Load switch circuit and chip

Abstract

The invention discloses a load switch circuit and a chip, which integrate various protection functions to prevent a load switch from being burnt or mistakenly triggered and improve the reliability of the load switch. The power tube is used for controlling on-off of a power supply and a load; the charge pump module is connected with an enable signal and a bias voltage and is used for providing a gate driving voltage for the power tube; the soft start module is connected with the charge pump module and the power tube and is used for controlling the soft start time of the output voltage; the current-limiting protection module is connected with the power tube and the soft start module and is used for limiting the grid voltage of the power tube when the sampling current is greater than a current threshold value; the burr eliminating module is connected with the power tube and the soft start module and is used for eliminating burrs of grid voltage of the power tube; the over-temperature protection module is connected with the power tube and the soft start module and is used for closing the power tube when the temperature of the power tube is higher than a temperature threshold value; and the discharge module accesses an enable signal, is connected with the power tube, and is used for lowering the output voltage when the enable signal is switched from the high level to the low level.

Description

Technical Field

[0001] The present invention relates to the field of integrated circuit design, and in particular to a load switch circuit and a chip. Background Art

[0002] A load switch is a switching circuit that connects a power source and a load. The power source and the load can be turned on and off by controlling the input signal of the load switch. This on-off function is not only stable but also efficient. Load switches are widely used in electronic devices and power management systems, such as electric vehicles, lighting systems, household appliances, and high-end electronic products.

[0003] However, in actual applications, load switches are easily burned out when encountering problems such as short circuit, overcurrent and overtemperature, resulting in low reliability of the load switch circuit. Summary of the invention

[0004] The present invention provides a load switch circuit and a chip, which can integrate multiple protection functions to prevent the load switch from being burned or triggered by mistake, thereby improving the reliability and stability of the load switch circuit.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme: In a first aspect, the present invention provides a load switch circuit, the load switch circuit comprising: Power tube, used to control the on and off of power supply and load; A charge pump module, the input end of which is connected to an enable signal and a bias voltage, and the output end is connected to the power tube, for providing a gate drive voltage to the power tube; A soft start module is connected to the charge pump module and the power tube, and is used to control the soft start time of the output voltage by controlling the gate voltage of the power tube; The current limiting protection module is connected to the power tube and the soft start module, and is used to generate a sampling current according to the current flowing through the power tube, and limit the gate voltage of the power tube when the sampling current is greater than the current threshold; A glitch elimination module is connected to the power tube and the soft start module to eliminate the glitch of the gate voltage of the power tube; The over-temperature protection module is connected to the power tube and the soft start module, and is used to detect the temperature of the power tube and shut down the power tube when the temperature is higher than the temperature threshold; The discharge module is connected to the enable signal and is also connected to the power tube, and is used to pull down the output voltage when the enable signal switches from a high level to a low level.

[0006] In a possible implementation, the discharge module includes: a first logic circuit, a first transistor, and a first resistor; One end of the first logic circuit is connected to the enable signal, and the other end is connected to the control electrode of the first transistor; A first electrode of the first transistor is grounded, and a second electrode is connected to one end of the first resistor; The other end of the first resistor is connected to the output end of the power tube.

[0007] In a possible implementation, the burr elimination module includes: a second transistor, a second resistor, a third resistor and a first capacitor; One end of the first capacitor is connected to the power supply voltage, and the other end is connected to one end of the second resistor; The other end of the second resistor is connected to one end of the third resistor and the control electrode of the second transistor, and the other end of the third resistor is grounded; The first electrode of the second transistor is connected to the gate of the power tube, and the second electrode is grounded.

[0008] In a possible implementation, the over-temperature protection module includes: a third transistor, a fourth transistor, a fifth transistor, a fourth resistor, a fifth resistor, a sixth resistor, and a second logic circuit; The control electrode of the third transistor is connected to the bias voltage, the first electrode of the third transistor is connected to the gate of the power tube and the soft start module, and the second electrode of the third transistor is connected to one end of the fourth resistor; The other end of the fourth resistor is connected to the first electrode of the fourth transistor; The control electrode of the fourth transistor is connected to one end of the second logic circuit, and the second electrode of the fourth transistor is grounded; The other end of the second logic circuit is connected to the first electrode of the fifth transistor and one end of the fifth resistor; The second electrode of the fifth transistor is grounded, the control electrode of the fifth transistor is connected to one end of a sixth resistor, and one end of the sixth resistor is connected to a bias current; The other end of the fifth resistor is connected to the bias voltage; The other end of the sixth resistor is grounded.

