LDO over-current protection circuit, method, device and medium without static power consumption

Abstract

The application discloses a static power consumption-free LDO overcurrent protection circuit, method, device and medium, and relates to the technical field of overcurrent protection circuits.The circuit comprises a current sampling module, which is used for collecting the output current of a power tube of an LDO in a first proportion; a switch module, which is connected with the gate of the power tube; a current limiting module, which is used for collecting the output current collected by the current sampling module in a second proportion, and which is connected with the switch module and the current sampling module, and which is further used for controlling whether the switch module is turned on; and an overcurrent starting module, which is connected with the current limiting module and the current sampling module, and which is used for controlling whether the current sampling module and the current limiting module are started; wherein, when the output current continues to rise to an overcurrent value, the switch module is turned on, the gate voltage of the power tube is limited, and the output current continues to rise; and the first preset value is smaller than the overcurrent value.The circuit can protect the LDO from overcurrent and reduce power consumption.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of over-current protection circuit, in particular to an LDO over-current protection circuit without static power consumption, method, device and medium. BACKGROUND

[0002] Low Dropout Regulator (LDO) is widely used in integrated circuits, which can provide high-precision, low-noise, high-stability power supply for each module in the integrated circuit. However, LDO will face the risk of burning out in the case of current overload or short circuit. As an auxiliary circuit of LDO, the over-current protection circuit can quickly adjust the working state of LDO when LDO appears short circuit or large load current, so as to avoid damage.

[0003] At present, there are two types of over-current protection circuits for LDO. One is the traditional fixed over-current limit LDO protection circuit (such as Figure 1 indicated), and the other is the foldback over-current protection circuit (such as Figure 2 indicated).

[0004] The maximum output current of the traditional fixed over-current limit protection circuit is a fixed value, which mainly includes three parts (such as Figure 1 indicated): a current sampling module composed of NM1 and PM1; a current comparison module composed of PM2, NM2 and NM3; and a switch tube composed of NM4. The current sampling module collects the current of the power tube (M POWER), and the current is mirrored to PM2 by PM1, and the reference current flowing through NM2 is mirrored by NM3. When the power tube current increases, the gate voltage of PM2 decreases, and the current flowing through PM2 tends to rise, but NM3 is biased by a fixed gate voltage. Therefore, in response to the rising current, the voltage at point P will rise. When it rises to a certain trend, the switch tube NM4 begins to conduct, and the gate voltage of the power tube is clamped, thereby limiting the current from rising continuously.

[0005] When the current of the foldback over-current protection circuit reaches the over-current value, the reference current will continuously decrease, and thus the output current of the LDO will also decrease, and finally reaches a lower level. It mainly consists of four parts (as shown in 2): a current collection circuit consisting of NM1 and PM1; a current comparison module consisting of PM2 and NM3; a switch tube consisting of NM2; a current foldback module consisting of NM4, PM3, PM4, NM5, resistors R1 and R2, and an error amplifier EA1. The current collection circuit, switch tube and current comparison circuit of the foldback over-current protection circuit are consistent with the working principle of the conventional fixed over-current limit protection circuit. The positive input end of the error amplifier EA1 of the current foldback module is connected to the output voltage of the LDO. When the LDO is working normally, the output voltage of the error amplifier remains stable, and the current limit value is stable at the initial size. When the load continues to increase, but the load current cannot continue to rise, the output voltage of the LDO will decrease, and thus the reference current will decrease, and thus the over-current value will decrease, and the output current of the LDO will also decrease until it decreases to a lower level.

[0006] By Figure 1 It can be seen that the fixed over-current limit LDO protection circuit is also in a working state when the LDO is not over-current, which increases the power consumption of the LDO when it is working normally. When the LDO is powered on, the gate voltage of the switch tube is not low, although the switch tube is in the cut-off state, but the tube still has the trend of continuing to rise the limited power tube gate voltage, which will have a great influence on the establishment time of the LDO.

[0007] The foldback over-current protection circuit is also in a working state when the LDO is not over-current, so it also has certain static power consumption, which will also have a certain influence on the overall system power consumption, and will also affect the establishment time of the LDO. Moreover, the foldback over-current protection circuit has a latch effect, which will face the risk of being unable to start the load. In addition, the foldback over-current protection circuit has a complex structure and a large area, and its practicability is lower than that of other over-current protection circuits. SUMMARY

[0008] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application proposes a static power consumption-free LDO over-current protection circuit, method, device and medium, which can protect the LDO from over-current and reduce power consumption.

[0009] In a first aspect, the static power consumption-free LDO over-current protection circuit according to the embodiments of the present application comprises:

[0010] A current sampling module is configured to collect the output current of the power tube of the LDO in a first proportion.

[0011] A switch module is connected to the gate of the power tube.

[0012] A current limiting module is configured to collect the output current collected by the current sampling module in a second proportion, the current limiting module is connected with the switch module and the current sampling module, and the current limiting module is further configured to control whether the switch module is turned on or not;

[0013] An overcurrent starting module is connected with the current limiting module and the current sampling module, and the overcurrent starting module is configured to control whether the current sampling module and the current limiting module are started or not;

[0014] When the output current of the LDO is lower than a first preset value, the current sampling module, the switch module, the current limiting module and the overcurrent starting module all do not work; when the output current rises to the first preset value, the current limiting module and the overcurrent starting module start to work, and the switch module is in an off state; when the output current continues to rise to an overcurrent value, the switch module is turned on, the gate voltage of the power tube is limited, so that the output current continues to rise is limited; and the first preset value is less than the overcurrent value.

[0015] According to some embodiments of the present application, the current sampling module comprises:

[0016] A first MOS tube, a gate of the first MOS tube is connected with a gate of the power tube, and a source of the first MOS tube is connected with a source of the power tube;

[0017] A second MOS tube, a drain of the second MOS tube is connected with a drain of the first MOS tube, and a gate of the second MOS tube is connected with the current limiting module and the overcurrent starting module;

[0018] A third MOS tube, a source of the third MOS tube is connected with a source of the second MOS tube, a gate of the third MOS tube is connected with the current limiting module and the overcurrent starting module.

