An enable circuit for use as a switch

Abstract

The present application relates to the technical field of integrated circuits, and in particular to an enabling circuit used as a switch, comprising: an enabling signal input processing unit adapted to access an enabling signal and convert a voltage signal of the enabling signal to obtain a first current; a first control unit adapted to turn on a second control unit when a voltage value of the enabling signal corresponding to the first current changes to not less than a preset circuit on voltage value, and turn off the second control unit when the voltage value of the enabling signal corresponding to the first current changes to not greater than a preset circuit off voltage value; wherein a circuit off voltage value is less than a circuit on voltage value under the action of a third current; the second control unit, when turned on, turns on a controlled circuit and generates a second current; and when turned off, turns off the controlled circuit; and a current detection unit adapted to generate the third current when the second current is detected. The present application solves the technical problem that the function of the enabling circuit as a switch is difficult to realize when the enabling signal oscillates.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit technology, and more particularly to an enable circuit used as a switch. Background Technology

[0002] Enable circuits are commonly used in integrated circuits to control the switching of other circuits. See also... Figure 1 , Figure 1 This is a circuit diagram of the enable circuit controlling the switch of the circuit in the prior art. Figure 1 In this circuit, the operation of the current mirror circuit is controlled by the input enable signal. When the enable signal is high, the field-effect transistor (MOSFET) Q3 is turned on, which reduces the gate voltage of MOSFETs Q1 and Q2, putting them in the cutoff region and thus turning off the circuit. Conversely, when the enable signal is low, MOSFET Q3 is turned off, and the gate voltages of MOSFETs Q1 and Q2 are at a higher level, thus not affecting the normal operation of the current mirror circuit.

[0003] In theory, existing technology can achieve the switching of other circuits using a simple enable circuit. However, in practical applications, the actual enable signal usually contains glitches or noise, which can easily cause instability in the enable circuit. Alternatively, when the ambient temperature rises, thermal oscillations can easily occur, thus affecting the enable circuit's function as a switch and resulting in frequent switching or switch failure. Summary of the Invention

[0004] Based on the above analysis, the present invention aims to provide an enabling circuit that can be used as a switch, thereby solving the technical problem that it is difficult to realize the function of an enabling circuit as a switch in the prior art.

[0005] The technical solution provided by this invention is:

[0006] This invention provides an enabling circuit used as a switch, comprising:

[0007] An enable signal input processing unit is adapted to receive an enable signal and convert the voltage signal of the enable signal into a first current;

[0008] The first control unit is adapted to activate the second control unit when the enable signal voltage value corresponding to the first current changes to a value not less than a preset circuit turn-on voltage value, and to deactivate the second control unit when the enable signal voltage value corresponding to the first current changes to a value not greater than a preset circuit turn-off voltage value; wherein, under the action of the third current, the circuit turn-off voltage value is less than the circuit turn-on voltage value;

[0009] The second control unit, when turned on, conducts the controlled circuit and generates a second current; and when turned off, it turns off the controlled circuit.

[0010] A current detection unit is adapted to generate the third current when the second current is detected.

[0011] Preferably, the enable signal input processing unit includes: a first current source, a first resistor, and a second resistor;

[0012] One end of the first resistor is used to receive the enable signal, and the other end is connected to the first current source and one end of the second resistor; the other end of the second resistor is connected to the first control unit.

[0013] Preferably, the first control unit includes: a first MOSFET;

[0014] The second control unit includes: a second MOSFET and a current mirror;

[0015] The gate and drain of the first MOS transistor are shorted together and connected to the source of the second MOS transistor;

[0016] The source of the first MOS transistor is connected to the other end of the second resistor, and is also connected to the gate of the second MOS transistor;

[0017] The gate and drain of the first MOS transistor are grounded.

