CN220306949U - Protection circuit and electronic equipment - Google Patents

Abstract

The utility model discloses a protection circuit and an electronic device, wherein the protection circuit comprises: the MOS tube is used for blocking the voltage of the signal receiving and transmitting external end, which is larger than the voltage of the power supply, from reaching the signal receiving and transmitting internal end. The utility model realizes a high-voltage prevention circuit based on an MOS tube, and solves the technical problem that the voltage stabilizing tube adopted in the related art is high in high-voltage prevention and power consumption.

Description

Protection circuit and electronic equipment

Technical Field

The utility model relates to the technical field of electronic circuits, in particular to a protection circuit and electronic equipment.

Background

Referring to fig. 1, fig. 1 is a schematic diagram of connection of a communication circuit in the related art, as shown in fig. 1, the left and right ends of a circuit such as "electrostatic protection" in the related art are generally directly connected, or connected with a component with small impedance. If an external high voltage, such as 40V, is introduced at the signal_output end of the communication circuit in an idle condition that does not perform the communication function, the high voltage is applied to the signal_input end via the right-to-left end of the "electrostatic protection circuit" and the r_coupling (coupling resistor), however, the signal_input end is not high in withstand voltage and is easily damaged, thereby causing communication failure or other failure.

One countermeasure is to add a small regulator between the signal_input terminal and the system ground so that the voltage applied to the signal_input terminal does not exceed its withstand voltage limit (shown by the broken line in fig. 1), however, the regulator needs a current of mA level when it functions to prevent high voltage, and thus this way of adding and combining the regulator causes an increase in power consumption.

In view of the above problems in the related art, no effective solution has been found yet.

Disclosure of Invention

The embodiment of the utility model provides a protection circuit and electronic equipment.

According to an aspect of an embodiment of the present application, there is provided a protection circuit including: the MOS tube is used for blocking the voltage of the signal receiving and transmitting external end, which is larger than the voltage of the power supply, from reaching the signal receiving and transmitting internal end.

Further, the protection circuit further comprises a first resistor, one end of the first resistor is connected with the grid electrode of the MOS tube, the other end of the first resistor is connected with the power supply of the communication circuit, and the power supply is used for supplying power to the internal ends of the signal receiving and transmitting device.

Further, the communication circuit further comprises a pull-up resistor, wherein one end of the pull-up resistor is connected with a power supply of the communication circuit, and the other end of the pull-up resistor is connected with the signal receiving and transmitting internal end.

Further, the communication circuit further comprises a coupler, wherein the coupler is connected in series between the drain electrode of the MOS tube and the signal receiving and transmitting external end of the communication circuit.

Further, the communication circuit further comprises an electrostatic protection circuit, wherein the electrostatic protection circuit is connected in series between the coupling resistor and a signal receiving and transmitting external end of the communication circuit.

Further, the resistance value of the first resistor is 100deg.C, and the drain withstand voltage value of the MOS tube is 60V.

Further, the resistance value of the pull-up resistor is 3.3kΩ.

Further, the coupler is a coupling resistor, and the resistance value of the coupling resistor is 100deg.C.

Further, the electrostatic protection circuit is a transient diode.

According to another aspect of embodiments of the present application, there is provided an electronic device, the communication circuit including the circuit described in the above embodiments.

The utility model provides a protection circuit, comprising: the MOS tube is used for blocking the voltage of the signal receiving and transmitting outer end, which is larger than the power supply, from reaching the signal receiving and transmitting inner end. According to the utility model, through the MOS tube, the characteristic of higher turn-off withstand voltage between the drain electrode and the source electrode of the MOS tube is utilized, when the voltage loaded on the external end of signal receiving and transmitting is too high, the MOS tube is turned off, so that the circuit high voltage at the internal end of signal receiving and transmitting is prevented, a high-voltage-preventing circuit based on the MOS tube is realized, and the MOS tube is turned off when the MOS tube plays a role in high voltage prevention, has a leakage current nA level and lower power consumption compared with the current of the mA level of the voltage-stabilizing tube, and solves the technical problem that the related technology adopts the voltage-stabilizing tube to prevent high voltage from consuming high power.