[0019] According to some embodiments of the present application, the current limiting module comprises:

[0020] A fourth MOS tube, a gate of the fourth MOS tube is connected with a gate of the second MOS tube and the overcurrent starting module, a drain of the fourth MOS tube is connected with the ground through a plurality of resistors connected in series, one end of one of the resistors is connected with the overcurrent starting module, and one end of another of the resistors is connected with the switch module;

[0021] A fifth MOS tube, a source of the fifth MOS tube is connected with a source of the fourth MOS tube, a gate of the fifth MOS tube is connected with a gate of the third MOS tube and the overcurrent starting module.

[0022] According to some embodiments of the present application, the over-current starting module comprises:

[0023] a sixth MOS tube, a source of the sixth MOS tube is connected to the power supply, a gate of the sixth MOS tube is connected to a drain of the sixth MOS tube, a gate of the third MOS tube and a gate of the fifth MOS tube;

[0024] a seventh MOS tube, a source of the seventh MOS tube is connected to a drain of the sixth MOS tube, a gate of the seventh MOS tube is connected to a gate of the second MOS tube, a gate of the fourth MOS tube and a drain of the first MOS tube;

[0025] an eighth MOS tube, a drain of the eighth MOS tube is connected to a drain of the seventh MOS tube, a gate of the eighth MOS tube is connected to one end of one of the resistors, and a source of the eighth MOS tube is grounded.

[0026] According to some embodiments of the present application, the switch module comprises a ninth MOS tube, a drain of the ninth MOS tube is connected to a gate of the first MOS tube and a gate of the power tube, a source of the ninth MOS tube is grounded, and a gate of the ninth MOS tube is connected to one end of another resistor.

[0027] According to some embodiments of the present application, a ratio of a gate length of the first MOS tube to a gate length of the power tube is the same, and a ratio of a gate width of the first MOS tube to a gate width of the power tube is equal to the first ratio.

[0028] According to some embodiments of the present application, the ratio of the gate length to the gate width of the second MOS tube and the ratio of the gate length to the gate width of the third MOS tube are set such that the first MOS tube operates in a nonlinear region when the output current rises to the over-current value.

[0029] In a second aspect, an over-current protection method according to an embodiment of the present application, based on the static power consumption-free LDO over-current protection circuit as described in the first aspect, the method comprises:

[0030] acquiring, by the current sampling module, an output current of a power tube of the LDO at a first ratio;

[0031] acquiring, by the current limiting module, the output current acquired by the current sampling module at a second ratio;

[0032] when the output current is lower than a first preset value, causing the current sampling module, the switch module, the current limiting module and the over-current starting module to all not work;

[0033] When the output current rises to the first preset value, the current sampling module, the current limiting module and the overcurrent starting module are enabled to make the switch module in an off state;

[0034] When the output current continues to rise to an overcurrent value, the switch module is turned on to limit the gate voltage of the power tube and limit the output current from continuing to rise; the first preset value is less than the overcurrent value.

[0035] In a third aspect, an electronic device according to the embodiment of the present application includes the static power consumption free LDO overcurrent protection circuit according to the first aspect.

[0036] In a fourth aspect, a storage medium according to the embodiment of the present application stores computer executable instructions for causing a computer to execute the overcurrent protection method according to the second aspect.

[0037] The static power consumption free LDO overcurrent protection circuit, method, device and medium according to the embodiment of the present application have at least the following beneficial effects: the overcurrent starting module is used to control whether the current sampling module and the current limiting module are enabled, when the output current of the power tube of the LDO is small, the LDO works normally and there is no overcurrent risk, and the current sampling module, the switch module, the current limiting module and the overcurrent starting module do not work, thereby saving the static power consumption of the LDO; when the output current of the power tube of the LDO gradually increases to a first preset value, the overcurrent starting module is enabled first to enable the current sampling module and the current limiting module; when the output current of the power tube of the LDO continues to increase to an overcurrent value, the switch module is turned on by the current limiting module to limit the gate voltage of the power tube, thereby limiting the output current from continuing to rise and realizing overcurrent protection of the LDO. The circuit works only when the output current is large, thereby reducing the static power consumption of the circuit.

[0038] Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and / or can be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0039] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, taken in conjunction with the accompanying drawings, in which:

[0040] Figure 1 A circuit schematic diagram of a fixed overcurrent limit LDO protection circuit in the prior art;

[0041] Figure 2 A circuit schematic diagram of a foldback overcurrent protection circuit according to the embodiment of the present application;

[0042] Figure 3 Module block diagram of the LDO over-current protection circuit without static power consumption of the embodiment of the present application;

[0043] Figure 4 Circuit principle diagram of the LDO over-current protection circuit without static power consumption of the embodiment of the present application;

[0044] Figure 5 Image of the output current of the power tube varying with the load impedance of the embodiment of the present application;

[0045] Figure 6 Image of the current of the first MOS tube varying with the load impedance of the embodiment of the present application;

[0046] Figure 7 Image of the gate voltage of the power tube varying with the load impedance of the embodiment of the present application;

[0047] Figure 8 Step flow chart of the over-current protection method of the embodiment of the present application. DETAILED DESCRIPTION

[0048] The embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only, and are used only for the purpose of explaining the present application, and should not be understood as limiting the present application. For the step numbers in the following embodiments, they are only set for the convenience of explanation, and the order between the steps is not limited in any way, and the execution order of each step in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0049] In the description of the present application, it should be understood that the orientation description, such as the orientation or position relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be understood as limiting the present application.

[0050] The terms "first", "second", "third", and "fourth" and the like in the description, claims, and drawings of the present application are used to distinguish different objects, and are not intended to describe a particular order. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but can optionally include steps or units not listed, or can optionally include other steps or units inherent to the process, method, product, or device.