[0009] In a possible implementation, the soft start module includes: a current mirror, a seventh resistor, and a second capacitor; The first end of the current mirror is connected to the output end of the charge pump module, the second end is connected to the bias current, and the third end is connected to the gate of the power tube and one end of the seventh resistor; The other end of the seventh resistor is connected to one end of the second capacitor; The other end of the second capacitor is grounded.

[0010] In a possible implementation, the current limiting protection module includes: a sixth transistor, a seventh transistor, an eighth resistor and a ninth resistor; The control electrode of the sixth transistor is connected to the gate of the power tube, the soft start module, and one end of the eighth resistor, the first electrode of the sixth transistor is connected to the power supply voltage, and the second electrode of the sixth transistor is connected to one end of the ninth resistor and the control electrode of the seventh transistor; The other end of the eighth resistor is connected to the first electrode of the seventh transistor; The second electrode of the seventh transistor is connected to the other end of the ninth resistor and the output end of the power tube.

[0011] In a possible implementation, the charge pump module includes: a charge pump unit, an eighth transistor, a tenth resistor, an eleventh resistor, a comparator, and a third capacitor; The first end of the charge pump unit is connected to the bias voltage, the second end is connected to the enable signal, the third end is connected to the output end of the comparator, and the output end of the charge pump unit is connected to the control electrode and the first electrode of the eighth transistor; The second electrode of the eighth transistor is connected to one end of the third capacitor and one end of the tenth resistor, and is used to output a gate driving voltage; The other end of the third capacitor is grounded; The other end of the tenth resistor is connected to one end of the eleventh resistor and the first input end of the comparator; The other end of the eleventh resistor is grounded; The second input terminal of the comparator is connected to the reference voltage.

[0012] In a possible implementation, the fifth transistor and the power transistor are located in the same area in the layout; the sixth resistor is located on one side of the reference circuit in the layout, and the reference circuit is used to provide a bias current to the sixth resistor.

[0013] In a second aspect, the present invention provides a chip, which may include the load switch circuit of the first aspect and any possible implementation thereof.

[0014] The load switch circuit provided by the present invention uses a charge pump module to provide a gate drive voltage for a power tube, and controls the climbing time of the gate voltage of the power tube through a soft start module to control the start time of the output voltage, so that the output voltage can rise slowly and smoothly. The gate voltage of the power tube is limited by a current limiting protection module to prevent the power tube from being burned due to excessive current. The burr elimination module is used to eliminate the burr of the gate voltage of the power tube, which can prevent the power tube from being triggered by mistake and affecting the subsequent circuit. The temperature of the power tube is detected by an over-temperature protection module, and the power tube is quickly turned off when the temperature of the power tube is too high to prevent the power tube from burning. When the enable signal is switched from a high level to a low level through a discharge module, the charge of the capacitor connected to the voltage output end is quickly released to quickly pull down the output voltage, so that when the load switch circuit stops working, the charge of the output end of the power tube can be discharged to the ground through the discharge module, which can ensure the stability of the load switch circuit. In summary, by integrating the soft start module, current limiting protection module, glitch elimination module, over-temperature protection module and discharge module in the load switch circuit, the load switch can be prevented from being burned or triggered by mistake, thereby improving the reliability and stability of the load switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A circuit principle block diagram of a load switch circuit provided by an embodiment of the present invention; Figure 2 A circuit schematic diagram of a discharge module provided by an embodiment of the present invention; Figure 3 A circuit schematic diagram of a burr elimination module provided in an embodiment of the present invention; Figure 4 A circuit schematic diagram of an over-temperature protection module provided by an embodiment of the present invention; Figure 5 A circuit schematic diagram of a current limiting protection module provided in an embodiment of the present invention; Figure 6 A circuit schematic diagram of a charge pump module provided by an embodiment of the present invention; Figure 7 A circuit schematic diagram of a soft start module provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, "multiple" means two or more. In addition, the use of "based on" or "according to" means openness and inclusiveness, because the process, steps, calculations or other actions "based on" or "according to" one or more of the conditions or values ​​may be based on additional conditions or values ​​beyond the described values ​​in practice.

