CN217445249U

CN217445249U - Power protection circuit and electronic equipment

Info

Publication number: CN217445249U
Application number: CN202220179396.0U
Authority: CN
Inventors: 涂贤玲; 陈孝良
Original assignee: Beijing SoundAI Technology Co Ltd
Current assignee: Beijing SoundAI Technology Co Ltd
Priority date: 2022-01-21
Filing date: 2022-01-21
Publication date: 2022-09-16
Anticipated expiration: 2032-01-21

Abstract

The application discloses power protection circuit and electronic equipment, this power protection circuit include discharge circuit, switch circuit and filter circuit. The discharge circuit can form a discharge path between the two input ends when the voltage difference between the positive input end and the negative input end is larger than a voltage threshold value so as to prevent overvoltage from being transmitted to a load. The switching circuit can control the first end and the second end to be switched off when the positive input end and the negative input end are reversely connected with the positive electrode and the negative electrode of the direct current power supply, so that the connection between the direct current power supply and a load is disconnected, and the performance of the load is prevented from being damaged. In addition, the filter circuit can filter interference signals in the power supply protection circuit, so that the stability of the direct-current voltage output by the power supply protection circuit is good. Based on the analysis, the power protection circuit provided by the application has rich functions and better protection effect on the direct current power supply and the load.

Description

Power protection circuit and electronic equipment

Technical Field

The present disclosure relates to electronic technologies, and particularly to a power protection circuit and an electronic device.

Background

Electronic equipment using a direct current power supply as a power supply is generally provided with a power supply protection circuit. The power protection circuit is respectively connected with a power interface of the electronic equipment and a load in the electronic equipment. When the positive and negative poles of the power interface and the direct current power supply are connected reversely, the power supply protection circuit is in a disconnected state, and therefore the performance of the direct current power supply or the load is prevented from being damaged.

However, the power protection circuit has a single function.

SUMMERY OF THE UTILITY MODEL

The application provides a power protection circuit and electronic equipment, which can solve the problem that the function of the power protection circuit in the related art is single. The technical scheme is as follows:

in one aspect, a power protection circuit is provided, the power protection circuit has a positive input terminal, a negative input terminal, a positive output terminal and a negative output terminal, the positive input terminal and the negative input terminal are used for connecting a direct current power supply, the positive output terminal and the negative output terminal are used for connecting a load, the power protection circuit includes: a discharge circuit, a switching circuit and a filter circuit;

the discharge circuit is respectively connected with the positive input end and the negative input end, and is used for forming a discharge path between the positive input end and the negative input end if the voltage difference between the positive input end and the negative input end is greater than a voltage threshold;

a control end of the switch circuit is connected with one of the positive input end and the negative input end, a first end of the switch circuit is connected with the other of the positive input end and the negative input end, a second end of the switch circuit is connected with an input end of the filter circuit, and the switch circuit is used for controlling the first end and the second end to be switched on if the positive input end and the negative input end are correspondingly connected with the positive and negative poles of the direct-current power supply, and controlling the first end and the second end to be switched off if the positive input end and the negative input end are reversely connected with the positive and negative poles of the direct-current power supply;

the input end of the filter circuit is further connected with one of the positive input end and the negative input end, the output end of the filter circuit is respectively connected with the positive output end and the negative output end, and the filter circuit is used for filtering interference signals.

Optionally, the discharge circuit comprises: a varistor and a discharge tube;

the piezoresistor and the discharge tube are connected in series between the positive input end and the negative input end.

Optionally, the switching circuit comprises: a P-type switching transistor;

the grid electrode of the P-type switch transistor is used as the control end and is connected with the negative electrode input end, the drain electrode of the P-type switch transistor is used as the first end and is connected with the positive electrode input end, and the source electrode of the P-type switch transistor is used as the second end and is connected with the input end of the filter circuit.

Optionally, the switching circuit comprises: an N-type switching transistor;

the grid electrode of the N-type switch transistor is used as the control end and connected with the positive input end, the drain electrode of the N-type switch transistor is used as the first end and connected with the negative input end, and the source electrode of the N-type switch transistor is used as the second end and connected with the input end of the filter circuit.