[0051] Reference to an "embodiment" in this disclosure means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. As will be apparent to those of ordinary skill in the art, embodiments described herein can be combined with other embodiments.

[0052] The embodiment of the application provides a static power consumption-free LDO overcurrent protection circuit, method, device and medium, the circuit comprises: a current sampling module, which is used for collecting an output current of a power tube of an LDO in a first proportion; a switch module connected with a gate of the power tube; a current limiting module, which is used for collecting the output current collected by the current sampling module in a second proportion, the current limiting module is connected with the switch module and the current sampling module, and the current limiting module is further used for controlling whether the switch module is turned on; an overcurrent starting module connected with the current limiting module and the current sampling module, the overcurrent starting module is used for controlling whether the current sampling module and the current limiting module are started; wherein, when the output current of the LDO is lower than a first preset value, the current sampling module, the switch module, the current limiting module and the overcurrent starting module are all not working; when the output current rises to the first preset value, the current limiting module and the overcurrent starting module start to work, and the switch module is in a disconnected state; when the output current continues to rise to an overcurrent value, the switch module is turned on, the gate voltage of the power tube is limited, and thus the output current continues to rise is limited; and the first preset value is smaller than the overcurrent value. The circuit controls whether the current sampling module and the current limiting module are started through the overcurrent starting module, when the output current of the power tube of the LDO is small, the LDO normally works, there is no overcurrent risk, and the current sampling module, the switch module, the current limiting module and the overcurrent starting module are all not working, so that the static power consumption of the LDO is saved; when the output current of the power tube of the LDO gradually increases to the set first preset value, at this time, the overcurrent is close, but there is no real overcurrent, at this time, the overcurrent starting module is started first, and the current sampling module and the current limiting module are started; when the output current of the power tube of the LDO continues to increase to the overcurrent value, at this time, the current limiting module controls the switch module to be turned on, so that the switch module limits the gate voltage of the power tube, and thus the output current continues to rise is limited, and the overcurrent protection of the LDO is realized. The circuit only works when the output current is large, so that the static power consumption of the circuit can be reduced.

[0053] The static power consumption-free LDO overcurrent protection circuit, method, device and medium of the embodiment of the application are described in detail below with reference to the drawings.

[0054] On the one hand, embodiments of the present invention propose an LDO overcurrent protection circuit with no static power consumption, such as... Figure 3 As shown, the circuit includes a current sampling module 100, a current limiting module 200, an overcurrent start-up module 300, and a switching module 400. The current sampling module 100 is used to sample the output current of the LDO's power transistor (M POWER) at a first ratio. The current limiting module 200 is connected to the switching module 400, the overcurrent start-up module 300, and the current sampling module 100. The current limiting module 200 is used to sample the output current sampled by the current sampling module 100 at a second ratio and also controls whether the switching module 400 is turned on. The switching module 400 is connected to the gate of the power transistor. The overcurrent start-up module 300 is connected to the current limiting module 200 and the current sampling module 100 and controls whether the current sampling module 100 and the current limiting module 200 are activated. When the LDO... When the output current is lower than the first preset value, the current sampling module 100, the switching module 400, the current limiting module 200, and the overcurrent start-up module 300 are all inactive. When the output current rises to the first preset value, the current sampling module 100, the current limiting module 200, and the overcurrent start-up module 300 start working, and the switching module 400 is in the off state. When the output current continues to rise to the overcurrent value, the switching module 400 turns on, limiting the gate voltage of the power transistor, thereby limiting the output current from continuing to rise. The first preset value is less than the overcurrent value.

[0055] According to the LDO overcurrent protection circuit with no static power consumption according to the embodiments of this application, the overcurrent activation module 300 controls whether the current sampling module 100 and the current limiting module 200 are activated. When the output current of the LDO power transistor is small, the LDO is working normally and there is no risk of overcurrent. The current sampling module 100, the switching module 400, the current limiting module 200, and the overcurrent activation module 300 are all inactive, thereby saving the static power consumption of the LDO. When the output current of the LDO power transistor gradually increases and reaches a set first preset value, it is close to overcurrent but has not yet actually become overcurrent. At this time, the overcurrent activation module 300 is activated, which also drives the current sampling module 100 and the current limiting module 200 to activate. When the output current of the LDO power transistor continues to increase to the overcurrent value, the current limiting module 200 controls the switching module 400 to conduct, so that the switching module 400 limits the gate voltage of the power transistor, thereby limiting the output current from continuing to rise and realizing overcurrent protection for the LDO. This circuit only operates when the output current is large, thereby reducing the static power consumption of the circuit.

[0056] Furthermore, such as Figure 4As shown, in some embodiments of the present application, the current sampling module 100 includes a first MOS NM6, a second MOS PM5 and a third MOS PM6, wherein the gate of the first MOS NM6 is connected with the gate of the power tube (M POWER), the source of the first MOS NM6 is connected with the source of the power tube, the drain of the power tube is connected with the power supply (VDD), the source of the power tube is grounded through the feedback resistor R, and the source of the power tube is used to output the output current (ILOAD) of the LDO; the drain of the second MOS PM5 is connected with the drain of the first MOS NM6, the gate of the second MOS PM5 is connected with the current limiting module 200 and the overcurrent starting module 300; the drain of the third MOS PM6 is connected with the source of the second MOS PM5, the source of the third MOS PM6 is connected with the power supply VDD, and the gate of the third MOS PM6 is connected with the current limiting module 200 and the overcurrent starting module 300.

