CN115313344A - Protection circuit, management chip and power supply unit - Google Patents

Protection circuit, management chip and power supply unit Download PDF

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Publication number
CN115313344A
CN115313344A CN202211065600.7A CN202211065600A CN115313344A CN 115313344 A CN115313344 A CN 115313344A CN 202211065600 A CN202211065600 A CN 202211065600A CN 115313344 A CN115313344 A CN 115313344A
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CN
China
Prior art keywords
circuit
voltage
switch
output end
power supply
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Pending
Application number
CN202211065600.7A
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Chinese (zh)
Inventor
王梨力
尚林林
周梦嵘
赵鹏
兰云鹏
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STMicroelectronics Shenzhen R&D Co Ltd
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STMicroelectronics Shenzhen R&D Co Ltd
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Priority to CN202211065600.7A priority Critical patent/CN115313344A/en
Publication of CN115313344A publication Critical patent/CN115313344A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H11/00—Emergency protective circuit arrangements for preventing the switching-on in case an undesired electric working condition might result
    • H02H11/006—Emergency protective circuit arrangements for preventing the switching-on in case an undesired electric working condition might result in case of too high or too low voltage
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H1/00—Details of emergency protective circuit arrangements
    • H02H1/06—Arrangements for supplying operative power
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/02—Details
    • H02H3/05—Details with means for increasing reliability, e.g. redundancy arrangements
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/20—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage

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Abstract

The application discloses protection circuit, management chip and power supply unit. The protection circuit includes: a first switching circuit for switching a path between a power supply input terminal and a power supply output terminal; a reference voltage circuit for generating a first reference voltage based on a voltage of the power supply input terminal; and the first switch control circuit is used for comparing the voltage of the power supply output end with the first reference voltage and correspondingly outputting a first control signal for controlling the first switch circuit. Because the working voltage of the first switch control circuit is provided by the power supply output end, the first switch control circuit can still be in a working state when the power supply is in a power failure state, and if the voltage of the power supply output end is greater than the voltage of the power supply input end, the first switch control circuit can still turn off the first switch circuit in time so as to prevent the generation of backward current. Also, the reference voltage circuit generates the first reference voltage using the zener diode, so that the present embodiment can be applied to a power supply having a wide input voltage range.

Description

Protection circuit, management chip and power supply unit
Technical Field
The application belongs to the technical field of power supplies, and particularly relates to a protection circuit, a management chip and a power supply device.
Background
The power supply may be used to provide the operating voltage required by the load. In practical applications, a switching circuit is usually used to switch on and off an output voltage of a power supply to control whether the power supply supplies power to a load. However, when the power supply is powered down, the power supply output terminal may still be in a charged state, or the voltage of the power supply output terminal may be greater than the voltage of the power supply input terminal (this phenomenon may occur, for example, when the capacitance to ground of the power supply output terminal is greater than the capacitance to ground of the power supply input terminal). At this time, if there is no corresponding protection measure, a backward current flowing from the power output terminal to the power input terminal may be generated.
Disclosure of Invention
An object of the application is to provide a protection circuit, a management chip and a power supply device, and the problem of backward flow current existing when a power supply is powered down is solved.
A first aspect of an embodiment of the present application provides a protection circuit, including:
a first switching circuit configured to switch a path between a power supply input terminal and a power supply output terminal;
a reference voltage circuit connected to the power input terminal and configured to provide a first reference voltage to the first switch control circuit based on a voltage of the power input terminal;
the first switch control circuit is connected with the first switch circuit, the reference voltage circuit and the power output end and is configured to control the first switch circuit to be switched off under the condition that the voltage of the power output end is greater than or equal to a first reference voltage, wherein the working voltage of the first switch control circuit is provided by the power output end or a first power supply, and the first power supply and the power supply providing the input voltage for the power input end are not the same power supply.
Optionally, the first switch control circuit comprises:
the first comparison circuit is connected with the reference voltage circuit and the power supply output end, is configured to compare the voltage of the power supply output end with the first reference voltage, and provides corresponding control voltage for the signal processing circuit;
and the signal processing circuit is connected with the first comparison circuit and the first switch circuit, is configured to process the control voltage and correspondingly outputs a first control signal, and the first control signal is used for controlling the first switch circuit to be switched off under the condition that the voltage of the power output end is greater than or equal to a first reference voltage, wherein the working voltage of the signal processing circuit is provided by the power output end or the first power supply, and the working voltage of the first comparison circuit is provided by the power output end or the first power supply.
Optionally, the first comparison circuit includes a first switch tube, a second switch tube, a first current source and a second current source;
the input end of the first switch tube is configured to receive a first reference voltage, the output end of the first switch tube, the input end of the first current source and the control end of the second switch tube are connected, the input end of the second switch tube is connected with the output end of the power supply, the output end of the second switch tube, the input end of the second current source and the control end of the first switch tube are connected, and the output end of the first current source and the output end of the second current source are grounded;
the control voltage comprises the voltage of the output end of the first switch tube and/or the voltage of the output end of the second switch tube.
Optionally, the first comparison circuit further comprises:
the input end of the adjustable element is connected with the power supply output end, the output end of the adjustable element is connected with the input end of the second switch tube, and the adjustable element is configured to adjust the on-resistance value of the adjustable element so as to change the overturning threshold voltage of the first comparison circuit.
