A protection circuit, management chip and power supply device

Abstract

The application discloses a protection circuit, a management chip and a power supply device. The protection circuit comprises: a first switch circuit for a passage between an input end of a switching power supply and an output end of a power supply; a reference voltage circuit for generating a first reference voltage based on a voltage of the input end of the power supply; and a first switch control circuit for comparing the voltage of the output end of the power supply with the first reference voltage and correspondingly outputting a first control signal for controlling the first switch circuit. Since the working voltage of the first switch control circuit is provided by the output end of the power supply, the first switch control circuit can still be in a working state when the power supply is powered off. If the voltage of the output end of the power supply is greater than the voltage of the input end of the power supply, the first switch control circuit can still timely turn off the first switch circuit to prevent the generation of a reverse current. Moreover, the reference voltage circuit generates the first reference voltage by using a Zener diode, so that the embodiment can be applicable to a power supply with a wide input voltage range.

Description

Technical Field

[0001] This application belongs to the field of power supply technology, and in particular relates to a protection circuit, a management chip, and a power supply device. Background Technology

[0002] A power supply provides the operating voltage required by a load. In practical applications, a switching circuit is typically used to turn the power supply's output voltage on and off to control whether the power supply provides power to the load. However, when the power supply fails, the output terminal may still be energized, or the voltage at the output terminal may be greater than the voltage at the input terminal (for example, this may occur when the capacitance to ground at the output terminal is greater than that at the input terminal). In this case, without appropriate protection measures, a reverse current may flow from the output terminal to the input terminal. Summary of the Invention

[0003] The purpose of this application is to provide a protection circuit, a management chip, and a power supply device to solve the problem of backflow current when the power supply fails.

[0004] A first aspect of this application provides a protection circuit, including:

[0005] The first switching circuit is configured as a path between the input terminal and the output terminal of the switching power supply.

[0006] A reference voltage circuit, connected to the power input terminal, is configured to provide a first reference voltage to the first switch control circuit based on the voltage at the power input terminal;

[0007] A first switch control circuit is connected to a first switch circuit, a reference voltage circuit, and a power output terminal. It is configured to control the first switch circuit to turn off when the voltage at the power output terminal is greater than or equal to the first reference voltage. The operating voltage of the first switch control circuit is provided by the power output terminal or a first power supply. The first power supply is not the same power supply that provides the input voltage to the power input terminal.

[0008] Optionally, the first switch control circuit includes:

[0009] The first comparison circuit is connected to the reference voltage circuit and the power supply output terminal, and is configured to compare the voltage at the power supply output terminal with the first reference voltage, and provide the corresponding control voltage to the signal processing circuit.

[0010] The signal processing circuit is connected to the first comparison circuit and the first switching circuit, and is configured to process the control voltage and output a first control signal accordingly. The first control signal is used to control the first switching circuit to turn off when the voltage at the power supply output terminal is greater than or equal to the first reference voltage. The operating voltage of the signal processing circuit is provided by the power supply output terminal or the first power supply, and the operating voltage of the first comparison circuit is provided by the power supply output terminal or the first power supply.

[0011] Optionally, the first comparison circuit includes a first switching transistor, a second switching transistor, a first current source, and a second current source;

[0012] The input terminal of the first switching transistor is configured to receive a first reference voltage. The output terminal of the first switching transistor, the input terminal of the first current source, and the control terminal of the second switching transistor are connected. The input terminal of the second switching transistor is connected to the power supply output terminal. The output terminal of the second switching transistor, the input terminal of the second current source, and the control terminal of the first switching transistor are connected. The output terminals of the first and second current sources are grounded.

[0013] The control voltage includes the voltage at the output terminal of the first switching transistor and / or the voltage at the output terminal of the second switching transistor.

[0014] Optionally, the first comparison circuit further includes:

[0015] An adjustable element is provided, with its input terminal connected to the power supply output terminal and its output terminal connected to the input terminal of a second switching transistor. The adjustable element is configured to adjust its on-resistance value to change the flip-threshold voltage of the first comparator circuit.

[0016] Optionally, the adjustable element includes a MOSFET or an adjustable resistor.

[0017] Optionally, the signal processing circuit includes a third switch, a fourth switch, a fifth switch, a sixth switch, and logic circuitry.

[0018] The input terminals of the third and fourth switching transistors are connected to the power output terminal. The output terminal of the third switching transistor, the control terminal of the fourth switching transistor, and the input terminal of the fifth switching transistor are connected. The output terminal of the fourth switching transistor, the control terminal of the third switching transistor, the input terminal of the sixth switching transistor, and the input terminal of the logic circuit are connected. The logic circuit is used to process the voltage at the output terminal of the fourth switching transistor and output the first control signal accordingly. The operating voltage of the logic circuit is provided by the power output terminal or the first power supply.

[0019] The output terminals of the fifth and sixth switching transistors are grounded, the output terminal of the first switching transistor is connected to the control terminal of the fifth switching transistor, and the output terminal of the second switching transistor is connected to the control terminal of the sixth switching transistor.