Optionally, the switching circuit further comprises: and the first capacitor is respectively connected with the grid electrode and the drain electrode.

Optionally, the power protection circuit further includes: a voltage dividing circuit;

the voltage division circuit is respectively connected with the positive input end, the negative input end and the control end of the switch circuit, and the voltage division circuit is used for dividing the power voltage provided by the direct-current power supply and then loading the divided power voltage to the control end of the switch circuit.

Optionally, the voltage divider circuit includes: a first resistor and a second resistor;

the first resistor and the second resistor are connected in series between the positive input end and the negative input end, and a series node between the first resistor and the second resistor is connected with the control end of the switch circuit.

Optionally, the filter circuit comprises: a first inductor and a second inductor;

one end of the first inductor is connected with the second end of the switch circuit, and the other end of the first inductor is connected with one of the positive output end and the negative output end;

one end of the second inductor is connected with one of the positive input end and the negative input end, and the other end of the second inductor is connected with the other of the positive output end and the negative output end.

Optionally, the filter circuit further includes: a second capacitor, a third capacitor and a fourth capacitor;

the second capacitor and the third capacitor are connected in parallel between the positive output end and the negative output end;

and the fourth capacitor is respectively connected with the positive input end and the negative input end.

Optionally, the power protection circuit further includes: a fuse;

the fuse is respectively connected with the positive input end and one end of the discharge circuit.

In another aspect, an electronic device is provided, which includes: the load and the power supply protection circuit provided by the aspect are provided;

and the positive output end and the negative output end of the power supply protection circuit are connected with the load.

Optionally, the electronic device further comprises: a voltage conversion circuit;

the input end of the voltage conversion circuit is connected with the positive output end and the negative output end of the power supply protection circuit, the output end of the voltage conversion circuit is connected with the load, and the voltage conversion circuit converts the voltage output by the power supply protection circuit and then loads the voltage to the load.

The beneficial effect that technical scheme that this application provided brought includes at least:

the application provides a power protection circuit and an electronic device. The discharge circuit can form a discharge path between the two input ends when the voltage difference between the positive input end and the negative input end is larger than a voltage threshold value so as to prevent overvoltage from being transmitted to a load. The switching circuit can control the first end and the second end to be switched off when the positive input end and the negative input end are reversely connected with the positive electrode and the negative electrode of the direct current power supply, so that the connection between the direct current power supply and a load is disconnected, and the performance of the load is prevented from being damaged. In addition, the filter circuit can filter interference signals in the power supply protection circuit, so that the stability of the direct-current voltage output by the power supply protection circuit is good. Based on the analysis, the power protection circuit provided by the application has rich functions and better protection effect on the direct current power supply and the load.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of an electronic device according to an embodiment of the present disclosure;

fig. 2 is a schematic structural diagram of a power protection circuit according to an embodiment of the present disclosure;

fig. 3 is a schematic structural diagram of another power protection circuit provided in an embodiment of the present application;

fig. 4 is a schematic structural diagram of another power protection circuit provided in the embodiment of the present application;

fig. 5 is a schematic structural diagram of another power protection circuit provided in an embodiment of the present application;

fig. 6 is a schematic structural diagram of another power protection circuit provided in an embodiment of the present application;

fig. 7 is a schematic structural diagram of another power protection circuit according to an embodiment of the present application.

Detailed Description

To make the objects, technical solutions and advantages of the present application more clear, embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

Fig. 1 is a schematic structural diagram of an electronic device provided in an embodiment of the present application, and referring to fig. 1, the electronic device includes: a power protection circuit 10 and a load 20.

Referring to fig. 1, the power protection circuit 10 has a positive input terminal IN1, a negative input terminal IN2, a positive output terminal O1, and a negative output terminal O2. The positive input terminal IN1 and the negative input terminal IN2 are used for connecting a dc power supply, and the positive output terminal O1 and the negative output terminal O2 are used for connecting the load 20.