[0018] Preferably, the current mirror includes a third MOS transistor and a fourth MOS transistor;

[0019] The sources of the third and fourth MOS transistors are connected to the operating voltage. The gate and drain of the third MOS transistor are shorted together, and the drain is connected to the drain of the second MOS transistor.

[0020] The drain of the fourth MOS transistor is connected to the controlled circuit.

[0021] Preferably, the threshold voltage of the first MOSFET is lower than the threshold voltage of the second MOSFET.

[0022] Preferably, the current detection unit includes a fifth MOSFET and a sixth MOSFET;

[0023] The source of the fifth MOS transistor is connected to the operating voltage, the gate is connected to the drain of the third MOS transistor, and the drain is connected to the source of the sixth MOS transistor.

[0024] The gate and drain of the sixth MOS transistor are shorted together and connected to the gate of the second MOS transistor, while the source is connected to the drain of the fifth MOS transistor.

[0025] Preferably, the second MOS transistor is an NMOS transistor, and the third, fourth, fifth, and sixth MOS transistors are all PMOS transistors.

[0026] Preferably, the circuit on-state voltage value is denoted as V. SW1 Then we have:

[0027]

[0028] Where R1 is the resistance of the first resistor, R2 is the resistance of the second resistor, and I B Let μ be the current of the first current source. p C represents hole mobility. ox The gate capacitance per unit area of ​​the MOSFET. V is the ratio of the width to the length of the first MOS transistor. th2 V is the threshold voltage of the second MOSFET. th1 The threshold voltage of the first MOSFET is denoted as .

[0029] Preferably, the circuit turn-off voltage value is denoted as V. SW2 Then we have:

[0030]

[0031] Where K is the size ratio of the third MOS transistor to the fifth MOS transistor, I2 is the second current value, and the third current = K*I2.

[0032] Preferably, the circuit further includes:

[0033] The voltage clamping unit, with one end connected to the other end of the second resistor and the other end grounded, includes a set of NMOS transistors, wherein the connection of each NMOS transistor to the circuit is equivalent to that of a diode.

[0034] In the technical solution provided by this invention, a first control unit controls the on / off state of a second control unit, and the second control unit controls the on / off state of the controlled circuit. After the first control unit receives a first current corresponding to the enable signal voltage value, as the enable signal voltage value increases, when it reaches the circuit turn-on voltage value, the second control unit is turned on, thereby turning on the controlled circuit. When the second control unit is turned on, a second current is generated, and a current detection unit generates a third current with the same direction of change based on the second current, feeding the third current back to the first control unit. The appearance of the third current changes the enable signal voltage value when the second control unit is turned off, so that the enable signal voltage value at this time is no longer equal to the circuit turn-on voltage value, but equal to a circuit turn-off voltage value smaller than the circuit turn-on voltage value. Thus, the control circuit is turned on or off by the enable signal. During the controlled circuit process, the circuit turn-on voltage value corresponding to the enable signal voltage value may differ from the circuit turn-off voltage value. This difference effectively reduces the occurrence of enable signal glitches or noise causing malfunctions when the enable signal is used as a control switch for the controlled circuit. Specifically, after the enable signal turns on the controlled circuit, if the enable signal oscillates above the circuit turn-off voltage value, or oscillates near the circuit turn-on voltage value at a level not lower than the circuit turn-off voltage value, it will not cause frequent switching of the controlled circuit. Similarly, after the enable signal turns off the controlled circuit, if the enable signal oscillates below the circuit turn-on voltage value, or oscillates near the circuit turn-off voltage value at a level not higher than the circuit turn-on voltage value, it will not cause frequent switching of the controlled circuit. This effectively solves the technical problem of the enable circuit's inability to function as a switch.

[0035] Furthermore, in the specific implementation of this invention, multiple MOSFETs are used to implement most functions. For the first MOSFET and the second MOSFET, in a high-temperature environment, based on the above connection method, the threshold voltages of the two MOSFETs change in the same direction with temperature, that is, they have the same trend of change. Therefore, it can effectively avoid the situation where the threshold voltage of one MOSFET changes due to temperature, while the other remains unchanged or changes inconsistently, resulting in inconsistent switching of the enable signal. The operating environment temperature of the enable circuit provided by the technical solution of this invention can be as high as about 185 degrees Celsius.