[0018] Figure 1 The circuit principle block diagram of a load switch circuit provided by an embodiment of the present invention is shown in FIG. Figure 1 As shown, the load switch circuit may include: a power tube 11 , a charge pump module 12 , a soft start module 13 , a current limiting protection module 14 , a burr elimination module 15 , an over-temperature protection module 16 and a discharge module 17 .

[0019] The power tube 11 is used to control the on and off of the power supply and the load.

[0020] In one implementation, the power transistor may be an NMOS transistor. Figure 1 In the figure, the power tube 11 is taken as an NMOS tube NM0 as an example.

[0021] The charge pump module 12 has an input terminal connected to an enable signal and a bias voltage, and an output terminal connected to the power tube 11 , so as to provide a gate drive voltage to the power tube 11 .

[0022] It is understandable that the enable signal is used to indicate the working state of the load switch circuit. If the enable signal is at a high level, it indicates that the load switch circuit starts working, and if the enable signal is at a low level, it indicates that the load switch circuit stops working. The bias voltage is used to supply power to the low-voltage module inside the load switch circuit.

[0023] The soft start module 13 is connected to the charge pump module 12 and the power tube 11, and is used to control the soft start time of the output voltage of the power tube 11 by controlling the gate voltage of the power tube 11. In this way, when the power supply is quickly powered on, the soft start module 13 controls the climbing time of the gate voltage of the power tube to make the output voltage rise slowly and smoothly, thereby avoiding the damage to the chip caused by the sudden increase of the output voltage due to the rapid power-on of the power supply, thereby improving the reliability of the chip.

[0024] The current limiting protection module 14 is connected to the power tube 11 and the soft start module 13, and is used to generate a sampling current according to the current flowing through the power tube 11, and when the sampling current is greater than the current threshold, limit the gate voltage of the power tube 11 to prevent the power tube 11 from burning.

[0025] The burr elimination module 15 is connected to the power tube 11 and the soft start module 13 , and is used to eliminate the burrs of the gate voltage of the power tube 11 .

[0026] The over-temperature protection module 16 is connected to the power tube 11 and the soft start module 13 , and is used to detect the temperature of the power tube 11 , and when the temperature is higher than the temperature threshold, shut down the power tube 11 to prevent the power tube 11 from burning.

[0027] The discharge module 17 has an input terminal connected to the enable signal and is also connected to the power tube 11, and is used to lower the output voltage of the power tube 11 when the enable signal switches from a high level to a low level, so as to quickly discharge the charge at the output terminal to the ground.

[0028] In this way, the charge pump module is used to provide the gate drive voltage for the power tube, and the soft start module is used to control the climbing time of the gate voltage of the power tube and then control the start-up time of the output voltage, so that the output voltage can rise slowly and smoothly. The gate voltage of the power tube is limited by the current limiting protection module to prevent the power tube from burning due to excessive current. The burr elimination module is used to eliminate the burrs of the gate voltage of the power tube, which can prevent the power tube from being triggered by mistake and affecting the subsequent circuit. The over-temperature protection module is used to detect the temperature of the power tube, and the power tube is quickly turned off when the temperature of the power tube is too high to prevent the power tube from burning. When the enable signal is switched from a high level to a low level through the discharge module, the charge of the capacitor connected to the voltage output end is quickly released to quickly pull down the output voltage, so that when the load switch circuit stops working, the charge at the output end of the power tube can be discharged to the ground through the discharge module, which can ensure the stability of the load switch circuit. In summary, by integrating the soft start module, current limiting protection module, glitch elimination module, over-temperature protection module and discharge module in the load switch circuit, the load switch can be prevented from being burned or triggered by mistake, thereby improving the reliability and stability of the load switch.

[0029] Optionally, in the embodiment of the present invention, refer to Figure 1 , Figure 2 FIG. 1 is a circuit schematic diagram of a discharge module 17 provided in an embodiment of the present invention. Figure 2 As shown, the discharge module 17 may include: a first logic circuit, a first transistor and a first resistor R1.

[0030] One end of the first logic circuit is connected to the enable signal, and the other end is connected to the control electrode of the first transistor.

[0031] A first electrode of the first transistor is grounded, and a second electrode is connected to one end of the first resistor R1.

