CN216699482U - Overload/short-circuit protection circuit and electronic equipment - Google Patents
Overload/short-circuit protection circuit and electronic equipment Download PDFInfo
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- CN216699482U CN216699482U CN202123295119.0U CN202123295119U CN216699482U CN 216699482 U CN216699482 U CN 216699482U CN 202123295119 U CN202123295119 U CN 202123295119U CN 216699482 U CN216699482 U CN 216699482U
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- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
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Abstract
The utility model provides an overload/short-circuit protection circuit and electronic equipment. The constant current control circuit is used for limiting the current of the front-end load CN 1; the load on-off control circuit is used for controlling power supply to a rear-end load CN 2; the driving circuit is coupled with the load on-off control circuit and the constant current control circuit and is used for driving the load on-off control circuit; the voltage reduction and stabilization circuit is coupled with the driving circuit and the constant current control circuit and is used for providing working voltage and reference voltage for operational amplifiers on the driving circuit and the constant current control circuit. Therefore, when the output is overloaded, short-circuited or started with a large capacitance load and the like, the current output can be limited, so that a rear-end power circuit is protected.
Description
Technical Field
The present invention relates to the field of power electronics technologies, and in particular, to an overload/short-circuit protection circuit and an electronic device.
Background
The safety of electronic products is an important index for measuring the quality of the electronic products. Overload protection is a protection mechanism when an electronic product performs control panel design.
Specifically, as shown in fig. 1, the output current of VOUT is limited by the matching of an EN port of an IC and a sampling resistor of an RSET port, and if the output load current is too large or short-circuited, the internal part of the IC gradually closes the conduction state of an MOS, so as to protect a switching power supply circuit at a front stage. The IC needs the MCU to control the high/low level of the EN port, thereby forming a complete system circuit.
SUMMERY OF THE UTILITY MODEL
The utility model provides an overload/short-circuit protection circuit which comprises a constant current control circuit, a load on-off control circuit, a drive circuit and a voltage reduction and stabilization circuit.
The constant current control circuit is used for limiting the current of the front-end load CN 1; the load on-off control circuit is used for controlling power supply to the rear-end load CN 2; the driving circuit is coupled with the load on-off control circuit and the constant current control circuit and is used for driving the load on-off control circuit; the voltage reduction and stabilization circuit is coupled with the driving circuit and the constant current control circuit and is used for providing working voltage and reference voltage for operational amplifiers on the driving circuit and the constant current control circuit.
In an embodiment, the load on-off control circuit includes a resistor R3, a resistor R4, a resistor R5, a resistor R17, a PMOS transistor Q1, and a transistor Q2, a front end of the resistor R4 is connected to a gate of the PMOS transistor Q1 and a rear end of the resistor R5, a rear end of the resistor R4 is connected to an input terminal of a power supply, a source of the PMOS transistor Q1 and a positive terminal of the rear end load CN2, a drain of the PMOS transistor Q1 is connected to an output terminal of the power supply and a positive terminal of the front end load CN1, a front end of the resistor R5 is connected to a collector of the transistor Q2, a rear end of the resistor R3 is connected to a base of the transistor Q2 and a rear end of the resistor R17, and a front end of the resistor R17 is grounded.
In an embodiment, the driving circuit includes a resistor R6, a resistor R7, a resistor R8, a diode D2, a capacitor C5, and an operational amplifier U1B, a front end of the resistor R6 is connected to a non-inverting input PIN5 of the operational amplifier U1B and a rear end of the resistor R7, a rear end of the resistor R6 is connected to an output PIN7 of the operational amplifier U1B and a front end of the resistor R3, a front end of the resistor R7 is connected to the resistor R8, the diode D2 and a rear end of the capacitor C5, and a front end of the capacitor C5 is grounded.
In an embodiment, the constant current control circuit includes a resistor R9, a resistor R18, a transistor Q3, and an operational amplifier U1A, a front end of the resistor R9 is connected to a base of the transistor Q3, a rear end of the resistor R9 is connected to the resistor R8, a front end of the diode D2, and an output PIN1 of the operational amplifier U1A, a rear end of the resistor R18 is connected to an emitter of the transistor Q3 and an inverting input PIN2 of the operational amplifier U1A, a front end of the resistor R18 is grounded, and a collector of the transistor Q3 is connected to a negative terminal of the front-end load CN 1.