Optionally, the adjustable element comprises a MOS transistor or an adjustable resistor.
Optionally, the signal processing circuit includes a third switching tube, a fourth switching tube, a fifth switching tube, a sixth switching tube and a logic circuit;
the input end of the third switching tube, the input end of the fourth switching tube and the power output end are connected, the output end of the third switching tube, the control end of the fourth switching tube and the input end of the fifth switching tube are connected, the output end of the fourth switching tube, the control end of the third switching tube and the input end of the sixth switching tube are connected with the input end of the logic circuit, the logic circuit is used for processing the voltage of the output end of the fourth switching tube and correspondingly outputting a first control signal, and the working voltage of the logic circuit is provided by the power output end or a first power supply;
the output end of the fifth switching tube is connected with the output end of the sixth switching tube in a grounding mode, the output end of the first switching tube is connected with the control end of the fifth switching tube, and the output end of the second switching tube is connected with the control end of the sixth switching tube.
Optionally, the reference voltage circuit comprises:
the input end of the third current source is connected with the power supply input end;
the cathode of the Zener diode and the output end of the third current source are connected with 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.
Optionally, the protection circuit further comprises:
a second switching circuit in series with the first switching circuit;
and a second switch control circuit connected to the second switch circuit, the second switch control circuit being configured to turn on or off the second switch circuit according to a relationship between the voltage of the power supply output terminal and a second reference voltage.
Optionally, the first switching circuit includes a seventh switching tube, and the second switching circuit includes an eighth switching tube connected in series with the seventh switching tube;
the control end of the seventh switch tube is connected with the output end of the first switch control circuit, the input end of the seventh switch tube is connected with the output end of the eighth switch tube, the output end of the seventh switch tube is a power output end, the input end of the eighth switch tube is connected with the power input end, and the control end of the eighth switch tube is connected with the output end of the second switch control circuit.
Optionally, the protection circuit further comprises:
the first end of the voltage division circuit is connected with the power output end, and the second end of the voltage division circuit is grounded;
the second switch control circuit is configured to compare a voltage of a divided voltage node of the divided voltage circuit with a second reference voltage and output a second control signal for turning on or off the second switch circuit, respectively.
A second aspect of an embodiment of the present application provides a management chip, including the protection circuit provided in the first aspect.
A third aspect of an embodiment of the present application provides a power supply device, including the protection circuit provided in the first aspect, or including the management chip provided in the second aspect.
Compared with the prior art, the embodiment of the invention has the following beneficial effects:
on one hand, when the voltage of the power output terminal is greater than the first reference voltage (for example, the first reference voltage is the voltage of the power input terminal or a preset threshold), the first switch control circuit may control the first switch circuit to turn off to disconnect the path between the power input terminal and the power output terminal, so as to avoid generating a backward current flowing from the power output terminal to the power input terminal, or avoid that the voltage of the power output terminal exceeds a voltage range allowed by the load. On the other hand, because the working voltage of the first switch control circuit is provided by the power output end or the first power supply, when the power supply is powered off, namely the power input end does not have voltage, the first switch control circuit can still be in a working state, even if the voltage of the power output end is greater than the voltage of the power input end, the first switch control circuit can still turn off the first switch circuit in time so as to prevent the generation of backward flow current, thereby solving the problem of backward flow current existing in the power supply power-off process.
Drawings
Fig. 1 to fig. 3 are schematic structural diagrams of a protection circuit according to an embodiment of the present application;
FIG. 4 is a diagram illustrating the relationship between a first reference voltage and the voltage at the input of the power supply;
fig. 5 is a diagram illustrating a first control signal.
Illustration of the drawings:
10. a reference voltage circuit; 20. a first switch control circuit; 21. a first comparison circuit; 22. a signal processing circuit; 30. a first switching circuit; 40. a second switch control circuit; 50. a voltage dividing circuit; 60. a second switching circuit;
m0, an adjustable element; m1, a first switch tube; m2, a second switch tube; m3, a third switch tube; m4, a fourth switching tube; m5, a fifth switch tube; m6, a sixth switching tube; m7, a seventh switch tube; m8, an eighth switching tube; ibias1, a first current source; ibias2, a second current source; ibias3, a third current source; INV1, a first inverter; INV2, a second inverter; INV3, a third inverter; r1 and a first resistor; r2 and a second resistor; d1, a Zener diode; GND, ground; A. a comparator;
VIN, power input terminal; VOUT and a power supply output end; v0, stable voltage; VB, a first reference voltage; VC, a first control signal; VREF, a second reference voltage; VFB, feedback voltage.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or be indirectly connected to the other element.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating 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 the present application, "a plurality" means two or more unless specifically limited otherwise.
The power supply may be used to provide the operating voltage required by the load. In practical applications, the first switch circuit is usually used to turn on and off the output voltage of the power supply to control whether the power supply supplies power to the load. However, when the power supply is powered down, the power supply output terminal may still be in a charged state, and thus a backward current flowing from the power supply output terminal to the power supply input terminal may be generated. Alternatively, when the power supply is powered down, the voltage of the power output terminal may be greater than the voltage of the power input terminal (for example, when the capacitance to ground of the power output terminal is greater than that of the power input terminal, the voltage of the power output terminal may decrease at a slower rate than that of the power input terminal, which may occur), and a backward current flowing from the power output terminal to the power input terminal may also be generated. At this time, if there is no corresponding protection measure, a backward current flowing from the power output terminal to the power input terminal may be generated.
