CN218514079U - Intrinsic safety system and overcurrent protection circuit thereof - Google Patents
Intrinsic safety system and overcurrent protection circuit thereof Download PDFInfo
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- CN218514079U CN218514079U CN202222869154.7U CN202222869154U CN218514079U CN 218514079 U CN218514079 U CN 218514079U CN 202222869154 U CN202222869154 U CN 202222869154U CN 218514079 U CN218514079 U CN 218514079U
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Abstract
The application discloses this ampere of system and overcurrent protection circuit thereof relates to electron technical field. The circuit comprises a first field effect transistor, a triode, a charging capacitor, a comparator, a first voltage divider, a second voltage divider, a feedback resistor and a delay resistor. The first fet is turned off for a short time on power up and then turned on until fully on. Then the second field effect transistor is slowly started, thereby effectively avoiding the problem of power-on failure caused by overlarge power-on impact current. When the current of the intrinsic safety device approaches the set overcurrent upper limit, the first field effect transistor works in the linear amplification area, and the output current is limited. When the current of the intrinsic safety device continues to increase and reaches the overcurrent upper limit, the first field effect tube enters a continuous periodic opening-closing mode, the circuit can enter a circulating protection and self-recovery state, and the heat productivity of the current limiting device is reduced in the state. Therefore, when the over-current or short-circuit fault occurs to the intrinsic safety equipment, the protection circuit generates heat lower than that of the traditional current-limiting type protection circuit.
Description
Technical Field
The utility model relates to the field of electronic technology, especially, relate to an intrinsic safety system and overcurrent protection circuit thereof.
Background
In recent years, along with the development of electronic technology, the application of the intrinsically safe protection circuit is increasing, and the intrinsically safe protection circuit provides safety protection for intrinsically safe devices used in an explosive gas environment, and can limit the spark energy (i.e., discharge current, discharge voltage, discharge time) generated when the circuit fails within a certain safety range. The schemes for implementing overcurrent protection on the current of the intrinsic safety equipment generally comprise a cut-off type, a current limiting type, a current reducing type and the like.
The current limiting type protection circuit detects the current condition of the protected intrinsic safety equipment, sets the output upper limit of the protection circuit, and enters a constant current state to prevent the current of the intrinsic safety equipment from increasing when the current of the intrinsic safety equipment reaches the upper limit value. The scheme has the advantages of simple structure and high heating of the current limiting device when the intrinsic safety equipment is short-circuited; the cut-off protection circuit adopts a switch to control output, has the advantages of thorough cut-off in overcurrent, and has the defects that the circuit structure of the scheme is more complicated than that of a current limiting type protection circuit, and the problem of starting failure caused by overlarge power-on impact current is easily encountered when the load capacitance is larger.
In view of the foregoing prior art, it is an urgent need for technical staff to find an overcurrent protection circuit that has a certain current limiting function when the load current approaches the upper protection limit, and when the load current exceeds the upper protection limit or a short-circuit fault occurs, the protection circuit enters a protection-self-recovery cycle state, the protection circuit generates less heat, and can effectively avoid power-on start failure.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing an this ampere of system and overcurrent protection circuit thereof possesses the current-limiting function when load current is close to the protection upper limit, and protection circuit gets into protection-self-resuming's circulation state when load current surpasss the protection upper limit or takes place short-circuit fault, has avoided when the load takes place to overflow or short-circuit fault the protection device problem of continuously generating heat, can avoid the last start-up problem that type protection circuit meets easily to a certain extent again simultaneously.