[0036] The technical solutions provided by the embodiments of the present invention are easy to implement and integrate, and have high application value.

[0037] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0038] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0039] Figure 1 This is a circuit diagram of the enable circuit controlling the switch of the circuit in the prior art;

[0040] Figure 2 This is a schematic diagram of the enabling circuit used as a switch in an embodiment of the present invention;

[0041] Figure 3 This is an example diagram of the implementation of the enable circuit used as a switch in an embodiment of the present invention;

[0042] Figure 4 This is a schematic diagram of the hysteresis characteristics of the enable circuit in an embodiment of the present invention;

[0043] Figure 5 In this embodiment of the invention, the enable signal voltage value is V SW1 Example chart of nearby oscillations;

[0044] Figure 6 In this embodiment of the invention, the enable signal voltage value is V SW2 Example diagram of nearby oscillations. Detailed Implementation

[0045] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and, together with the embodiments of the present invention, serve to illustrate the principles of the present invention.

[0046] This invention provides an enabling circuit used as a switch, see [link to relevant documentation]. Figure 2 , Figure 2 This is a schematic diagram of the structure of an enabling circuit used as a switch in an embodiment of the present invention. The enabling circuit may include:

[0047] Enable signal input processing unit 201, first control unit 202, second control unit 203 and current detection unit 204;

[0048] The enable signal input processing unit 201 is connected to the first control unit 202;

[0049] The first control unit 202 is connected to the enable signal input processing unit 201, the second control unit 203 and the current detection unit 204;

[0050] The second control unit 203 is connected to the first control unit 202, the current detection unit 204 and the controlled circuit;

[0051] The current detection unit 204 is connected to the first control unit 202 and the second control unit 203;

[0052] The enable signal input processing unit 201 is adapted to receive an enable signal and convert the voltage signal of the enable signal into a first current;

[0053] In this embodiment of the invention, the enable signal input processing unit 201 converts the voltage signal of the input enable signal into a current signal that is consistent with its changing direction. That is, if the voltage signal indicates that the voltage value increases, the current signal indicates that the current value also increases; if the voltage signal indicates that the voltage value decreases, the current signal indicates that the current value also decreases. Thus, the enable signal can be conveniently used to control the switch of the controlled circuit.

[0054] The first control unit 202 is adapted to turn on the second control unit 203 when the enable signal voltage value corresponding to the first current changes to a value not less than a preset circuit turn-on voltage value, and to turn off the second control unit 203 when the enable signal voltage value corresponding to the first current changes to a value not greater than a preset circuit turn-off voltage value; wherein, under the action of the third current, the circuit turn-off voltage value is less than the circuit turn-on voltage value.

[0055] The second control unit 203, when turned on, conducts the controlled circuit and generates a second current; and when turned off, it turns off the controlled circuit.

[0056] The current detection unit 204 is adapted to generate the third current when the second current is detected.

