Short-circuit fast protection circuit and chip for high-voltage LDO

Abstract

The present invention discloses a short-circuit fast protection circuit and chip for high-voltage LDO, wherein the LDO includes an error amplifier, a power tube, and a voltage feedback module; the circuit includes: a sampling module and a shutdown module; the sampling module is respectively connected to the error amplifier and the power tube, and is used to monitor the current flowing through the power tube, and output a shutdown trigger signal to the shutdown module when the current exceeds a set value; the shutdown module is respectively connected to the sampling module and the power tube, and is used to shut down the power tube according to the shutdown trigger signal. By using the protection circuit of the present invention, the LDO can be quickly responded to when the output end of the LDO is short-circuited to protect the LDO, thereby preventing the chip from being damaged by a large current.

Description

Technical Field

[0001] The present invention relates to the field of circuit technology, and in particular to a short-circuit fast protection circuit and chip for a high-voltage LDO. Background Art

[0002] For harsh electrical application environments, such as industrial electronics, automotive electronics, medical electronics and other systems, there are factors such as large operating current, high power supply voltage, wide temperature range, and power supply voltage jitter. Therefore, with the continuous iteration of chip technology, high-performance power management chips have gradually become the focus and difficulty of modern chip design. Among them, LDO (Low-dropout regulator) as one of the important components of power management chips has received extensive attention and research from scholars due to its advantages such as small size, low cost, low noise, large load current, and strong ripple suppression ability.

[0003] LDO, also known as low dropout linear regulator, is a type of linear DC regulator used to provide a stable DC voltage supply. Understanding the various performance indicators of LDO is an important step in designing a fully MCU design process, but it is also very important to protect LDO from damage and some unexpected events. These unexpected situations actually occur in all aspects of chip application, and because it is a power chip, once an unexpected situation occurs, it is often a devastating blow, such as: loss of function, logical disorder, chip burnout, etc. The first line of defense to prevent these damages is the protection circuit in the circuit, especially when the power level exceeds the normal working range of LDO, so various LDO protection circuits are derived. Their main function is to ensure that LDO can detect these abnormal conditions in various harsh or sudden use scenarios and then output a control signal to the switch tube, thereby triggering the protection module to shut down the LDO output to protect the chip.

[0004] Generally, LDO abnormal protection circuits are divided into overcurrent protection, overtemperature protection, overvoltage and undervoltage protection, etc. Overcurrent means that when the external load increases and exceeds the maximum current capacity of the LDO, the LDO is insufficient to provide a strong current output, resulting in a decrease in the LDO output voltage. In severe cases, due to the sharp increase in external load, the power consumption generated by the LDO chip is very large, which may cause the LDO chip to heat up and burn.

[0005] LDOs are generally designed with an overcurrent protection circuit to limit the LDO output current capability, thereby preventing the LDO chip from carrying huge power consumption. However, under the premise of meeting low power consumption, the response speed of the overcurrent protection circuit of traditional LDO chips is difficult to guarantee. When the external load increases rapidly in a short period of time, such as a momentary short circuit or huge instantaneous power consumption, the overcurrent protection circuit is often difficult to respond quickly and function. At this time, the LDO chip is likely to be burned and damaged in an instant. Summary of the invention

[0006] The embodiment of the present invention provides a short-circuit fast protection circuit and chip for a high-voltage LDO, which can quickly respond to protect the LDO when the output end of the LDO is short-circuited, thereby preventing the chip from being damaged by a large current.

[0007] On the one hand, an embodiment of the present invention provides a short-circuit fast protection circuit for a high-voltage LDO, wherein the LDO includes an error amplifier, a power tube, and a voltage feedback module; the circuit includes: a sampling module and a shutdown module;

[0008] The sampling module is connected to the error amplifier and the power tube respectively, and is used to monitor the current flowing through the power tube, and output a shutdown trigger signal to the shutdown module when the current exceeds a set value;

[0009] The shutdown module is connected to the sampling module and the power tube respectively, and is used to shut down the power tube according to the shutdown trigger signal.