[0057] In the present example, the current sampling module 100 is composed of NM6, PM5 and PM6, the current of the power tube is accurately copied through the first MOS NM6, the gate and source of the first MOS NM6 are connected with the gate and source of the power tube M POWER, so that the VGS (Voltage between Gate and Source) is equal, the current of the power tube can be sampled, and in order to improve the sampling accuracy, the gate length of the first MOS NM6 is consistent with the gate length of the power tube. Since the size of the current of the power tube is too large, it is necessary to scale down the current by a first proportion, and the gate length of the first MOS NM6 is consistent, so that the sampled current is K1 times (K1 1, K1 is the first proportion) of the load current ILOAD of the power tube, and the gate width of the first MOS NM6 is only adjusted to K1 times of the gate width of the power tube. The second MOS PM5 and the third MOS PM6 flow through the current of the first MOS NM6, wherein the second MOS PM5 is diode-connected, the gate voltage is self-biased, the gate voltages of the second MOS PM5 and the third MOS PM6 are provided by the overcurrent starting module 300, and the second MOS PM5 and the third MOS PM6 are controlled by the overcurrent starting module 300 to be non-conductive when there is no overcurrent, but when there is overcurrent, the voltage drop of the second MOS PM5 and the third MOS PM6 to the drain of the first MOS NM6 is the VDSAT (saturation drain-source voltage) of PM6 and the VGS of PM5. In order to avoid that the first MOS NM6 enters the linear region when working in overcurrent, the width-length ratio of the second MOS PM5 and the third MOS PM6 can be set to be larger, so that the VDSAT of PM6 and the VGS of PM5 are slightly smaller when working in overcurrent, so as not to make the first MOS NM6 enter the linear region and cause inaccurate sampling current.

[0058] Furthermore, such as Figure 4 As shown, in some embodiments of this application, the current limiting module 200 includes: a fourth MOSFET PM8 and a fifth MOSFET PM7. The gate of the fourth MOSFET PM8 is connected to the gate of the second MOSFET PM5 and the overcurrent startup module 300. The drain of the fourth MOSFET PM8 is grounded through a plurality of resistors connected in series. One end of one resistor is connected to the overcurrent startup module 300, and one end of the other resistor is connected to the switching module 400. The drain of the fifth MOSFET PM7 is connected to the source of the fourth MOSFET PM8. The source of the fifth MOSFET PM7 is connected to the power supply. The gate of the fifth MOSFET PM7 is connected to the gate of the third MOSFET PM6 and the overcurrent startup module 300. In this example, multiple resistors connected in series include resistors R3, R4, and R5. One end of resistor R3 is connected to the drain of the fourth MOSFET PM8, the other end of resistor R3 is connected to one end of resistor R4, the other end of resistor R4 is connected to one end of resistor R5, and the other end of resistor R5 is grounded. One end of resistor R4 is connected to the overcurrent startup module 300, and the other end of resistor R5 is connected to the switching module 400. It should be noted that the number of resistors connected in series can be set according to actual needs, and is not limited to this.

[0059] In this example, PM7, PM8, R3, R4, and R5 constitute the current limiting module 200. Within the current limiting module 200, PM7 and PM8 precisely replicate the output current collected by the current sampling module 100, and the connected resistors generate a voltage to provide a gate voltage to the switching module 400, controlling whether the switching module 400 is turned on. Since one end of resistor R4 is connected to the overcurrent startup module 300, the voltage at one end of resistor R4 can control whether the overcurrent startup module 300 operates. The overcurrent startup module 300 then controls whether PM5, PM6, PM7, and PM8 are turned on, thereby controlling the operating state of the current limiting module 200 and the current sampling module 100. Because the gate of PM7 is connected to the gate of PM6, and the gate of PM8 is connected to the gate of PM5, PM8 and PM7 form a common-source, common-gate current mirror, which can precisely replicate the currents of PM6 and PM5 at a second ratio. Even after the current sampling module (100) reduces the current by a factor of 1, the output current of the power transistor is still relatively large. We need to further reduce it. Therefore, we make the gate length of PM7 equal to that of PM5, and the gate width of PM7 K2 times that of PM5 (K2 is less than 1, so K2 is the second factor). The gate length of PM8 is equal to that of PM5, and the gate width of PM8 is K2 times that of PM5. Therefore, the current flowing through PM8 and PM7 when they are turned on is ILOAD. K2 K1. This current then passes through resistors R3, R4, and R5, generating a voltage at the positive terminal of the resistors. The positive terminal of R5 is connected to the switch module 400 to control whether the switch module 400 is turned on, and the positive terminal of R4 is connected to the overcurrent start module 300 to control whether the overcurrent start module 300 is started.

[0060] Furthermore, such as Figure 4 As shown, in some embodiments of this application, the overcurrent start-up module 300 includes a sixth MOSFET PM9, a seventh MOSFET PM10, and an eighth MOSFET NM8. The source of the sixth MOSFET PM9 is connected to the power supply, and the gate of the sixth MOSFET PM9 is connected to the drain of the sixth MOSFET PM9, the gate of the third MOSFET PM6, and the gate of the fifth MOSFET PM7. The source of the seventh MOSFET PM10 is connected to the drain of the sixth MOSFET PM9, and the gate of the seventh MOSFET PM10 is connected to the gate of the second MOSFET PM5, the gate of the fourth MOSFET PM8, and the drain of the first MOSFET NM6. The drain of the eighth MOSFET NM8 is connected to the drain of the seventh MOSFET PM10, the gate of the eighth MOSFET NM8 is connected to one end of the resistor R4, and the source of the eighth MOSFET NM8 is grounded.

[0061] In the overcurrent startup module 300, the sixth MOSFET PM9 is connected as a diode, and its gate voltage generated by self-biasing is provided to PM6 and PM7 to control whether the entire circuit works. The gate voltage of the seventh MOSFET PM10 is provided by the gate voltage generated by the self-biasing of PM5. PM9 and PM10 form a pseudo common-source common-gate current mirror, the purpose of which is to make its current consistent with that of PM7 and PM8 when it is turned on.

[0062] Furthermore, such as Figure 4 As shown, in some embodiments of this application, the switching module 400 includes a ninth MOSFET NM7. The drain of the ninth MOSFET NM7 is connected to the gate of the first MOSFET NM6 and the gate of the power transistor. The source of the ninth MOSFET NM7 is grounded, and the gate of the ninth MOSFET NM7 is connected to one end of a resistor R5. The gate of the first MOSFET NM6 and the gate of the power transistor are also connected to a bias voltage VGAT.