[0057] In this embodiment of the invention, the first control unit 202 controls the on / off state of the second control unit 203, and the second control unit 203 controls the on / off state of the controlled circuit. After the first control unit 202 receives a first current corresponding to the enable signal voltage value, as the enable signal voltage value increases, when it increases to the circuit turn-on voltage value, the second control unit 203 is turned on, thereby turning on the controlled circuit. When the second control unit 203 is turned on, a second current is generated, and the current detection unit 204 generates a third current with the same direction of change based on the detected second current, and feeds the third current back to the first control unit 202. The appearance of the third current will change the enable signal voltage value when the second control unit 203 is turned off, so that the enable signal voltage value at this time is no longer equal to the circuit turn-on voltage value, but equal to a value lower than the circuit turn-on voltage value. A small circuit turn-off voltage value can prevent the circuit from malfunctioning when the enable signal turns the controlled circuit on or off. This difference between the enable signal voltage and the turn-off voltage effectively reduces glitches or noise in the enable signal, thus preventing malfunctions when the enable signal is used to control the circuit. Specifically, when the enable signal turns on the controlled circuit, oscillations above the turn-off voltage, or oscillations near the turn-off voltage at a level not lower than the turn-off voltage, will not cause frequent switching of the controlled circuit. Similarly, when the enable signal turns off the controlled circuit, oscillations below the turn-off voltage, or oscillations near the turn-off voltage at a level not higher than the turn-off voltage, will also prevent frequent switching of the controlled circuit.

[0058] See Figure 3 , Figure 3 This is an example diagram of the implementation of the enable circuit used as a switch in an embodiment of the present invention. Figure 3 In the process, the enable signal input processing unit 201 may include: a first current source IB1, a first resistor R1 and a second resistor R2; wherein, one end of the first resistor R1 is used to receive the enable signal, and the other end is connected to the first current source IB1 and one end of the second resistor R2; the other end of the second resistor R2 is connected to the first control unit 202.

[0059] Figure 3 In the first control unit 202, a first MOSFET MP0 may be included; the second control unit 203 may include a second MOSFET MN4 and a current mirror; wherein the gate and drain of the first MOSFET MP0 are shorted together and connected to the source of the second MOSFET MN4; the source of the first MOSFET MP0 is connected to the other end of the second resistor R2 and connected to the gate of the second MOSFET MN4; the gate and drain of the first MOSFET MP0 are connected to ground, and optimally, can be connected via... Figure 3The second current source IB2 is grounded, and the function of the second current source IB2 is to give the current I2 a relatively certain current value.

[0060] Figure 3 In the process, the current mirror may include: a third MOSFET MP1 and a fourth MOSFET Q23; wherein the source of the third MOSFET MP1 and the fourth MOSFET Q23 is connected to the operating voltage Vsupply, the gate and drain of the third MOSFET MP1 are shorted, and the drain is connected to the drain of the second MOSFET MN4; the drain of the fourth MOSFET Q23 is connected to the controlled circuit.

[0061] Figure 3 In the process, the current detection unit 204 may include: a fifth MOSFET MP2 and a sixth MOSFET MP3; wherein, the source of the fifth MOSFET MP2 is connected to the working voltage Vsupply, the gate is connected to the drain of the third MOSFET MP1, and the drain is connected to the source of the sixth MOSFET MP3; the gate and drain of the sixth MOSFET MP3 are shorted and connected to the gate of the second MOSFET MN4, and the source is connected to the drain of the fifth MOSFET MP2.

[0062] In the specific implementation, the first MOSFET MP0 is a PMOS transistor, the second MOSFET MN4 is an NMOS transistor, and the third MOSFET MP1, fourth MOSFET Q23, fifth MOSFET MP2, and sixth MOSFET MP3 are all PMOS transistors. In practical applications, the first MOSFET can also be an NMOS transistor, as long as its threshold voltage is lower than that of the second MOSFET. Alternatively, in practical applications, the second MOSFET can be a PMOS transistor, while the third, fourth, fifth, and sixth MOSFETs are all NMOS transistors, and the connection circuit... Figure 3 similar.

[0063] See Figure 3 In a specific implementation of this invention, during the stage when the controlled circuit is not turned on, as the enable signal voltage increases, the current Ien decreases. Since the first current source IB1 generates a constant current I, its current value is expressed as I. B The decrease in current Ien will cause the current value I1 through the second resistor R2 to increase. Current I1 is the first current mentioned above. It can be seen that, based on the circuit connection of the first current source IB1, the first resistor R1 and the second resistor R2, the direction of change of current I1 can be consistent with the direction of change of enable signal voltage value, thereby facilitating the switching control of the subsequent controlled circuit by the enable signal.