Drawings

The accompanying drawings, which are included to provide a further understanding of the utility model and are incorporated in and constitute a part of this application, illustrate embodiments of the utility model and together with the description serve to explain the utility model and do not constitute a limitation on the utility model. In the drawings:

FIG. 1 is a schematic diagram of a communication circuit in the related art;

FIG. 2 is a schematic diagram of a protection circuit according to an embodiment of the present utility model;

FIG. 3 is a schematic diagram of a protection circuit for an external communication port according to an embodiment of the present utility model;

FIG. 4 is a schematic diagram of another protection circuit for an external communication port according to the present utility model;

fig. 5 is a schematic structural diagram of another protection circuit for an external communication port example 3 according to the present utility model.

The achievement of the objects, functional features and advantages of the present utility model will be further described with reference to the accompanying drawings, in conjunction with the embodiments.

Detailed Description

In order to make the present application solution better understood by those skilled in the art, the following description will be made in detail and with reference to the accompanying drawings in the embodiments of the present application, it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, shall fall within the scope of the present application. It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other.

It should be noted that the terms "first," "second," and the like in the description and claims of the present application and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that embodiments of the present application described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

In the related art, the voltage withstanding of the signal transmitting and receiving internal end of the communication circuit is often not high, for example, the signal pin of the MCU (Microcontroller Unit, micro control unit) is usually designed to withstand a voltage higher than VCC (Volt Current Condenser, power supply voltage) by a fraction of a volt, for example, if VCC is 3.3V, the signal pin of the MCU is typically 3.6V, if VCC is 5V, the signal pin of the MCU is typically 5.5V, etc., and if external high voltage is applied to the transmitting and receiving internal end, the internal end is damaged, so that poor communication or other defects occur.

In order to solve the above problems, an embodiment of the present utility model provides a protection circuit, including: the MOS tube is used for blocking the voltage (namely, the voltage greater than the grid) of the signal receiving and transmitting external end from reaching the signal receiving and transmitting internal end.

If the external signal receiving and transmitting external end is supplied with a low-level signal, the MOS tube is conducted, and the signal receiving and transmitting internal end can receive the low-level signal sent by the outside; if the external signal receiving and transmitting external end is supplied with a high-level signal, the MOS tube is closed at the moment, so that the high-voltage protection of the internal signal receiving and transmitting end is realized.

Through the MOS tube, the characteristic of higher turn-off withstand voltage between the drain electrode and the source electrode of the MOS tube is utilized, when the voltage loaded on the external end of signal receiving and transmitting is too high, the MOS tube is turned off, the circuit high voltage of the internal end of signal receiving and transmitting is prevented, the high-voltage-preventing circuit based on the MOS tube is realized, in addition, the MOS tube is turned off when the MOS tube plays a role of high voltage prevention, the leakage current nA level is lower in power consumption compared with the current of the voltage-stabilizing tube mA level, and the technical problem that the related technology adopts the voltage-stabilizing tube to prevent high voltage consumption is solved.

Optionally, the protection circuit further includes a first resistor, one end of the first resistor is connected to the gate of the MOS tube, and the other end of the first resistor is connected to the power supply of the communication circuit, and the power supply is used for supplying power to the internal end of the signal transceiver. The voltage of the grid electrode is the voltage of a power supply (VCC), and the MOS tube is used for blocking the voltage larger than the power supply of the signal receiving and transmitting external end from reaching the signal receiving and transmitting internal end.

In the embodiment of the utility model, when the voltage between the grid electrode and the source electrode is positive, the MOS tube is opened. In fig. 2, the gate voltage is VCC, and it is assumed that the voltage higher than VCC reaches the source of the MOS transistor, and the voltage between the gate and the source is not positive at this time, and the drain and the source of the MOS transistor are disconnected, so that the voltage higher than VCC cannot stay at the drain of the MOS transistor, i.e., the "voltage clamp", and the source voltage is clamped by the gate voltage VCC and cannot be higher than VCC. By stringing the MOS tube into the communication line, the characteristic of higher turn-off withstand voltage between the drain electrode and the source electrode of the MOS tube is utilized, so that external high voltage is blocked, and the voltage allowed to come in from the Signal_outlide end is improved. The voltage protection circuit is protected by the MOS tube and the first resistor, the MOS tube carries out high-voltage protection on the internal end of signal receiving and transmitting, and the first resistor carries out current limiting protection on the MOS tube by utilizing the characteristics that the withstand voltage parameter Vds (max) between the drain electrode and the source electrode of the MOS tube can reach 60V or even higher and the voltage clamping between the grid electrode and the source electrode of the MOS tube.