[0010] Optionally, the sampling module includes: a first current acquisition unit and a first voltage generation unit;

[0011] The first current acquisition unit is used to acquire the current of the power tube;

[0012] The first voltage generating unit is used to output a first voltage according to the current of the power tube.

[0013] Optionally, the first current acquisition unit includes a first current mirror.

[0014] Optionally, the first voltage generating unit includes: a first voltage dividing resistor and a second voltage dividing resistor connected in series, and a connection end of the first voltage dividing resistor and the second voltage dividing resistor is an output end of the first voltage generating unit.

[0015] Optionally, a first diode is further connected between the output end of the first voltage generating unit and the output end of the power tube.

[0016] Optionally, the shutdown module includes: a second current acquisition unit, a second voltage generation unit, a first switch tube, a second switch tube, and a third current acquisition unit; the first switch tube and the second switch tube are connected in series on the protection branch;

[0017] The second current acquisition unit is used to acquire the current on the first current acquisition unit;

[0018] The second voltage generating unit is used to generate a second voltage according to the current on the first current acquiring unit, and the second voltage is a stable voltage that does not change with the current on the first current acquiring unit;

[0019] The first switch tube is used to maintain an off state when the first voltage is less than a first set value, and enter an on state otherwise;

[0020] The second switch tube is used to remain in an open state according to the second voltage;

[0021] The third current acquisition unit is used to acquire the current of the protection branch and control the power tube to be turned off according to the current of the protection branch.

[0022] Optionally, the second current acquisition unit includes a second current mirror.

[0023] Optionally, the second current acquisition unit is a Zener diode, the anode of the Zener diode is connected to the output end of the power tube, and the cathode of the Zener diode is connected.

[0024] Optionally, the third current acquisition unit and the second current acquisition unit form a current mirror.

[0025] Optionally, the third current acquisition unit is a MOS tube.

[0026] Optionally, the first switch tube is an NMOS tube, and the second switch tube is a PMOS tube;

[0027] The gate of the NMOS tube is connected to the output end of the first voltage generating unit, the gate of the PMOS tube is connected to the reference branch of the second current mirror, and the source of the NMOS tube is connected to the drain of the PMOS tube.

[0028] Optionally, a second diode is further connected between the connecting end of the NMOS tube and the PMOS tube and the output end of the power tube.

[0029] Optionally, a first capacitor is connected between the output end of the first voltage generating unit and the first switch tube; and a second capacitor is connected between the output end of the second voltage generating unit and the first switch tube.

[0030] On the other hand, an embodiment of the present invention further provides a chip, wherein the chip includes the short-circuit fast protection circuit for high-voltage LDO.

[0031] The short-circuit fast protection circuit for high-voltage LDO provided by the embodiment of the present invention sets a sampling module and a shutdown module between the error amplifier and the power tube of the LDO, uses the sampling module to monitor the current flowing through the power tube, and outputs a shutdown trigger signal to the shutdown module when the current exceeds a set value. The shutdown module shuts down the power tube according to the shutdown trigger signal, which can achieve a fast response and protect the LDO during the short circuit of the output end, thereby avoiding damage to the chip caused by large current.

[0032] Furthermore, the current on the power tube is transmitted through the current mirror, and the two switch tubes arranged on the protection branch control the on and off of the protection branch. When the current on the power tube is normal, the second switch tube controlled by the shutdown module remains in the open state, and the first switch tube controlled by the sampling module is in the off state; when the current on the power tube exceeds a certain value, the sampling module controls the first switch tube to open, so that a current is generated on the protection branch, and the power tube is controlled to be turned off by the current. The circuit structure is simple, and the short-circuit rapid protection of the high-voltage LDO can be achieved through the current mirror and the switch tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the structure of a traditional high-voltage LDO without a protection circuit;

[0034] Figure 2 It is a structural schematic diagram of a short-circuit fast protection circuit for a high-voltage LDO provided by an embodiment of the present invention;

[0035] Figure 3 It is a specific structural schematic diagram of a short-circuit fast protection circuit for a high-voltage LDO provided by an embodiment of the present invention;