The dc power source may be a battery, which can output a dc voltage, for example, a dc voltage of ± 12 volts (V), or ± 24V. The load 20 may be an electronic device in an electronic device, and may include, for example, a main control chip, a sensor, and the like. The power protection circuit 10 is used for applying a dc voltage provided by a dc power source to a load 20 to drive the load 20 to operate. The power supply protection circuit 10 can also perform a protection operation to protect the dc power supply and the load 20 when an abnormality occurs in the dc power supply.

For example, when the dc power supply is subjected to static electricity or lightning strike to cause the output dc voltage to be excessive, the power protection circuit 10 can form a discharge path between two input terminals thereof, thereby protecting the dc power supply and the load 20. When the positive and negative poles of the dc power supply are connected to the positive input terminal IN1 and the negative input terminal IN2 of the power protection circuit 10, the power protection circuit 10 can cut off the connection between the dc power supply and the load 20, thereby protecting the dc power supply and the load 20.

Optionally, with continued reference to fig. 1, the electronic device may further include: a voltage conversion circuit 30. The input terminal of the voltage conversion circuit 30 is connected to the positive output terminal O1 and the negative output terminal O2 of the power protection circuit 10, and the output terminal of the voltage conversion circuit 30 is connected to the load 20. The voltage conversion circuit 30 is used to convert the voltage output by the power protection circuit 10 and load the converted voltage to the load 20.

The voltage converting circuit 30 may be a direct current-direct current (DC-DC) converting circuit. The voltage conversion circuit 30 can convert a dc voltage (e.g., 3V) with a certain value output by the power protection circuit 10 into an operating voltage (e.g., 1.5V or 5V) of the load 20, so as to ensure that the load 20 can operate normally. That is, the voltage conversion circuit 30 can convert the operating voltage of the dc power supply into the operating voltage of the load 20.

In the embodiment of the present application, the electronic device may be any device powered by a dc power supply. For example, the electronic device may be an illumination lamp with an operating voltage of 12V, or the electronic device may be a sound box with an operating voltage of 12V, or the electronic device is a fan with an operating voltage of 24V, which is not limited herein.

Fig. 2 is a schematic structural diagram of a power protection circuit according to an embodiment of the present application. The power protection circuit can be applied to the electronic device shown in fig. 1. Referring to fig. 2, the power protection circuit 10 includes: a discharge circuit 110, a switching circuit 120, and a filter circuit 130.

As shown IN fig. 2, the power protection circuit 10 has a positive input terminal IN1, a negative input terminal IN2, a positive output terminal O1, and a negative output terminal O2. The positive input terminal IN1 and the negative input terminal IN2 are used for connecting a dc power supply, and the positive output terminal O1 and the negative output terminal O2 are used for connecting the load 20. The discharge circuit 110 is connected to the positive input terminal IN1 and the negative input terminal IN2, respectively. The discharge circuit 110 is configured to form a discharge path between the positive input terminal IN1 and the negative input terminal IN2 if a voltage difference between the positive input terminal IN1 and the negative input terminal IN2 is greater than a voltage threshold.

It is understood that the operating state of the dc power supply is susceptible to external environment interference, such as static electricity or lightning strike, so that the dc power supply outputs an overvoltage (typically, a voltage of the order of kilovolts or ten thousand volts) much higher than its normal operating voltage (typically, several tens of volts). When the positive input terminal IN1 and the negative input terminal IN2 of the power protection circuit 10 receive an overvoltage of the dc power output, the overvoltage may cause a voltage difference between the positive input terminal IN1 and the negative input terminal IN2 to be greater than a voltage threshold (e.g., 70V). At this time, the discharge circuit 110 forms a discharge path between the positive input terminal IN1 and the negative input terminal IN 2. The discharge circuit 110 can absorb the input overvoltage and discharge the overvoltage, thereby preventing the overvoltage from being transmitted to the load 20 and causing damage to the performance of the load 20.

