阅读说明：本技术 一种过流延时保护模块及电压比较延时电路 (Overcurrent delay protection module and voltage comparison delay circuit ) 是由 王益凡 杨圣敏 毕庆生 刘西安 刘转 �田�浩 韩高鹏 张红静 姚恩源 于 2020-05-18 设计创作，主要内容包括：本发明公开了一种过流延时保护模块及电压比较延时电路,该模块包括开关电路,用于在输入电流过流时切断输入；电流采集电路,用于电流采集；电压比较延时电路,用于将所述电流采集电路采集到的电流对应的电压与基准电压进行比较,当存在持续过流时存在输出控制所述开关电路关断。本发明提供的过流保护模块通过电压比较延时电路存在持续过流时存在输出控制开关电路关断,该模块需过流信号持续一段时间再输出控制开关电路关断,避免了因尖峰电流而导致误保护的情况。(The invention discloses an overcurrent delay protection module and a voltage comparison delay circuit, wherein the module comprises a switch circuit for cutting off input when input current is overcurrent; the current acquisition circuit is used for acquiring current; and the voltage comparison delay circuit is used for comparing the voltage corresponding to the current acquired by the current acquisition circuit with the reference voltage, and when continuous overcurrent exists, the output is output to control the switching circuit to be switched off. The overcurrent protection module provided by the invention has the advantages that the output control switch circuit is turned off when the voltage comparison delay circuit has continuous overcurrent, and the module needs the overcurrent signal to continue for a period of time and then outputs the control switch circuit to be turned off, so that the condition of error protection caused by peak current is avoided.)

1. An overcurrent delay protection module, comprising:

a switching circuit for cutting off an input when an input current is overcurrent;

the current acquisition circuit is used for acquiring current;

and the voltage comparison delay circuit is used for comparing the voltage corresponding to the current acquired by the current acquisition circuit with the reference voltage, and when continuous overcurrent exists, the output is output to control the switching circuit to be switched off.

2. The overcurrent delay protection module of claim 1, wherein: the voltage comparison delay circuit comprises:

the comparison circuit is used for comparing the voltage corresponding to the current acquired by the current acquisition circuit with a reference voltage and outputting a high level or a low level according to a comparison result;

the delay circuit receives the high level/low level output by the comparison circuit, and outputs when continuous overcurrent exists;

and the feedback circuit outputs an overcurrent feedback signal to be loaded on the switch circuit to control the switch circuit to be switched off when the delay circuit outputs.

3. The overcurrent delay protection module of claim 2, wherein: the overcurrent feedback signal is also loaded to the comparison circuit and used for locking the comparison circuit.

4. The overcurrent delay protection module of claim 3, wherein: a reconnect circuit for releasing the latch mechanism of the compare circuit is also included.

5. The overcurrent delay protection module of claim 2, wherein: the comparison circuit comprises a reference voltage generation circuit and a comparator, wherein the reference voltage generation circuit is used for generating reference voltage, the reference voltage is input to the reverse input end of the comparator, and the output of the current acquisition circuit is input to the forward input end of the comparator.

6. The overcurrent delay protection module of claim 2, wherein: the delay circuit comprises a resistor R6 and a capacitor C.

7. The overcurrent delay protection module of claim 2, wherein: the feedback circuit includes a transistor Q3 and a diode D.

8. The overcurrent delay protection module of claim 1, wherein: the intelligent power supply also comprises a state indicating circuit, wherein the state indicating circuit is used for indicating whether the front end has current or not, and indicating whether the rear end has current or not and/or indicating the overcurrent state.

9. The overcurrent delay protection module of claim 7, wherein: the status indicating circuit comprises an OC gate, and the output end of the OC gate is used for connecting an indicating device.

10. A voltage comparison delay circuit is characterized in that: the circuit comprises a resistor R1, a resistor R2, a comparator, a first triode Q1, a resistor R6, a capacitor C, a second triode Q2, a third triode Q3 and a diode D, wherein the resistor R1 and the resistor R2 are connected between a power supply and the ground in series, the reverse input end of the comparator is connected with one end of the resistor R1 connected with the resistor R2, and the homodromous input end of the comparator is used for inputting a comparison signal; the output end of the comparator is connected with the base electrode of the first triode Q1, the collector electrode of the first triode Q1 is connected with a power supply, the emitter electrode is used as the output end and is connected with the first polar plate of the capacitor C through the resistor R6, and the emitter electrode is grounded through the resistor R5; the first polar plate of the capacitor C is also connected with the base electrode of the second triode Q2, and the second polar plate of the capacitor C and the emitting electrode of the second triode Q2 are grounded; the collector of the second triode Q2 is connected with a power supply and serves as an output end to be connected with the base of the third triode Q3, the emitter of the third triode Q3 is connected with the power supply, the collector is grounded and serves as an output end to be connected with the anode of the diode D, and the cathode of the diode D serves as an output end.