The first resistor in this example may be a gate resistor in fig. 2, a resistance value of the first resistor may be 100 Ω, and a drain withstand voltage value of the MOS transistor may be 60V.

In this embodiment, as shown in fig. 2, the communication circuit is a circuit related to Signal transceiving, such as a Signal transceiving circuit, or a control circuit, etc., and includes a Signal transceiving internal terminal (signal_input) and a Signal transceiving external terminal (signal_output), a source electrode of the MOS transistor is connected to the Signal transceiving internal terminal, and a drain electrode of the MOS transistor is connected to the Signal transceiving external terminal of the communication circuit.

In an example, the communication circuit further includes a pull-up resistor, wherein one end of the pull-up resistor is connected to a power supply of the communication circuit, and the other end of the pull-up resistor is connected to the signal receiving and transmitting internal end.

The pull-up resistor is connected in series between the power supply of the communication circuit and the internal end of the signal receiving and transmitting, so as to prevent the circuit short circuit between the power supply and the internal end of the signal receiving and transmitting. In one embodiment, the pull-up resistor may have a resistance of 3.3kΩ.

In an example, the communication circuit further includes a coupler, where the coupler is connected in series between the drain of the MOS transistor and a signal receiving/transmitting external end of the communication circuit.

The coupler plays a role in signal coupling between the signal receiving and transmitting internal end and the signal receiving and transmitting external end. The source electrode of the MOS tube is connected with the signal receiving and transmitting inner end, the drain electrode of the MOS tube is connected with the coupler, and the other end of the coupler is connected with the signal receiving and transmitting outer end, so that the coupler is connected with the signal receiving and transmitting inner end and the outer end in series.

The coupler in this example may be a coupling resistor, for example, a coupling resistor having a resistance value of 100deg.C.

In an example, the communication circuit further includes an electrostatic protection circuit, wherein the electrostatic protection circuit is connected in series between the coupling resistor and a signal receiving and transmitting external terminal of the communication circuit.

The electrostatic protection circuit of the embodiment is an overvoltage and antistatic protection circuit, and the circuit is prevented from being influenced by electrostatic discharge.

The static electricity protection circuit further comprises a grounding end connected with the ground. The electrostatic protection circuit may be a transient diode (Transient Voltage Suppressor, TVS for short). The TVS is a high-efficiency protection device in a diode mode, when two poles of the TVS diode are impacted by reverse transient high energy, the high-resistance between the two poles of the TVS diode can be changed into low-resistance very fast, the surge power of thousands of watts is absorbed, and the voltage clamp between the two poles is located at a preset value, so that precise components in a circuit are effectively protected from being damaged by various surge pulses.

Referring to fig. 2, fig. 2 is a schematic structural diagram of a protection circuit according to an embodiment of the present utility model, as shown in fig. 2, the circuit includes: q1 (MOS transistor), r_gate (gate resistor, i.e., first resistor), r_pull up (pull-up resistor), r_coupling (coupling resistor of coupler), signal_input (Signal transmitting/receiving internal end), signal_output (Signal transmitting/receiving external end), VCC (power supply), electrostatic protection, and other circuits.

The gate of the MOS transistor Q1 is connected with R_gate, the source is connected with an internal signal_input of Signal receiving and transmitting end, and the drain is connected with a resistor R_coupling; one end of the resistor R_gate is connected with a weak current power supply VCC of the system, and the other end of the resistor R_gate is connected with the grid electrode of the MOS tube Q1, namely the gate electrode; one end of the resistor R_pullup is connected with a weak current power supply VCC of the system, and the other end of the resistor R_pullup is connected with a signal_input of an internal Signal receiving and transmitting end; one end of the resistor R_coupling is connected with the drain electrode of the MOS tube Q1, and the other end is connected with circuits such as static protection; one end of the circuit such as static protection is connected with the resistor R_coupling, one end is connected with the signal_output of the Signal transceiver, and the other end is connected with the system ground.