In one embodiment, the buck regulator circuit includes a diode D1, a resistor R10, a resistor R11, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a capacitor C16, and a three-terminal regulator, the front end of the diode D16 is connected to the rear ends of the resistor R16 and the resistor R16, the rear end of the diode D16 is connected to a power source, the front ends of the resistor R16 and the resistor R16 are connected to the rear ends of the capacitor C16, the capacitor C16 and the input port of the three-terminal regulator, the front ends of the capacitor C16 and the capacitor C16 are grounded, the output port of the three-terminal regulator is connected to the output port of the capacitor C16, the resistor R16 and the rear end of the resistor R16, the front ends of the capacitor C16 and the capacitor C16 are grounded, the front end of the resistor R16 is connected to the rear end of the PIN amplifier U6851 of the PIN 16 and the input terminal of the PIN 16, the front end of the resistor R14 is grounded, the front end of the resistor R15 is connected with the rear end of the resistor R16 and the non-inverting input PIN3 of the operational amplifier U1A, and the front end of the resistor R16 is grounded.
In one embodiment, the overload/short-circuit protection circuit further comprises a resistor R1 connected to the positive terminal of the back-end load CN 2.
In one embodiment, the overload/short-circuit protection circuit further comprises a resistor R2 connected to the negative terminal of the back-end load CN 2.
In one embodiment, the voltage reduction and regulation circuit provides a working voltage and a reference voltage VREF1 to the operational amplifier U1A, and provides a working voltage and a reference voltage VREF2 to the operational amplifier U1B.
In one embodiment, the reference voltage VREF1 at the non-inverting input of the operational amplifier U1A is used to control the maximum current of the front-end load CN 1.
The utility model also provides an electronic device comprising the overload/short-circuit protection circuit according to any one of the embodiments.
One advantage of the present invention is to provide an overload/short-circuit protection circuit and an electronic device, in which, by means of the arrangement of a constant current control circuit, a load on-off control circuit, a driving circuit, and a step-down voltage stabilizing circuit, when the output is overloaded, short-circuited or started by a load with a large capacitance, the current output can be limited without using a special IC, so as to protect a rear-end power supply circuit, and the present invention has a low production cost and a wide market application prospect. In addition, a weak positive feedback circuit can be formed by the resistor R6 and the resistor R7, so that the high-level and low-level outputs of the operational amplifier U1B are more stable.
Another advantage of the present invention is to provide an overload/short-circuit protection circuit and an electronic device, which can conveniently adjust the limited current of a load by adjusting the reference voltage VREF 1; by adjusting the reference voltage VREF2, the duty ratio of the on-off of the load can be adjusted, so that the heating of the triode Q3 can be controlled, and the load can be suitable for different load types. In addition, the applicable voltage range of the overload/short-circuit protection circuit and the electronic equipment is wide.
Additional features and advantages of the utility model will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the utility model. The objectives and other advantages of the utility model will be realized and attained by the structure particularly pointed out in the written description and claims hereof.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts; in the following description, the drawings are illustrated in a schematic view, and the drawings are not intended to limit the present invention.
Fig. 1 is a circuit schematic of a prior art overload protection circuit;
fig. 2 is a schematic structural diagram of an overload/short-circuit protection circuit according to an embodiment of the present invention;
fig. 3 is a schematic circuit diagram of an overload/short-circuit protection circuit according to an embodiment of the present invention.
Reference numerals:
10-overload/short-circuit protection circuit; 12-a constant current control circuit; 14-load on-off control circuit; 16-a drive circuit; and 18-voltage reduction and stabilization circuit.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments; the technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other; all other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it is to be understood that the terms "center", "lateral", "up", "down", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations and positional relationships based on those shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or component in question must have a particular orientation or be constructed and operated in a particular orientation, and therefore, should not be taken as limiting the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified. In addition, the term "comprises" and any variations thereof mean "including at least".
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integrally formed connection; can be mechanically or electrically connected; the two components can be directly connected or indirectly connected through an intermediate medium, and the two components can be communicated with each other. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
Referring to fig. 2 and fig. 3, fig. 2 is a schematic structural diagram of an overload/short-circuit protection circuit 10 according to an embodiment of the present invention, and fig. 3 is a schematic diagram of the overload/short-circuit protection circuit 10 according to the embodiment of the present invention. To achieve at least one of the above advantages or other advantages, an embodiment of the present invention provides an overload/short-circuit protection circuit 10, which is applicable to a dc load, such as: the load is used for direct current 12V/24V/36V load. As shown in the figure, the overload/short-circuit protection circuit 10 is coupled to a front-end load CN1 and a back-end load CN2, and the overload/short-circuit protection circuit 10 includes a constant current control circuit 12, a load on-off control circuit 14, a driving circuit 16, and a voltage reduction and stabilization circuit 18.