Technical Field

The invention belongs to the field of electronic circuits, and particularly relates to an overcurrent delay protection module and a voltage comparison delay circuit.

Background

Many electronic devices have a current rating that is not allowed to exceed or otherwise burn out the device. Some devices are made as current protection modules. When the current exceeds the set current, the equipment is automatically powered off to protect the equipment. For example, the USB interface of the mainboard CPU generally has USB overcurrent protection, so that the mainboard is protected from being burnt out.

The current universal overcurrent protection device mainly comprises a semiconductor device, a quick fuse, a current relay, an overload relay, a direct current quick breaker and the like. The overcurrent protection device is connected in series between the power supply and the power supply input end of the electric equipment, and when the overcurrent condition occurs, the overcurrent protection device is disconnected to cut off the power supply, so that the electric equipment is prevented from being burnt out due to overcurrent, and overcurrent protection is realized.

Because the power supply has the condition of transient peak current in the process of switching on, switching off or supplying power, when the overcurrent protection device is adopted for overcurrent protection, whether the overcurrent condition is caused by the power supply or the peak current cannot be judged, and the condition of error protection exists.

Disclosure of Invention

In order to solve the technical problems in the prior art, an object of the present invention is to provide an overcurrent delay protection module capable of effectively avoiding overcurrent misprotection.

To achieve the object of the present invention, an overcurrent delay protection module provided herein includes:

a switching circuit for cutting off an input when an input current is overcurrent;

the current acquisition circuit is used for acquiring current;

and the voltage comparison delay circuit is used for comparing the voltage corresponding to the current acquired by the current acquisition circuit with the reference voltage, and when continuous overcurrent exists, the output is output to control the switching circuit to be switched off.

The invention has the beneficial effects that: the overcurrent protection module provided by the invention has the advantages that the output control switch circuit is turned off when the voltage comparison delay circuit has continuous overcurrent, and the module needs the overcurrent signal to continue for a period of time and then outputs the control switch circuit to be turned off, so that the condition of error protection caused by peak current is avoided.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. In the drawings:

fig. 1 is a schematic block diagram of an overcurrent delay protection module according to the present invention;

FIG. 2 is a circuit diagram of a voltage comparison delay circuit according to the present invention;

fig. 3 is a partial circuit diagram of an overcurrent delay protection module provided by the present invention;

FIG. 4 is an overall block diagram of an overcurrent delay protection module provided by the present invention;

fig. 5 is a circuit diagram of a reconnecting circuit provided by the present invention.

Detailed Description

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art.

Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the inventive arrangements can be practiced without one or more of the specific details, or with other methods. In other instances, well-known methods, implementations, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

The invention provides an overcurrent delay protection module for avoiding the condition of error protection during overcurrent, which comprises:

the switching circuit is used for cutting off input when input current is over-current and comprises an MOS switching tube and a driving circuit used for driving the MOS switching tube; the drain electrode of the MOS switching tube is used as an input current end and is used for current input;

the current acquisition circuit is used for acquiring current, and the output end of the current acquisition circuit is used as an output current end for outputting current and is connected with an electric load; the current acquisition circuit samples in a current sensor or sampling resistor mode, the current sensor converts a current analog signal into a voltage signal and transmits the voltage signal to the voltage comparison delay circuit, and the larger the measuring range of the current sensor is, the lower the precision is, and the smaller the measuring range is, the higher the precision is; the sampling resistor is connected in series with a small resistor in a current loop for collection, and the sampling resistor is connected through voltage drop at two ends of the small resistor, so that the circuit is simple in structure and high in cost performance due to the sampling resistor;

and the voltage comparison delay circuit is used for comparing the voltage corresponding to the current acquired by the current acquisition circuit with the reference voltage, and when continuous overcurrent exists in the voltage comparison delay circuit within a certain time, the voltage comparison delay circuit outputs to control the switch circuit to be switched off, so that the aim of overcurrent delay protection is fulfilled.

The voltage comparison delay circuit comprises a comparison circuit, a delay circuit and a feedback circuit, wherein the comparison circuit is used for comparing the voltage corresponding to the current acquired by the current acquisition circuit with a reference voltage and outputting a high level or a low level according to a comparison result; the delay circuit receives the high level/low level output by the comparison circuit, and when the continuous overcurrent exists in a certain time, the output exists; when the output of the delay circuit exists, the feedback circuit outputs an overcurrent feedback signal as a control signal to be loaded on a driving circuit in the switching circuit, and the MOS switching tube is controlled to be switched off through the driving circuit to cut off the current input, so that the aim of overcurrent protection is fulfilled.