The application provides an overcurrent protection circuit is applied to this ampere of system, includes: the circuit comprises a first field effect transistor, a triode, a charging capacitor, a comparator, a first voltage divider, a second voltage divider, a feedback resistor and a delay resistor;
the non-inverting input end of the comparator is connected with the voltage division node of the first voltage divider, the inverting input end of the comparator is connected with the voltage division node of the second voltage divider, and the output end of the comparator is connected with the grid electrode of the first field effect transistor;
the source electrode of the first field effect transistor is connected with an external power supply, and the drain electrode of the first field effect transistor is connected with the external power supply;
the base electrode of the triode is connected with the first end of the charging capacitor, the emitter electrode of the triode is connected with virtual ground, the collector electrode of the triode is connected with the inverting input end of the comparator, and the second end of the charging capacitor is connected with the source electrode of the first field effect transistor;
the first end of the first voltage divider is connected with the source electrode of the first field effect transistor, the second end of the first voltage divider is connected with virtual ground, the first end of the second voltage divider is connected with the source electrode of the first field effect transistor, and the second end of the second voltage divider is connected with virtual ground;
the first end of the feedback resistor is connected with the non-inverting input end of the comparator, the second end of the feedback resistor is connected with the output end of the comparator, the first end of the delay resistor is connected with the first end of the charging capacitor, and the second end of the delay resistor is connected with the virtual ground.
Preferably, the method further comprises the following steps: the second field effect transistor and the auxiliary circuit thereof are as follows: the source electrode of the second field effect transistor is connected with the drain electrode of the first field effect transistor, and the drain electrode of the second field effect transistor is connected with intrinsic safety equipment;
the auxiliary circuit comprises a first starting capacitor, a second starting capacitor and a third field effect transistor;
the first end of the first starting capacitor is connected with the drain electrode of the first field effect transistor and the source electrode of the second field effect transistor, and the second end of the first starting capacitor is connected with the grid electrode of the second field effect transistor;
the first end of the second starting capacitor is used as the drain electrode of the second field effect transistor, and the second end of the second starting capacitor is connected with the grid electrode of the third field effect transistor;
the drain electrode of the third field effect transistor is connected with the grid electrode of the second field effect transistor, and the source electrode of the third field effect transistor is grounded.
Preferably, the method further comprises the following steps: a first capacitor;
the first end of the first capacitor is connected with the first end of the first voltage divider, and the second end of the first capacitor is connected with the non-inverting input end of the comparator.
Preferably, the method further comprises the following steps: a precision voltage stabilizer;
the positive pole of the precision voltage stabilizer is connected with the non-inverting input end of the comparator, and the negative pole of the precision voltage stabilizer is connected with the virtual ground; the precision voltage regulator may be replaced by a zener diode.
Preferably, the method further comprises the following steps: sampling a resistor;
the first end of the sampling resistor is connected with the first end of the first voltage divider, and the second end of the sampling resistor is connected with the second end of the second voltage divider.
Preferably, also includes; a first resistor, a first diode;
the first end of the first resistor is connected with the base electrode of the triode, and the second end of the first resistor is connected with the first end of the charging capacitor;
the cathode of the first diode is connected with the second end of the first resistor, and the anode of the first diode is connected with the virtual ground.
Preferably, the method further comprises the following steps: the second resistor, the third resistor, the second diode and the bias resistor;
the first end of the second resistor is connected with the source electrode of the first field effect transistor, and the second end of the second resistor is connected with the output end of the comparator;
the first end of the third resistor is connected with the second end of the second resistor, and the second end of the third resistor is connected with the grid electrode of the first field effect transistor;
the anode of the second diode is connected with the grid electrode of the first field effect transistor, and the cathode of the second diode is connected with the source electrode of the first field effect transistor;
the first end of the bias resistor is connected with a virtual ground, and the second end of the bias resistor is connected with the ground.
Preferably, the accessory circuit further comprises: the third diode, the fourth resistor, the fifth resistor, the sixth resistor, the seventh resistor and the third starting capacitor;
the anode of the third diode is connected with the second end of the first starting capacitor, and the cathode of the third diode is connected with the grid electrode of the second field effect transistor;
the first end of the fourth resistor is connected with the anode of the third diode, and the second end of the fourth resistor is connected with the cathode of the third diode;
the first end of the third starting capacitor is connected with the grid electrode of the third field effect transistor, and the second end of the third starting capacitor is connected with the drain electrode of the second field effect transistor;
the first end of the fifth resistor is connected with the grid electrode of the third field effect transistor, and the second end of the fifth resistor is grounded;
the first end of the sixth resistor is connected with the source electrode of the third field effect transistor, and the second end of the sixth resistor is grounded;
the first end of the seventh resistor is connected with the drain electrode of the third field effect transistor, and the second end of the seventh resistor is grounded.