The constant current control circuit 12 is used for limiting the current of the front-end load CN 1; the load on-off control circuit 14 is used for controlling power supply to the back-end load CN 2; the driving circuit 16 is coupled to the load on-off control circuit 14 and the constant current control circuit 12, and is configured to drive the load on-off control circuit 14; the voltage-reducing and stabilizing circuit 18 is coupled to the driving circuit 16 and the constant current control circuit 12, and is configured to provide an operating voltage and a reference voltage to the operational amplifiers of the driving circuit 16 and the constant current control circuit 12.
Specifically, the load on-off control circuit 14 includes a resistor R3, a resistor R4, a resistor R5, a resistor R17, a PMOS transistor Q1, and a transistor Q2. The connection relationship of the components of the load on-off control circuit 14 is as follows: the rear end of the resistor R4 is connected with the input end of a power supply, the source electrode of the PMOS tube Q1 and the positive end of a rear-end load CN2, the front end of the resistor R4 is connected with the grid electrode of the PMOS tube Q1 and the rear end of the resistor R5, the drain electrode of the PMOS tube Q1 is connected with the output end of the power supply and the positive end of the front-end load CN1, the front end of the resistor R5 is connected with the collector electrode of the triode Q2, the rear end of the resistor R3 is connected with the base electrode of the triode Q2 and the rear end of the resistor R17, and the front end of the resistor R17 is grounded.
The working process of the load on-off control circuit 14 is as follows: when the front end voltage V3 of the resistor R3 is at a high level, the triode Q2 is conducted, the PMOS transistor Q1 is conducted, and a 24V power supply is switched on to supply power to the rear end load CN 2; when the front end voltage V3 of the resistor R3 is at a low level, the triode Q2 is cut off, the PMOS transistor Q1 is turned off, and a 24V power supply is cut off to supply power to a rear end load.
The driving circuit 16 includes a resistor R6, a resistor R7, a resistor R8, a diode D2, a capacitor C5, and an operational amplifier U1B. The connection relationship of the devices of the driving circuit 16 is as follows: the rear end of the resistor R6 is connected with the output end PIN7 of the operational amplifier U1B and the front end of the resistor R3, the front end of the resistor R6 is connected with the non-inverting input end PIN5 of the operational amplifier U1B and the rear end of the resistor R7, the front end of the resistor R7 is connected with the rear ends of the resistor R8, the diode D2 and the capacitor C5, and the front end of the capacitor C5 is grounded.
The operation of the drive circuit 16 is as follows: when the input voltage V1 rises, the input voltage V1 charges the capacitor C5 through the resistor R8, and the voltage of the capacitor C5 rises to make the voltage of the non-inverting input PIN5 of the operational amplifier U1B higher than the voltage of the inverting input PIN2, so that the operational amplifier U1B outputs a high level. When the input voltage V1 decreases, the capacitor C5 voltage discharges quickly through diode D2, and when the voltage of capacitor C5 is low enough that the voltage at the non-inverting input PIN5 of op-amp U1B is lower than the voltage at the inverting input PIN6, the op-amp U1B outputs a low level. In other words, when the driving circuit 16 realizes that V1 is increased, the voltage of the capacitor C5 is charged and slowly increased through the resistor R8 and the RC of the capacitor C5, that is, when V1 is at a high voltage, the driving circuit 16 can delay and drive the load on-off control circuit 14, so that the PMOS transistor Q1 is turned on in a delayed manner; when the voltage of the V1 is reduced, the voltage of the capacitor C5 is rapidly discharged through the diode D2, that is, when the voltage of the V1 is low, the driving circuit 16 can rapidly turn off the PMOS transistor Q1 of the load on-off control circuit 14, so that the power supply of the 24V power supply is rapidly turned off when the load CN2 at the rear end is too large, and a protection effect is achieved. The driving circuit 16 can rapidly turn off the PMOS transistor Q1 when the load is abnormal, turn off the rear end 24V load CN2, and turn off the 24V load CN2 without current, the voltage of V1 will become high, and due to the charging time of RC (resistor R8 and capacitor C5), turn on the PMOS transistor Q1 with a delay. Therefore, when the load is abnormal, the load can be switched off for a long time after being switched on for a short time so as to protect the transistor Q3 on the constant current control circuit 12.