[0032] The other end of the first resistor R1 is connected to the output end of the power transistor NM0 .

[0033] In a possible implementation, the first transistor may be a MOS transistor, a triode, or other types of transistors. Figure 2 As shown, the first transistor may be an NMOS transistor NM1, a gate of NM1 is connected to one end of the first logic circuit, a source of NM1 is grounded, and a drain of NM1 is connected to the first resistor R1.

[0034] The working principle of the discharge module 17 is as follows: when the enable signal switches from a high level to a low level, the load switch circuit is quickly closed and the power tube NM0 is turned off. The enable signal is at a low level so that the first logic control circuit outputs a control signal to control NM1 to turn on, so that the charge of the output voltage can be quickly discharged to the ground through the resistors R1 and NM1. Among them, the main function of R1 is to control the discharge speed and the current flowing through NM1.

[0035] Optionally, in the embodiment of the present invention, refer to Figure 1 , Figure 3 FIG. 1 is a circuit schematic diagram of a burr elimination module 15 provided in an embodiment of the present invention. Figure 3 As shown, the burr elimination module 15 may include: a second transistor, a second resistor R2, a third resistor R3 and a first capacitor C1.

[0036] One end of the first capacitor C1 is connected to the power supply voltage VIN, and the other end is connected to one end of the second resistor R2.

[0037] The other end of the second resistor R2 is connected to one end of the third resistor R3 and the control electrode of the second transistor, and the other end of the third resistor R3 is grounded.

[0038] A first electrode of the second transistor is connected to the gate of the power transistor NM0 and the soft start module 13 , and a second electrode is grounded.

[0039] In one implementation, the second transistor may be a MOS transistor or other types of transistors, which are not limited here. Figure 3 As shown, the second transistor may be an NMOS transistor NM2 , the gate of NM2 is connected to the node between R2 and R3 , the source is grounded, and the drain is connected to the gate of the power transistor NM0 and the output end of the soft start module 13 .

[0040] The working principle of the glitch elimination module 15 is as follows: when the power tube NM0 is in the off state, after the power supply voltage VIN generates a glitch or fluctuation, the glitch of VIN will pass through the capacitor C1 and the resistor R2, and generate a voltage drop on the resistor R3. When the glitch of VIN is higher than a certain voltage, the voltage on the resistor R3 turns on the transistor NM2 to quickly pull down the gate voltage of NM0, thereby preventing the power tube NM0 from being falsely triggered due to the glitch.

[0041] Optionally, in the embodiment of the present invention, refer to Figure 1 , Figure 4 FIG. 1 is a circuit diagram of an over-temperature protection module 16 provided in an embodiment of the present invention. Figure 4 As shown, the over-temperature protection module 16 may include: a third transistor, a fourth transistor, a fifth transistor, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6 and a second logic circuit.

[0042] The control electrode of the third transistor is connected to the bias voltage, the first electrode of the third transistor is connected to the gate of the power transistor NM0 and the output end of the soft start module 13, and the second electrode of the third transistor is connected to one end of the fourth resistor R4.

[0043] The other end of the fourth resistor R4 is connected to the first electrode of the fourth transistor.

[0044] The control electrode of the fourth transistor is connected to one end of the second logic circuit, and the second electrode of the fourth transistor is grounded.

[0045] The other end of the second logic circuit is connected to the first electrode of the fifth transistor and one end of the fifth resistor R5.

[0046] A second electrode of the fifth transistor is grounded, a control electrode of the fifth transistor is connected to one end of a sixth resistor R6, and one end of the sixth resistor R6 is connected to a bias current.

[0047] The other end of the fifth resistor R5 is connected to the bias voltage.

[0048] The other end of the sixth resistor R6 is grounded.

[0049] It is understandable that the third, fourth and fifth transistors can be any transistors that can achieve the over-temperature protection function, and are not limited here. Figure 4 As shown, the third transistor may be an NMOS transistor NM3, the fourth transistor may be an NMOS transistor NM4, and the fifth transistor may be an NPN transistor Q1. Among them, the gate of NM3 is connected to the bias voltage and is connected to the other end of R5, the drain of NM3 is connected to the gate of the power tube NM0 and the output end of the soft start module 13, and the source of NM3 is connected to one end of R4. The gate of NM4 is connected to one end of the second logic circuit, the source of NM4 is grounded, and the drain of NM4 is connected to the other end of R4. The base of Q1 is connected to one end of R6, the emitter of Q1 is grounded, and the collector of Q1 is connected to one end of R5 and the other end of the second logic circuit.