In view of this, the embodiment of the present application provides a protection circuit, which aims to solve the problem of reverse current existing when a power supply is powered off. The design idea of the protection circuit is as follows:
the voltage of the power output end is compared with a first reference voltage (for example, the first reference voltage is the voltage of the power input end or a preset threshold), and when the voltage of the power output end is greater than or equal to the first reference voltage, a first control signal output by the first switch control circuit can turn off the first switch circuit, so that the backward flow current is avoided. And the working voltage of the first switch control circuit is set to be the voltage of the power output end, so that when the power supply is powered down, namely the power input end does not have the voltage, the first switch control circuit can still be in a working state, even if the voltage of the power output end is greater than the voltage of the power input end, the first switch control circuit can still turn off the first switch circuit in time, the backward flow current is prevented from being generated, and the problem of the backward flow current existing when the power supply is powered down is solved.
In order to explain the technical solution described in the present application, the following description will be given by way of specific examples.
Fig. 1 shows a schematic structural diagram of a protection circuit provided in an embodiment of the present application, and for convenience of description, only the portions related to the embodiment are shown, which are detailed as follows: the protection circuit includes a first switch circuit 30, a reference voltage circuit 10, and a first switch control circuit 20.
As an example, the first switch circuit 30 is connected to the first switch control circuit 20, and the first switch control circuit 20 is configured to control the first switch circuit 30 to be turned on and off. 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 a path between the power supply input terminal VIN and the power supply output terminal VOUT. When the first switch circuit 30 is turned on, a path between the power input terminal VIN and the power output terminal VOUT is opened. When the first switching circuit 30 is turned off, the path between the power input terminal VIN and the power output terminal VOUT is closed.
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 the first switch control circuit 20 with the first reference voltage VB based on the voltage of the power supply input terminal VIN. The skilled person can set the first reference voltage VB to a voltage greater than, equal to, or less than the power supply input terminal VIN as required.
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 in a case where the voltage of the power output terminal VOUT is greater than or equal to the first reference voltage VB.
It should be noted that, in some embodiments, the voltage value of the first reference voltage VB is a threshold value of the protection circuit, and 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, so that the first switch circuit 30 is turned off.
In this embodiment, how to compare the magnitude relationship between the voltage of the power output terminal VOUT and the first reference voltage VB is not specifically limited, and a skilled person can select the comparison according to needs. For example, the comparison is performed by a first circuit having a voltage comparison function, and the first switch control circuit 20 includes the first circuit.
In this embodiment, when the voltage of the power output terminal VOUT is greater than or equal to the first reference voltage VB, the protection circuit is triggered, so that the first switch control circuit 20 turns off the first switch circuit 30, thereby preventing the generation of the backward current. For example, the first switch control circuit 20 may output the first control signal VC, which may control the first switch circuit 30 to turn off when the voltage of the power output terminal VOUT is greater than or equal to the first reference voltage VB. For another example, when the voltage of the power output terminal VOUT is less than the first reference voltage VB, the first control signal VC may control the first switch circuit 30 to be turned on. In one possible implementation manner of the present application, in a case that the voltage of the power input terminal VIN is greater than the voltage of 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 be turned on.
In this embodiment, the signal type of the first control signal VC is not specifically limited, and a skilled person may select the signal type according to needs. For example, the first control signal VC may be an analog signal or a digital signal. For another example, the first control signal VC may be a high-level signal or a low-level signal. When the signal is a high level signal, the first control signal VC controls the first switch circuit 30 to be turned off (or turned on). When the signal is a low level signal, the first control signal VC controls the first switch circuit 30 to be turned on (or off).
In one possible implementation manner of the present application, the operating voltage of the first switch control circuit 20 may be provided by the power output terminal VOUT or may be provided by the first power source. The first power supply and the power supply providing the input voltage to the power input terminal VIN are not the same power supply. In this implementation, when the power source fails, that is, the power input terminal VIN does not have a voltage, the first switch control circuit 20 may still be in a working state, and even if the voltage of the power output terminal VOUT is greater than the voltage of the power input terminal VIN, the first switch control circuit 20 may still turn off the first switch circuit 30 in time to prevent generation of the backward current, thereby solving the problem of the backward current existing when the power source fails.
In this embodiment, the working voltage of the first switch control circuit 20 is set to be provided by the power output terminal VOUT or the first power supply, so that the reliability of the first switch control circuit 20 can be improved, thereby improving the reliability of the protection circuit.
In this embodiment, specific circuit structures of the first switch circuit 30, the reference voltage circuit 10 and the first switch control circuit 20 and specific voltage values of the first reference voltage VB are not limited, and a skilled person may select the voltage values as needed.
For example, in some embodiments, the voltage value of the first reference voltage VB may be set to be equal to or less than the voltage value of the power input terminal VIN to avoid the voltage of the power output terminal VOUT being too high.
