large current, and the excessive current may cause the device to break down and be damaged. Therefore, it is necessary to design a current-limiting circuit to control the maximum current that can flow during overcurrent.

[0003] Conventionally, the protection current for a linear voltage regulator usually samples the output current using a small resistor. As the output current increases, when the voltage drop across the sampling resistor reaches the transistor threshold, the current-limiting circuit is turned on. There are two factors that affect the current-limiting threshold in this structure, namely the resistance value of the sampling resistor and the transistor threshold, both of which will drift with temperature, causing the current-limiting threshold to drift. When ensuring the output current, the current-limiting threshold within the temperature range will have a large change. Especially at high temperatures, the excessive current-limiting threshold causes the device to bear a greater power when there is an overcurrent operation at high temperatures, which may damage the device. Therefore, minimizing the temperature drift of the current-limiting value and making the current-limiting value smaller can reduce the power borne by the device during overcurrent and avoid chip breakdown and damage. Summary of the Invention

[0004] The technical problem solved by the present invention is to provide a low-temperature-drift current-limiting protection circuit applied to a linear voltage regulator to solve the technical problem in the prior art that the resistance value of the sampling resistor and the transistor threshold will drift with temperature, resulting in the drift of the current-limiting threshold and thus damaging the device.

[0005] The basic solution provided by the present invention: A low-temperature-drift current-limiting protection circuit applied to a linear voltage regulator, including a dual-channel current sampling unit circuit, a transistor threshold cancellation unit circuit, a sampling resistor cancellation unit circuit, a current-limiting control unit circuit, and a bias circuit;

[0006] The dual-channel current sampling unit circuit includes a current mirror sampling channel and a sampling resistor sampling channel; the current mirror sampling channel includes a sampling transistor Q1 and several power transistors QN1 - QNn, and the ratio of the sampling transistor to the power transistors is 1:n, sampling the current of the power transistor of the linear voltage regulator in proportion; the sampling resistor sampling channel includes several sampling resistors RL1 - RLn corresponding to the power transistors for use as ballast resistors for the power transistors, and realizes the function of converting the load current to voltage by sampling the current of the power transistor of the linear voltage regulator;

[0007] In the transistor threshold cancellation unit circuit, one end of the first current-limiting threshold comparison resistor is connected to the sampling resistor RL1 and the emitter of the power transistor QN1, and the other end is connected to the emitter of the current-limiting threshold comparison transistor Q4. The base of the current-limiting threshold comparison transistor Q4 is connected to one end of the resistor R10, and the other end of R10 is respectively connected to the base of the bias transistor Q6 and the node V1. The node V1 is the connection intersection of the bias transistor Q9 and the third current-limiting threshold comparison resistor R9. The other end of the third current-limiting resistor R9 is connected to the node V2. The node V2 is the connection intersection between the third current-limiting threshold comparison resistor R9, the collector of the current-limiting threshold comparison transistor Q4, and the resistor R11.

[0008] In the sampling resistor cancellation unit circuit, one end of the second current-limiting threshold comparison resistor is connected to the emitter of the current-limiting turn-on transistor Q5. The base of the current-limiting turn-on transistor Q5 is respectively connected to the first end of the RC resistor-capacitor network and the other end of the resistor R11. The collector of the current-limiting turn-on transistor Q5 is connected to the node V3. The node V3 is the connection intersection of the collector of the bias transistor Q10, the emitter of the bias transistor Q6, the second end of the RC resistor-capacitor network, and the base of the NPN transistor Q7 in the current-limiting control unit circuit.

[0009] In the current-limiting control unit circuit, the collector of the NPN transistor Q7 is connected to the power supply VIN. The emitter of the NPN transistor Q7 is respectively connected to the resistor R14 and the base of the PNP transistor Q8. The emitter of the PNP transistor Q8 and the other end of the resistor R14 are both connected to the output terminal VOUT of the linear regulator error amplifier.

[0010] The bias circuit includes a bias transistor Q6, a bias transistor Q9, a bias transistor Q10, and a resistor R13. One end of the resistor R13 is connected to the power supply VIN, and the other end of the resistor R13 is connected to the emitters of the bias transistor Q9 and the bias transistor Q10.