The constant current control circuit 12 includes a resistor R9, a resistor R18, a transistor Q3, and an operational amplifier U1A. The connection relationship of the devices of the constant current control circuit 12 is as follows: the rear end of the resistor R9 is connected with the resistor R8, the front end of the diode D2 and the output end PIN1 of the operational amplifier U1A, the front end of the resistor R9 is connected with the base electrode of the triode Q3, the rear end of the resistor R18 is connected with the emitter electrode of the triode Q3 and the inverting input end PIN2 of the operational amplifier U1A, the front end of the resistor R18 is grounded, and the collector electrode of the triode Q3 is connected with the negative end of the front-end load CN 1. Resistor R18 may be used for load circuit sampling.
The operation of the constant current control circuit 12 is as follows: when the current is increased, the voltage of the resistor R18 is increased until the voltage of the inverting input terminal PIN2 of the operational amplifier U1A is lower than the voltage of the non-inverting input terminal PIN3, the output voltage of the operational amplifier U1A is reduced, so that the triode Q3 enters an amplification state, and finally, the voltage of the non-inverting input terminal PIN3 is consistent with the voltage of the inverting input terminal PIN2, so that the driving voltage of the triode Q3 is balanced. When the output voltage of the operational amplifier U1A decreases, the voltage of the capacitor C5 in the driving circuit 16 is pulled down, so that the operational amplifier U1B outputs a low level, and the PMOS transistor Q1 is turned off, thereby cutting off the 24V back-end load. When the current decreases, the voltage of the resistor R18 decreases, the voltage of the inverting input PIN2 of the operational amplifier U1A is lower than the voltage of the non-inverting input PIN3, and the output voltage of the operational amplifier U1A increases, so that the transistor Q3 enters a saturation state. When the current is normal, that is, the load current is smaller than the limit value, the output high voltage of the operational amplifier U1A drives the load on-off control circuit 14 through the driving circuit 16 to turn on the PMOS transistor Q1, so as to maintain the load CN2 to be continuously powered.
Preferably, the resistor R6 and the resistor R7 form a weak positive feedback circuit, which makes the output of the operational amplifier U1B more stable at high and low levels. The reference voltage VREF1 of the non-inverting input PIN3 of the operational amplifier U1A determines the maximum current of the load.
The voltage-reducing and stabilizing circuit 18 comprises a diode D1, a resistor R10, a resistor R11, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4 and a three-terminal regulator U2. The connection relationship of the components of the voltage reduction and stabilization circuit 18 is as follows: the rear end of a diode D1 is connected with a power supply, the front end of a diode D1 is connected with the rear ends of a resistor R10 and a resistor R11, the front ends of a resistor R10 and a resistor R11 are connected with the rear ends of a capacitor C1, a capacitor C2 and the input port of a three-terminal regulator U2, the front ends of a capacitor C1 and a capacitor C2 are grounded, the output port of a three-terminal regulator U2 is connected with the rear ends of a capacitor C3, a capacitor C4, a resistor R13 and a resistor R15, the front ends of a capacitor C3 and a capacitor C4 are grounded, the front end of a resistor R13 is connected with the rear end of a resistor R14 and the inverting input end PIN6 of an operational amplifier U1B, the front end of a resistor R14 is grounded, the front end of a resistor R15 is connected with the rear end of a resistor R16 and the non-inverting input end 3 of an operational amplifier U1A, and the front end of the resistor R16 is grounded.