In summary, the present embodiment can not only prevent the generation of the backward flow current, but also prevent the protection circuit provided by the present embodiment from having a better reliability because the working voltage of the first switch control circuit 20 is provided by the power output terminal VOUT or the first power supply, and even if the power supply fails, the first switch control circuit 20 can still be in the working state.
Fig. 2 shows a schematic structural diagram of a protection circuit according to another embodiment of the present application. In this embodiment, the first switch control circuit 20 includes a first comparison circuit 21 and a signal processing circuit 22.
The first comparison circuit 21, the power output terminal VOUT, and the reference voltage circuit 10 are connected. The first comparison circuit 21 is configured to compare the voltage of the power supply output terminal VOUT with the first reference voltage VB and provide a corresponding control voltage. According to the magnitude relation between the voltage of the power output end VOUT and the first reference voltage VB, the voltage value of the control voltage comprises the voltage values of two conditions, namely when the voltage of the power output end VOUT is greater than or equal to the first reference voltage VB, the voltage value of the control voltage is the first voltage value; when the voltage of the power output terminal VOUT is less than the first reference voltage VB, the voltage value of the control voltage is a second voltage value.
The signal processing circuit 22, the first comparison circuit 21, and the first switch circuit 30 are connected. The first comparison circuit 21 supplies the above-described control voltage to the signal processing circuit 22. The signal processing circuit 22 is configured to process the control voltage and correspondingly output the first control signal VC. The first control signal VC is different according to the voltage value of the control voltage. For example, when the voltage of the power output terminal VOUT is greater than or equal to the first reference voltage VB, the voltage value of the control voltage is the first voltage value, and the processed first control signal VC can be a high level signal, which can control the first switch circuit 30 to turn off. On the contrary, when the voltage of the power output terminal VOUT is smaller than the first reference voltage VB, the voltage value of the control voltage is the second voltage value, and the processed first control signal VC may be a low level signal, which may control the first switch circuit 30 to be turned on.
The arrangement in which the operating voltage of the signal processing circuit 22 is set to be supplied from the power supply output terminal VOUT or the first power supply and the operating voltage of the first comparison circuit 21 is set to be supplied from the power supply output terminal VOUT or the first power supply can improve the reliability of the protection circuit.
In this embodiment, specific circuit structures of the first comparison circuit 21 and the signal processing circuit 22 are not limited, and a skilled person may select the circuit structures as needed.
For example, the first comparison circuit 21 is the first circuit having the voltage comparison function described above. For another example, the signal processing circuit 22 may be implemented by a digital circuit to convert the control voltage into the first control signal VC for controlling the first switching circuit 30 to be turned on or off.
In this embodiment, the first comparing circuit 21 and the signal processing circuit 22 are used to implement the function of the first switch control circuit 20, that is, when the power supply is powered down, if the power output terminal VOUT is in a charged state, or the voltage of the power output terminal VOUT is greater than the voltage of the power input terminal VIN, the first comparing circuit 21 and the signal processing circuit 22 can be used to turn off the first switch circuit 30 in time, so as to prevent the generation of the backward current.
In another embodiment of the present application, a specific circuit structure of the first comparison circuit 21 is disclosed.
The first comparing circuit 21 includes a first switch tube M1, a second switch tube M2, a first current source Ibias1 and a second current source Ibias2, and the first comparing circuit 21 implements a voltage comparing function through these four devices.
In this embodiment, the types of the first switching tube M1 and the second switching tube M2 are not specifically limited, and a technician may select the types as needed. For example, the first switching tube M1 and the second switching tube M2 may be MOS tubes, IGBT tubes, triodes, and the like.
By way of example and not limitation, as shown in fig. 3, the first switching tube M1 and the second switching tube M2 are both PMOS tubes.
The input terminal of the first switching tube M1 is connected to the reference voltage circuit 10, and is configured to receive the first reference voltage VB. The output end of the first switch tube M1, the input end of the first current source Ibias1 and the control end of the second switch tube M2 are connected. The input end of the second switch tube M2 is connected with the power output end VOUT, the output end of the second switch tube M2, the input end of the second current source Ibias2 and the control end of the first switch tube M1 are connected, and the output end of the first current source Ibias1 and the output end of the second current source Ibias2 are grounded.
The control voltage includes a voltage at the output terminal of the first switching tube M1 and/or a voltage at the output terminal of the second switching tube M2.
According to the characteristics of the MOS transistor, the input end, the output end and the control end of the first switch transistor M1 respectively correspond to the source electrode, the drain electrode and the grid electrode of the first switch transistor M1. The input end, the output end and the control end of the second switch tube M2 respectively correspond to the source electrode, the drain electrode and the grid electrode of the second switch tube M2.
By analyzing the first comparison circuit 21 shown in fig. 3, it can be seen that:
when the voltage of the power output end VOUT is greater than or equal to the first reference voltage VB, the first switching tube M1 is turned off, the second switching tube M2 is turned on, the voltage of the drain electrode of the first switching tube M1 is equal to the voltage of the ground end GND, and the voltage of the drain electrode of the second switching tube M2 is equal to the voltage of the power output end VOUT;
when the voltage of the power output terminal VOUT is less than the first reference voltage VB, the first switching tube M1 is turned on, the second switching tube M2 is turned off, the voltage of the drain of the first switching tube M1 is equal to the first reference voltage VB, and the voltage of the drain of the second switching tube M2 is equal to the voltage of the ground terminal GND.