With continued reference to fig. 2 and 3, the control terminal C of the switch circuit 120 is connected to one of the positive input terminal IN1 and the negative input terminal IN2, the first terminal 1 of the switch circuit 120 is connected to the other of the positive input terminal IN1 and the negative input terminal IN2, and the second terminal 2 of the switch circuit 120 is connected to the input terminal of the filter circuit 130. For example, referring to fig. 2, the control terminal C of the switch circuit 120 is connected to the negative input terminal IN2, and the first terminal 1 of the switch circuit 120 is connected to the positive input terminal IN 1. Alternatively, referring to fig. 3, the control terminal C of the switch circuit 120 is connected to the positive input terminal IN1, and the first terminal 1 of the switch circuit 120 is connected to the negative input terminal IN 2.

The switch circuit 120 is configured to control the first terminal 1 and the second terminal 2 to be conducted if the positive input terminal IN1 and the negative input terminal IN2 are connected to the positive and negative terminals of the dc power supply. When the first terminal 1 and the second terminal 2 are turned on, the dc voltage received by the positive input terminal IN1 and the negative input terminal IN2 can be normally transmitted to the load 20, so as to drive the load 20 to normally operate.

The switch circuit 120 is further configured to control the first terminal 1 and the second terminal 2 to be turned off if the positive input terminal IN1 and the negative input terminal IN2 are opposite to the positive and negative terminals of the dc power supply. When the first terminal 1 and the second terminal 2 are turned off, the two input terminals and the two output terminals of the power protection circuit 10 are in an open circuit state, the dc voltage output by the dc power supply cannot be loaded to the load 20, and the load 20 stops working.

With continued reference to fig. 2 and 3, the input of the filter circuit 130 is also connected to one of the positive input IN1 and the negative input IN2, and the output of the filter circuit 130 is connected to the positive output O1 and the negative output O2, respectively. For example, referring to fig. 2, the input of the filter circuit 130 may be connected to the negative input IN 2. Alternatively, referring to fig. 3, the input terminal of the filter circuit 130 may be connected to the positive input terminal IN 1. The filter circuit 130 is used for filtering out interference signals.

In this embodiment, interference signals (e.g., common mode interference signals) may exist in the two paths of signals received by the input end of the filter circuit 130, and the filter circuit 130 may filter the interference signals, so that the stability of the dc voltage applied to the load 20 by the positive output end O1 and the negative output end O2 is better.

In summary, the embodiment of the present application provides a power protection circuit, which includes a discharge circuit, a switch circuit and a filter circuit. The discharge circuit can form a discharge path between the two input ends when the voltage difference between the positive input end and the negative input end is larger than a voltage threshold value so as to prevent overvoltage from being transmitted to a load. The switching circuit can control the first end and the second end to be switched off when the positive input end and the negative input end are reversely connected with the positive electrode and the negative electrode of the direct current power supply, so that the connection between the direct current power supply and a load is disconnected, and the performance of the load is prevented from being damaged. In addition, the filter circuit can filter interference signals in the power supply protection circuit, so that the stability of the direct-current voltage output by the power supply protection circuit is good. Based on the above analysis, the power protection circuit provided by the embodiment of the application has rich functions and better protection effect on the direct current power supply and the load.

Fig. 4 is a schematic structural diagram of another power protection circuit provided in the embodiment of the present application. The power protection circuit can be applied to the electronic device shown in fig. 1. Referring to fig. 4, the discharge circuit 110 may include: a varistor (varistor) RV1 and a discharge tube GDT 1. The varistor RV1 and the discharge tube GDT1 are connected IN series between the positive input terminal IN1 and the negative input terminal IN 2. The discharge tube GDT1 may be a Gas Discharge Tube (GDT).