[0020] Optionally, the reference voltage circuit includes:

[0021] The third current source is connected to the power input terminal;

[0022] The Zener diode has its cathode connected to the output terminal of the third current source and the first switch control circuit. The anode of the Zener diode is grounded, and the voltage at the cathode of the Zener diode is the first reference voltage.

[0023] Optionally, the protection circuit also includes:

[0024] A second switching circuit connected in series with the first switching circuit shown.

[0025] A second switch control circuit connected to the second switch circuit is configured to turn on or off the second switch circuit based on the relationship between the voltage at the power supply output terminal and the second reference voltage.

[0026] Optionally, the first switching circuit includes a seventh switching transistor, and the second switching circuit includes an eighth switching transistor connected in series with the seventh switching transistor.

[0027] The control terminal of the seventh switch is connected to the output terminal of the first switch control circuit, the input terminal of the seventh switch is connected to the output terminal of the eighth switch, the output terminal of the seventh switch is the power output terminal, the input terminal of the eighth switch is connected to the power input terminal, and the control terminal of the eighth switch is connected to the output terminal of the second switch control circuit.

[0028] Optionally, the protection circuit also includes:

[0029] The voltage divider circuit has its first terminal connected to the power output terminal and its second terminal grounded.

[0030] The second switch control circuit is configured to compare the voltage of the voltage divider node of the voltage divider circuit with the second reference voltage, and output a second control signal for turning on or off the second switch circuit.

[0031] A second aspect of this application provides a management chip that includes the protection circuit provided in the first aspect.

[0032] A third aspect of this application provides a power supply device, including the protection circuit provided in the first aspect, or the management chip provided in the second aspect.

[0033] The beneficial effects of the embodiments of the present invention compared with the prior art are as follows:

[0034] On the one hand, when the voltage at the power output terminal is greater than the first reference voltage (e.g., the first reference voltage is the voltage at the power input terminal or a preset threshold), the first switch control circuit can control the first switch circuit to turn off, thereby disconnecting the path between the power input terminal and the power output terminal. This prevents reverse current from flowing from the power output terminal to the power input terminal, or prevents the voltage at the power output terminal from exceeding the allowable voltage range of the load. On the other hand, since the operating voltage of the first switch control circuit is provided by the power output terminal or the first power supply, the first switch control circuit can still be in operation when the power is off, i.e., when there is no voltage at the power input terminal. Even if the voltage at the power output terminal is greater than the voltage at the power input terminal, the first switch control circuit can still turn off the first switch circuit in time to prevent reverse current from being generated, thereby solving the problem of reverse current when the power is off. Attached Figure Description

[0035] Figures 1 to 3 These are schematic diagrams of the protection circuit provided in an embodiment of this application;

[0036] Figure 4 This is a schematic diagram showing the relationship between the first reference voltage and the voltage at the power supply input terminal.

[0037] Figure 5 This is a schematic diagram of the first control signal.

[0038] Illustration:

[0039] 10. Reference voltage circuit; 20. First switch control circuit; 21. First comparator circuit; 22. Signal processing circuit; 30. First switch circuit; 40. Second switch control circuit; 50. Voltage divider circuit; 60. Second switch circuit;

[0040] M0, Adjustable element; M1, First switch transistor; M2, Second switch transistor; M3, Third switch transistor; M4, Fourth switch transistor; M5, Fifth switch transistor; M6, Sixth switch transistor; M7, Seventh switch transistor; M8, Eighth switch transistor; Ibias1, First current source; Ibias2, Second current source; Ibias3, Third current source; INV1, First inverter; INV2, Second inverter; INV3, Third inverter; R1, First resistor; R2, Second resistor; D1, Zener diode; GND, Ground terminal; A, Comparator;

[0041] VIN, power input terminal; VOUT, power output terminal; V0, stable voltage; VB, first reference voltage; VC, first control signal; VREF, second reference voltage; VFB, feedback voltage. Detailed Implementation

[0042] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0043] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0044] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0045] A power supply provides the operating voltage required by a load. In practical applications, a first switching circuit is typically used to turn the power supply's output voltage on and off to control whether the power supply provides power to the load. However, when the power supply fails, the output terminal may still be energized, potentially causing a reverse current to flow from the output terminal to the input terminal. Alternatively, when the power supply fails, the voltage at the output terminal may be greater than the voltage at the input terminal (for example, if the capacitance to ground at the output terminal is greater than that at the input terminal, the voltage drop rate at the output terminal may be slower than that at the input terminal), also potentially causing a reverse current to flow from the output terminal to the input terminal. In such cases, without appropriate protection measures, a reverse current may flow from the output terminal to the input terminal.

[0046] In view of this, this application provides a protection circuit designed to solve the problem of reverse current during power failure. The design concept of this protection circuit is as follows:

[0047] The voltage at the power supply output terminal is compared with a first reference voltage (e.g., the voltage at the power supply input terminal or a preset threshold). When the voltage at the power supply output terminal is greater than or equal to the first reference voltage, the first control signal output by the first switch control circuit can turn off the first switch circuit, thereby preventing reverse current. Furthermore, the operating voltage of the first switch control circuit is set to the voltage at the power supply output terminal, so that the first switch control circuit can still operate even when the power supply is off, i.e., when there is no voltage at the power supply input terminal. Even if the voltage at the power supply output terminal is greater than the voltage at the power supply input terminal, the first switch control circuit can still turn off the first switch circuit in time to prevent reverse current, thus solving the problem of reverse current during power outages.