Preferably, the first voltage divider and the second voltage divider are both voltage dividers consisting of two resistors.
The application also provides an intrinsic safety system which comprises all the overcurrent protection circuits mentioned above.
An overcurrent protection circuit is applied to an intrinsic safety system and comprises: the circuit comprises a first field effect transistor, a triode, a charging capacitor, a comparator, a first voltage divider, a second voltage divider, a feedback resistor and a delay resistor; the non-inverting input end of the comparator is connected with the voltage division node of the first voltage divider, the inverting input end of the comparator is connected with the voltage division node of the second voltage divider, and the output end of the comparator is connected with the grid electrode of the first field effect transistor; the source electrode of the first field effect transistor is connected with an external power supply, and the drain electrode of the first field effect transistor is connected with the external power supply; the base electrode of the triode is connected with the first end of the charging capacitor, the emitter electrode of the triode is connected with virtual ground, the collector electrode of the triode is connected with the inverting input end of the comparator, and the second end of the charging capacitor is connected with the source electrode of the first field effect transistor; the first end of the first voltage divider is connected with the source electrode of the first field effect transistor, the second end of the first voltage divider is connected with virtual ground, the first end of the second voltage divider is connected with the source electrode of the first field effect transistor, and the second end of the second voltage divider is connected with virtual ground; the first end of the feedback resistor is connected with the non-inverting input end of the comparator, the second end of the feedback resistor is connected with the output end of the comparator, the first end of the delay resistor is connected with the first end of the charging capacitor, and the second end of the delay resistor is connected with the virtual ground. When the input voltage starts to increase after the first power-on, a certain current flows through the collector of the triode, the potential of the reverse input end of the comparator is forced to be lower than the non-inverting input end of the comparator, and therefore the first field effect transistor is turned off in a short time when being powered on and then turned on until being completely conducted. Then the second field effect transistor is slowly started, thereby effectively avoiding the problem of starting failure caused by overlarge power-on impact current. When the current of the intrinsic safety equipment is close to the set overcurrent upper limit, the comparator can firstly control the first field effect transistor to work in the linear amplification region. Subsequently, if the current of the intrinsic safety equipment continues to increase and exceeds the protection upper limit, the first field effect transistor enters a continuous periodic on-off mode, the circuit can enter a protection-self-recovery circulation protection state, and the heat productivity of the current limiting device can be reduced when the current of the intrinsic safety equipment exceeds the protection upper limit or short circuit occurs.
The application also provides an intrinsic safety system, and the beneficial effects are the same as above.
Drawings
In order to illustrate the embodiments of the present invention more clearly, the drawings needed for the embodiments will be briefly described, it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained without inventive efforts.
Fig. 1 is a circuit diagram of an overcurrent protection circuit according to an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, the ordinary skilled in the art can obtain all other embodiments without creative work, which all belong to the protection scope of the present invention.
The core of the utility model is to provide an this ampere of system and overcurrent protection circuit thereof, possesses the current-limiting function when load current is close to the protection upper limit, protection circuit gets into protection-self-resuming's circulation state when load current surpasses the protection upper limit or takes place short-circuit fault, has avoided when the load takes place to overflow or short-circuit fault the protection device problem of generating heat continuously, can avoid the last start-up problem that cut-off protection circuit meets easily to a certain extent again simultaneously.
In order to make the technical field better understand the solution of the present invention, the following detailed description is given with reference to the accompanying drawings and the detailed description.