[0064] Figure 3 In the process, as the current I1 increases, the gate-source voltage V on the first MOSFET MP0 increases. GS1 As V increases, GS1The threshold voltage V of the first MOSFET MP0 is greater than th1 Then the first MOSFET MP0 is turned on. As V... GS1 Increase the gate-source voltage V of the second MOSFET MN4 GS2 It also increases accordingly, when V GS2 Increase to the threshold voltage V of the second MOSFET MN4 th2 When the second MOSFET MN4 is turned on, a second current, I2 (as shown in the diagram), is generated on the second control unit 203, which consists of the second MOSFET MN4, the third MOSFET MP1, and the fourth MOSFET Q23. Due to the current mirror effect, after the second MOSFET MN4 generates current I2, a mirrored current I23 is generated on the side of the fourth MOSFET Q23, thus turning on the controlled circuit. Furthermore, to ensure circuit safety, V is required to... th1 <V th2 .

[0065] It can be assumed that when the second MOSFET MN4 is turned on, the controlled circuit is also turned on. At this time, corresponding to the threshold voltage of the second MOSFET MN4, the enable signal voltage value at the enable signal point will be equal to the preset circuit turn-on voltage value V. SW1 .

[0066] The following explains the circuit's on-state voltage V. SW1 The derivation process, Equation 1:

[0067]

[0068] Where I0 is the current value of I0 through the first MOSFET MP0, μ p C represents hole mobility. ox The gate capacitance per unit area of ​​the MOSFET. This is the ratio of the width to the length of the first MOSFET MP0.

[0069] During the period when the second MOSFET MN4 is not turned on, I0 = I1, and we have Equation 2:

[0070]

[0071] Where R1 is the resistance of the first resistor R1, R2 is the resistance of the second resistor R2, and V in The input enable signal voltage value;

[0072] Combining equations one and two, we have equation three:

[0073]

[0074] Figure 3In the diagram, the third MOSFET MP1 and the fifth MOSFET MP2 also form a current mirror structure. When current I2 is generated, the current detection unit 204 composed of the fifth MOSFET MP2 and the sixth MOSFET MP3 will be turned on. After detecting current I2, a third current is generated based on the current mirror structure, namely the current I3 shown in the figure.

[0075] The current I3 will be fed back to the first MOSFET MP0, affecting the enable signal voltage value corresponding to the turn-off of the second MOSFET MN4. To turn off the second MOSFET MN4, the enable signal voltage value is no longer equal to the circuit turn-on voltage value shown in Equation 3 above, but equal to the preset circuit turn-off voltage value V. SW2 Regarding the circuit turn-off voltage V SW2 The derivation is as follows:

[0076] When the second MOSFET is turned on, the generated current I2 is not zero. Let its current value be I2. Then the current value of the third current I3 through the fifth MOSFET MP2 and the sixth MOSFET MP3 is I3 = K * I2, and we have Equation 4:

[0077]

[0078] Combining equations one and four, we have equation five:

[0079]

[0080] When the enable signal voltage value approaches the circuit turn-off voltage value V SW2 When the second MOSFET MN4 is turned off, I2 = 0, and the current value of its mirror current I23 is I. 23 =0, thus shutting off the controlled circuit.

[0081] See Figure 4 , Figure 4 This is a schematic diagram of the hysteresis characteristic of the enable circuit in an embodiment of the present invention. The so-called hysteresis characteristic refers to the conduction voltage V of the above circuit. SW1 With circuit turn-off voltage V SW2 Unequal, circuit turn-off voltage value V SW2 Less than the circuit's on-state voltage V SW1 This causes the circuit to shut down with a delay. Figure 4 In order to facilitate comparison, the change of current I2 over time and the change of enable signal ENABLE over time are plotted on the same graph.