[0048] To illustrate the technical solution described in this application, specific embodiments are provided below.

[0049] Figure 1 A schematic diagram of the protection circuit provided in an embodiment of this application is shown. For ease of explanation, only the parts related to this embodiment are shown, and the details are as follows: The protection circuit includes a first switching circuit 30, a reference voltage circuit 10, and a first switching control circuit 20.

[0050] As an example, a first switching circuit 30 is connected to a first switching control circuit 20, which controls the on and off states of the first switching circuit 30. The first switching circuit 30 is connected in series between the power input terminal VIN and the power output terminal VOUT. The first switching circuit 30 is configured to switch the path between the power input terminal VIN and the power output terminal VOUT. When the first switching circuit 30 is on, the path between the power input terminal VIN and the power output terminal VOUT is open. When the first switching circuit 30 is off, the path between the power input terminal VIN and the power output terminal VOUT is closed.

[0051] The reference voltage circuit 10 is connected to the first switch control circuit 20 and the power input terminal VIN. The reference voltage circuit 10 is configured to provide a first reference voltage VB to the first switch control circuit 20 based on the voltage at the power input terminal VIN. Technicians can set the first reference voltage VB to be greater than, equal to, or less than the voltage at the power input terminal VIN as needed.

[0052] The first switch control circuit 20 is also connected to the power output terminal VOUT. The first switch control circuit 20 is configured to control the first switch circuit 30 to turn off when the voltage at the power output terminal VOUT is greater than or equal to the first reference voltage VB.

[0053] It should be noted that in some embodiments, the voltage value of the first reference voltage VB is the threshold value for triggering the protection circuit. When the voltage of the power output terminal VOUT is greater than or equal to the first reference voltage VB, the protection circuit should be triggered, causing the first switching circuit 30 to be turned off.

[0054] This embodiment does not specifically limit how to compare the voltage at the power output terminal VOUT and the first reference voltage VB; those skilled in the art can choose according to their needs. For example, the comparison can be made using a first circuit with voltage comparison functionality, and the first switch control circuit 20 includes this first circuit.

[0055] In this embodiment, when the voltage at the power output terminal VOUT is greater than or equal to the first reference voltage VB, the protection circuit is triggered, causing the first switch control circuit 20 to turn off the first switch circuit 30, thereby preventing reverse current. For example, the first switch control circuit 20 can output a first control signal VC, which can control the first switch circuit 30 to turn off when the voltage at the power output terminal VOUT is greater than or equal to the first reference voltage VB. Alternatively, when the voltage at the power output terminal VOUT is less than the first reference voltage VB, the first control signal VC can control the first switch circuit 30 to turn on. In one possible implementation of this application, when the voltage at the power input terminal VIN is greater than the voltage at the power output terminal VOUT, the first control signal VC output by the first switch control circuit 20 can control the first switch circuit 30 to turn on.

[0056] This embodiment does not specifically limit the signal type of the first control signal VC; those skilled in the art can select it as needed. For example, the first control signal VC can be an analog signal or a digital signal. Furthermore, the first control signal VC can be a high-level signal or a low-level signal. When it is a high-level signal, the first control signal VC controls the first switching circuit 30 to turn off (or on). When it is a low-level signal, the first control signal VC controls the first switching circuit 30 to turn on (or off).

[0057] In one possible implementation of this application, the operating voltage of the first switch control circuit 20 can be provided by the power output terminal VOUT or by a first power source. The first power source and the power source providing the input voltage to the power input terminal VIN are not the same power source. In this implementation, when the power supply is off, i.e., when the power input terminal VIN has no voltage, the first switch control circuit 20 can still be in operation. Even if the voltage at the power output terminal VOUT is greater than the voltage at the power input terminal VIN, the first switch control circuit 20 can still promptly turn off the first switch circuit 30 to prevent reverse current from being generated, thereby solving the problem of reverse current when the power supply is off.

[0058] In this embodiment, the operating voltage of the first switch control circuit 20 is set to be provided by the power output terminal VOUT or the first power supply, which can improve the reliability of the first switch control circuit 20, thereby improving the reliability of the protection circuit.

[0059] This embodiment does not limit the specific circuit structure of the first switch circuit 30, the reference voltage circuit 10, and the first switch control circuit 20, nor the specific voltage value of the first reference voltage VB. Technicians can make selections as needed.

[0060] For example, in some embodiments, the voltage value of the first reference voltage VB can be set to be equal to or less than the voltage value of the power input terminal VIN in order to avoid the voltage of the power output terminal VOUT being too high.

[0061] In summary, this embodiment not only prevents backflow current, but also ensures that the first switch control circuit 20 can remain operational even if the power supply fails, as its operating voltage is provided by the power output terminal VOUT or the first power supply. This results in a highly reliable protection circuit provided by this embodiment.