[0036] Figure 4 It is a specific structural schematic diagram of a high-voltage LDO having a protection circuit provided by an embodiment of the present invention;

[0037] Figure 5 yes Figure 4 The schematic diagram of the working state of the high voltage LDO when the protection circuit is not triggered;

[0038] Figure 6 yes Figure 4 Schematic diagram of the working state when the high-voltage LDO triggers the protection circuit. DETAILED DESCRIPTION

[0039] The principle and spirit of the present invention will be described below with reference to the exemplary embodiments shown in the accompanying drawings. It should be understood that these embodiments are described only to enable those skilled in the art to better understand and implement the present invention, and are not intended to limit the scope of the present invention in any way.

[0040] As one of the most widely used analog power devices, LDO is particularly suitable for filtering the voltage ripple generated by the switching power supply because of its linear operation.

[0041] like Figure 1 As shown, LDO usually consists of an error amplifier (error detection amplifier) ​​OP1, a reference power tube , and resistors and The feedback network consists of the power tube Working in linear working mode, Vs is the working power supply.

[0042] As a standard negative feedback loop, when the input or load changes and the output voltage Vout begins to fluctuate, the error amplifier OP1 continuously compares the feedback voltage from the output voltage with the reference voltage. , and control the power tube The difference between them is made zero, thus keeping the output voltage Vout constant.

[0043] In the feedback loop, the voltage at the non-inverting pin of the error amplifier OP1 always tries to match the reference voltage. The same, so the current flowing through the resistor The current flowing through the resistor is constant. and The current can be passed through Therefore, the output voltage can be calculated according to the following formula:

[0044] ;

[0045] Power tube working in saturation region It can be considered as a voltage-controlled current source. The control circuit continuously monitors (senses) the output voltage and adjusts the current source (according to the load demand) to keep the output voltage at the desired value.

[0046] When the external load exceeds the maximum current capability of the LDO, especially when a short circuit occurs, the LDO chip will generate huge power consumption, which may cause the LDO chip to heat up and burn. The overcurrent protection circuit of traditional LDO chips has a slow response speed and cannot achieve rapid protection against overcurrent of the LDO.

[0047] To this end, an embodiment of the present invention provides a short-circuit fast protection circuit for a high-voltage LDO. A sampling module and a shutdown module are set between the error amplifier and the power tube of the LDO. The sampling module is used to monitor the current flowing through the power tube, and when the current exceeds a set value, a shutdown trigger signal is output to the shutdown module. The shutdown module shuts down the power tube according to the shutdown trigger signal, which can achieve a fast response and protect the LDO during the output short circuit process, thereby avoiding damage to the chip caused by large current.

[0048] like Figure 2 1 is a schematic diagram of a structure of a short-circuit fast protection circuit for a high-voltage LDO provided by an embodiment of the present invention.

[0049] For ease of understanding, Figure 2 The LDO is also shown in FIG. The short-circuit fast protection circuit 200 for high-voltage LDO includes: a sampling module 201 and a shutdown module 202. Among them:

[0050] The sampling module 201 is respectively connected to the error amplifier OP1 and the power tube Connection for monitoring power tube The current flowing through the shutdown module 202 is detected, and when the current exceeds the set value, a shutdown trigger signal is output to the shutdown module 202;

[0051] The shut-down module 202 is respectively connected to the sampling module 201 and the power tube Connection, used to shut down the power tube according to the shutdown trigger signal .

[0052] In specific implementation, the sampling module 201 obtains the power tube The shutdown module 202 obtains the current on the sampling module 201, and a protection branch is set in the shutdown module 202. The first switch tube controlled according to the current obtained by the sampling module 201 and the second switch tube controlled according to the current obtained by the shutdown module 202 are connected in series on the protection branch. When the LDO is working normally, the first switch tube remains in the off state and the second switch tube remains in the on state, so that the protection branch is disconnected, no current is generated, and no power tube is damaged. In the event of an abnormal situation such as a short circuit at the LDO output or an increase in the load exceeding the maximum current capability of the LDO, the first switch tube is triggered to open, thereby turning on the protection branch, generating current and triggering the power tube Shut down to protect the LDO.