The comparison circuit and the delay circuit, and the delay circuit and the feedback circuit are isolated by using a light coupling element or a triode element. Of course, the switch circuit and the current collecting circuit and the voltage comparison delay circuit are also isolated by using the optical coupling element or the triode element. The triode element also has the function of signal amplification when being used as an isolation element.

Any of the comparison circuits, delay circuits, and feedback circuits described herein may be used, where the comparison circuit includes resistor R1, resistor R2, and a comparator. As shown in FIG. 2, the resistor R1 and the resistor R2 are connected in series between the power supply and the ground, and the reverse input terminal of the comparator is connected with the end of the resistor R1 connected with the resistor R2. The resistor R1 and the resistor R2 form a reference voltage generating circuit, a reference voltage is generated and loaded on the reverse input end of the comparator, and the output of the current acquisition circuit is input to the same-direction input end of the comparator through the resistor R3.

The voltage of the reverse input end of the comparator is set to be the voltage corresponding to the overcurrent point collected by the sampling circuit, namely the reference voltage, by dividing the voltage through the resistor R1 and the resistor R2. The overcurrent protection point can be realized by distributing the resistance values of the resistors R1 and R2 according to the formula V VCC R2/(R1+ R2). The VCC should convert the 5V voltage into a stable voltage to supply power to the VCC by using a DC/DC technology, where whether the voltage is stable directly affects the accuracy and error of the current protection point. The comparator outputs a high level when a forward input terminal voltage of the comparator is greater than a reverse input terminal voltage, and outputs a low level when the reverse input terminal voltage is greater than the forward input terminal voltage.

As shown in fig. 2, the delay circuit includes a resistor R6 and a capacitor C, the output of the comparator is loaded at the base of the first transistor Q1, the emitter of the first transistor Q1 is grounded via the resistor R5 and connected to the first plate of the capacitor C via the resistor R6, the collector of the first transistor Q1 is connected to the power supply, and the second plate of the capacitor C is grounded. The base electrode of the first triode Q1 is also connected with a power supply through a resistor R4, the first triode Q1 is an isolation element and is used for isolating the comparison circuit and the delay circuit, realizing signal coupling and coupling the output of the comparison circuit to the delay circuit.

The RC circuit is adopted to form a delay circuit, and the charging and discharging of the capacitor C are delayed. The delay time can be calculated by t-RC x ln ((E-V)/E), R6 current limiting resistor, C charging capacitor, E charging voltage, i.e. control signal voltage, and V voltage to be charged.

As shown in fig. 2, the feedback circuit includes a third transistor Q3 and a diode D, a first plate of a capacitor C is connected to a base of the second transistor Q2, a collector of the second transistor Q2 is connected to a power supply via a resistor R7 and is connected as an output to a base of the third transistor Q3, a collector of the third transistor Q3 is connected to ground via a resistor R8 and is connected as an output to an anode of the diode D, and an emitter of the third transistor Q3 is connected to the power supply. The cathode of the diode D is used as the output of the feedback circuit to output an overcurrent feedback signal. The second triode Q2 is an isolation element for isolating the delay circuit from the feedback circuit, and also for coupling signals, and coupling the output of the delay circuit to the feedback circuit. When the voltage of the capacitor C is charged to 0.7V, the second transistor Q2 turns on the output signal to be low level to control the third transistor Q3.

In the feedback circuit, when the base of the third triode Q3 is at low level, the third triode Q3 is conducted, the diode D plays a role in limiting voltage, and only when the voltage of the positive terminal of the diode D is greater than the conduction voltage drop of the diode D, the diode D can be conducted, and an overcurrent feedback signal is formed into a control signal to be loaded on the drive circuit.

The overcurrent feedback signal output by the feedback circuit is also loaded at the positive input end of the comparator, so that the comparator can carry out locking processing on the module, and false triggering in the circuit can be prevented.

The first transistor Q1 and the second transistor Q2 can be replaced by optical isolation devices as isolation elements.

The overcurrent delay protection module provided by the invention further comprises a state indicating circuit, and the state indicating circuit is used for indicating whether the front end has current or not, indicating whether the rear end has current or not and/or indicating the overcurrent state. The front end is the front end of the MOS switch tube, and the rear end is the rear end of the current acquisition circuit.