[0011] Further, one end of the sampling resistor RL1 in the dual-channel current sampling unit circuit is connected to the emitter of the power transistor QN1 and the first current-limiting threshold comparison resistor, and the other end is connected to the linear regulator output VOUT; the base and collector of the sampling transistor Q1 in the dual-channel current sampling unit circuit are connected to each other and are respectively connected to the base of the power transistor QN1 and the collector of the PNP driving transistor Q2; the emitter of the sampling transistor Q1 is sequentially connected to the resistor R3 and the resistor R2, and the other end of the resistor R2 is respectively connected to the resistor R1 and the second current-limiting threshold comparison resistor. The emitter of the PNP driving transistor Q2 is connected to the power supply VIN. The base of the PNP driving transistor Q2 is respectively connected to the collector of the NPN transistor Q3 and one end of the resistor R4. The emitter of the PNP driving transistor Q2 and the other end of the resistor R4 are both connected to the power supply VIN. The emitter of the NPN transistor Q3 is connected to the connection intersection of the resistor R2 and the resistor R3. The base of the NPN transistor Q3 is connected to the output end of the linear regulator error amplifier and the emitter of the NPN transistor Q8.

[0012] Further, the first current-limiting threshold comparison resistor is a resistor string including the resistor R5 and the resistor R6, and the second current-limiting threshold comparison resistor is a resistor string including the resistor R7 and the resistor R8.

[0013] Further, the RC resistor-capacitor network includes the resistor R12 and the capacitor C1. One end of the resistor R12 serves as the first segment of the RC resistor-capacitor network, the other end of the resistor R12 is connected to one end of the capacitor C1, and the other end of the capacitor C1 serves as the second segment of the RC resistor-capacitor network.

[0014] Further, the sampling transistor Q1 and the power transistor are NPN transistors of the same type.

[0015] The principle and advantages of the present invention are as follows: In this solution, the dual-channel current sampling unit circuit samples the circuit load current of the power transistor. The dual-channel current sampling unit circuit is respectively connected to the transistor threshold cancellation unit circuit and the sampling resistor cancellation unit circuit. Its output current-limiting control signal is connected to the current-limiting control unit circuit and then connected to the output end of the error amplifier; the bias unit circuit is used to provide bias current for the transistor threshold cancellation unit circuit and the sampling resistor cancellation unit circuit; by using the dual-channel current sampling circuit to sample the load current, and using the sampling resistor cancellation circuit and the transistor threshold cancellation circuit to eliminate two factors affecting the current-limiting threshold within the temperature range, so that the current-limiting threshold is only related to the sizes of two resistors of the same type, thereby obtaining a current-limiting threshold independent of temperature. In actual use, the current-limiting threshold of the linear regulator can be reduced, and the device power consumption in the case of overcurrent can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1Schematic diagram of an embodiment of a low-temperature-drift current-limiting protection circuit applied to a linear voltage regulator according to the present invention.

[0017] Figure 2 Circuit structure diagram of an embodiment of a low-temperature-drift current-limiting protection circuit applied to a linear voltage regulator according to the present invention.

[0018] Figure 3 Circuit structure diagram of a traditional scheme of an embodiment of a low-temperature-drift current-limiting protection circuit applied to a linear voltage regulator according to the present invention.

[0019] Figure 4 Curve graph of temperature drift of the current-limiting threshold of a traditional current-limiting circuit in an embodiment of a low-temperature-drift current-limiting protection circuit applied to a linear voltage regulator according to the present invention.

[0020] Figure 5 Current-limiting threshold graph of a linear voltage regulator in the temperature range in an embodiment of a low-temperature-drift current-limiting protection circuit applied to a linear voltage regulator according to the present invention. Detailed implementation manners

[0021] The following is a further detailed description through specific implementation manners:

[0022] The specific implementation process is as follows:

[0023] Embodiment 1

[0024] As shown in the appendix Figure 1 A low-temperature-drift current-limiting protection circuit applied to a linear voltage regulator includes a dual-channel current sampling unit circuit, a transistor threshold cancellation unit circuit, a sampling resistor cancellation unit circuit, a current-limiting control unit circuit, and a bias circuit. The dual-channel current sampling unit circuit samples the load current of the power transistor circuit, is respectively connected to the transistor threshold cancellation unit circuit and the sampling resistor cancellation unit circuit, outputs a current-limiting control signal connected to the current-limiting control unit circuit, and then connected to the output end of the error amplifier, that is, the input end of the power transistor. The bias unit circuit provides a bias current for the transistor threshold cancellation unit circuit and the sampling resistor cancellation unit circuit.