[0053] like Figure 3 FIG. 1 is a schematic diagram of a specific structure of a short-circuit fast protection circuit for a high-voltage LDO provided by an embodiment of the present invention.

[0054] Also refer to Figure 2 , Figure 3 In the illustrated embodiment, the sampling module 201 includes a first current acquisition unit 211 and a first voltage generation unit 212. Wherein:

[0055] The first current acquisition unit 211 is used to acquire the power tube The current;

[0056] The first voltage generating unit 212 is used to generate a voltage according to the power tube The current outputs a first voltage.

[0057] The first current acquisition unit 211 may be implemented by a current mirror, for example, and the first voltage generation unit may be implemented by resistor voltage division.

[0058] The shutdown module 202 includes: a second current acquisition unit 221, a second voltage generation unit 222, a first switch tube 223, a second switch tube 224, and a third current acquisition unit 225. The first switch tube 223 and the second switch tube 224 are connected in series on the protection branch.

[0059] The second current acquisition unit 221 is used to acquire the current on the first current acquisition unit 211;

[0060] The second voltage generating unit 222 is used to generate a second voltage according to the current on the first current acquiring unit 211; the second voltage is a stable voltage that does not change with the current on the first current acquiring unit;

[0061] The first switch tube 223 is used to maintain an off state when the first voltage is less than a first set value, otherwise enter an on state; that is, the first voltage controls the off or on of the first switch tube 223;

[0062] The second switch tube 224 is used to keep an open state according to the second voltage;

[0063] The third current acquisition unit 225 is used to acquire the current of the protection branch and control the power tube according to the current of the protection branch. Shut down.

[0064] The second current acquisition unit 221 and the third current acquisition unit 225 may also be implemented by using current mirrors.

[0065] The second voltage generating unit 222 can be implemented by a Zener diode, which is also called a voltage regulator diode. It uses the reverse breakdown state of the PN junction, the current can change in a wide range while the voltage remains basically unchanged, and can play a role in voltage stabilization. Therefore, even if the current on the first current acquisition unit 211 is affected by the power tube The voltage output by the second voltage generating unit 222 does not change, so that the second switch tube 224 remains in the open state.

[0066] It should be noted that in the power tube In normal operation, the first switch tube 223 is in the off state and the second switch tube 224 is in the on state, so that the protection branch is disconnected and no current flows through the protection branch. In abnormal situations such as LDO output short circuit or load increase exceeding the maximum current capacity of LDO, the second switch tube 224 is still in the on state. At this time, due to the power tube The increase of the current on the upper circuit causes the first voltage generated based on the current to increase, triggering the first switch tube 223 to open, so that the protection branch is turned on and a corresponding current is generated; accordingly, the third current acquisition unit 225 acquires the corresponding current, triggering the power tube Shut down, the power tube Play a protective role.

[0067] The first setting value may be determined according to the type and process parameters of the first switch tube 223. Accordingly, the size of the voltage-dividing resistor for generating the first voltage may be determined by calculation according to the first setting value.

[0068] Next, continue to combine Figure 4 The working principle and process of the short-circuit fast protection circuit for high-voltage LDO provided by the embodiment of the present invention are described in detail by example.

[0069] Reference Figure 4 , Figure 4 The figure is a specific structural diagram of a high voltage LDO having a protection circuit provided by an embodiment of the present invention.

[0070] In this example, the sampling module 201 monitors the power tube The shutdown module 202 is used to shut down the power tube when a short circuit occurs. gate, thereby achieving the function of quickly shutting down the output in case of short circuit.

[0071] Also refer to Figure 3 , Figure 4 NMOS tube in and is the first current mirror, as Figure 3 The first current acquisition unit 211 in the first voltage dividing resistor and the second voltage divider resistor composition Figure 3 The first voltage generating unit 212 in.