[0063] The following details how the entire overcurrent protection circuit works:

[0064] When the load current of the power transistor is small, if the current limiting module 200 is turned on, the current flowing through PM7 and PM8 should be ILOAD. K2 If K1 is given, then the voltage at the gate of NM8 should be (R4 + R5). ILOAD K2 K1. When this voltage is less than the turn-on voltage V of NM8.ON·NM8 When the load current is zero, the over-current starting module 300 is not turned on, the gate voltage of PM9 generated by self-bias is close to VDD, PM7 and PM6 are not turned on, and thus the whole circuit is not started. In fact, the current flowing through the resistor is 0, and the gate voltage of NM8 is also 0. With the increase of the load current of the power tube, although no current flows through the resistor, the resistor has a tendency to generate voltage. Once (R4+R5) ILOAD K2 K1 is greater than V ON·NM8 , NM8 has a tendency to be turned on, the gate voltage of PM9 generated by self-bias is provided to PM7 and PM6, PM7 and PM6 are turned on, and thus the protection circuit is formally turned on. In order to make the over-current starting module 300 have a tendency to be turned on while the whole protection circuit is turned on, we can make the width-length ratio of PM9 slightly larger than that of PM7, and the width-length ratio of PM10 remains the same as that of PM8. In this way, when the over-current starting module 300 is turned on, the VGS generated by PM9 is slightly larger than the VGS required by PM7 and PM6, and the circuit is certainly turned on. Therefore, we can see that when the protection circuit is started, the load current of the power tube is:

[0065] ;

[0066] In order to make the protection circuit work more stably, we do not make the protection circuit and the switching module 400 open at the same time, which will cause the gate voltage of NM7 to be extremely unstable, and the over-current protection circuit will switch between the turned-on and turned-off states. Therefore, we make the whole over-current protection circuit be turned on at a certain current value (i.e. the first preset value) before reaching the over-current value, and NM7 is turned on only when the over-current value is reached. Let the over-current value be I OVERLOAD , then I START <I OVERLOAD .

[0067] After the over-current protection circuit is turned on, with the continuous increase of the load current of the power tube, the current flowing through R3 will continue to increase, and the gate voltage R3 ILOAD K2 K1 increases, and when the gate voltage is greater than the turn-on voltage VON of the switching tube, the switching tube is turned on, and thus the gate voltage of the power tube is limited, and the current of the power tube continues to rise. At this time, the over-current value is:

[0068] .

[0069] Next, we simulate and verify the circuit. As shown in Figure 5 , the output current of the power tube changes with the load impedance. The vertical coordinate IPOWERMOS is the output current of the power tube, and the horizontal coordinate RLOAD is the load impedance. As shown in Figure 6As shown in the figure, it is a graph of the current of the first MOS NM6 changing with the load impedance, the vertical coordinate INM6 is the current of NM6; as Figure 7 As shown in the figure, it is a graph of the voltage VGAT changing with the load impedance. It can be seen that with the decrease of the load impedance, the output current of the power tube begins to gradually rise, and when the load impedance is about 80 ohms at point A, the load current of the power tube is about 67 mA, at this time the current of the first MOS NM6 of the current sampling module 100 is about 21.4 nA, which tends to zero, and the gate voltage provided by the switch tube NM7 is about 0.7 mV. It can be seen that at this time, the current limiting module 200, the overcurrent starting module 300 and the switch module 400 do not work. When the load impedance decreases to about 29 ohms, at this time the load current of the power tube is 180 mA, the current of the first MOS NM6 begins to rise to 25 uA, and the current limiting module 200 and the overcurrent starting module 300 begin to work. At this time, the gate voltage of NM7 begins to rise, but does not reach the starting condition, and does not begin to limit the current. When the load impedance decreases to about 20 ohms, the gate voltage of NM7 rises to 850 mV, begins to conduct, begins to limit the current and makes it slowly decrease to a lower level.

[0070] It can be seen that when the LDO works normally, the whole overcurrent protection circuit does not start, and there is no static power consumption. When the load current of the LDO is large, the current limiting module 200 and the overcurrent starting module 300 start first, at this time NM7 does not conduct. When the load current reaches the set overcurrent value, NM7 conducts, at this time the load current begins to be limited. The current when the whole overcurrent protection circuit starts and the overcurrent can be adjusted by adjusting the resistance value and the size of the MOS tube.

[0071] Compared with the traditional fixed overcurrent limiting protection circuit and the foldback overcurrent protection circuit, the static power consumption-free LDO overcurrent protection circuit according to the application has no influence on the establishment process of the LDO, no latch-up effect, fast recovery ability, simple structure, small area and strong practicability.

[0072] On the other hand, as shown in the figure, based on the static power consumption-free LDO overcurrent protection circuit, the embodiment of the application further proposes an overcurrent protection method, which comprises the following steps: Figure 8

[0073] Step S100: collecting the output current of the power tube of the LDO by the current sampling module 100 in a first proportion;

[0074] Step S200: collecting the output current collected by the current sampling module 100 by the current limiting module 200 in a second proportion;

[0075] ​Step S300: when the output current is lower than the first preset value, the current sampling module 100, the switch module 400, the current limiting module 200 and the overcurrent starting module 300 are all not working;

[0076] Step S400: when the output current rises to the first preset value, the current sampling module 100, the current limiting module 200 and the overcurrent starting module 300 start working, and the switch module 400 is in the off state;

[0077] Step S500: when the output current continues to rise to the overcurrent value, the switch module 400 is turned on, the gate voltage of the power tube is limited, and the output current continues to rise; the first preset value is less than the overcurrent value.