It can be understood that when the voltage across the varistor RV1 is less than its varistor voltage, the resistance of the varistor RV1 is infinite and the discharge tube GDT1 is not operated. When the voltage at the two ends of the voltage dependent resistor RV1 is larger than the voltage dependent voltage, the resistance value of the voltage dependent resistor RV1 is rapidly reduced and approaches infinity, the voltage dependent resistor RV1 is equivalent to a short circuit, and the voltage between the anode input end IN1 and the cathode input end IN2 is directly loaded to the discharge tube GDT 1. When the voltage across the discharge tube GDT1 is higher than the protection voltage of the discharge tube GDT1, an arc discharge phenomenon occurs inside the discharge tube GDT1 to release the absorbed overvoltage. It can be understood that the discharge phenomenon of the discharge tube GDT1 occurs only when the voltage difference between the positive input terminal IN1 and the negative input terminal IN2 is greater than the sum of the voltage-dependent voltage value of the voltage-dependent resistor RV1 and the protection voltage value of the discharge tube GDT 1. That is, the voltage threshold of the discharge circuit 110 may be determined based on the sum of the voltage-dependent voltage value of the voltage-dependent resistor RV1 and the protection voltage value of the discharge tube GDT 1.

For example, when the dc power supply normally operates, the dc voltage received by the positive input terminal IN1 is +12V, and the dc voltage received by the negative input terminal IN2 is-12V; the voltage-dependent voltage of the voltage-dependent resistor RV1 is 25V. When the dc power supply normally operates, the voltage difference between the positive input terminal IN1 and the negative input terminal IN2 is 24V, the voltage applied to the two ends of the voltage dependent resistor RV1 is smaller than the voltage dependent voltage, and the discharge circuit 110 does not operate.

When the dc power supply generates static electricity or is struck by lightning, the voltage difference between the positive input terminal IN1 and the negative input terminal IN2 is also IN kv level, at this time, the resistance value of the voltage dependent resistor RV1 is instantly reduced, and the dc voltage received by the positive input terminal IN1 and the negative input terminal IN2 can be transmitted to the discharge tube GDT1 through the voltage dependent resistor RV 1. The discharge tube GDT1 can then absorb the overvoltage and discharge it by arcing.

As a first possible example, referring to fig. 4, the switching circuit 120 may include: a P-type switching transistor Q1. The Gate (Gate, G) of the P-type switching transistor Q1 is connected to the negative input terminal IN2 as the control terminal of the switching circuit 120, the Drain (Drain, D) of the P-type switching transistor Q1 is connected to the positive input terminal IN1 as the first terminal of the switching circuit 120, and the Source (Source, S) of the P-type switching transistor Q1 is connected to the input terminal of the filter circuit 130 as the second terminal of the switching circuit 120.

IN this example, when the positive input terminal IN1 and the negative input terminal IN2 are connected to the positive and negative poles of the dc power source, the positive input terminal IN1 and the negative input terminal IN2 can generate a negative turn-on voltage between the gate G and the source S of the P-type switching transistor Q1, so that the drain D and the source S of the P-type switching transistor Q1 are turned on. When the positive input terminal IN1 and the negative input terminal IN2 are connected to the negative and positive terminals of the dc power source, the positive input terminal IN1 and the negative input terminal IN2 can generate a positive voltage between the gate G and the source S of the P-type switching transistor Q1, so that the drain D and the source S of the P-type switching transistor Q1 are disconnected, and the P-type switching transistor Q1 is IN a cut-off state.

As a second possible example, referring to fig. 5, the switching circuit 120 may include: an N-type switching transistor Q2. The gate G of the N-type switching transistor Q2 is connected as a control terminal to the positive input terminal IN1, the drain D of the N-type switching transistor Q2 is connected as a first terminal 1 to the negative input terminal IN2, and the source S of the N-type switching transistor Q2 is connected as a second terminal 2 to the input terminal of the filter circuit 130.

IN this example, when the positive input terminal IN1 and the negative input terminal IN2 are connected to the positive and negative poles of the dc power source, the positive input terminal IN1 and the negative input terminal IN2 can form a forward conducting voltage between the gate G and the source S of the N-type switching transistor Q2, so that the drain D and the source S of the N-type switching transistor Q2 are conducted. When the positive input terminal IN1 and the negative input terminal IN2 are connected to the negative and positive terminals of the dc power supply, the positive input terminal IN1 and the negative input terminal IN2 can generate a negative voltage between the gate G and the source S of the N-type switching transistor Q2, so that the drain D and the source S of the N-type switching transistor Q2 are disconnected, and the N-type switching transistor Q2 is IN an off state.