[0062] Figure 2 A schematic diagram of a protection circuit according to another embodiment of this application is shown. In this embodiment, the first switch control circuit 20 includes a first comparison circuit 21 and a signal processing circuit 22.

[0063] The first comparator circuit 21 is connected to the power output terminal VOUT and the reference voltage circuit 10. The first comparator circuit 21 is configured to compare the voltage at the power output terminal VOUT with the first reference voltage VB and provide a corresponding control voltage. Based on the relationship between the voltage at the power output terminal VOUT and the first reference voltage VB, the control voltage value includes two cases: when the voltage at the power output terminal VOUT is greater than or equal to the first reference voltage VB, the control voltage value is a first voltage value; when the voltage at the power output terminal VOUT is less than the first reference voltage VB, the control voltage value is a second voltage value.

[0064] The signal processing circuit 22, the first comparison circuit 21, and the first switching circuit 30 are connected. The first comparison circuit 21 provides the aforementioned control voltage to the signal processing circuit 22. The signal processing circuit 22 is configured to process the control voltage and output the aforementioned first control signal VC accordingly. The first control signal VC varies depending on the voltage value of the control voltage. For example, when the voltage at the power output terminal VOUT is greater than or equal to the first reference voltage VB, the control voltage value is the first voltage value, and the processed first control signal VC can be a high-level signal, which can control the first switching circuit 30 to turn off. Conversely, when the voltage at the power output terminal VOUT is less than the first reference voltage VB, the control voltage value is the second voltage value, and the processed first control signal VC can be a low-level signal, which can control the first switching circuit 30 to turn on.

[0065] The operating voltage of the signal processing circuit 22 is set to be provided by the power output terminal VOUT or the first power supply, and the operating voltage of the first comparison circuit 21 is set to be provided by the power output terminal VOUT or the first power supply. These settings can improve the reliability of the protection circuit.

[0066] This embodiment does not limit the specific circuit structure of the first comparison circuit 21 and the signal processing circuit 22; technicians can choose according to their needs.

[0067] For example, the first comparison circuit 21 is the first circuit with voltage comparison function described above. As another example, the signal processing circuit 22 can be implemented using digital circuitry to convert the control voltage into a first control signal VC for controlling the first switching circuit 30 to turn on or off.

[0068] In this embodiment, the first comparison circuit 21 and the signal processing circuit 22 realize the function of the first switch control circuit 20. That is, when the power supply is off, if the power output terminal VOUT is in a energized state, or the voltage of the power output terminal VOUT is greater than the voltage of the power input terminal VIN, the first switch circuit 30 can be turned off in time by the first comparison circuit 21 and the signal processing circuit 22 to prevent the generation of reverse current.

[0069] In another embodiment of this application, a specific circuit structure of the first comparison circuit 21 is disclosed.

[0070] The first comparison circuit 21 includes a first switching transistor M1, a second switching transistor M2, a first current source Ibias1, and a second current source Ibias2. The first comparison circuit 21 implements the voltage comparison function through these four devices.

[0071] This embodiment does not specifically limit the types of the first switching transistor M1 and the second switching transistor M2; those skilled in the art can select them as needed. For example, the first switching transistor M1 and the second switching transistor M2 can be MOSFETs, IGBTs, transistors, etc.

[0072] As an example rather than a limitation, such as Figure 3 As shown, both the first switch M1 and the second switch M2 are PMOS transistors.

[0073] The input terminal of the first switching transistor M1 is connected to the reference voltage circuit 10 and configured to receive the first reference voltage VB. The output terminal of the first switching transistor M1, the input terminal of the first current source Ibias1, and the control terminal of the second switching transistor M2 are connected. The input terminal of the second switching transistor M2 is connected to the power output terminal VOUT, and the output terminal of the second switching transistor M2, the input terminal of the second current source Ibias2, and the control terminal of the first switching transistor M1 are connected. The output terminals of the first current source Ibias1 and the second current source Ibias2 are grounded.

[0074] The control voltage includes the voltage at the output terminal of the first switching transistor M1 and / or the voltage at the output terminal of the second switching transistor M2.

[0075] Based on the characteristics of MOSFETs, the input, output, and control terminals of the first switching transistor M1 correspond to the source, drain, and gate of the first switching transistor M1, respectively. The input, output, and control terminals of the second switching transistor M2 correspond to the source, drain, and gate of the second switching transistor M2, respectively.

[0076] right Figure 3 Analyzing the first comparator circuit 21 shown, we can see that:

[0077] When the voltage at the power output terminal VOUT is greater than or equal to the first reference voltage VB, the first switch M1 is turned off and the second switch M2 is turned on. The voltage at the drain of the first switch M1 is equal to the voltage at the ground terminal GND, and the voltage at the drain of the second switch M2 is equal to the voltage at the power output terminal VOUT.

[0078] When the voltage at the power output terminal VOUT is less than the first reference voltage VB, the first switch M1 is turned on and the second switch M2 is turned off. The voltage at the drain of the first switch M1 is equal to the first reference voltage VB, and the voltage at the drain of the second switch M2 is equal to the voltage at the ground terminal GND.