[0078] Specifically, referring to Figure 4 In the example, the current sampling module 100 is composed of NM6, PM5 and PM6. The current of the power tube is accurately copied through the first MOS tube NM6. The first MOS tube NM6 is connected with the gate and source of the power tube M POWER, so that the VGS (Voltage between Gate and Source) is equal, and the current of the power tube can be sampled. In order to improve the sampling accuracy, the gate length of the first MOS tube NM6 is consistent with the gate length of the power tube. Because the size of the current of the power tube is too large, the current needs to be scaled down. The output current of the power tube is collected according to the first proportion. The gate length has been made consistent. In order to make the sampled current K1 times (K1 1, K1 is the first proportion) of the load current ILOAD of the power tube, we only need to adjust the gate width of the first MOS tube NM6 to K1 times of the gate width of the power tube. The second MOS tube PM5 and the third MOS tube PM6 flow through the current of the first MOS tube NM6. The second MOS tube PM5 is diode connected, and the gate voltage is self-biased. The gate voltages of the second MOS tube PM5 and the third MOS tube PM6 are provided by the overcurrent starting module 300. When there is no overcurrent, the second MOS tube PM5 and the third MOS tube PM6 are not turned on. When there is overcurrent, the voltage drop from the second MOS tube PM5 and the third MOS tube PM6 to the drain of the first MOS tube NM6 is PM6 VDSAT (saturation drain-source voltage) and PM5 VGS. In order to avoid that the first MOS tube NM6 enters the linear region when working in overcurrent, we can set the width-length ratio of the second MOS tube PM5 and the third MOS tube PM6 to be larger, so that PM6 VDSAT and PM5 VGS are slightly smaller when working in overcurrent, so as not to make the first MOS tube NM6 enter the linear region and cause inaccurate collection of current.

[0079] As Figure 4As shown, in this example, PM7, PM8, R3, R4, and R5 constitute the current limiting module 200. Within the current limiting module 200, PM7 and PM8 precisely replicate the output current collected by the current sampling module 100, and the connected resistors generate a voltage to provide a gate voltage to the switching module 400, controlling whether the switching module 400 is turned on. Since one end of resistor R4 is connected to the overcurrent startup module 300, the voltage at one end of resistor R4 can control whether the overcurrent startup module 300 operates. The overcurrent startup module 300 then controls whether PM5, PM6, PM7, and PM8 are turned on, thereby controlling the operating state of the current limiting module 200 and the current sampling module 100. Because the gate of PM7 is connected to the gate of PM6, and the gate of PM8 is connected to the gate of PM5, PM8 and PM7 form a common-source, common-gate current mirror, which can precisely replicate the currents of PM6 and PM5 at a second ratio. Even after the current sampling module (100) reduces the current by a factor of 1, the output current of the power transistor is still relatively large. We need to further reduce it. Therefore, we make the gate length of PM7 equal to that of PM5, and the gate width of PM7 K2 times that of PM5 (K2 is less than 1, so K2 is the second factor). The gate length of PM8 is equal to that of PM5, and the gate width of PM8 is K2 times that of PM5. Therefore, the current flowing through PM8 and PM7 when they are turned on is ILOAD. K2 K1. This current then passes through resistors R3, R4, and R5, generating a voltage at the positive terminal of the resistors. The positive terminal of R5 is connected to the switch module 400 to control whether the switch module 400 is turned on, and the positive terminal of R4 is connected to the overcurrent start module 300 to control whether the overcurrent start module 300 is started.

[0080] Furthermore, such as Figure 4 As shown, in some embodiments of this application, the overcurrent start-up module 300 includes a sixth MOSFET PM9, a seventh MOSFET PM10, and an eighth MOSFET NM8. The source of the sixth MOSFET PM9 is connected to the power supply, and the gate of the sixth MOSFET PM9 is connected to the drain of the sixth MOSFET PM9, the gate of the third MOSFET PM6, and the gate of the fifth MOSFET PM7. The source of the seventh MOSFET PM10 is connected to the drain of the sixth MOSFET PM9, and the gate of the seventh MOSFET PM10 is connected to the gate of the second MOSFET PM5, the gate of the fourth MOSFET PM8, and the drain of the first MOSFET NM6. The drain of the eighth MOSFET NM8 is connected to the drain of the seventh MOSFET PM10, the gate of the eighth MOSFET NM8 is connected to one end of the resistor R4, and the source of the eighth MOSFET NM8 is grounded.

[0081] In the over-current starting module 300, the sixth MOS PM9 is diode-connected, and the self-bias generated gate voltage is provided to PM6 and PM7, which controls whether the whole circuit works or not. The gate voltage of the seventh MOS PM10 is provided by the self-bias generated gate voltage of PM5. PM9 and PM10 constitute a pseudo common-source common-gate current mirror, and the purpose is that when it is turned on, it can be consistent with the current of PM7 and PM8.

[0082] Further, as shown in some embodiments of the present application, the switch module 400 includes the ninth MOS NM7, the drain of the ninth MOS NM7 is connected with the gate of the first MOS NM6 and the gate of the power tube, the source of the ninth MOS NM7 is grounded, and the gate of the ninth MOS NM7 is connected with one end of the resistor R5. The gate of the first MOS NM6 and the gate of the power tube are also connected with the bias voltage VGAT. Figure 4

[0083] The following will be described in detail, and the whole over-current protection circuit is how to work:

[0084] When the load current of the power tube is small, if the current limiting module 200 is turned on, the current flowing through PM7 and PM8 should be ILOAD K2 K1, then the voltage at the gate of NM8 should be (R4+R5) ILOAD K2 K1. When this voltage is less than the turn-on voltage V ON·NM8 of NM8, the over-current starting module 300 is not turned on, the self-bias generated gate voltage of PM9 is close to VDD, PM7 and PM6 are not turned on, so the whole circuit is not started, and actually the current flowing through the resistor is 0, and the gate voltage of NM8 is also 0. As the load current of the power tube increases, although no current flows through the resistor, it has a tendency to generate a voltage. Once (R4+R5) ILOAD K2 K1 is greater than V ON·NM8 , NM8 has a tendency to turn on, the self-bias generated gate voltage of PM9 is provided to PM7 and PM6, PM7 and PM6 are turned on, and at this time the protection circuit is formally turned on. In order to make the over-current starting module 300 have a tendency to turn on, the whole protection circuit must be turned on, we can make the width-length ratio of PM9 slightly larger than that of PM7, and the width-length ratio of PM10 remains the same as that of PM8. In this way, when the over-current starting module 300 is turned on, the VGS generated by PM9 is slightly larger than the VGS required by PM7 and PM6, and the circuit is certainly turned on. Therefore, we can see that when the protection circuit is started, the load current of the power tube is:

[0085] ;​

[0086] In order to make the protection circuit work more stably, we do not make the protection circuit and the switch module 400 open at the same time, which will cause the gate voltage of NM7 to be unstable, and the overcurrent protection circuit will switch between the on and off states. Therefore, we make the entire overcurrent protection circuit conduct at a certain current value (i.e. the first preset value) before reaching the overcurrent value, and NM7 is only turned on when the overcurrent value is reached. Let the overcurrent value be I OVERLOAD , then I START <I OVERLOAD .

[0087] After the overcurrent protection circuit is turned on, as the load current of the power tube continues to increase, the current flowing through R3 will continue to increase, and its gate voltage R3 ILOAD K2 K1 increases, and when the gate voltage is greater than the turn-on voltage VON·NM2 of the switch tube, the switch tube is turned on, thereby limiting the gate voltage of the power tube, so that the current of the power tube continues to rise, and the overcurrent value at this time is:

[0088] .

[0089] Next, we simulate and verify the circuit, as shown in Figure 5 , the output current of the power tube changes with the load impedance image, the vertical coordinate IPOWERMOS is the output current of the power tube, and the horizontal coordinate RLOAD is the load impedance; as shown in Figure 6 , the current of the first MOS tube NM6 changes with the load impedance image, the vertical coordinate INM6 is the current of NM6; as shown in Figure 7 , the voltage VGAT changes with the load impedance image. It can be seen that as the load impedance decreases, the output current of the power tube begins to gradually rise, and at point A, the load impedance is about 80 ohms, and the load current of the power tube is about 67 mA. At this time, the current of the first MOS tube NM6 of the current sampling module 100 is 21.4 nA, which tends to zero, and the gate voltage provided by the switch tube NM7 is about 0.7 mV. It can be seen that at this time, the current limiting module 200, the overcurrent starting module 300 and the switch module 400 are not working. When the load impedance decreases to about 29 ohms, the load current of the power tube is 180 mA, and the current of the first MOS tube NM6 begins to rise to 25 uA, and the current limiting module 200 and the overcurrent starting module 300 begin to work. At this time, the gate voltage of NM7 begins to rise, but has not reached the starting condition, and has not begun to limit the current. When the load impedance decreases to about 20 ohms, the gate voltage of NM7 rises to 850 mV, and begins to conduct, and begins to limit the current and make it slowly decrease to a lower level.

[0090] It can be seen that when the LDO is normally working, the whole over-current protection circuit is not started, and there is no static power consumption. When the load current of the LDO is large, the current limiting module 200 and the over-current starting module 300 are started first, and NM7 is not turned on at this time. When the load current reaches the set over-current value, NM7 is turned on, and at this time the load current is limited. The current at which the whole over-current protection circuit is started and the over-current can be adjusted by adjusting the resistance value and the size of the MOS tube.

[0091] Compared with the traditional fixed over-current limiting protection circuit and the foldback over-current protection circuit, the static power consumption-free LDO over-current protection circuit according to the present application has no static power consumption, has no influence on the establishment process of the LDO, has no latch-up effect, has a faster recovery capability, has a simple structure, a small area, and strong practicability.

[0092] In a third aspect, the embodiments of the present application further provide an electronic device comprising the static power consumption-free LDO over-current protection circuit according to the first aspect.

[0093] In a fourth aspect, the embodiments of the present application further provide a storage medium, which is a computer readable storage medium, and stores a computer program. The computer program is executed by a processor to implement the over-current protection method.

[0094] The memory is a non-transitory computer readable storage medium, and can be used to store a non-transitory software program and a non-transitory computer executable program. In addition, the memory can include a high-speed random access memory, and can also include a non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state memory device. In some embodiments, the memory can optionally include a memory remotely arranged relative to the processor, and these remote memories can be connected to the processor through a network. Examples of the network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof. The above-described device embodiments are only schematic, and units described as separate components can or can not be physically separate, and can be implemented in one place or distributed on multiple network units. Part or all of the modules can be selected according to actual needs to achieve the purpose of the present embodiment.

[0095] While specific embodiments are described herein, one of ordinary skill in the art will appreciate that many other modifications or alternative embodiments are within the scope of the present disclosure. For example, any of the functions and / or process capabilities described in connection with a particular device or component can be performed by any other device or component. Additionally, while various exemplary implementations and architectures have been described in accordance with embodiments of the present disclosure, one of ordinary skill in the art will appreciate that many other modifications to the exemplary implementations and architectures described herein are within the scope of the present disclosure.

[0096] Certain aspects of the present disclosure are described above with reference to block and flow diagrams of systems, methods, systems, and / or computer program products according to example embodiments. It will be understood that one or more blocks of the block diagrams and flow diagrams, and combinations of blocks in the block diagrams and flow diagrams, can be implemented by

[0097] Thus, the blocks in the block diagrams and flow diagrams support combinations of means for performing the specified functions, combinations of elements or steps for performing the specified functions, and program instruction means for performing the specified functions. It will also be understood that each block of the block diagrams and flow diagrams, and combinations of blocks in the block diagrams and flow diagrams, can be implemented by dedicated hardware-based computer systems which perform the specified functions, or combinations of dedicated hardware and computer instructions.