[0025] In this solution, the dual-channel current sampling unit circuit samples the circuit load current of the power transistor. The dual-channel current sampling unit circuit is respectively connected to the transistor threshold cancellation unit circuit and the sampling resistor cancellation unit circuit, and its output current limiting control signal is connected to the current limiting control unit circuit and then to the output end of the error amplifier. The bias unit circuit is used to provide bias current for the transistor threshold cancellation unit circuit and the sampling resistor cancellation unit circuit. By using the dual-channel current sampling circuit to sample the load current and adopting the sampling resistor cancellation circuit and the transistor threshold cancellation circuit to eliminate the two factors affecting the current limiting threshold within the temperature range, the current limiting threshold is only related to the sizes of two resistors of the same type, so as to obtain a current limiting threshold independent of temperature. In actual use, the current limiting threshold of the linear regulator can be reduced, and the device power consumption in the case of overcurrent can be reduced.

[0026] Specifically, as Figure 2 shown, the dual-channel current sampling unit circuit includes a current mirror sampling channel and a sampling resistor sampling channel. The current mirror sampling channel includes a sampling transistor Q1 and several power transistors, and the ratio of the sampling transistor to the power transistors is 1:n, sampling the current of the linear regulator power transistor in proportion. The sampling resistor sampling channel includes several sampling resistors corresponding to the power transistors for use as ballast resistors of the power transistors, and realizes the function of converting the load current to voltage by sampling the current of the linear regulator power transistor.

[0027] The power transistors in the dual-channel current sampling unit circuit include QN1 - QNn, and the sampling resistors include RL1 - RLn. One end of the sampling resistor RL1 is connected to the emitter of the power transistor QN1 and the first current limiting threshold comparison resistor, and the other end is connected to the linear regulator output VOUT. The base and collector of the sampling transistor Q1 in the dual-channel current sampling unit circuit are connected, and are respectively connected to the base of the power transistor QN1 and the collector of the PNP driving transistor Q2. The emitter of the sampling transistor Q1 is sequentially connected to the resistor R3 and the resistor R2, and the other end of the resistor R2 is respectively connected to the resistor R1 and the second current limiting threshold comparison resistor. The emitter of the PNP driving transistor Q2 is connected to the power supply VIN, the base of the PNP driving transistor Q2 is respectively connected to the collector of the NPN transistor Q3 and one end of the resistor R4, the emitter of the PNP driving transistor Q2 and the other end of the resistor R4 are both connected to the power supply VIN, the emitter of the NPN transistor Q3 is connected to the connection intersection of the resistor R2 and the resistor R3, and the base of the NPN transistor Q3 is connected to the output end of the linear regulator error amplifier and the emitter of the NPN transistor Q8.

[0028] In the transistor threshold cancellation unit circuit, one end of the first current-limiting threshold comparison resistor is connected to the sampling resistor RL1 and the emitter of the power transistor QN1, and the other end is connected to the emitter of the current-limiting threshold comparison transistor Q4. The base of the current-limiting threshold comparison transistor Q4 is connected to one end of the resistor R10, and the other end of R10 is respectively connected to the base of the biasing transistor Q6 and the node V1. The node V1 is the connection intersection of the biasing transistor Q9 and the third current-limiting threshold comparison resistor R9. The other end of the third current-limiting resistor R9 is connected to the node V2. The node V2 is the connection intersection among the third current-limiting threshold comparison resistor R9, the collector of the current-limiting threshold comparison transistor Q4, and the resistor R11.