Based on the above analysis, when the voltage of the power output terminal VOUT is different from the first reference voltage VB, the voltage of the drain of the first switching tube M1 is different from the voltage of the drain of the second switching tube M2. Therefore, by using this feature, the voltage of the drain of the first switching tube M1 and/or the voltage of the drain of the second switching tube M2 can be used as the control voltage, and the control voltage is processed by the signal processing circuit 22 to obtain the first control signal VC with different level signals, thereby controlling the first switching circuit 30 to be turned on or off.
In other words, when the voltage of the power output terminal VOUT is greater than or equal to the first reference voltage VB, the voltage value of the control voltage is equal to the first voltage value, which is equivalent to the voltage of the drain of the first switch M1 being equal to the voltage of the ground GND, and/or the voltage of the drain of the second switch M2 being equal to the voltage of the power output terminal VOUT.
When the voltage of the power output terminal VOUT is less than the first reference voltage VB, the voltage value of the control voltage is equal to the second voltage value, which is equivalent to the voltage of the drain of the first switch transistor M1 equal to the first reference voltage VB, and the voltage of the drain of the second switch transistor M2 equal to the voltage of the ground GND.
As shown in fig. 3, as an alternative implementation manner of this embodiment, the first comparison circuit 21 further includes an adjustable element M0, an input terminal of the adjustable element M0 is connected to the power output terminal VOUT, and an output terminal of the adjustable element M0 is connected to an input terminal of the second switch tube M2. The adjustable element M0 is configured to adjust its on-resistance value to change the switching threshold voltage of the first comparison circuit 21. In some embodiments, the flipping threshold voltage means that when the voltage of the source of the second switching transistor M2 is greater than the flipping threshold voltage, the second switching transistor M2 is turned on; when the voltage of the source electrode of the second switching tube M2 is smaller than the overturning threshold voltage, the second switching tube M2 is turned off.
Since the voltage of the source of the first switching tube M1 and the voltage of the source of the second switching tube M2 are the objects of comparison by the first comparing circuit 21, the voltage of the source of the second switching tube M2 can be changed by connecting the adjustable element M0 in series and adjusting the on-resistance value of the adjustable element M0, so as to change the switching threshold voltage of the first comparing circuit 21.
The specific type of the adjustable element M0 is not limited in this embodiment, and a skilled person may select the type according to needs.
By way of example and not limitation, tunable element M0 may comprise a MOS transistor or a tunable resistor. The MOS tube can change the on-resistance value thereof by adjusting the width-length ratio of the conducting channel thereof. The adjustable resistor can change the on-resistance value thereof by adjusting the effective conductive length thereof.
Alternatively, as shown in fig. 3, the tunable element M0 is selected as a PMOS transistor, and the input end and the output end of the PMOS transistor correspond to the source and the drain thereof, respectively. And in order to make the PMOS tube conduct, the grid electrode and the drain electrode of the PMOS tube are in short circuit, so that the voltage of the grid electrode is smaller than that of the source electrode of the PMOS tube.
In another embodiment of the present application, a specific circuit structure of the signal processing circuit 22 is disclosed. As shown in fig. 3, the signal processing circuit 22 includes a third switching tube M3, a fourth switching tube M4, a fifth switching tube M5, a sixth switching tube M6 and a logic circuit. The signal processing circuit 22 implements a signal processing function by the four switching tubes and the logic circuit. In this embodiment, the control circuit includes the voltage of the drain of the first switching tube M1 and the voltage of the drain of the second switching tube M2.
In this embodiment, the types of the third switching tube M3, the fourth switching tube M4, the fifth switching tube M5, the sixth switching tube M6 and the logic circuit are not specifically limited, and a skilled person may select the types according to needs.
For example, the third switching tube M3, the fourth switching tube M4, the fifth switching tube M5, and the sixth switching tube M6 may be MOS tubes, IGBT tubes, triodes, and the like. For example, the logic circuit may include an and circuit, an or gate circuit, or a not gate circuit. The not gate circuit may also be referred to as an inverter.
By way of example and not limitation, as shown in fig. 3, the third switching tube M3 and the fourth switching tube M4 are both PMOS tubes, the fifth switching tube M5 and the sixth switching tube M6 are both NMOS tubes, and the logic circuit includes a first inverter INV1, a second inverter INV2, and a third inverter INV3 connected in series.
The input end of the third switching tube M3 and the input end of the fourth switching tube M4 are connected with the power output end VOUT, the output end of the third switching tube M3 and the control end of the fourth switching tube M4 are connected with the input end of the fifth switching tube M5, the output end of the fourth switching tube M4, the control end of the third switching tube M3 and the input end of the sixth switching tube M6 are connected with the input end of the logic circuit, and the output end of the logic circuit is used for outputting the first control signal VC.
The output end of the fifth switch tube M5 and the output end of the sixth switch tube M6 are grounded, the output end of the first switch tube M1 is connected with the control end of the fifth switch tube M5, and the output end of the second switch tube M2 is connected with the control end of the sixth switch tube M6.