[0082] Figure 4 In the diagram, the left vertical axis represents the current value I2, and the right vertical axis represents the ENABLE voltage value. The ENABLE voltage value does not reach the voltage indicated by point A at V. SW1 At that time, the current value of I2 is almost 0, and as the ENABLE voltage value rises to V...SW1 The current value of I2 changes abruptly, and simultaneously the second MOSFET MN4 turns on, turning on the controlled circuit. When the ENABLE voltage reaches V... SW2 The current value of I2 jumps to 0, and at the same time the second MOS transistor MN4 turns off, and the controlled circuit is turned off.

[0083] See Figure 5 , Figure 5 In this embodiment of the invention, the enable signal voltage value is V SW1 Example diagram of nearby oscillations. See also Figure 6 , Figure 6 In this embodiment of the invention, the enable signal voltage value is V SW2 Example diagram of nearby oscillations. For the circuit's on-state voltage value V... SW1 The enable signal voltage value of the nearby oscillation can still be higher than the circuit turn-off voltage value V. SW2 Therefore, frequent switching of the controlled circuit will not occur. And for the circuit turn-off voltage value V... SW2 The enable signal voltage value of the nearby oscillation can still be lower than the circuit turn-on voltage value V. SW1 Therefore, there will be no situation where the controlled circuit is frequently switched on and off.

[0084] See also Figure 3 , Figure 3 The enable circuit further includes a voltage clamping unit, one end of which is connected to the other end of the second resistor and the other end is grounded. This unit includes at least one NMOS transistor, wherein each NMOS transistor is connected to the circuit in a manner equivalent to a diode. Specifically, the gate and drain of MOS transistor MN1 are shorted and connected to the other end of the second resistor R2, and its source is connected to the gate and drain of the next MOS transistor MN2. Similarly, the source of MOS transistor MN2 is connected to the gate and drain of the next MOS transistor MN3. When the enable signal voltage is large, this voltage clamping unit can shunt the current at current I1, clamping the voltage at the gate of the second MOS transistor MN4 to a safer value.

[0085] Figure 3 In this circuit, the main function of MOSFET Q24 is to meet the different switching requirements of the controlled circuit. The switching on and off of MOSFET Q24 is determined by the gate voltage of the second MOSFET MN4. Additionally, a capacitor C1 can be connected at the first resistor to act as a low-pass filter.

[0086] In summary, in this embodiment of the invention, the first control unit 202 controls the on / off state of the second control unit 203, and the second control unit 203 controls the on / off state of the controlled circuit. After the first control unit 202 receives a first current corresponding to the enable signal voltage value, as the enable signal voltage value increases, when it increases to the circuit conduction voltage value, the second control unit 203 is turned on, thereby turning on the controlled circuit. When the second control unit 203 is turned on, a second current is generated, and the current detection unit 204 generates a third current with the same direction of change based on the second current, and feeds the third current back to the first control unit 202. The appearance of the third current will change the enable signal voltage value when the second control unit 203 is turned off, so that the enable signal voltage value at this time is no longer equal to the circuit conduction voltage value, but equal to the circuit conduction voltage value. A low circuit turn-off voltage value means that, during the process of turning the controlled circuit on or off via the enable signal, the circuit turn-on voltage value corresponding to the enable signal voltage value may differ from the circuit turn-off voltage value. This difference effectively reduces glitches or noise in the enable signal, preventing malfunctions when the enable signal is used as a control switch for the controlled circuit. Specifically, after the enable signal turns on the controlled circuit, if the enable signal oscillates above the circuit turn-off voltage value, or oscillates near the circuit turn-on voltage value at a level not lower than the circuit turn-off voltage value, it will not cause frequent switching of the controlled circuit. Similarly, after the enable signal turns off the controlled circuit, if the enable signal oscillates below the circuit turn-off voltage value, or oscillates near the circuit turn-off voltage value at a level not higher than the circuit turn-off voltage value, it will not cause frequent switching of the controlled circuit.