[0029] In the sampling resistor cancellation unit circuit, one end of the second current-limiting threshold comparison resistor is connected to the emitter of the current-limiting turn-on transistor Q5. The base of the current-limiting turn-on transistor Q5 is respectively connected to the first end of the RC resistor-capacitor network and the other end of the resistor R11. The collector of the current-limiting turn-on transistor Q5 is connected to the node V3. The node V3 is the connection intersection of the collector of the biasing transistor Q10, the emitter of the biasing transistor Q6, the second end of the RC resistor-capacitor network, and the base of the NPN transistor Q7 in the current-limiting control unit circuit.

[0030] In the current-limiting control unit circuit, the collector of the NPN transistor Q7 is connected to the power supply VIN. The emitter of the NPN transistor Q7 is respectively connected to the resistor R14 and the base of the PNP transistor Q8. The emitter of the PNP transistor Q8 and the other end of the resistor R14 are both connected to the output VOUT of the linear regulator error amplifier.

[0031] The biasing circuit includes the biasing transistor Q6, the biasing transistor Q9, the biasing transistor Q10, and the resistor R13. One end of the resistor R13 is connected to the power supply VIN, and the other end of the resistor R13 is connected to the emitter of the biasing transistor Q9 and the emitter of the biasing transistor Q10.

[0032] The structure of the traditional current-limiting protection circuit is as Figure 3 shown, which is a current-limiting protection circuit structure that uses a resistor to sample the load current and compare it with the transistor threshold voltage. Among them: The sampling resistor RL1 samples the load current IOUT, and the voltage drop on RL1 can be expressed as VRL1 = RL1 * IOUT. When VRL1 increases with the increase of the load current until it is greater than the turn-on threshold voltage VBE-Q8 of the transistor Q8, the Q8 transistor turns on, pulls down the output of the error amplifier, and turns off the linear regulator. As shown in Figure 4 it, the current-limiting threshold has a large temperature drift and increases with the increase of temperature. When an overcurrent occurs at high temperature, the excessive current-limiting threshold will cause a large amount of heat and there is a risk of thermal breakdown. Therefore, the circuit of the present invention is proposed.

[0033] Specifically, for the position of the circuit of the present invention in the linear voltage regulator, by using a dual-channel current sampling circuit to sample the load current and adopting a sampling resistor cancellation circuit and a transistor threshold cancellation circuit to eliminate two factors affecting the current limiting threshold within the temperature range, the current limiting threshold is only related to the magnitudes of two resistors of the same type, thereby obtaining a current limiting threshold independent of temperature.

[0034] For the circuit structure of the present invention to reasonably distribute the power transistor current, it is evenly divided into 16 parts, namely QN1......QN8......QN16. In the transistor threshold cancellation circuit, the voltage at node V1 is:

[0035] V1 = VBE - Q4 + VR5 + VR6 + VRL1

[0036] Wherein, VBE - Q4 is the threshold voltage of transistor Q4, VR5 and VR6 are the voltage drops across resistors R5 and R6 respectively, VRL1 is the voltage drop across sampling resistor RL1, and VRL1 can be written as:

[0037] VRL1 = 1 / 16IOUT * RL1

[0038] The voltage at node V2 is:

[0039] V2 = V1 - VR9

[0040] Wherein, VR9 is the voltage drop across resistor R9;

[0041] In the sampling resistor cancellation circuit, Q1 replicates the current of power transistor QN proportionally, and the ratio between the two is QN1:Q1 = N:1. Therefore, the voltage at node V2 can be rewritten as

[0042] V2 = VR1 + VR7 + VR8 + VBE - Q5

[0043] Wherein, VBE - Q5 is the threshold voltage of transistor Q5, VR7 and VR8 are the voltage drops across resistors R7 and R8 respectively, VR1 is the voltage drop across sampling resistor R1, and VR1 can be written as:

[0044] VR1 = 1 / NIOUT * R1

[0045] As the load current increases, when:

[0046] V2 = V1 - VR9 = VBE - Q4 + VR5 + VR6 + 1 / 16IOUT * RL1 - VR9 ≥ 1 / NIOUT * R1 + VR7 + VR8 + VBE - Q5, the current limiting turn-on transistor Q5 turns on; since transistors Q4 and Q5 are of the same type, it can be approximately considered that their turn-on thresholds are equal:

[0047] VBE - Q4 ≈ VBE - Q5

[0048] In the sampling resistor cancellation circuit, by reasonably setting the ratio of the sampling resistor to the mirror transistor, it is ensured that:

[0049] VR5 + VR6 + 1 / 16IOUT * RL1 - VR9 ≥ 1 / NIOUT * R1 + VR7 + VR8

[0050] It can be obtained that:

[0051] VR5 + VR6 ≥ VR7 + VR8 + VR9

[0052] When the current-limiting turn-on transistor Q5 is just turned on, VR7 + VR8 ≈ 0,

[0053] VR5 + VR6 ≥ VR9

[0054] Finally, it is deduced that:

[0055] IQ9 * R5 + IQ9 * R6 ≥ IQ9 * R9

[0056] R5 + R6 ≥ R9

[0057] After Q5 is turned on, the collector, i.e., node V3, is pulled low, causing Q7 to turn off and Q8 to turn on, thus enabling current limiting.

[0058] From the above formula, it can be obtained that the current-limiting threshold of the current-limiting circuit of the present invention is only related to the magnitudes of two resistors of the same type, and the terms related to temperature in their expansion formulas can be offset, thereby obtaining a current-limiting threshold independent of temperature.

[0059] As Figure 4 shown, it is the temperature drift curve of the current-limiting threshold of the traditional current-limiting circuit. In the temperature range, the temperature drift of the current-limiting threshold exceeds 0.8A, with a large temperature drift and low accuracy, and there is a risk of thermal breakdown. As Figure 5 shown, it is the current-limiting threshold of the linear voltage regulator using the circuit of the present invention in the temperature range. In the temperature range from -55°C to 125°C, the temperature drift of the current-limiting threshold does not exceed 0.1A, achieving the circuit design goal.

[0060] In summary, a low-temperature-drift current-limiting protection circuit applied to a linear voltage regulator in the present invention can sample the load current by adopting a dual-channel current sampling circuit, and eliminate two factors affecting the current-limiting threshold in the temperature range by using a sampling resistor cancellation circuit and a transistor threshold cancellation circuit, so that the current-limiting threshold is only related to the magnitudes of two resistors of the same type, thereby obtaining a current-limiting threshold independent of temperature. In actual use, the current-limiting threshold of the linear voltage regulator can be reduced, and the device power consumption in the case of overcurrent can be reduced. Moreover, the circuit structure of this solution is simple and easy to implement, without a comparator, with low power consumption and small occupied area, and can also be applied to the design of the current-limiting protection circuit of a linear voltage regulator with a large load current, improving the reliability of the current-limiting protection of the linear voltage regulator and simplifying the design cost.

[0061] The above are only embodiments of the present invention. Specific structures and common knowledge such as characteristics that are well-known in the art are not described in detail herein. Those of ordinary skill in the art know all the general technical knowledge in the technical field to which the invention pertains before the filing date or the priority date, can learn all the prior art in this field, and have the ability to apply the conventional experimental means before this date. Those of ordinary skill in the art can, under the inspiration given in this application, combine their own abilities to improve and implement this solution. Some typical well-known structures or well-known methods should not become an obstacle for those of ordinary skill in the art to implement this application. It should be noted that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can still be made, and these should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be based on the content of its claims, and the specific implementation manners and the like recorded in the specification can be used to interpret the content of the claims.