According to the characteristics of the MOS transistor, the input end, the output end, and the control end of the third switching transistor M3 correspond to the source, the drain, and the gate of the third switching transistor M3, respectively. The input end, the output end and the control end of the fourth switching tube M4 correspond to the source electrode, the drain electrode and the grid electrode of the fourth switching tube M4 respectively. The input end, the output end and the control end of the fifth switching tube M5 respectively correspond to the drain electrode, the source electrode and the grid electrode of the fifth switching tube M5. The input end, the output end and the control end of the sixth switching tube M6 respectively correspond to the drain electrode, the source electrode and the grid electrode of the sixth switching tube M6.
The working voltage of the logic circuit is provided by the power output terminal VOUT or the first power supply, so that the reliability of the protection circuit is improved. It should be understood that a skilled person can select a corresponding number of inverters as required to compose the logic circuit described above.
As shown in fig. 3, when the first comparison circuit 21 and the signal processing circuit 22 are analyzed, it can be seen that:
when the voltage of the output end VOUT of the power supply is greater than or equal to the first reference voltage VB, the first switching tube M1 is turned off, the fifth switching tube M5 is turned off, the fourth switching tube M4 is turned off, the second switching tube M2 is turned on, the sixth switching tube M6 is turned on, and the third switching tube M3 is turned on, so that the voltage of the drain electrode of the fourth switching tube M4 is equal to the voltage of the ground end GND, namely the voltage of the input end of the logic circuit is equal to the voltage of the ground end GND;
when the voltage of the power output end VOUT is smaller than the first reference voltage VB, the first switch tube M1 is switched on, the fifth switch tube M5 is switched on, the fourth switch tube M4 is switched on, the second switch tube M2 is switched off, the sixth switch tube M6 is switched off, and the third switch tube M3 is switched off, so that the voltage of the drain electrode of the fourth switch tube M4 is equal to the voltage of the power output end VOUT, namely the voltage of the input end of the logic circuit is equal to the voltage of the power output end VOUT.
In this embodiment, since the logic circuit includes an odd number of inverters connected in series, when the voltage of 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 equal to a high level signal; when the voltage of the power output terminal VOUT is less than the first reference voltage VB, the first control signal VC output by the logic circuit is equal to the low level signal.
The signal processing circuit 22 disclosed in this embodiment utilizes the voltage of the drain of the first switching tube M1 and the voltage of the drain of the second switching tube M2 at the same time, so that the output first control signal VC can be more reliable and stable.
In another embodiment of the present application, as shown in fig. 3, 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 and the output terminal of the third current source Ibias3 are connected to the first switch control circuit 20, the anode of the zener diode D1 is grounded, and the voltage of the cathode of the zener diode D1 is the first reference voltage VB.
Therefore, as shown in fig. 4, when the voltage of the power input terminal VIN is smaller than the stable voltage V0 of the zener diode D1, even if the voltage of the power input terminal VIN varies, the first reference voltage VB can be kept consistent with, i.e. equal to, the voltage of the power input terminal VIN.
When the voltage of the power input terminal VIN is greater than or equal to the regulated voltage V0 of the zener diode D1, the first reference voltage VB is equal to the regulated voltage V0 of the zener diode D1, which enables the protection circuit provided by this embodiment to avoid the load from working at a larger voltage.
In some embodiments, as shown in fig. 4 and 5, when the voltage of 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, so that the first switch circuit 30 is turned off. When the voltage of the power output terminal VOUT is less than the first reference voltage VB, the first control signal VC is a low level signal, so that the first switch circuit 30 is turned on.
In another embodiment of the present application, as shown in fig. 3, the protection circuit further includes a second switch circuit 60 and a second switch control circuit 40. The second switch circuit 60 is connected in series with the first switch circuit 30, the second switch control circuit 40 is connected to the second switch circuit 60, and the second switch control circuit 40 is configured to turn on the second switch circuit 60 or turn off the second switch circuit 60 according to a relationship between the voltage of the power supply output terminal VOUT and the second reference voltage VREF.
It should be noted that, one function of the first switch circuit 30 is to prevent the generation of the backward flow current, that is, in the case that the voltage of 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 switch circuit 30 to turn off, so that the power input terminal VIN and the power output terminal VOUT are disconnected, thereby implementing the protection function. And one function of the second switch circuit 60 is to output the voltage of the power input terminal VIN to the first switch circuit 30 or to confirm that the path between the power input terminal VIN and the power output terminal VOUT is closed.
Therefore, when the protection circuit does not need to be triggered, the voltage of 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 according to the relationship between the voltage of the power output terminal VOUT and the second reference voltage VREF to output the voltage of the power input terminal VIN to the power output terminal VOUT through the first switch circuit 30 and the second switch circuit 60. For example, the relationship is that the voltage of the power output terminal VOUT is greater than or equal to the second reference voltage VREF.
When the protection circuit is triggered, an abnormality occurs in the voltage of the power supply output terminal VOUT, for example, the voltage drops to zero. At this time, the second switch control circuit 40 is configured to turn off the second switch circuit 60 according to the relationship between the voltage of the power supply output terminal VOUT and the second reference voltage VREF, so that the first switch circuit 30 and the second switch circuit 60 are turned off in common. For example, the relationship is that the voltage of the power output terminal VOUT is smaller than the second reference voltage VREF.