As shown in fig. 3, the status indication circuit used herein includes a front end status indication circuit and a back end status indication circuit, and both the front end status indication circuit and the back end status indication circuit are OC gates. As shown in fig. 3, the front end status indicating circuit includes a fourth transistor Q4, a base of the fourth transistor Q4 is connected to the drain of the MOS switch via a resistor R9, and a resistor R10 is connected in series between the base and the emitter of the fourth transistor Q4; the collector of the fourth transistor Q4 is used as an output terminal for an indicator device, such as an LED. When the input current end loads current, the fourth triode Q4 is conducted, so that the indicating device connected to the output end of the fourth triode Q4 is in a working state for prompting the current input at the input current end.

As shown in fig. 3, the rear-end status indicating circuit includes a fifth transistor Q5, a base of the fifth transistor Q5 is connected to an output terminal of the current collecting circuit through a resistor R11, a resistor R12 is connected in series between the base and an emitter of the fifth transistor Q5, and a collector of the fifth transistor Q5 is used as an output terminal for connecting an indicating device, such as an LED. When the current output exists at the output current end, the fifth triode Q5 is conducted, so that the indicating device connected to the output end of the fifth triode Q5 is in a working state and is used for prompting the current input existing at the output current end.

To achieve an over-current indication, an LED lamp may be connected in series between the output of the feedback circuit and ground, such as between the collector of the third transistor Q3 and ground. When the feedback circuit outputs (namely, overcurrent exists), the LED lamp is in a working state, and the purpose of overcurrent indication is achieved.

The power supply is output to the electric load through the MOS switch tube and the current acquisition circuit, the MOS switch tube needs to be driven by the driving circuit, and the control signal is input from the driving end of the driving circuit to control the driving circuit to work. When the front end of the MOS switch tube has current, the front end state indicating circuit can be used for indicating whether the front end has electricity, the current parameters are converted into voltage parameters after being sampled by the current acquisition circuit and then enter the comparison circuit as shown in the attached figure 2, the resistors R1 and R2 divide the voltage to provide a stable voltage comparison point for one end of the comparator, the voltage corresponds to a current protection point needing to be set, R3 is a current limiting resistor, when the current exceeds the protection point, the comparator outputs a signal to the first triode Q1, a fault signal drives the first triode Q1 through the pull-up resistor R4 to switch on the first triode Q1, namely the voltage of the resistor R6 is 4.3V to charge the capacitor C, and the charging process is delay time. When the capacitor C is fully charged, the second triode Q2 is controlled to be switched on, so that the base voltage of the third triode Q3 is at a low level, the third triode Q3 is a PNP type triode, the third triode Q3 is switched on, the anode voltage of the diode D is at a high level, the cathode of the diode D is connected with the positive end of the comparator, the positive end of the comparator is constantly at 4.3V, the circuit is locked, and if the locking state needs to be released, the comparator needs to be powered on again.

As shown in fig. 1 and 4, the overcurrent delay protection module of the present disclosure includes a circuit protection module for input/output control, variable current detection, and controllable overcurrent protection time and each status indication bit. When the input end is connected with current, the driving circuit is controlled to switch on the MOS switch tube, the current acquisition circuit acquires current parameters and compares the current parameters with a preset voltage value to output a feedback signal, the feedback signal is protected by the delay circuit, and the state of the control end, the state of the front end and the rear end of the MOS switch tube and the over-current protection state are indicated. If the overcurrent happens, the comparator is locked through the signal output by the comparator, and the circuit can be operated again as long as the dead-lock state of the comparator is eliminated through the reconnection circuit, so that the overcurrent protection delay control function is realized.

The reconnection circuit structure herein is shown in fig. 5, and includes a sixth triode Q6, a resistor R13, and a resistor R14, one end of the resistor R13 is used as a reconnection pin, and the other end is connected to the base of the sixth triode Q6; the collector of the sixth triode Q6 is connected with the power supply through a resistor R14 and is used as an output end to be connected with the positive power supply end of the comparator. The normal state of the reconnection pin is a suspension state, when reconnection is needed, the pin is connected with a high level by pressing the switch, and then the positive power supply end of the comparator is at a low level, which is equivalent to powering off the comparator and removing a locking mechanism. The external part of the reconnection pin can be connected with a high level pulse to realize the reconnection function.

The overcurrent delay protection module can perform delay protection under the condition of overcurrent, can control overcurrent protection points and protection time, namely, collects current through the sampling resistor, converts current parameters into voltage parameters, compares the voltage parameters with the voltage corresponding to the preset current protection points through the voltage comparator to output feedback signals, and performs delay feedback protection through the delay circuit.

The present disclosure has been described in terms of the above-described embodiments, which are merely exemplary of the implementations of the present disclosure. It must be noted that the disclosed embodiments do not limit the scope of the disclosure. Rather, variations and modifications are possible within the spirit and scope of the disclosure, and these are all within the scope of the disclosure.