[0079] Based on the above analysis, when the voltage at the power output terminal VOUT and the first reference voltage VB are different, the drain voltages of the first switching transistor M1 and the second switching transistor M2 will also be different. Therefore, utilizing this characteristic, the drain voltages of the first switching transistor M1 and / or the drain voltages of the second switching transistor M2 can be used as the control voltages. These control voltages, after processing by the signal processing circuit 22, can generate first control signals VC with different level signals, thereby controlling the first switching circuit 30 to turn on or off.

[0080] In other words, when the voltage at the power output terminal VOUT is greater than or equal to the first reference voltage VB, the control voltage value is equal to the aforementioned first voltage value, which is equivalent to the voltage at the drain of the first switching transistor M1 being equal to the voltage at the ground terminal GND, and / or the voltage at the drain of the second switching transistor M2 being equal to the voltage at the power output terminal VOUT.

[0081] When the voltage at the power output terminal VOUT is less than the first reference voltage VB, the control voltage value is equal to the second voltage value mentioned above, which is equivalent to the voltage at the drain of the first switching transistor M1 being equal to the first reference voltage VB, and the voltage at the drain of the second switching transistor M2 being equal to the voltage at the ground terminal GND.

[0082] like Figure 3 As shown, in an optional implementation of this embodiment, the first comparator circuit 21 further includes an adjustable element M0. The input terminal of the adjustable element M0 is connected to the power output terminal VOUT, and the output terminal of the adjustable element M0 is connected to the input terminal of the second switch M2. The adjustable element M0 is configured to adjust its on-resistance value to change the switching threshold voltage of the first comparator circuit 21. In some embodiments, the switching threshold voltage means that when the voltage at the source of the second switch M2 is greater than the switching threshold voltage, the second switch M2 is turned on; when the voltage at the source of the second switch M2 is less than the switching threshold voltage, the second switch M2 is turned off.

[0083] Since the first comparator circuit 21 compares the source voltage of the first switch M1 and the source voltage of the second switch M2, the source voltage of the second switch M2 can be changed by connecting an adjustable element M0 in series and adjusting the on-resistance value of the adjustable element M0, thereby changing the flip threshold voltage of the first comparator circuit 21.

[0084] This embodiment does not limit the specific type of the adjustable element M0; technicians can select it as needed.

[0085] By way of example and not limitation, the adjustable element M0 includes a MOSFET or an adjustable resistor. A MOSFET can change its on-resistance by adjusting the width-to-length ratio of its conductive channel. An adjustable resistor can change its on-resistance by adjusting its effective conductive length.

[0086] Optionally, such as Figure 3 As shown, the adjustable element M0 is selected as a PMOS transistor, with its input and output terminals corresponding to its source and drain, respectively. Furthermore, to turn on the PMOS transistor, its gate and drain are shorted, so that the gate voltage is lower than the source voltage.

[0087] In another embodiment of this application, a specific circuit structure of the signal processing circuit 22 is disclosed. For example... Figure 3 As shown, the signal processing circuit 22 includes a third switch M3, a fourth switch M4, a fifth switch M5, a sixth switch M6, and logic circuitry. The signal processing circuit 22 implements signal processing functions through these four switches and the logic circuitry. In this embodiment, the control circuit also includes the voltage at the drain of the first switch M1 and the voltage at the drain of the second switch M2.

[0088] This embodiment does not specifically limit the types of the third switch M3, the fourth switch M4, the fifth switch M5, the sixth switch M6, and the logic circuit; technicians can select them as needed.

[0089] For example, the third switch M3, the fourth switch M4, the fifth switch M5, and the sixth switch M6 can be MOSFETs, IGBTs, transistors, etc. For example, the logic circuit can include AND gates, OR gates, or NOT gates. The NOT gate can also be called an inverter.

[0090] As an example rather than a limitation, such as Figure 3 As shown, the third switch M3 and the fourth switch M4 are both PMOS transistors, and the fifth switch M5 and the sixth switch M6 are both NMOS transistors. The logic circuit includes a first inverter INV1, a second inverter INV2 and a third inverter INV3 connected in series.

[0091] The input terminals of the third switch M3, the fourth switch M4, and the power output terminal VOUT are connected. The output terminal of the third switch M3, the control terminal of the fourth switch M4, and the input terminal of the fifth switch M5 are connected. The output terminal of the fourth switch M4, the control terminal of the third switch M3, the input terminal of the sixth switch M6, and the input terminal of the logic circuit are connected. The output terminal of the logic circuit is used to output the first control signal VC.

[0092] The output terminals of the fifth switch M5 and the sixth switch M6 are grounded. The output terminal of the first switch M1 is connected to the control terminal of the fifth switch M5, and the output terminal of the second switch M2 is connected to the control terminal of the sixth switch M6.

[0093] Based on the characteristics of MOSFETs, the input, output, and control terminals of the third switch M3 correspond to the source, drain, and gate of the third switch M3, respectively. The input, output, and control terminals of the fourth switch M4 correspond to the source, drain, and gate of the fourth switch M4, respectively. The input, output, and control terminals of the fifth switch M5 correspond to the drain, source, and gate of the fifth switch M5, respectively. The input, output, and control terminals of the sixth switch M6 correspond to the drain, source, and gate of the sixth switch M6, respectively.