[0072] The NMOS transistor in the shutdown module 202 and is the second current mirror, as Figure 3 The second current acquisition unit 221 in the embodiment. The Zener diode D3 is used as Figure 3 The second voltage acquisition unit 222 is arranged on the reference branch of the second current mirror, and its anode is connected to the power tube The output end of the current mirror is connected to the cathode of the NMOS tube The drain of NMOS tube As Figure 3 The first switch tube 223, PMOS tube As Figure 3 The second switch tube 224, NMOS tube and PMOS tube The branch where the current is located, that is, the mirror branch of the second current mirror, serves as a protection branch.

[0073] like Figure 4 As shown, the resistance and resistor The connection point is Figure 4 Node A in the NMOS tube The gate of the NMOS tube The gate of the Zener diode D3 outputs the first voltage. The cathode of the Zener diode D3 is connected to the PMOS tube The gate of the PMOS tube Outputting a second voltage.

[0074] NMOS tube As Figure 3 The third current acquisition unit 225 in and The current mirror is formed to obtain the current on the protection branch. Drain connection power tube The gate of the power tube The gate control plays a protective role for the LDO. Specifically, when the protection branch is disconnected, There is no current on the power tube. When the protection branch is turned on, The current is generated on the power tube The gate voltage Pull up to turn off the power tube Output, protect the power tube and the internal circuits are not damaged.

[0075] Figure 4 In the resistor , , , , is a current limiting resistor. In addition, the output end (i.e., node A) of the first voltage generating unit is connected to the power tube A first diode is also connected between the output end (i.e., node B) of , and The connection end and the power tube A second diode is also connected between the output end (i.e., node B) of ,diode and A Zener diode can be used to clamp the diode. and The voltage across the two ends does not exceed the breakdown voltage of the Zener diode (usually 5V), thus achieving protection.

[0076] In addition, the output terminal (i.e., node A) of the first voltage generating unit is connected to the first switch tube A first capacitor is connected between the source (i.e., node C) of The output terminal (i.e., node B) of the second voltage generating unit is connected to the first switch tube A second capacitor is connected between the source (i.e., node C) of . The first capacitor and the second capacitor In the power tube Charging during operation, The output terminal is short-circuited to prevent the power tube from discharging Be penetrated.

[0077] It should be noted that the first capacitor and the second capacitor The capacitance values ​​can be the same or different, depending on the speed of the fast response you want to design. Under abnormal conditions that trigger a short circuit, it is often necessary to quickly and effectively perform protection processing. The change in the capacitance value will also change the circuit response speed. In specific implementation, the first capacitor and the second capacitor The capacitance value can be determined according to the circuit response speed requirements.

[0078] Figure 4 Capacitance in and resistor is the output filter capacitor and load of the LDO.

[0079] It should also be noted that Figure 4 It is just a specific example of the above modules. According to the working principle of the protection circuit of the present invention, the above modules may also have other modified structures as long as they can achieve the above functions.

[0080] Refer to the following Figure 5 and Figure 6 ,illustrate Figure 4 The fast protection principle of the protection circuit of the present invention for the LDO shown in the LDO. Figure 5 yes Figure 4 The schematic diagram of the working state of the high voltage LDO when the protection circuit is not triggered; Figure 6 yes Figure 4 Schematic diagram of the working state when the high-voltage LDO triggers the protection circuit.

[0081] Reference Figure 5 , when the power tube When the output current changes, it will cause and The current flowing through also changes accordingly. Under normal circumstances, the power tube There is no overcurrent phenomenon. At this time, the power tube The current flowing through is small, and the power tube The gate voltage Raise, thus The current in the branch is also small. and is the current mirror, Copying an Image branch current and the second voltage divider resistor Multiplying them together gives the voltage at node A. Since there is no overcurrent, The copied current is very small, so the voltage at node A is low, and the first switch In the off state. There is also current in the branch, but because there is a Zener diode below it , so the voltage at node D is the power tube The output voltage Vout plus the Zener diode Clamping voltage , Generally, it is about 5V. At this time, the second switch tube Is in the open state. Shutdown, Open, There is no current path in the branch (i.e. the protection branch). and To form a current mirror, In the off state, No current flows to the power tube in the branch The protection circuit does not work at this time and the power consumption is very low.