Claims

1. A low-temperature drift current-limiting protection circuit applied to a linear voltage regulator, characterized in that: It includes a dual-channel current sampling unit circuit, a transistor threshold cancellation unit circuit, a sampling resistor cancellation unit circuit, a current limiting control unit circuit, and a bias circuit; The dual-channel current sampling unit circuit includes a current mirror sampling channel and a sampling resistor sampling channel; the current mirror sampling channel includes a sampling transistor Q1 and several power transistors QN1-QNn, and the ratio of the sampling transistor to the power transistors is 1:n, sampling the linear regulator power transistor current proportionally; the sampling resistor sampling channel includes several sampling resistors RL1-RLn corresponding to the power transistors for ballast resistors of the power transistors, realizing the function of converting load current to voltage by sampling the linear regulator power transistor current; In the transistor threshold cancellation unit circuit, one end of the first current limiting threshold comparison resistor is connected to the sampling resistor RL1 and the emitter of the power transistor QN1, and the other end is connected to the emitter of the current limiting threshold comparison transistor Q4. The base of the current limiting threshold comparison transistor Q4 is connected to one end of the resistor R10, and the other end of R10 is respectively connected to the base of the bias transistor Q6 and the node V1. The node V1 is the connection intersection of the bias transistor Q9 and the third current limiting threshold comparison resistor R9. The other end of the third current limiting resistor R9 is connected to the node V2. The node V2 is the connection intersection among the third current limiting threshold comparison resistor R9, the collector of the current limiting threshold comparison transistor Q4, and the resistor R11; In the sampling resistor cancellation unit circuit, one end of the second current limiting threshold comparison resistor is connected to the emitter of the current limiting turn-on transistor Q5. The base of the current limiting turn-on transistor Q5 is respectively connected to the first end of the RC resistor-capacitor network and the other end of the resistor R11. The collector of the current limiting turn-on transistor Q5 is connected to the node V3. The node V3 is the connection intersection of the collector of the bias transistor Q10, the emitter of the bias transistor Q6, the second end of the RC resistor-capacitor network, and the base of the NPN transistor Q7 in the current limiting control unit circuit; In the current limiting control unit circuit, the collector of the NPN transistor Q7 is connected to the power supply VIN, and the emitter of the NPN transistor Q7 is respectively connected to the resistor R14 and the base of the PNP transistor Q8. The emitter of the PNP transistor Q8 and the other end of the resistor R14 are both connected to the output terminal VOUT of the linear regulator error amplifier; The bias circuit includes a bias transistor Q6, a bias transistor Q9, a bias transistor Q10, and a resistor R13. One end of the resistor R13 is connected to the power supply VIN, and the other end of the resistor R13 is connected to the emitters of the bias transistor Q9 and the bias transistor Q10.

2. The low-temperature-drift current-limiting protection circuit applied to a linear voltage regulator according to claim 1, wherein: One end of the sampling resistor RL1 in the dual-channel current sampling unit circuit is connected to the emitter of the power transistor QN1 and the first current-limiting threshold comparison resistor, and the other end is connected to the output VOUT of the linear voltage regulator; in the dual-channel current sampling unit circuit, the base and the collector of the sampling transistor Q1 are connected to each other and are respectively connected to the base of the power transistor QN1 and the collector of the PNP driving transistor Q2; the emitter of the sampling transistor Q1 is sequentially connected to the resistor R3 and the resistor R2, the other end of the resistor R2 is respectively connected to the resistor R1 and the second current-limiting threshold comparison resistor, the emitter of the PNP driving transistor Q2 is connected to the power supply VIN, the base of the PNP driving transistor Q2 is respectively connected to the collector of the NPN transistor Q3 and one end of the resistor R4, the emitter of the PNP driving transistor Q2 and the other end of the resistor R4 are both connected to the power supply VIN, the emitter of the NPN transistor Q3 is connected to the connection intersection of the resistor R2 and the resistor R3, and the base of the NPN transistor Q3 is connected to the output end of the error amplifier of the linear voltage regulator and the emitter of the NPN transistor Q8.

3. The low-temperature-drift current-limiting protection circuit applied to a linear voltage regulator according to claim 2, wherein: The first current-limiting threshold comparison resistor is a resistor string including the resistors R5 and R6, and the second current-limiting threshold comparison resistor is a resistor string including the resistors R7 and R8.

4. The low-temperature-drift current-limiting protection circuit applied to a linear voltage regulator according to claim 3, characterized in that: The RC resistor-capacitor network includes a resistor R12 and a capacitor C1. One end of the resistor R12 serves as the first segment of the RC resistor-capacitor network, the other end of the resistor R12 is connected to one end of the capacitor C1, and the other end of the capacitor C1 serves as the second segment of the RC resistor-capacitor network.

5. The low-temperature-drift current-limiting protection circuit applied to a linear voltage regulator according to claim 4, wherein: The sampling transistor Q1 and the power transistor are NPN transistors of the same type.

Images