[0098] The program modules, applications, and the like described herein can include one or more software components, including, for example, software objects, methods, data structures, and the like. Each such software component can include computer-executable instructions that, in response to execution, cause at least a portion of the functionality described herein (e.g., one or more operations of the example methods described herein) to be performed.

[0099] Software components can be coded in any of a variety of programming languages. One illustrative programming language can be a low-level programming language such as an assembly language associated with a specific hardware architecture and / or operating system platform. Software components comprising assembly language instructions can need to be translated via an assembler before execution by the hardware architecture and / or platform. Another illustrative programming language can be a higher-level programming language that can be portable to multiple architectures. Software components comprising a higher-level programming language can need to be translated to an intermediate representation via an interpreter or compiler before execution. Other examples of programming languages include, but are not limited to, a macro language, a shell or command language, a job control language, a script language, a database query or search language, or a report writing language. In one or more illustrative embodiments, a software component containing instructions in one of the above examples of programming languages can be executed directly by an operating system or other software component without first being converted to another form.

[0100] Software components can be stored as files or other data storage constructs. Software components of a similar type or related function can be stored together such as in a particular directory, folder, or library. Software components can be static (e.g., preset or fixed) or dynamic (e.g., created or modified at execution time).

[0101] The above embodiments of the present application have been described in detail but not limited to the above examples, within the scope of knowledge of those skilled in the art, various changes can be made without departing from the spirit of the present application.

Claims

1. An LDO overcurrent protection circuit with no static power consumption, characterized in that, include: The current sampling module is used to sample the output current of the power transistor of the LDO according to a first ratio; A switching module is connected to the gate of the power transistor; A current limiting module is used to collect the output current collected by the current sampling module according to a second ratio. The current limiting module is connected to the switching module and the current sampling module. The current limiting module is also used to control whether the switching module is turned on. An overcurrent start-up module is connected to the current limiting module and the current sampling module. The overcurrent start-up module is used to control whether the current sampling module and the current limiting module are started. Specifically, when the output current of the LDO is lower than a first preset value, the current sampling module, the switching module, the current limiting module, and the overcurrent start-up module are all inactive; when the output current rises to the first preset value, the overcurrent start-up module starts first, driving the current sampling module and the current limiting module to start, while the switching module is in an off state; when the output current continues to rise to the overcurrent value, the switching module turns on, limiting the gate voltage of the power transistor, thereby limiting the output current from continuing to rise; the first preset value is less than the overcurrent value. The current sampling module includes: The first MOSFET has its gate connected to the gate of the power transistor, and its source connected to the source of the power transistor. The second MOSFET has its drain connected to the drain of the first MOSFET, and its gate connected to the current limiting module and the overcurrent start-up module. The third MOS transistor has its drain connected to the source of the second MOS transistor, its source connected to a power supply, and its gate connected to the current limiting module and the overcurrent start-up module. The current limiting module includes: The fourth MOS transistor has its gate connected to the gate of the second MOS transistor and the overcurrent startup module. The drain of the fourth MOS transistor is grounded through multiple resistors connected in series. One end of one of the resistors is connected to the overcurrent startup module, and one end of the other resistor is connected to the switching module. The fifth MOS transistor has its drain connected to the source of the fourth MOS transistor, its source connected to the power supply, and its gate connected to the gate of the third MOS transistor and the overcurrent start-up module. The overcurrent startup module includes: The sixth MOS transistor has its source connected to the power supply, and its gate is connected to its drain, the gate of the third MOS transistor, and the gate of the fifth MOS transistor. The seventh MOS transistor has its source connected to the drain of the sixth MOS transistor, and its gate connected to the gate of the second MOS transistor, the gate of the fourth MOS transistor, and the drain of the first MOS transistor. An eighth MOS transistor, a drain of the eighth MOS transistor is connected with a drain of the seventh MOS transistor, a gate of the eighth MOS transistor is connected with one end of one of the resistors, and a source of the eighth MOS transistor is grounded.

2. The static-power-free LDO over-current protection circuit of claim 1, wherein, The switch module comprises a ninth MOS transistor, a drain of the ninth MOS transistor is connected with a gate of the first MOS transistor and a gate of the power transistor, a source of the ninth MOS transistor is grounded, and a gate of the ninth MOS transistor is connected with one end of another resistor.

3. The quiescent current free LDO over-current protection circuit of claim 1, wherein, A ratio of a gate length of the first MOS transistor to a gate length of the power transistor is the same as a ratio of a gate width of the first MOS transistor to a gate width of the power transistor.

4. The quiescent current free LDO over-current protection circuit of claim 1, wherein, The ratio of the gate length to the gate width of the second MOS transistor and the ratio of the gate length to the gate width of the third MOS transistor are set such that the first MOS transistor operates in a nonlinear region when the output current rises to the overcurrent value.

5. An overcurrent protection method, characterized by, The method based on the static power consumption free LDO overcurrent protection circuit according to any one of claims 1-4, the method comprising: collecting, by a current sampling module, an output current of a power transistor of an LDO at a first ratio; collecting, by a current limiting module, the output current collected by the current sampling module at a second ratio; when the output current is lower than a first preset value, causing the current sampling module, the switch module, the current limiting module and the overcurrent starting module to all not operate; when the output current rises to the first preset value, causing the overcurrent starting module to start first, and causing the current sampling module and the current limiting module to start, and causing the switch module to be in an off state; when the output current continues to rise to an overcurrent value, causing the switch module to be turned on, causing the gate voltage of the power transistor to be limited, and causing the output current to continue to rise to be limited; and the first preset value is less than the overcurrent value.

6. An electronic device, comprising: The static power consumption free LDO overcurrent protection circuit according to any one of claims 1-4.

7. A storage medium, characterized by The storage medium stores computer executable instructions for causing a computer to execute the overcurrent protection method according to claim 5. The storage medium stores computer executable instructions for causing a computer to execute the overcurrent protection method according to claim 5.

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