[0050] The working principle of the over-temperature protection module 16 is as follows: the bias current forms a stable voltage on the resistor R6 that does not change with temperature, and the voltage is the base voltage of the transistor Q1. When the temperature is low, the base voltage of Q1 is less than the conduction voltage, the transistor Q1 is turned off, and Q1 outputs a high level to the second logic circuit. The second logic unit outputs a control signal to control the transistor NM4 to turn off. When the temperature gradually rises until it is higher than the temperature threshold, the conduction voltage of the transistor Q1 decreases as the temperature rises, the transistor Q1 is turned on, and Q1 outputs a low level to the second logic circuit. The second logic circuit outputs a control signal to control the transistor NM4 to turn on. The gate voltage of the power tube NM0 is pulled down to the ground through the transistor NM3, the resistor R4, and the transistor NM4, and the power tube NM0 is turned off, thereby preventing NM0 from burning due to excessive temperature.

[0051] It should be noted that, in the embodiment of the present invention, the fifth transistor Q1 and the power tube NM0 are located in the same area in the layout. It is easy to understand that the power tube NM0 usually occupies a large area in the chip, and by arranging Q1 in the area where the power tube NM0 is located and making Q1 surrounded by the power tube NM0, the temperature of NM0 can be detected in time by Q1, and the power tube can be further effectively protected from being burned.

[0052] Moreover, the sixth resistor R6 is located on one side of the reference circuit in the layout, and the reference circuit is used to provide a bias current to the sixth resistor R6. In other words, the position of R6 in the chip is always next to the position of the reference circuit, which can ensure the accuracy of the base voltage of Q1, thereby ensuring the accuracy of the over-temperature protection point.

[0053] Optionally, in the embodiment of the present invention, refer to Figure 1 , Figure 5 FIG. 1 is a circuit diagram of a current limiting protection module 14 provided in an embodiment of the present invention. Figure 5 As shown, the current limiting protection module 14 may include: a sixth transistor, a seventh transistor, an eighth resistor R8 and a ninth resistor R9.

[0054] Among them, the control electrode of the sixth transistor is connected to the gate of the power tube NM0, the soft start module 13, and one end of the eighth resistor R8, the first electrode of the sixth transistor is connected to the power supply voltage, and the second electrode of the sixth transistor is connected to one end of the ninth resistor R9 and the control electrode of the seventh transistor.

[0055] The other end of the eighth resistor R8 is connected to the first electrode of the seventh transistor.

[0056] The second electrode of the seventh transistor is connected to the other end of the ninth resistor R9 and the output end of the power transistor NM0.

[0057] It is understandable that the sixth and seventh transistors can be any tubes that can achieve the current limiting protection function, and are not limited here. For example, the sixth transistor can be an NMOS tube NM6, and the seventh transistor can be a transistor Q2. The gate of NM6 is connected to the gate of the power tube NM0, the output end of the soft start module 13, and one end of R8, the drain of NM6 is connected to the power supply voltage, and the source of NM6 is connected to one end of R9 and the base of the transistor Q2. The collector of Q2 is connected to the other end of R8, and the emitter of Q2 is connected to the other end of R9 and the output end of the power tube NM0.

[0058] The working principle of the current limiting protection module 14 is as follows: the transistor NM6 can proportionally collect the current flowing through the power tube NM0, and the sampled current forms a voltage drop on the resistor R9, which serves as the base voltage of the transistor Q2. When the current flowing through the power tube NM0 is small, the sampled current is also small, the base voltage of Q2 is also small, and Q2 is turned off. When the sampled current is greater than the current threshold, the base voltage of Q2 is large, Q1 is turned on, and the gate voltage of NM0 is pulled to the output end through the resistor R8 and the transistor Q2, so that the VGS of the power tube NM0 is less than the threshold voltage of the power tube, thereby turning off the power tube NM0 to prevent the power tube NM0 from being burned due to the large current.

[0059] In the embodiment of the present invention, since both the current limiting protection module 14 and the over-temperature protection module 16 have the function of limiting the gate of the power tube NM0, in practical applications, usually the two protection functions can shut down the power tube NM0 regardless of which one is triggered first.