As an alternative to this embodiment, the first switch circuit 30 includes a seventh switch tube M7, and the second switch circuit 60 includes an eighth switch tube M8 connected in series with the seventh switch tube M7.
The control end of the seventh switch tube M7 is connected to the output end of the first switch control circuit 20, the input end of the seventh switch tube M7 is connected to the output end of the eighth switch tube M8, the output end of the seventh switch tube M7 is a power output end VOUT, the input end of the eighth switch tube M8 is connected to the power input end VIN, and the control end of the eighth switch tube M8 is connected to the output end of the second switch control circuit 40.
In this embodiment, specific types of the seventh switch tube M7 and the eighth switch tube M8 are not limited, and a technician may select the switch tubes as needed. For example, the seventh switching tube M7 and the eighth switching tube M8 may be MOS tubes, IGBT tubes, triodes, or the like.
By way of example and not limitation, the seventh switching tube M7 and the eighth switching tube M8 are both PMOS tubes.
According to the characteristics of the MOS transistor, the input end, the output end, and the control end of the seventh switching transistor M7 correspond to the source, the drain, and the gate thereof, respectively, and the input end, the output end, and the control end of the eighth switching transistor M8 correspond to the drain, the source, and the gate thereof, respectively.
One effect that seventh switch tube M7 and eighth switch tube M8 all adopt the PMOS pipe lies in that, the parasitic diode of seventh switch tube M7 and the parasitic diode of eighth switch tube M8 are connected in opposite direction, make when seventh switch tube M7 and eighth switch tube M8 all turn-offs, do not have the leakage current, can not produce the forward current between power input end VIN and power output end VOUT promptly, also can not produce the backward flow electric current between power output end VOUT and power input end VIN.
As an optional implementation manner of this embodiment, the protection circuit further includes a voltage divider circuit 50, a first terminal of the voltage divider circuit 50 is connected to the power output terminal VOUT, and a second terminal of the voltage divider circuit 50 is grounded. The second switch control circuit 40 is configured to compare a voltage of the divided voltage node of the voltage dividing circuit 50 with the second reference voltage VREF, and correspondingly output a second control signal for turning on the second switch circuit 60 or turning off the second switch circuit 60.
In this embodiment, the specific circuit structure of the voltage dividing circuit 50, the voltage value of the second reference voltage VREF, and the type of the second control signal are not limited, and a skilled person may select the voltage value and the type of the second control signal according to needs.
For example, the voltage divider circuit 50 includes a plurality of resistors connected in series, and as shown in fig. 3, includes a first resistor R1 and a second resistor R2 connected in series. A connection node of the first resistor R1 and the second resistor R2 is a divided voltage node of the voltage dividing circuit 50, and a voltage of the divided voltage node is input to the second switch control circuit 40 as the feedback voltage VFB. The second switch control circuit 40 compares the feedback voltage VFB with the second reference voltage VREF, and correspondingly outputs a second control signal for turning on the second switch circuit 60 or turning off the second switch circuit 60.
For example, the second control signal is a high level signal or a low level signal.
As an alternative to this embodiment, the second switch control circuit 40 is a comparator a, which can be implemented by an operational amplifier and can function as a stable loop.
In another embodiment of the present application, a management chip is further provided, where the management chip includes the protection circuit provided in any of the above embodiments. The management chip is used for managing the power supply, for example, the management chip can take on the duties of conversion, distribution, detection and other power management of the power supply. For another example, if the power supply providing the input voltage to the power input terminal VIN is a rechargeable battery, the management chip may manage the charging process and the discharging process of the power supply.
Therefore, in some embodiments, the management chip may include a voltage conversion circuit, a state detection circuit, a charge/discharge control circuit, or the like. The state detection circuit may be connected to the output terminal of the signal processing circuit 22, and detect the first control signal VC output by the signal processing circuit 22 to determine whether the protection circuit is triggered. For example, when the first control signal VC is detected as a high level signal, it is confirmed that the protection circuit is triggered.
In some embodiments, the specific form of the management chip may be an integrated circuit, a control circuit, a circuit board, a system-on-chip, or the like.
The management chip provided by this embodiment also has the beneficial effects of the protection circuit described above, for example, the first switch circuit 30 can be turned off in time when the voltage of the power output terminal VOUT is greater than the voltage of the power input terminal VIN, so as to cut off the path between the power output terminal VOUT and the power input terminal VIN, thereby preventing the generation of the backward flow current.
In another embodiment of the present application, there is also provided a power supply device including a power supply for supplying power and the protection circuit or the management chip provided in any of the above embodiments.
For example, the power supply for supplying power is connected to the power input terminal VIN and the management chip, and is used for supplying an input voltage to the power input terminal VIN and supplying an operating voltage to the management chip.
The power supply device provided by this embodiment also has the beneficial effects of the protection circuit, for example, when 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 to cut off the path between the power output terminal VOUT and the power input terminal VIN, so as to prevent the generation of the backward flow current.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.