As can be seen from the above analysis, IN the above two examples, if the positive input terminal IN1 and the negative input terminal IN2 are connected to the positive and negative poles of the dc power supply, the switching transistor can control the drain D and the source S to be turned on. Accordingly, the dc voltage received by the positive input terminal IN1 and the negative input terminal IN2 can be normally transmitted to the load 20 to drive the load 20 to normally operate. If the positive input terminal IN1 and the negative input terminal IN2 are connected to the negative and positive terminals of the dc power supply, the switching transistor controls the drain D and the source S to be turned off, i.e., the switching transistor is IN the off state. Accordingly, the two input terminals and the two output terminals of the power protection circuit 10 are in an open circuit state, the dc voltage output by the dc power supply cannot be applied to the load 20, and the load 20 stops operating.

It is understood that the P-type switching transistor Q1 and the N-type switching transistor Q2 may be metal-oxide-semiconductor (MOS) transistors.

Alternatively, referring to fig. 6 and 7, the switching circuit 120 may further include: and a first capacitor C1, the first capacitor C1 being connected to the gate G and the drain D of the switching transistor, respectively.

The first capacitor C1 can provide a stable conduction voltage drop for the switching transistor. In addition, the first capacitor C1 can also increase the interelectrode capacitance between the gate G and the drain D of the switching transistor, thereby prolonging the power-up time or charging time of the switching transistor.

It will be appreciated that if the power-up time of the switching transistor is too fast, it is likely to impact the load 20. Therefore, a first capacitor can be arranged between the grid electrode G and the drain electrode D of the switch transistor to prolong the power-on time of the switch transistor, so that the slow start function is achieved.

With continued reference to fig. 6 and 7, the power protection circuit 10 may further include: a voltage divider circuit 140. The voltage divider circuit 140 is connected to the positive input terminal IN1, the negative input terminal IN2, and the control terminal of the switch circuit 120. The voltage divider circuit 140 is used for dividing the dc voltage provided by the dc power supply and loading the divided voltage to the control terminal of the switch circuit 120.

It will be appreciated that to ensure proper operation of the switching transistor, the turn-on voltage between its gate G and source S should be less than the threshold voltage of the switching transistor (typically ± 12V or ± 20V). Therefore, the voltage dividing circuit 140 may be configured to divide the dc voltage provided by the dc power source and apply the divided voltage to the control terminal of the switch circuit 120 (i.e., the gate G of the switch transistor), so as to avoid the voltage applied between the gate G and the source S of the switch transistor being greater than the limit voltage. Also, the voltage applied between the gate G and the source S of the switching transistor by the positive input terminal IN1 and the negative input terminal IN2 can be adapted to the on-voltage of the switching transistor by voltage division.

Alternatively, as shown in fig. 6 and 7, the voltage dividing circuit 140 may include: a first resistor R1 and a second resistor R2. The first resistor R1 and the second resistor R2 are connected IN series between the positive input terminal IN1 and the negative input terminal IN2, and a series node between the first resistor R1 and the second resistor R2 is connected to the control terminal of the switch circuit 120.

For example, it is assumed that the dc voltage received by the positive input terminal IN1 and the negative input terminal IN2 is ± 12V, the on voltage of the switching transistor is ± 8V, and the limit voltage is ± 12V. The resistance value of the first resistor R1 may be set to 10 kilo-ohms (k Ω) and the resistance value of the second resistor R2 may be set to 2k Ω. And then the voltage between the grid G and the source S of the switch transistor is +10V or-10V, and the voltage value is larger than the conduction voltage (+ -8V) of the switch transistor and is smaller than the limit voltage of the switch transistor by +/-12V.