[0060] Optionally, in the embodiment of the present invention, refer to Figure 1 , Figure 6 FIG. 1 is a circuit schematic diagram of a charge pump module 12 provided in an embodiment of the present invention. Figure 6 As shown, the charge pump module 12 may include: a charge pump unit, an eighth transistor, a tenth resistor R10, an eleventh resistor R11, a comparator and a third capacitor C3.

[0061] The first end of the charge pump unit is connected to the bias voltage, the second end is connected to the enable signal, the third end is connected to the output end of the comparator, and the output end of the charge pump unit is connected to the control electrode and the first electrode of the eighth transistor.

[0062] The second electrode of the eighth transistor is connected to one end of the third capacitor C3 and one end of the tenth resistor R10 for outputting a gate driving voltage.

[0063] The other end of the third capacitor C3 is grounded.

[0064] The other end of the tenth resistor R10 is connected to one end of the eleventh resistor R11 and the first input end of the comparator.

[0065] The other end of the eleventh resistor R11 is grounded.

[0066] The second input terminal of the comparator is connected to the reference voltage.

[0067] Exemplarily, the eighth transistor may be an NMOS transistor NM8 , the gate of which is connected to the source of NM8 and the output end of the charge pump unit, the drain of which is connected to one end of C3 and one end of R10 , and the drain of NM8 is the output end of the charge pump module 12 .

[0068] The working principle of the charge pump module 12 is as follows: when the enable signal is at a high level, the output voltage VCP of the charge pump module 12 is divided by resistors R10 and R11. After the voltage is divided, the comparator compares the voltage on R11 with the reference voltage. When the voltage on R11 is greater than the reference voltage, the comparator flips and turns off the charge pump unit, thereby reducing the output voltage VCP. When the voltage on R11 is less than the reference voltage, the comparator controls the charge pump unit to turn on, thereby increasing the output voltage VCP. By adjusting the size of VCP, the reliability of the charge pump module 12 can be guaranteed.

[0069] Optionally, in the embodiment of the present invention, refer to Figure 1 , Figure 7 FIG. 1 is a circuit diagram of a soft start module 13 provided in an embodiment of the present invention. Figure 7 As shown, the soft start module 13 may include a current mirror, a seventh resistor R7 and a second capacitor C2.

[0070] The first end of the current mirror is connected to the output end of the charge pump module 12, the second end is connected to the bias current, and the third end is connected to the gate of the power tube NM0 and one end of the seventh resistor R7. In one implementation, the current mirror may include a ninth transistor PMOS tube PM9 and a tenth transistor PMOS tube PM10. The connection method of PM9 and PM10 is as follows: Figure 7 shown.

[0071] The other end of the seventh resistor R7 is connected to one end of the second capacitor C2.

[0072] The other end of the second capacitor C2 is grounded.

[0073] The working principle of the soft start module 13 is as follows: when the charge pump module 12 works normally, the VCP voltage rises, and the resistor R7 and the capacitor C2 are charged through the current mirror. The rising slope of the gate voltage of the power tube NM0 is changed through C2, thereby changing the soft start time of the output voltage of the power tube NM0.

[0074] It is worth noting that, in the embodiment of the present invention, the capacitor C2 may be integrated in the chip or may be an external capacitor. When C2 is an external capacitor, an adjustable soft start time may be achieved through C2.

[0075] The embodiment of the present invention further provides a chip, which may include Figure 1-Figure 7 Any load switching circuit in .

[0076] In a possible implementation, the chip may be a power management chip, and of course, may be other types of chips, which are not specifically limited here.

[0077] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A load switch circuit, characterized in that: include: Power tube, used to control the on and off of power supply and load; A charge pump module, the input end of which is connected to an enable signal and a bias voltage, and the output end of which is connected to the power tube, for providing a gate drive voltage to the power tube; A soft start module, connected to the charge pump module and the power tube, and used to control the soft start time of the output voltage by controlling the gate voltage of the power tube; A current limiting protection module, connected to the power tube and the soft start module, for generating a sampling current according to the current flowing through the power tube, and limiting the gate voltage of the power tube when the sampling current is greater than a current threshold; A burr elimination module, connected to the power tube and the soft start module, and used to eliminate the burrs of the gate voltage of the power tube; An over-temperature protection module, connected to the power tube and the soft start module, for detecting the temperature of the power tube and shutting down the power tube when the temperature is higher than a temperature threshold; The discharge module is connected to the enable signal and is also connected to the power tube, and is used to pull down the output voltage when the enable signal switches from a high level to a low level.