[0094] The operating voltage of the logic circuit is provided by the power supply output terminal VOUT or the first power supply to improve the reliability of the protection circuit. It should be understood that technicians can select the appropriate number of inverters to construct the above logic circuit as needed.

[0095] like Figure 3 As shown, analysis of the first comparison circuit 21 and the signal processing circuit 22 reveals that:

[0096] When the voltage at the power output terminal VOUT is greater than or equal to the first reference voltage VB, the first switch M1 is turned off, the fifth switch M5 is turned off, the fourth switch M4 is turned off, the second switch M2 is turned on, the sixth switch M6 is turned on, and the third switch M3 is turned on, so that the voltage at the drain of the fourth switch M4 is equal to the voltage at the ground terminal GND, that is, the voltage at the input terminal of the logic circuit is equal to the voltage at the ground terminal GND.

[0097] When the voltage at the power output terminal VOUT is less than the first reference voltage VB, the first switch M1 is turned on, the fifth switch M5 is turned on, the fourth switch M4 is turned on, the second switch M2 is turned off, the sixth switch M6 is turned off, and the third switch M3 is turned off, so that the voltage at the drain of the fourth switch M4 is equal to the voltage at the power output terminal VOUT, that is, the voltage at the input terminal of the logic circuit is equal to the voltage at the power output terminal VOUT.

[0098] In this embodiment, since the logic circuit includes an odd number of inverters connected in series, when the voltage at the power output terminal VOUT is greater than or equal to the first reference voltage VB, the first control signal VC output by the logic circuit is a high-level signal; when the voltage at the power output terminal VOUT is less than the first reference voltage VB, the first control signal VC output by the logic circuit is a low-level signal.

[0099] The signal processing circuit 22 disclosed in this embodiment utilizes the voltage of the drain of the first switching transistor M1 and the voltage of the drain of the second switching transistor M2 simultaneously, thus making its output first control signal VC more reliable and stable.

[0100] like Figure 3 As shown, in another embodiment of this application, the reference voltage circuit 10 includes a third current source Ibias3 and a Zener diode D1. The input terminal of the third current source Ibias3 is connected to the power input terminal VIN. The cathode of the Zener diode D1, the output terminal of the third current source Ibias3, and the first switch control circuit 20 are connected. The anode of the Zener diode D1 is grounded, and the voltage at the cathode of the Zener diode D1 is the first reference voltage VB.

[0101] Therefore, as Figure 4 As shown, when the voltage at the power input terminal VIN is less than the stable voltage V0 of the Zener diode D1, even if the voltage at the power input terminal VIN changes, the first reference voltage VB can remain consistent with the voltage at the power input terminal VIN, that is, the two are equal. This feature makes the protection circuit provided in this embodiment applicable to power supplies with a wide input voltage range.

[0102] When the voltage at the power input terminal VIN is greater than or equal to the stable voltage V0 of the Zener diode D1, the first reference voltage VB is equal to the stable voltage V0 of the Zener diode D1. This feature enables the protection circuit provided in this embodiment to prevent the load from operating at a large voltage.

[0103] In some embodiments, such as Figure 4 and Figure 5 As shown, when the voltage at the power output terminal VOUT is greater than or equal to the first reference voltage VB, the first control signal VC is a high-level signal, causing the first switching circuit 30 to turn off. When the voltage at the power output terminal VOUT is less than the first reference voltage VB, the first control signal VC is a low-level signal, causing the first switching circuit 30 to turn on.

[0104] like Figure 3 As shown, in another embodiment of this application, the protection circuit further includes a second switch circuit 60 and a second switch control circuit 40. The second switch circuit 60 and the first switch circuit 30 are connected in series, and the second switch control circuit 40 and the second switch circuit 60 are connected. The second switch control circuit 40 is configured to turn on or off the second switch circuit 60 according to the relationship between the voltage at the power output terminal VOUT and the second reference voltage VREF.

[0105] It should be noted that one function of the first switching circuit 30 is to prevent reverse current. Specifically, when the voltage at the power output terminal VOUT is greater than or equal to the first reference voltage VB, the first switch control circuit 20 controls the first switching circuit 30 to turn off, thus disconnecting the power input terminal VIN and the power output terminal VOUT, achieving a protection function. One function of the second switching circuit 60 is to output the voltage at the power input terminal VIN to the first switching circuit 30, or to confirm the disconnection of the path between the power input terminal VIN and the power output terminal VOUT.

[0106] Therefore, when the protection circuit is not triggered, the voltage at the power output terminal VOUT is normal. At this time, the second switch control circuit 40 is configured to turn on the second switch circuit 60 based on the relationship between the voltage at the power output terminal VOUT and the second reference voltage VREF, so that the voltage at the power input terminal VIN is output to the power output terminal VOUT through the first switch circuit 30 and the second switch circuit 60. For example, this relationship is that the voltage at the power output terminal VOUT is greater than or equal to the second reference voltage VREF.