Fig. 1 is a structural diagram of an overcurrent protection circuit provided in an embodiment of the present application, and as shown in fig. 1, an overcurrent protection circuit applied to an intrinsically safe system includes: the circuit comprises a comparator U1, a first field effect transistor Q2, a triode Q1, a charging capacitor C2, a first voltage divider, a second voltage divider, a feedback resistor R7 and a delay resistor R6; in addition, a bias resistor R10, a precision voltage stabilizer V1 and a sampling resistor R3 are also arranged;
the non-inverting input end of the comparator U1 is connected with a voltage division node of the first voltage divider, the inverting input end of the comparator U1 is connected with a voltage division node of the second voltage divider, and the output end of the comparator U1 is connected with a grid electrode of the first field effect transistor Q2;
the source electrode of the first field effect transistor Q2 is connected with an external power supply, and the drain electrode of the first field effect transistor Q2 is connected with the source electrode of the second field effect transistor Q3;
the base electrode of the triode Q1 is connected with the first end of the charging capacitor C2, the emitting electrode of the triode Q1 is connected with virtual ground, the collecting electrode of the triode Q1 is connected with the inverting input end of the comparator U1, and the second end of the charging capacitor C2 is connected with the source electrode of the first field effect transistor Q2;
the first end of the first voltage divider is connected with the first end of the sampling resistor R3, the second end of the first voltage divider is connected with virtual ground, the first end of the second voltage divider is connected with the source electrode of the first field effect transistor Q2 and the second end of the sampling resistor R3, and the second end of the second voltage divider is connected with virtual ground;
the first end of the feedback resistor R7 is connected with the non-inverting input end of the comparator U1, the second end of the feedback resistor R7 is connected with the output end of the comparator U1, the first end of the delay resistor R6 is connected with the first end of the charging capacitor C2, and the second end of the delay resistor R6 is connected with the virtual ground.
The first end of the bias resistor R10 is connected with a virtual ground, and the second end of the bias resistor R10 is connected with the ground;
the positive pole of the precision voltage stabilizer V1 is connected with an input power supply, and the negative pole is connected with a virtual ground;
the first end of the sampling resistor R3 is connected with an input power supply, and the second end of the sampling resistor R3 is connected with the first end of the second voltage divider and the source electrode of the first field effect transistor Q2.
In the present embodiment, the above-mentioned elements are not limited, and it is understood that, in the present safety system, the power supply input to the present overcurrent protection circuit is a voltage processed by a previous stage circuit.
The first fet Q2 is typically a P-channel fet, and the precision regulator V1 and the first voltage divider provide a reference voltage to the non-inverting input of the comparator U1. The comparator U1 is supplied with the compared voltage by a second voltage divider, which is generally formed by resistors R1 and R2, and similarly formed by resistors R4 and R5. At the moment of initial electrification, the external power supply charges the charging capacitor C2 to enable the triode Q1 to be saturated, a certain current flows through the collector of the triode Q1 to force the reverse input end potential of the comparator U1 to be lower than the non-inverting input end of the comparator U1, so that the comparator U1 outputs a high level, the temporary disconnection of the first field effect transistor Q2 is ensured through short-time disconnection, then the charging capacitor C2 is gradually filled, the base potential of the triode Q1 falls, and the transistor is in a disconnection state. After the input power supply voltage is stable and the intrinsic safety device is not in an overcurrent state, the potential of the non-inverting input end of the comparator U1 is lower than the potential of the inverting input end of the comparator U1, and the comparator U1 outputs low level, so that the first field effect transistor Q2 is conducted to supply power for the rear stage normally.
When the intrinsic safety device current is increased to a set value, the node voltage of the second voltage divider approaches to the node voltage of the first voltage divider, the comparator U1 works in a linear amplification region, negative feedback is provided by the first field effect transistor Q2 and the sampling resistor R3, the first field effect transistor Q2 works in a saturation region, and the output is in a current limiting state. If the current continues to increase, the voltage drop on the sampling resistor R3 increases immediately, the output voltage of the comparator U1 also increases immediately, when the output voltage increases to be lower than the starting voltage of the first field effect transistor Q2, the first field effect transistor Q2 is turned off, the source voltage of the first field effect transistor Q2 suddenly rises at the moment, the charging capacitor C2 is charged, the base voltage of the triode Q1 is rapidly increased, the triode Q1 is turned on, the junction voltage of the second voltage divider is pulled down, the positive feedback effect of the feedback resistor R7 is superposed, and the second field effect transistor Q3 is rapidly and deeply turned off as a result, and then the second field effect transistor Q3 is kept off. The turn-off maintaining time is determined by a delay circuit formed by a charging capacitor C2 and a delay resistor R6, after the holding time is over, the triode Q1 is turned off again, and the first field effect transistor Q2 tries to be turned on again.