Claims (12)

1. A protection circuit, comprising:
a first switching circuit configured to switch a path between a power supply input terminal and a power supply output terminal;
a reference voltage circuit connected to the power input terminal and configured to provide a first reference voltage to a first switch control circuit based on a voltage of the power input terminal;
the first switch control circuit is connected to the first switch circuit, the reference voltage circuit and the power output end, and is configured to control the first switch circuit to be turned off when the voltage at the power output end is greater than or equal to the first reference voltage, wherein the working voltage of the first switch control circuit is provided by the power output end or a first power supply, and the first power supply and the power supply providing the voltage at the power input end are not the same power supply.
2. The protection circuit of claim 1, wherein the first switch control circuit comprises:
a first comparison circuit, connected to the reference voltage circuit and the power output terminal, configured to compare the voltage of the power output terminal with the first reference voltage and provide a corresponding control voltage to a signal processing circuit;
the signal processing circuit is connected with the first comparison circuit and the first switch circuit, and is configured to process the control voltage and output a first control signal, and the first control signal is used for triggering the first switch circuit to be turned off.
3. The protection circuit of claim 2, wherein the first comparison circuit comprises a first switch tube, a second switch tube, a first current source and a second current source;
the input end of the first switch tube is configured to receive the first reference voltage, the output end of the first switch tube, the input end of the first current source and the control end of the second switch tube are connected, the input end of the second switch tube is connected with the power output end, the output end of the second switch tube, the input end of the second current source and the control end of the first switch tube are connected, and the output end of the first current source and the output end of the second current source are grounded;
the control voltage comprises the voltage of the output end of the first switch tube and/or the voltage of the output end of the second switch tube.
4. The protection circuit of claim 3, wherein the first comparison circuit further comprises:
the input end of the adjustable element is connected with the power supply output end, the output end of the adjustable element is connected with the input end of the second switch tube, and the adjustable element is configured to adjust the on-resistance value of the adjustable element so as to change the overturning threshold voltage of the first comparison circuit.
5. The protection circuit of claim 4, wherein the adjustable element comprises a MOS transistor or an adjustable resistor.
6. The protection circuit of claim 3, wherein the signal processing circuit comprises a third switching tube, a fourth switching tube, a fifth switching tube, a sixth switching tube and a logic circuit;
the input end of the third switching tube, the input end of the fourth switching tube and the output end of the power supply are connected, the output end of the third switching tube, the control end of the fourth switching tube and the input end of the fifth switching tube are connected, the output end of the fourth switching tube, the control end of the third switching tube and the input end of the sixth switching tube are connected with the input end of the logic circuit, the logic circuit is used for processing the voltage of the output end of the fourth switching tube and correspondingly outputting the first control signal, wherein the working voltage of the logic circuit is provided by the output end of the power supply or the first power supply;
the output end of the fifth switch tube is grounded with the output end of the sixth switch tube, the output end of the first switch tube is connected with the control end of the fifth switch tube, and the output end of the second switch tube is connected with the control end of the sixth switch tube.
7. The protection circuit according to any one of claims 1 to 6, wherein the reference voltage circuit includes:
a third current source, an input of the third current source being connected to the power input;
the cathode of the Zener diode, the output end of the third current source and the first switch control circuit are connected, the anode of the Zener diode is grounded, and the voltage of the cathode of the Zener diode is the first reference voltage.
8. The protection circuit according to any one of claims 1 to 6, characterized in that the protection circuit further comprises:
a second switching circuit in series with the first switching circuit;
a second switch control circuit connected to the second switch circuit, the second switch control circuit being configured to turn on the second switch circuit or turn off the second switch circuit according to a relationship between a voltage of the power supply output terminal and a second reference voltage.
9. The protection circuit of claim 8, wherein the first switching circuit comprises a seventh switching tube, and the second switching circuit comprises an eighth switching tube connected in series with the seventh switching tube;
the control end of the seventh switch tube is connected with the output end of the first switch control circuit, the input end of the seventh switch tube is connected with the output end of the eighth switch tube, the output end of the seventh switch tube is the power output end, the input end of the eighth switch tube is connected with the power input end, and the control end of the eighth switch tube is connected with the output end of the second switch control circuit.
10. The protection circuit of claim 8, further comprising:
the first end of the voltage division circuit is connected with the power output end, and the second end of the voltage division circuit is grounded;
the second switch control circuit is configured to compare a voltage of a divided voltage node of the voltage dividing circuit with the second reference voltage, and output a second control signal for turning on or off the second switch circuit.
11. A management chip comprising the protection circuit according to any one of claims 1 to 10.
12. A power supply device comprising the protection circuit of any one of claims 1 to 10, or comprising the management chip of claim 11.
CN202211065600.7A 2022-08-29 2022-08-29 Protection circuit, management chip and power supply unit Pending CN115313344A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202211065600.7A CN115313344A (en) 2022-08-29 2022-08-29 Protection circuit, management chip and power supply unit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202211065600.7A CN115313344A (en) 2022-08-29 2022-08-29 Protection circuit, management chip and power supply unit

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117713506A (en) * 2024-02-06 2024-03-15 苏州贝克微电子股份有限公司 Low-power consumption power supply with wide output voltage range

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117713506A (en) * 2024-02-06 2024-03-15 苏州贝克微电子股份有限公司 Low-power consumption power supply with wide output voltage range
CN117713506B (en) * 2024-02-06 2024-04-19 苏州贝克微电子股份有限公司 Low-power consumption power supply with wide output voltage range

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