It is understood that the resistance of the second resistor R2 in the voltage divider circuit 140 also affects the power-on time of the switching transistor. In the embodiment of the present application, if the capacitance value of the first capacitor C1 is C1, and the resistance value of the second resistor R2 is R2, the calculation formula of the rise time Tr of the switching transistor can be represented as:

for example, assuming that the capacitance C1 of the first capacitor C1 is 10 nano-farads (nF), and the resistance R2 of the second resistor R2 is 2 kilo-ohms (k Ω), the rise time Tr of the switching transistor can be calculated to be 5 microseconds (μ s) by the above formula.

Alternatively, referring to fig. 4, 5, 6, and 7, the filter circuit 130 may include: a first inductance L1 and a second inductance L2. One end of the first inductor L1 is connected to the second end of the switch circuit 120, and the other end of the first inductor L1 is connected to one of the positive output terminal O1 and the negative output terminal O2. One end of the second inductor L2 is connected to one of the positive input terminal IN1 and the negative input terminal IN2, and the other end of the second inductor L2 is connected to the other of the positive output terminal O1 and the negative output terminal O2.

As a possible example, referring to fig. 4 and 6, if the switching transistor is a P-type switching transistor Q1, one end of the first inductor L1 is connected to the second terminal 2 of the switching circuit 120 (i.e., the source S of the P-type switching transistor Q1), and the other end of the first inductor L1 is connected to the positive output terminal O1. One end of the second inductor L2 is connected to the negative input terminal IN2, and the other end of the second inductor L2 is connected to the negative output terminal O2.

As another possible example, referring to fig. 5 and 7, if the switch transistor is an N-type switch transistor Q2, one end of the first inductor L1 is connected to the second terminal 2 of the switch circuit 120 (i.e., the source S of the N-type switch transistor Q2), and the other end of the first inductor L1 is connected to the negative output terminal O2. One end of the second inductor L2 is connected to the positive input terminal IN1, and the other end of the second inductor L2 is connected to the positive output terminal O1.

In the embodiment of the present application, two paths of signals received by the input end of the filter circuit 130 may have an interference signal (e.g., a common mode interference signal), and the first inductor L1 and the second inductor L2 in the filter circuit 130 may filter the interference signal, so that the stability of the dc voltage applied to the load by the positive output end O1 and the negative output end O2 is good.

For example, in the embodiment of the present application, the inductance value L1 of the first inductor L1 and the inductance value L2 of the second inductor L2 may both be 3.3 microhenries (μ H).

Optionally, as shown in fig. 6 and 7, the filter circuit 130 may further include: a second capacitor C2, a third capacitor C3, and a fourth capacitor C4. The second capacitor C2 and the third capacitor C3 are connected in parallel between the positive output terminal O1 and the negative output terminal O2. The fourth capacitor C4 is connected to the positive input terminal IN1 and the negative input terminal IN2, respectively.

The second capacitor C2 and the third capacitor C3 are used for filtering out an alternating current component (which may also be referred to as a ripple) in the dc voltage, so as to stabilize the dc voltage output by the positive output terminal O1 and the negative output terminal O2. The fourth capacitor C4 is used for filtering low-frequency noise signals IN the dc voltage received by the positive input terminal IN1, thereby stabilizing the dc voltages at the two ends of the positive input terminal IN1 and the negative input terminal IN 2.

For example, in the embodiment of the present application, the capacitance value C2 of the second capacitor C2 and the capacitance value C3 of the third capacitor C3 may both be 22 microfarads (μ F). The fourth capacitor C4 may be an electrolytic capacitor, and the capacitance C4 may be 110 μ F.

With continued reference to fig. 6 and 7, the power protection circuit 10 includes: fuse F1. The fuse F1 is connected to the positive input terminal IN1 and one end of the discharge circuit 110, respectively.

In the embodiment of the present application, the fuse F1 is used to cut off the transmission of abnormal dc voltage by blowing itself by self-thermal performance when the operating state of the dc power supply is abnormal.