In view of the problem of starting failure caused by overlarge load starting impact current when the circuit is started, the preferable scheme is provided, and the preferable scheme further comprises the following steps: a second field effect transistor Q3 and its auxiliary circuit;
the auxiliary circuit comprises a first starting capacitor C3, a second starting capacitor C4, a third starting capacitor C5, a second field effect transistor Q3, a fourth resistor R12, a fifth resistor R13, a third diode D3 and a third field effect transistor Q4;
a first end of the first starting capacitor C3 is connected with a drain electrode of the first field effect transistor Q2 and a source electrode of the second field effect transistor Q3, and a second end of the first starting capacitor C3 is connected with an anode of the third diode D3 and a drain electrode of the third field effect transistor Q4;
a first end of the second starting capacitor C4 is connected with a drain electrode of the second field effect transistor Q3, and a second end of the second starting capacitor C4 is connected with a grid electrode of the second field effect transistor Q3;
a first end of the third start capacitor C5 is connected to the gate of the third fet Q4, and a second end of the third start capacitor C5 is connected to the drain of the second fet Q3.
The source electrode of the second field effect transistor Q3 is connected with the first end of the first starting capacitor C3, and the drain electrode of the second field effect transistor Q3 is connected with the first end of the second starting capacitor C4;
a first end of the fourth resistor R12 is connected to the anode of the third diode D3, and a second end of the fourth resistor R12 is connected to the cathode of the third diode D3;
a first end of the fifth resistor R13 is connected with the grid electrode of the third field effect transistor Q4, and a second end of the fifth resistor R13 is grounded;
the anode of the third diode D3 is connected with the drain electrode of the third field effect transistor Q4, and the cathode of the third diode D3 is connected with the grid electrode of the second field effect transistor Q3;
the drain electrode of the third field effect transistor Q4 is connected with the anode of the third diode D3, and the source electrode of the third field effect transistor Q4 is grounded.
The second field effect transistor Q3 and the auxiliary circuit thereof are used for limiting the impact current when the first field effect transistor is electrified or the first field effect transistor is electrified again after being turned off, so that the problem that the overcurrent protection circuit is easy to start failure due to sudden current change at the starting moment of intrinsic safety equipment is avoided. When the intrinsically safe device is powered on for the first time or the first field effect tube is powered on again after being turned off, the first starting capacitor C3 and the second starting capacitor C4 are charged quickly, the third starting capacitor C5 is charged slowly, the grid voltage of the second field effect tube Q3 rises at a certain slope, then the second field effect tube Q3 is conducted weakly to enable the drain voltage of the second field effect tube Q3 to rise, further the grid voltage of the third field effect tube Q4 is increased slowly through the coupling effect of the third starting capacitor C5, when the grid voltage is increased to the starting voltage of the third field effect tube Q4, the conducting drain of the third field effect tube Q4 is conducted to be lowered, further the grid voltage of the second field effect tube Q3 is slowly lowered, the second starting capacitor C4 is discharged reversely, the second starting capacitor C4 forms a Miller capacitor, and finally the second field effect tube Q3 is started slowly until the second field effect tube Q3 is conducted completely to limit the impact current of the intrinsically safe device and the rising rate of the output voltage.
In view of preventing the interference of the input power, for the normal operation of the overcurrent protection circuit, as shown in fig. 1, the method further includes: a first capacitor C1.
The first end of the first capacitor C1 is connected to the first end of the voltage divider, and the second end of the first capacitor C1 is connected to the non-inverting input terminal of the comparator U1.
The capacitor is used for filtering noise and enhancing the starting and locking functions, and it should be noted that in occasions with low requirements, the precision voltage stabilizer can be replaced by a voltage stabilizing diode.
In view of the protection problem of the triode Q1 and the field effect transistor, the preferable scheme is provided and further comprises the following steps; a first resistor R15, a first diode D1;
the first end of the first resistor R15 is connected with the base electrode of the triode Q1, and the second end of the first resistor R15 is connected with the first end of the charging capacitor C2;
the cathode of the first diode D1 is connected to the second end of the first resistor R15, and the anode of the first diode D1 is connected to the virtual ground.