The voltage-reducing and stabilizing circuit 18 is used for providing stable power and reference voltages VREF1 and VREF2 for the operational amplifier U1A and the operational amplifier U1B. That is, the voltage-reducing regulator 18 provides the operational voltage and the reference voltage VREF1 to the operational amplifier U1A, and provides the operational voltage and the reference voltage VREF2 to the operational amplifier U1B. The reference voltage VREF1 is used to define the maximum current of the front-end load CN1, i.e., the maximum current that the constant current driver on the constant current control circuit 12 can pass through. When the reference voltage VREF2 is adjusted high, the RC charging voltage increases, so that when the operational amplifier U1A outputs a high voltage, a longer time delay is needed to enable the operational amplifier U1B to output a high level, so as to drive the PMOS transistor Q1 to be turned on. When the operational amplifier U1A outputs a low voltage, the operational amplifier U1B can be made to output a low level more quickly to turn off the PMOS transistor Q1. That is, the increase of the reference voltage VREF2 can reduce the on duty ratio of the PMOS transistor Q1 when the load is abnormal, so that the problem of excessive power consumption of the transistor Q3 when the load is abnormal can be avoided.
The overload/short-circuit protection circuit can further comprise a resistor R1 and a resistor R2, wherein the resistor R1 is connected with the positive end of the back-end load CN2, the resistor R2 is connected with the negative end of the back-end load CN2, and the resistor R1 and the resistor R2 can play an isolation role to reduce the influence of external interference.
Overall, when the front-end load CN1 is normal, the current is within the protection range, the voltage V of the PIN2 port of the operational amplifier U1A is smaller than the reference voltage VREF1, the PIN1 port of the operational amplifier U1A outputs the high level V1, the base voltage of the triode Q3 becomes high, and the triode Q3 is turned on to be always in a saturated conduction state; the voltage V1 charges the capacitor C5 through the resistor R8 synchronously until the voltage V2 is greater than the reference voltage VREF2, and the PIN7 port of the operational amplifier U1B outputs the high level V3, so that the base voltage of the transistor Q2 becomes high, the transistor Q2 is turned on, the transistor Q2 is always in a conducting state, the gate of the PMOS transistor Q1 is input with a low level, and then the PMOS transistor Q1 is turned on, so that the front-end load CN1 is always in a conducting state, and the front-end load CN1 is ensured to be in a normal working state.
When the front-end load CN1 has a short circuit or an overcurrent abnormal working condition, after the current flows through the constant current control circuit 12, the transistor Q3 is in an amplification state, the current is limited to I ═ VREF1/R18, so that the transistor Q3 bears most of the dissipated power P ═ 24V ═ I, and the resistor R18 shares a small part. In order to solve the problem of power dissipation of the triode Q3, an overload and short-circuit protection turn-off circuit formed by an operational amplifier U1B, a triode Q2, a capacitor C5, a diode D2, a resistor R8, a PMOS (P-channel metal oxide semiconductor) transistor Q1 and the like is added, so that the power loss of the triode Q3 is reduced.
The specific working process is as follows: after the protection state is entered, the voltage V of the PIN2 port of the operational amplifier U1A is greater than VREF1, the output voltage V1 of the PIN1 port of the operational amplifier U1A becomes low level, the voltage V2 at two ends of the capacitor C5 discharges to V1 through the diode D2, when the voltage of the PIN5 port of the operational amplifier U1B is less than VREF2, the output voltage V3 of the PIN7 port of the operational amplifier U1B is low level, the resistor R6 and the resistor R7 form positive feedback to enable the output of V3 to be stable low level, the base voltage of the triode Q2 is low, the triode Q2 is closed and is always in a cut-off state, the gate input of the PMOS transistor Q1 is high level, the PMOS transistor Q1 is closed, and the voltage input of +24V is cut off. With the cut-off of the +24V voltage, the PIN2 voltage V of the operational amplifier U1A changes from high to low and V < VREF1, then the PIN1 port of the operational amplifier U1A outputs a voltage V1 which becomes high level, C5 is charged through the resistor R8, the voltage is V2, and after the voltage V2> VREF2, the PIN7 port of the operational amplifier U1B outputs a high level V3, the resistor R6 and the resistor R7 form positive feedback to make the V3 output a stable high level, the base voltage of the transistor Q2 becomes high, the transistor Q2 is opened to be in a conducting state, so that the gate input of the PMOS transistor Q1 is low level, and then the PMOS transistor Q1 is opened to be in a conducting state.
Specifically, if the fault of the front-end load CN1 is not cleared, the PMOS transistor Q1 and the triode Q3 of the whole circuit loop are always in an on-off cycle state, and the normal operating state can be automatically recovered until the fault of the load CN1 is cleared. In addition, the present embodiment is illustrated by being applied to a 24V load, and is not intended to limit the utility model.
The present embodiment also provides an electronic device, which includes the overload/short-circuit protection circuit 10 according to any one of the above embodiments.