[0082] In steady state: copy The output current is continuously fed to the capacitor Charge, To capacitor Charge, The current in the branch is recorded as , The current in the branch is recorded as , the voltage of each node in steady state is as follows:

[0083] , represents the voltage of node C;

[0084] , represents the voltage of node A;

[0085] , represents the voltage at node D, that is The gate voltage of

[0086] From the above formula, we can see that There is enough gate voltage to keep it on.

[0087] The formula for calculating capacitor storage energy is: Q=CV=IT, where Q represents the charge stored on the capacitor plates, C represents the capacitance of the capacitor, V represents the voltage between the capacitor plates; I represents the current intensity in the circuit, and T represents the time taken for the charge Q to flow through.

[0088] According to the above formula, the first capacitance can be obtained Energy storage and second capacitor Storage energy calculation formula:

[0089] ;

[0090] ;

[0091] in, represents the sampling response time, Indicates the time it takes for the protection circuit to take action.

[0092] The sampling response time can be obtained from the above formula: and the time it takes for the protection circuit to take action , and can be adjusted by Amplify current ratio, capacitance and Capacitance and resistance , The resistance value is used to adjust the speed of the loop response.

[0093] like Figure 6 As shown, when the power tube When the output terminal of the power tube is suddenly short-circuited to ground, The gate voltage of will be reduced to provide strong driving capability. The mirror image gets a larger current, so The current in the branch also increases suddenly. When the voltage at node A is greater than When the turn-on voltage is conduction, thus The branch generates corresponding current, Will be from The branch copy current is injected into the power tube The gate of the power tube The gate voltage is pulled up, thereby turning off the power tube Output, to protect the power tube and the function of internal circuits.

[0094] In addition, when the power tube When the output terminal is short-circuited, the capacitor and The charge on the power tube is discharged quickly, and the error amplifier OP1 The gate is discharged, and the discharge current is Power tube The gate voltage then decreases, and The output current and the discharge current of the error amplifier OP1 can be detected. When the output current is abnormal, The power tube The gate voltage is raised to protect the power tube , thus preventing it from being punctured.

[0095] When the output branch current When a certain value is reached, the short-circuit protection circuit enters the working state. The certain value can be calculated according to the following formula:

[0096] ;

[0097] in, Indicates power tube The aspect ratio, express The aspect ratio, Indicates power tube The threshold voltage of the power tube The gate-source voltage corresponding to the formation of the channel.

[0098] Accordingly, the parameters of each device in the circuit can be calculated based on the above current value, which will not be described in detail in the embodiment of the present invention.

[0099] It can be seen that the short-circuit fast protection circuit for high-voltage LDO provided in the embodiment of the present invention utilizes the instantaneous current of the sampled output driving power MOS tube to quickly turn on the protection function to achieve the purpose of limiting the output power tube and avoid damage to the chip caused by large current.

[0100] The short-circuit fast protection circuit for high-voltage LDO provided by the embodiment of the present invention has the following advantages:

[0101] (1) The sampling loop exists inside the LDO loop and has an extremely fast response speed;

[0102] (2) The protection circuit is in silent state when the LDO is working normally, and the power consumption is extremely low, which meets the low power consumption requirements of various products today;

[0103] (3) This design provides a practical and effective solution to the large current generated by the power MOS when the LDO is quickly short-circuited, avoiding the problem of the power MOS being broken down due to the large current and ensuring the high reliability of the circuit.

[0104] Correspondingly, an embodiment of the present invention further provides a chip or a chip module, which may include the short-circuit fast protection circuit for high-voltage LDO of any of the above embodiments.

[0105] It should be understood that the term "and / or" in this article is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article indicates that the associated objects before and after are in an "or" relationship.

[0106] The “plurality” mentioned in the embodiments of the present invention refers to two or more than two.

[0107] The first, second, etc. descriptions appearing in the embodiments of the present invention are only used for illustration and distinction of the description objects. There is no order, nor does it indicate any special limitation on the number of devices in the embodiments of the present application, and cannot constitute any limitation on the embodiments of the present application.