Further comprising: a second resistor R8, a third resistor R9, and a second diode D2;
a first end of the second resistor R8 is connected with a source electrode of the first field effect transistor Q2, and a second end of the second resistor R8 is connected with an output end of the comparator U1;
a first end of the third resistor R9 is connected with a second end of the second resistor R8, and a second end of the third resistor R9 is connected with a grid electrode of the first field-effect transistor Q2;
the anode of the second diode D2 is connected to the gate of the first field effect transistor Q2, and the cathode of the second diode D2 is connected to the source of the first field effect transistor Q2.
Through the above elements, it is ensured that the triode Q1 and the field effect transistor are not damaged, the specific working principle is that the second resistor R8 is used as a pull-up resistor, the third resistor R9 and the second diode D2 provide voltage protection between the gate and the drain for the first field effect transistor Q2, and the first field effect transistor Q2 is protected from being damaged, and the working principles of other related elements are the same as above and are not repeated herein.
The auxiliary circuit further comprises: a sixth resistor R11 and a seventh resistor R14;
the sixth resistor R11 and the seventh resistor R14 are both used for resetting the state of the protection circuit after the first field effect transistor Q2 is turned off.
In order to solve the above problem, the present application further provides an intrinsic safety system, which includes the above overcurrent protection circuit.
The core improvement point of the intrinsic safety system provided by the application is in the overcurrent protection circuit included in the intrinsic safety system, and therefore relevant embodiments and corresponding beneficial effects are shown in an overcurrent protection circuit part, which is not repeated herein.
It is right above the utility model provides an this ampere of system and overcurrent protection circuit thereof introduces in detail. The embodiments are described in a progressive manner in the specification, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed in the embodiment corresponds to the method disclosed in the embodiment, so that the description is simple, and the relevant points can be referred to the description of the method part. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, the present invention can be further modified and modified, and such modifications and modifications also fall within the scope of the appended claims.
It should also be noted that, in this specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising a," "8230," "8230," or "comprising" does not exclude the presence of additional like elements in a process, method, article, or apparatus that comprises the element.
Claims (10)
1. An overcurrent protection circuit, which is applied to an intrinsic safety system, comprises: the circuit comprises a first field effect transistor, a triode, a charging capacitor, a comparator, a first voltage divider, a second voltage divider, a feedback resistor and a delay resistor;
the non-inverting input end of the comparator is connected with the voltage dividing node of the first voltage divider, the inverting input end of the comparator is connected with the voltage dividing node of the second voltage divider, and the output end of the comparator is connected with the grid electrode of the first field effect transistor;
the source electrode of the first field effect transistor is connected with an external power supply, and the drain electrode of the first field effect transistor is connected with the external power supply;
the base electrode of the triode is connected with the first end of the charging capacitor, the emitter electrode of the triode is connected with virtual ground, the collector electrode of the triode is connected with the inverting input end of the comparator, and the second end of the charging capacitor is connected with the source electrode of the first field effect transistor;
the first end of the first voltage divider is connected with the source electrode of the first field effect transistor, the second end of the first voltage divider is connected with virtual ground, the first end of the second voltage divider is connected with the source electrode of the first field effect transistor, and the second end of the second voltage divider is connected with virtual ground;
the first end of the feedback resistor is connected with the non-inverting input end of the comparator, the second end of the feedback resistor is connected with the output end of the comparator, the first end of the delay resistor is connected with the first end of the charging capacitor, and the second end of the delay resistor is connected with a virtual ground.