Alternatively, the fuse F1 may be a resettable fuse. When the dc power supply is operating normally, the fuse F1 is in a low-resistance state, thereby ensuring the normal operation of the power protection circuit 10. When a short circuit occurs in the dc power supply or an abnormally large current (i.e., overcurrent) is output, the fuse F1 increases its impedance by self-heating, thereby limiting the transmission of the abnormal current and performing an overcurrent protection function. The fuse F1 also provides over-temperature protection. The fuse F1 can automatically return to a low resistance state when the over-current and over-temperature faults of the dc power source are removed.

In summary, the embodiment of the present application provides a power protection circuit, which includes a discharge circuit, a switch circuit and a filter circuit. The discharge circuit can form a discharge path between the two input ends when the voltage difference between the positive input end and the negative input end is larger than a voltage threshold value so as to prevent overvoltage from being transmitted to a load. The switching circuit can control the first end and the second end to be switched off when the positive input end and the negative input end are reversely connected with the positive electrode and the negative electrode of the direct current power supply, so that the connection between the direct current power supply and a load is disconnected, and the performance of the load is prevented from being damaged. In addition, the filter circuit can filter interference signals in the power supply protection circuit, so that the stability of the direct-current voltage output by the power supply protection circuit is good. Based on the above analysis, the power protection circuit provided by the embodiment of the application has rich functions and has a good protection effect on the direct current power supply and the load.

In this application, the terms "first," "second," and the like are used for distinguishing identical or similar items with substantially identical functions and functionalities, and it should be understood that "first," "second," and "n" have no logical or temporal dependency, and no limitation on the number or execution order.

The above description is only exemplary of the application and should not be taken as limiting the application, and any modifications, equivalents, improvements and the like that are made within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. The utility model provides a power protection circuit, its characterized in that, power protection circuit has positive input, negative pole input, positive output and negative output, positive input with negative pole input is used for connecting DC power supply, positive output with negative output is used for connecting the load, power protection circuit includes: a discharge circuit, a switching circuit and a filter circuit;

the control end of the switch circuit is connected with one of the positive input end and the negative input end, the first end of the switch circuit is connected with the other of the positive input end and the negative input end, the second end of the switch circuit is connected with the input end of the filter circuit, and the switch circuit is used for controlling the first end to be conducted with the second end if the positive input end and the negative input end are correspondingly connected with the positive and negative poles of the direct-current power supply, and controlling the first end to be turned off with the second end if the positive input end and the negative input end are reversely connected with the positive and negative poles of the direct-current power supply;

2. The power protection circuit according to claim 1, wherein the discharge circuit comprises: a varistor and a discharge tube;

3. The power protection circuit of claim 1, wherein the switching circuit comprises: a P-type switching transistor;

the grid electrode of the P-type switch transistor is used as the control end and connected with the negative input end, the drain electrode of the P-type switch transistor is used as the first end and connected with the positive input end, and the source electrode of the P-type switch transistor is used as the second end and connected with the input end of the filter circuit.

4. The power protection circuit of claim 1, wherein the switching circuit comprises: an N-type switching transistor;

5. The power protection circuit according to claim 3 or 4, wherein the switching circuit further comprises: and the first capacitor is respectively connected with the grid electrode and the drain electrode.

6. The power protection circuit according to any one of claims 1 to 4, wherein the power protection circuit further comprises: a voltage dividing circuit;

7. The power protection circuit according to claim 6, wherein the voltage dividing circuit comprises: a first resistor and a second resistor;

8. The power protection circuit according to any one of claims 1 to 4, wherein the filter circuit comprises: a first inductor and a second inductor;

9. The power protection circuit of claim 8, wherein the filter circuit further comprises: a second capacitor, a third capacitor and a fourth capacitor;

10. The power protection circuit according to any one of claims 1 to 4, wherein the power protection circuit further comprises: a fuse;

11. An electronic device, characterized in that the electronic device comprises: a load and a power protection circuit as claimed in any one of claims 1 to 10;

12. The electronic device of claim 11, further comprising: a voltage conversion circuit;