The MOS transistor in this example may be an N-channel MOS transistor. When the voltage between the grid electrode and the source electrode is positive, the MOS tube is opened. In fig. 2, the gate voltage is VCC, and it is assumed that the voltage higher than VCC reaches the source of the MOS transistor, and the voltage between the gate and the source is not positive at this time, and the drain and the source of the MOS transistor are disconnected, so that the voltage higher than VCC cannot stay at the drain of the MOS transistor, i.e., the "voltage clamp", and the source voltage is clamped by the gate voltage VCC and cannot be higher than VCC. By stringing the MOS tube into the communication line, the characteristic of higher turn-off withstand voltage between the drain electrode and the source electrode of the MOS tube is utilized, so that external high voltage is blocked, and the voltage allowed to come in from the Signal_outlide end is improved.

By adopting the embodiment of the utility model, the normal operation of a communication function can be ensured on the basis of high voltage prevention, specifically, when the signal_input end is taken as a Signal receiving end (namely, the signal_output end is taken as a transmitting party), the signal_input end is in a high impedance receiving state (the high impedance state is an output state of a digital circuit and is neither in a high level nor in a low level, if an output pin of an IC is in a high impedance state, the voltage of the pin to the ground and a power supply can be respectively measured by a universal meter, the result is 0V, the high impedance receiving state refers to the Signal which is fed by a port in the high impedance state), if the external signal_output end is fed with a low level Signal, at the moment, the Q1 is conducted, and the level of the signal_input end is pulled down by an external low level Signal, so that the signal_input end successfully receives the externally transmitted low level Signal; if the external signal_output terminal is a high level Signal, at this time, Q1 is turned off, and the level of the signal_input terminal is pulled up to the system power VCC by r_pullup, so that equivalently, the signal_input terminal successfully receives the externally supplied high level Signal.

When the signal_input terminal is used as a Signal transmitting terminal (i.e., the signal_output is a receiving party, and the signal_output is in a high impedance receiving state), if the signal_input sends a low-level Signal to the outside, the level of the signal_input terminal will be autonomously pulled down, so that Q1 is turned on, and the level of the signal_output terminal is pulled down, thereby realizing low-level Signal transmission; if the signal_input sends a high-level Signal to the outside, the signal_input terminal automatically changes to a high-impedance sending state (the high-impedance sending state refers to that the port sends a Signal to the receiving terminal when the port is in a high-impedance state), so that Q1 is turned off, and because the right circuit of the signal_output terminal, that is, the other party of communication, there is a circuit similar to r_pullup and VCC to realize communication, so that the signal_output terminal is pulled up to a high level by the right circuit, thereby realizing high-level Signal sending.

In a specific embodiment, the typical value of r_pullup may be 3.3kΩ, the typical value of r_gate may be 100 Ω, the typical value of Q1 may be model 2N7002K (its drain-source withstand voltage is 60V), the typical value of r_coupling may be 100 Ω, and the circuit "such as" electrostatic protection "may be a TVS (Transient Voltage Suppressor, transient voltage suppression diode) of 24V.

It is understood that in other embodiments, the resistance value and the MOS transistor model may be appropriately adjusted according to the actual situation.

Fig. 3 is a schematic structural diagram of a protection circuit according to the present utility model for example 1 of external communication ports, wherein the MOS transistor is selected from the model 2n7002k, the r_pull typical value is selected from the model 3.3kΩ, the r_gate typical value is selected from the model 100 Ω, and the external communication ports are SDA and SCL.

Fig. 4 is a schematic structural diagram of another protection circuit for an external communication port example 2 according to the present utility model, where the MOS transistor is selected from the model CJ2310, the r_pull typical value is selected from the model 10kΩ, the r_gate typical value is selected from the model 1kΩ, and the external communication ports are TX and RX.