[0087] Furthermore, in the specific implementation of this invention, multiple MOSFETs are used to implement most functions. For the first MOSFET and the second MOSFET, in a high-temperature environment, based on the above connection method, the threshold voltages of the two MOSFETs change in the same direction with temperature, that is, they have the same trend of change. Therefore, it can effectively avoid the situation where the threshold voltage of one MOSFET changes due to temperature, while the other remains unchanged or changes inconsistently, resulting in inconsistent switching of the enable signal. The operating environment temperature of the enable circuit provided by the technical solution of this invention can be as high as about 185 degrees Celsius.

[0088] The technical solutions provided by the embodiments of the present invention are easy to implement and integrate, and have high application value.

[0089] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0090] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. An enabling circuit used as a switch, characterized in that, include: An enable signal input processing unit is adapted to receive an enable signal and convert the voltage signal of the enable signal into a first current; The first control unit is adapted to activate the second control unit when the enable signal voltage value corresponding to the first current changes to a value not less than a preset circuit turn-on voltage value, and to deactivate the second control unit when the enable signal voltage value corresponding to the first current changes to a value not greater than a preset circuit turn-off voltage value; wherein, under the action of the third current, the circuit turn-off voltage value is less than the circuit turn-on voltage value; The second control unit, when turned on, conducts the controlled circuit and generates a second current; and when turned off, it turns off the controlled circuit. A current detection unit is adapted to generate the third current when the second current is detected; The enable signal input processing unit includes: a first current source, a first resistor, and a second resistor; One end of the first resistor is used to receive the enable signal, and the other end is connected to the first current source and one end of the second resistor; the other end of the second resistor is connected to the first control unit. The first control unit includes: a first MOSFET; The second control unit includes: a second MOSFET and a current mirror; The gate and drain of the first MOS transistor are shorted together and connected to the source of the second MOS transistor; The source of the first MOSFET is connected to the other end of the second resistor, and then to the gate of the second MOSFET. The gate and drain of the first MOSFET are grounded; The current mirror includes: a third MOSFET and a fourth MOSFET; The sources of the third and fourth MOS transistors are connected to the operating voltage. The gate and drain of the third MOS transistor are shorted together, and the drain is connected to the drain of the second MOS transistor. The drain of the fourth MOS transistor is connected to the controlled circuit; The threshold voltage of the first MOSFET is lower than the threshold voltage of the second MOSFET; The current detection unit includes: a fifth MOSFET and a sixth MOSFET; The source of the fifth MOS transistor is connected to the operating voltage, the gate is connected to the drain of the third MOS transistor, and the drain is connected to the source of the sixth MOS transistor. The gate and drain of the sixth MOS transistor are shorted together and connected to the gate of the second MOS transistor, while the source is connected to the drain of the fifth MOS transistor. The second MOS transistor is an NMOS transistor, while the third, fourth, fifth, and sixth MOS transistors are all PMOS transistors.

2. The enabling circuit used as a switch according to claim 1, characterized in that, Let the on-state voltage of the circuit be... Then we have: ， in, Let be the resistance value of the first resistor. This is the resistance value of the second resistor. The current from the first current source is... Hole mobility The gate capacitance per unit area of ​​the MOSFET. The width to length ratio of the first MOS transistor. The threshold voltage of the second MOSFET is . The threshold voltage of the first MOSFET is given.

3. The enabling circuit used as a switch according to claim 2, characterized in that, Let the circuit turn-off voltage be... Then we have: ， in, K The size ratio of the third MOS transistor to the fifth MOS transistor. The second current value, the third current = .

4. The enabling circuit used as a switch according to claim 1, characterized in that, The circuit also includes: The voltage clamping unit, with one end connected to the other end of the second resistor and the other end grounded, includes a set of NMOS transistors, wherein the connection of each NMOS transistor to the circuit is equivalent to that of a diode.

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