2. The load switch circuit according to claim 1, characterized in that: The discharge module includes: a first logic circuit, a first transistor and a first resistor; One end of the first logic circuit is connected to the enable signal, and the other end is connected to the control electrode of the first transistor; A first electrode of the first transistor is grounded, and a second electrode is connected to one end of the first resistor; The other end of the first resistor is connected to the output end of the power tube.

3. The load switch circuit according to claim 1 or 2, characterized in that: The burr elimination module includes: a second transistor, a second resistor, a third resistor and a first capacitor; One end of the first capacitor is connected to the power supply voltage, and the other end is connected to one end of the second resistor; The other end of the second resistor is connected to one end of the third resistor and the control electrode of the second transistor, and the other end of the third resistor is grounded; The first electrode of the second transistor is connected to the gate of the power tube, and the second electrode is grounded.

4. The load switch circuit according to claim 1 or 2, characterized in that: The over-temperature protection module includes: a third transistor, a fourth transistor, a fifth transistor, a fourth resistor, a fifth resistor, a sixth resistor and a second logic circuit; The control electrode of the third transistor is connected to the bias voltage, the first electrode of the third transistor is connected to the gate of the power tube and the soft start module, and the second electrode of the third transistor is connected to one end of the fourth resistor; The other end of the fourth resistor is connected to the first electrode of the fourth transistor; The control electrode of the fourth transistor is connected to one end of the second logic circuit, and the second electrode of the fourth transistor is grounded; The other end of the second logic circuit is connected to the first electrode of the fifth transistor and one end of the fifth resistor; The second electrode of the fifth transistor is grounded, the control electrode of the fifth transistor is connected to one end of the sixth resistor, and one end of the sixth resistor is connected to the bias current; The other end of the fifth resistor is connected to the bias voltage; The other end of the sixth resistor is grounded.

5. The load switch circuit according to claim 1 or 2, characterized in that: The soft start module includes: a current mirror, a seventh resistor and a second capacitor; The first end of the current mirror is connected to the output end of the charge pump module, the second end is connected to the bias current, and the third end is connected to the gate of the power tube and one end of the seventh resistor; The other end of the seventh resistor is connected to one end of the second capacitor; The other end of the second capacitor is grounded.

6. The load switch circuit according to claim 1 or 2, characterized in that: The current limiting protection module includes: a sixth transistor, a seventh transistor, an eighth resistor and a ninth resistor; The control electrode of the sixth transistor is connected to the gate of the power tube, the soft start module, and one end of the eighth resistor, the first electrode of the sixth transistor is connected to the power supply voltage, and the second electrode of the sixth transistor is connected to one end of the ninth resistor and the control electrode of the seventh transistor; The other end of the eighth resistor is connected to the first electrode of the seventh transistor; The second electrode of the seventh transistor is connected to the other end of the ninth resistor and the output end of the power tube.

7. The load switch circuit according to claim 1 or 2, characterized in that: The charge pump module comprises: a charge pump unit, an eighth transistor, a tenth resistor, an eleventh resistor, a comparator and a third capacitor; The first end of the charge pump unit is connected to the bias voltage, the second end is connected to the enable signal, the third end is connected to the output end of the comparator, and the output end of the charge pump unit is connected to the control electrode and the first electrode of the eighth transistor; The second electrode of the eighth transistor is connected to one end of the third capacitor and one end of the tenth resistor, and is used to output the gate driving voltage; The other end of the third capacitor is grounded; The other end of the tenth resistor is connected to one end of the eleventh resistor and the first input end of the comparator; The other end of the eleventh resistor is grounded; The second input terminal of the comparator is connected to a reference voltage.

8. The load switch circuit according to claim 4, characterized in that: The fifth transistor and the power transistor are located in the same area in the layout; The sixth resistor is located on one side of the reference circuit in the layout, and the reference circuit is used to provide the bias current to the sixth resistor.

9. A chip, characterized in that: The chip includes the load switch circuit according to any one of claims 1-8.

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