Fig. 5 is a schematic structural diagram of another protection circuit for an external communication port example 3 according to the present utility model, wherein the MOS transistor is selected from the model YJL05N06AL, the r_pull typical value is selected from the model 1kΩ, the r_gate typical value is selected from the model 10 Ω, and the external communication ports are TXD and RXD.

As shown in fig. 3 to 5, different types of resistors and MOS transistors used in the three protection circuits are exemplified.

In summary, by adopting the protection circuit in the embodiment of the utility model, the characteristic that the turn-off withstand voltage between the drain electrode and the source electrode of the MOS tube is higher is utilized, so that external high voltage is blocked, and the high voltage cannot enter the Signal transceiving internal end, thereby improving the voltage allowed to enter from the signal_outide end, for example, only the voltage not higher than 3.6V is allowed to enter originally, otherwise, the internal circuit is damaged.

In addition, because the voltage stabilizing tube needs current with mA level when playing a role in preventing high voltage, compared with a mode of adding the voltage stabilizing tube, the MOS tube in the embodiment of the utility model is turned off when playing a role in preventing high voltage, has the nA level of leakage current and consumes less power.

The present embodiment also provides an electronic device, which includes the protection circuit described in the foregoing embodiment, and the electronic device may be a battery, a communication device, a new energy automobile, or the like.

The foregoing embodiment numbers of the present utility model are merely for the purpose of description, and do not represent the advantages or disadvantages of the embodiments.

In the foregoing embodiments of the present utility model, the descriptions of the embodiments are emphasized, and for a portion of this disclosure that is not described in detail in this embodiment, reference is made to the related descriptions of other embodiments.

In the several embodiments provided in the present utility model, it should be understood that the disclosed technology may be implemented in other manners. The above-described embodiments of the apparatus are merely exemplary, and the division of the units, such as the division of the units, is merely a logical function division, and may be implemented in another manner, for example, multiple units or components may be combined or may be integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be through some interfaces, units or modules, or may be in electrical or other forms.

The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in the embodiments of the present utility model may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.

The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present utility model may be embodied essentially or in part or all of the technical solution or in part in the form of a software product stored in a storage medium, including instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present utility model. And the aforementioned storage medium includes: a U-disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a removable hard disk, a magnetic disk, or an optical disk, or other various media capable of storing program codes.

The foregoing is merely a preferred embodiment of the present utility model and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present utility model, which are intended to be comprehended within the scope of the present utility model.

Claims (10)

1. A protection circuit, the protection circuit comprising: the MOS tube is used for blocking the voltage of the signal receiving and transmitting external end, which is larger than the voltage of the power supply, from reaching the signal receiving and transmitting internal end.

2. The circuit of claim 1, wherein the protection circuit further comprises a first resistor, one end of the first resistor is connected to the gate of the MOS transistor, and one end of the first resistor is connected to a power supply of the communication circuit, and the power supply is used for supplying power to the internal terminal of the signal transceiver.

3. The circuit of claim 1, wherein the communication circuit further comprises a pull-up resistor, wherein one end of the pull-up resistor is connected to a power supply of the communication circuit, and the other end is connected to the signal receiving and transmitting internal end.

4. The circuit of claim 1, wherein the communication circuit further comprises a coupler, wherein the coupler is connected in series between the drain of the MOS transistor and a signal-receiving external terminal of the communication circuit.

5. The circuit of claim 4, wherein the communication circuit further comprises an electrostatic protection circuit, wherein the electrostatic protection circuit is connected in series between the coupler and a signal receiving and transmitting external terminal of the communication circuit.

6. The circuit of claim 2, wherein the resistance of the first resistor is 100deg.C, and the drain withstand voltage of the MOS transistor is 60V.

7. A circuit as claimed in claim 3, wherein the pull-up resistor has a resistance value of 3.3kΩ.

8. The circuit of claim 4, wherein the coupler is a coupling resistor having a resistance value of 100 Ω.

9. The circuit of claim 5, wherein the electrostatic protection circuit is a transient diode.

10. An electronic device, wherein the communication circuit comprises: the protection circuit of any one of claims 1 to 9.