[0107] When the protection circuit is triggered, the voltage at the power output terminal VOUT becomes abnormal, for example, it drops to zero. At this time, the second switch control circuit 40 is configured to turn off the second switch circuit 60 based on the relationship between the voltage at the power output terminal VOUT and the second reference voltage VREF, causing both the first switch circuit 30 and the second switch circuit 60 to turn off. For example, this relationship is that the voltage at the power output terminal VOUT is less than the second reference voltage VREF.

[0108] As an optional implementation of this embodiment, the first switching circuit 30 includes a seventh switching transistor M7, and the second switching circuit 60 includes an eighth switching transistor M8 connected in series with the seventh switching transistor M7.

[0109] The control terminal of the seventh switch M7 is connected to the output terminal of the first switch control circuit 20. The input terminal of the seventh switch M7 is connected to the output terminal of the eighth switch M8. The output terminal of the seventh switch M7 is the power output terminal VOUT. The input terminal of the eighth switch M8 is connected to the power input terminal VIN. The control terminal of the eighth switch M8 is connected to the output terminal of the second switch control circuit 40.

[0110] This embodiment does not limit the specific types of the seventh switch M7 and the eighth switch M8; those skilled in the art can select them as needed. For example, the seventh switch M7 and the eighth switch M8 can be MOSFETs, IGBTs, or transistors, etc.

[0111] As an example and not a limitation, both the seventh switch M7 and the eighth switch M8 are PMOS transistors.

[0112] Based on the characteristics of MOSFETs, the input, output, and control terminals of the seventh switch M7 correspond to its source, drain, and gate, respectively, and the input, output, and control terminals of the eighth switch M8 correspond to its drain, source, and gate, respectively.

[0113] One advantage of using PMOS transistors for both the seventh switch M7 and the eighth switch M8 is that the parasitic diodes of the seventh switch M7 and the eighth switch M8 are connected in opposite directions. This ensures that when both the seventh switch M7 and the eighth switch M8 are turned off, there is no leakage current. That is, no forward current will be generated between the power input terminal VIN and the power output terminal VOUT, and no reverse current will be generated between the power output terminal VOUT and the power input terminal VIN.

[0114] As an optional implementation of this embodiment, the protection circuit further includes a voltage divider circuit 50, with its first terminal connected to the power output terminal VOUT and its second terminal grounded. The second switch control circuit 40 is configured to compare the voltage at the voltage divider node of the voltage divider circuit 50 with the second reference voltage VREF, and output a second control signal for turning on or off the second switch circuit 60 accordingly.

[0115] This embodiment does not limit the specific circuit structure of the voltage divider circuit 50, the voltage value of the second reference voltage VREF, or the type of the second control signal; technicians can make selections as needed.

[0116] For example, voltage divider circuit 50 includes multiple resistors connected in series, such as Figure 3 The circuit includes a first resistor R1 and a second resistor R2 connected in series. The connection node of the first resistor R1 and the second resistor R2 is the voltage divider node of the voltage divider circuit 50. The voltage at this voltage divider node is used as the feedback voltage VFB and input to the second switch control circuit 40. The second switch control circuit 40 compares the feedback voltage VFB with the second reference voltage VREF and outputs a second control signal to turn on or off the second switch circuit 60 accordingly.

[0117] For example, the second control signal can be a high-level signal or a low-level signal.

[0118] As an optional implementation of this embodiment, the second switch control circuit 40 is a comparator A, which can be implemented by an operational amplifier and can play a role in stabilizing the loop.

[0119] In another embodiment of this application, a management chip is also provided, which includes the protection circuit provided in any of the above embodiments. This management chip is used to manage the power supply; for example, it can perform functions such as power conversion, distribution, detection, and other power management. Furthermore, if the power supply providing the input voltage to the power input terminal VIN is a rechargeable battery, the management chip can manage the charging and discharging processes of the power supply.

[0120] Therefore, in some embodiments, the management chip may include a voltage conversion circuit, a status detection circuit, or a charge / discharge control circuit. The status detection circuit may be connected to the output of the signal processing circuit 22, and detects the first control signal VC output by the signal processing circuit 22 to confirm whether the protection circuit has been triggered. For example, when the first control signal VC is detected to be a high-level signal, it is confirmed that the protection circuit has been triggered.

[0121] In some embodiments, the management chip may take the form of an integrated circuit, a control circuit, a circuit board, a system-on-a-chip, etc.

[0122] The management chip provided in this embodiment also has the beneficial effects of the protection circuit mentioned above. For example, when the voltage at the power output terminal VOUT is greater than the voltage at the power input terminal VIN, it can promptly turn off the first switch circuit 30 to cut off the path between the power output terminal VOUT and the power input terminal VIN, thereby preventing the generation of reverse current.

[0123] In another embodiment of this application, a power supply device is also provided, which includes a power supply for providing electrical energy and a protection circuit or management chip provided in any of the above embodiments.

[0124] For example, the power supply and power input terminal VIN are connected to the management chip to provide input voltage to the power input terminal VIN and operating voltage to the management chip.