2. The overcurrent protection circuit of claim 1, further comprising: the second field effect transistor and the auxiliary circuit thereof are as follows: the source electrode of the second field effect transistor is connected with the drain electrode of the first field effect transistor, and the drain electrode of the second field effect transistor is connected with intrinsic safety equipment;
the auxiliary circuit comprises a first starting capacitor, a second starting capacitor and a third field effect transistor;
the first end of the first starting capacitor is connected with the drain electrode of the first field effect transistor and the source electrode of the second field effect transistor, and the second end of the first starting capacitor is connected with the grid electrode of the second field effect transistor;
a first end of the second starting capacitor is used as a drain electrode of the second field effect transistor, and a second end of the second starting capacitor is connected with a grid electrode of the third field effect transistor;
the drain electrode of the third field effect transistor is connected with the grid electrode of the second field effect transistor, and the source electrode of the third field effect transistor is grounded.
3. The overcurrent protection circuit of claim 1, further comprising: a first capacitor;
the first end of the first capacitor is connected with the first end of the first voltage divider, and the second end of the first capacitor is connected with the non-inverting input end of the comparator.
4. The overcurrent protection circuit of claim 3, wherein the protection circuit further comprises: a precision voltage stabilizer;
the positive electrode of the precision voltage stabilizer is connected with the non-inverting input end of the comparator, and the negative electrode of the precision voltage stabilizer is connected with virtual ground; the precision voltage regulator may be replaced by a zener diode.
5. The overcurrent protection circuit of claim 4, further comprising: sampling a resistor;
the first end of the sampling resistor is connected with the first end of the first voltage divider, and the second end of the sampling resistor is connected with the second end of the second voltage divider.
6. The overcurrent protection circuit of any of claim 5, further comprising; a first resistor, a first diode;
the first end of the first resistor is connected with the base electrode of the triode, and the second end of the first resistor is connected with the first end of the charging capacitor;
the cathode of the first diode is connected with the second end of the first resistor, and the anode of the first diode is connected with virtual ground.
7. The overcurrent protection circuit of claim 6, further comprising: the second resistor, the third resistor, the second diode and the bias resistor;
the first end of the second resistor is connected with the source electrode of the first field effect transistor, and the second end of the second resistor is connected with the output end of the comparator;
the first end of the third resistor is connected with the second end of the second resistor, and the second end of the third resistor is connected with the grid electrode of the first field-effect tube;
the anode of the second diode is connected with the grid electrode of the first field effect transistor, and the cathode of the second diode is connected with the source electrode of the first field effect transistor;
the first end of the bias resistor is connected with a virtual ground, and the second end of the bias resistor is connected with the ground.
8. The overcurrent protection circuit of claim 2, wherein the auxiliary circuit further comprises: the third diode, the fourth resistor, the fifth resistor, the sixth resistor, the seventh resistor and the third starting capacitor;
the anode of the third diode is connected with the second end of the first starting capacitor, and the cathode of the third diode is connected with the grid electrode of the second field effect transistor;
a first end of the fourth resistor is connected with an anode of the third diode, and a second end of the fourth resistor is connected with a cathode of the third diode;
the first end of the third starting capacitor is connected with the grid electrode of the third field effect transistor, and the second end of the third starting capacitor is connected with the drain electrode of the second field effect transistor;
the first end of the fifth resistor is connected with the grid electrode of the third field effect transistor, and the second end of the fifth resistor is grounded;
the first end of the sixth resistor is connected with the source electrode of the third field effect transistor, and the second end of the sixth resistor is grounded;
the first end of the seventh resistor is connected with the drain electrode of the third field effect transistor, and the second end of the seventh resistor is grounded.
9. The over-current protection circuit according to any one of claims 1 to 8, wherein each of the first voltage divider and the second voltage divider is a voltage divider formed by two resistors.
10. An intrinsically safe system comprising the overcurrent protection circuit of any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222869154.7U CN218514079U (en) | 2022-10-28 | 2022-10-28 | Intrinsic safety system and overcurrent protection circuit thereof |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222869154.7U CN218514079U (en) | 2022-10-28 | 2022-10-28 | Intrinsic safety system and overcurrent protection circuit thereof |
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| CN218514079U true CN218514079U (en) | 2023-02-21 |
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|---|---|---|---|
| CN202222869154.7U Active CN218514079U (en) | 2022-10-28 | 2022-10-28 | Intrinsic safety system and overcurrent protection circuit thereof |
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| Country | Link |
|---|---|
| CN (1) | CN218514079U (en) |
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2022
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