[0108] The “connection” that appears in the embodiments of the present invention refers to various connection modes such as direct connection or indirect connection to achieve communication between devices, and the embodiments of the present application do not impose any limitation on this.

[0109] In the several embodiments provided by the present invention, it should be understood that the disclosed circuits can also be implemented in other ways. For example, the circuit embodiments described above are only schematic; for example, the division of the units is only a logical function division, and there may be other division methods in actual implementation; for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0110] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may be physically included separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0111] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A short-circuit fast protection circuit for a high-voltage LDO, wherein the LDO comprises an error amplifier, a power tube, and a voltage feedback module; characterized in that: The circuit comprises: a sampling module and a shut-down module; The sampling module is connected to the error amplifier and the power tube respectively, and is used to monitor the current flowing through the power tube, and output a shutdown trigger signal to the shutdown module when the current exceeds a set value; The shutdown module is connected to the sampling module and the power tube respectively, and is used to shut down the power tube according to the shutdown trigger signal; The sampling module includes: a first current acquisition unit and a first voltage generation unit; The first current acquisition unit is used to acquire the current of the power tube; The first voltage generating unit is used to output a first voltage according to the current of the power tube; The shutdown module includes: a second current acquisition unit, a second voltage generation unit, a first switch tube, a second switch tube, and a third current acquisition unit; the first switch tube and the second switch tube are connected in series on the protection branch; The second current acquisition unit is used to acquire the current on the first current acquisition unit; The second voltage generating unit is used to generate a second voltage according to the current on the first current acquiring unit, and the second voltage is a stable voltage that does not change with the current on the first current acquiring unit; The first switch tube is used to maintain an off state when the first voltage is less than a first set value, and enter an on state otherwise; The second switch tube is used to remain in an open state according to the second voltage; The third current acquisition unit is used to acquire the current of the protection branch and control the power tube to be turned off according to the current of the protection branch.

2. The short-circuit fast protection circuit for high-voltage LDO according to claim 1, characterized in that: The first current acquisition unit includes a first current mirror.

3. The short-circuit fast protection circuit for high-voltage LDO according to claim 1, characterized in that: The first voltage generating unit includes: a first voltage dividing resistor and a second voltage dividing resistor connected in series, and a connection end of the first voltage dividing resistor and the second voltage dividing resistor is an output end of the first voltage generating unit.

4. The short-circuit fast protection circuit for high-voltage LDO according to claim 3, characterized in that: A first diode is also connected between the output end of the first voltage generating unit and the output end of the power tube.

5. The short-circuit fast protection circuit for high-voltage LDO according to claim 1, characterized in that: The second current acquisition unit includes a second current mirror.

6. The short-circuit fast protection circuit for high-voltage LDO according to claim 1, characterized in that: The second current acquisition unit is a Zener diode, the anode of the Zener diode is connected to the output end of the power tube, and the cathode of the Zener diode is connected.

7. The short-circuit fast protection circuit for high-voltage LDO according to claim 1, characterized in that: The third current acquisition unit and the second current acquisition unit form a current mirror.

8. The short-circuit fast protection circuit for high-voltage LDO according to claim 1, characterized in that: The third current acquisition unit is a MOS tube.

9. The short-circuit fast protection circuit for high-voltage LDO according to claim 5, characterized in that: The first switch tube is an NMOS tube, and the second switch tube is a PMOS tube; The gate of the NMOS tube is connected to the output end of the first voltage generating unit, the gate of the PMOS tube is connected to the reference branch of the second current mirror, and the source of the NMOS tube is connected to the drain of the PMOS tube.

10. The short-circuit fast protection circuit for high-voltage LDO according to claim 9, characterized in that: A second diode is also connected between the connecting end of the NMOS tube and the PMOS tube and the output end of the power tube.

11. The short-circuit fast protection circuit for high-voltage LDO according to claim 10, characterized in that: A first capacitor is connected between the output end of the first voltage generating unit and the first switch tube; and a second capacitor is connected between the output end of the second voltage generating unit and the first switch tube.

12. A chip, characterized in that: The chip comprises the short-circuit fast protection circuit for high-voltage LDO as claimed in any one of claims 1 to 11.

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