[0125] The power supply device provided in this embodiment also has the beneficial effects of the protection circuit described above. For example, when the voltage at the power output terminal VOUT is greater than the voltage at the power input terminal VIN, the first switch circuit 30 can be turned off in time to cut off the path between the power output terminal VOUT and the power input terminal VIN, thereby preventing the generation of reverse current.

[0126] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A protection circuit, characterized in that, include: The first switching circuit is configured as a path between the input terminal and the output terminal of the switching power supply. A reference voltage circuit, connected to the power input terminal, is configured to provide a first reference voltage to the first switch control circuit based on the voltage at the power input terminal; The first switch control circuit is connected to the first switch circuit, the reference voltage circuit, and the power output terminal, and is configured to control the first switch circuit to turn off when the voltage at the power output terminal is greater than or equal to the first reference voltage. The operating voltage of the first switch control circuit is provided by the power output terminal or a first power source, and the first power source is not the same power source as the power source that provides voltage to the power input terminal. The first switch control circuit includes: A first comparison circuit is connected to the reference voltage circuit and the power supply output terminal, and is configured to compare the voltage at the power supply output terminal with the first reference voltage, and provide a corresponding control voltage to the signal processing circuit. The signal processing circuit is connected to the first comparison circuit and the first switching circuit, and is configured to process the control voltage and output a first control signal, which is used to trigger the first switching circuit to turn off. The first comparator circuit includes a first switch transistor, a second switch transistor, a first current source, and a second current source; The input terminal of the first switch is configured to receive the first reference voltage. The output terminal of the first switch, the input terminal of the first current source, and the control terminal of the second switch are connected. The input terminal of the second switch is connected to the power supply output terminal. The output terminal of the second switch, the input terminal of the second current source, and the control terminal of the first switch are connected. The output terminals of the first current source and the second current source are grounded. The control voltage includes the voltage at the output terminal of the first switching transistor and / or the voltage at the output terminal of the second switching transistor.

2. The protection circuit according to claim 1, characterized in that, The first comparison circuit further includes: An adjustable element is provided, wherein the input terminal of the adjustable element is connected to the power supply output terminal, and the output terminal of the adjustable element is connected to the input terminal of the second switching transistor. The adjustable element is configured to adjust its on-resistance value to change the switching threshold voltage of the first comparator circuit.

3. The protection circuit according to claim 2, characterized in that, The adjustable element includes a MOSFET or an adjustable resistor.

4. The protection circuit according to claim 1, characterized in that, The signal processing circuit includes a third switch, a fourth switch, a fifth switch, a sixth switch, and logic circuitry. The input terminal of the third switch, the input terminal of the fourth switch, and the power output terminal are connected. The output terminal of the third switch, the control terminal of the fourth switch, and the input terminal of the fifth switch are connected. The output terminal of the fourth switch, the control terminal of the third switch, the input terminal of the sixth switch, and the input terminal of the logic circuit are connected. The logic circuit is used to process the voltage at the output terminal of the fourth switch and output the first control signal accordingly. The operating voltage of the logic circuit is provided by the power output terminal or the first power supply. The output terminals of the fifth and sixth switches are grounded, the output terminal of the first switch is connected to the control terminal of the fifth switch, and the output terminal of the second switch is connected to the control terminal of the sixth switch.

5. The protection circuit according to any one of claims 1 to 4, characterized in that, The reference voltage circuit includes: A third current source, the input terminal of which is connected to the power input terminal; A Zener diode is provided, wherein the cathode of the Zener diode is connected to the output terminal of the third current source and the first switch control circuit, the anode of the Zener diode is grounded, and the voltage of the cathode of the Zener diode is the first reference voltage.

6. The protection circuit according to any one of claims 1 to 4, characterized in that, The protection circuit also includes: A second switching circuit connected in series with the first switching circuit shown. A second switch control circuit connected to the second switch circuit is configured to turn on or off the second switch circuit based on the relationship between the voltage at the power supply output terminal and the second reference voltage.

7. The protection circuit according to claim 6, characterized in that, The first switching circuit includes a seventh switching transistor, and the second switching circuit includes an eighth switching transistor connected in series with the seventh switching transistor; The control terminal of the seventh switch is connected to the output terminal of the first switch control circuit, the input terminal of the seventh switch is connected to the output terminal of the eighth switch, the output terminal of the seventh switch is the power output terminal, the input terminal of the eighth switch is connected to the power input terminal, and the control terminal of the eighth switch is connected to the output terminal of the second switch control circuit.

8. The protection circuit according to claim 6, characterized in that, The protection circuit also includes: A voltage divider circuit, wherein the first terminal of the voltage divider circuit is connected to the power output terminal, and the second terminal of the voltage divider circuit is grounded; The second switch control circuit is configured to compare the voltage of the voltage divider node of the voltage divider circuit with the second reference voltage, and output a second control signal for turning on or off the second switch circuit.

9. A management chip, characterized in that, Includes the protection circuit described in any one of claims 1 to 8.

10. A power supply device, characterized in that, It includes the protection circuit as described in any one of claims 1 to 8, or the management chip as described in claim 9.

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