One advantage of the present invention is to provide an overload/short-circuit protection circuit 10 and an electronic device, in which, through the matching arrangement of the constant current control circuit 12, the load on-off control circuit 14, the driving circuit 16 and the voltage reduction and voltage stabilization circuit 18, when the output is overloaded, short-circuited or started by a load with a large capacitance, etc., the current output can be limited without using a special IC, so as to protect the rear-end power supply circuit, and the present invention has a low production cost and a wide market application prospect. In addition, a weak positive feedback circuit can be formed by the resistor R6 and the resistor R7, so that the high-level and low-level outputs of the operational amplifier U1B are more stable.
Another advantage of the present invention is to provide an overload/short-circuit protection circuit 10 and an electronic device, which can conveniently adjust the limited current of the front-end load CN1 by adjusting the reference voltage VREF 1; by adjusting the reference voltage VREF2, the duty ratio of the on-off of the rear-end load CN2 can be adjusted, so that the heat generation of the triode Q3 can be controlled, and the method can be applied to different load types. In addition, the overload/short-circuit protection circuit 10 and the electronic device have a wide applicable voltage range.
In addition, it will be appreciated by those skilled in the art that, although there may be many problems with the prior art, each embodiment or aspect of the present invention may be improved only in one or several respects, without necessarily simultaneously solving all the technical problems listed in the prior art or in the background. It will be understood by those skilled in the art that nothing in a claim should be taken as a limitation on that claim.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the utility model has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. An overload/short-circuit protection circuit, coupled to a front-end load CN1 and a back-end load CN2, comprising: the overload/short-circuit protection circuit includes:
the constant current control circuit is used for limiting the current of the front-end load CN 1;
the load on-off control circuit is used for controlling power supply to the rear-end load CN 2;
the driving circuit is coupled with the load on-off control circuit and the constant current control circuit and is used for driving the load on-off control circuit;
and the voltage reduction and stabilization circuit is coupled with the driving circuit and the constant current control circuit and is used for providing working voltage and reference voltage for operational amplifiers on the driving circuit and the constant current control circuit.
2. The overload/short-circuit protection circuit of claim 1, wherein: the load on-off control circuit comprises a resistor R3, a resistor R4, a resistor R5, a resistor R17, a PMOS tube Q1 and a triode Q2, wherein the rear end of the resistor R4 is connected with the input end of a power supply, the source of the PMOS tube Q1 and the positive end of a rear-end load CN2, the front end of the resistor R4 is connected with the grid of the PMOS tube Q1 and the rear end of the resistor R5, the drain of the PMOS tube Q1 is connected with the output end of the power supply and the positive end of the front-end load CN1, the front end of the resistor R5 is connected with the collector of the triode Q2, the rear end of the resistor R3 is connected with the base of the triode Q2 and the rear end of the resistor R17, and the front end of the resistor R17 is grounded.
3. The overload/short-circuit protection circuit of claim 2, wherein: the driving circuit comprises a resistor R6, a resistor R7, a resistor R8, a diode D2, a capacitor C5 and an operational amplifier U1B, wherein the rear end of the resistor R6 is connected with an output end PIN7 of the operational amplifier U1B and the front end of the resistor R3, the front end of the resistor R6 is connected with a non-inverting input end PIN5 of the operational amplifier U1B and the rear end of the resistor R7, the front end of the resistor R7 is connected with the rear ends of the resistor R8, the diode D2 and the capacitor C5, and the front end of the capacitor C5 is grounded.
4. The overload/short-circuit protection circuit of claim 3, wherein: the constant current control circuit comprises a resistor R9, a resistor R18, a triode Q3 and an operational amplifier U1A, wherein the rear end of the resistor R9 is connected with the resistor R8, the front end of the diode D2 and an output end PIN1 of the operational amplifier U1A, the front end of the resistor R9 is connected with the base electrode of the triode Q3, the rear end of the resistor R18 is connected with the emitter electrode of the triode Q3 and an inverting input end PIN2 of the operational amplifier U1A, the front end of the resistor R18 is grounded, and the collector electrode of the triode Q3 is connected with the negative end of the front-end load CN 1.
5. The overload/short-circuit protection circuit of claim 4, wherein: the buck voltage stabilizing circuit comprises a diode D1, a resistor R10, a resistor R11, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a capacitor C16 and a three-terminal voltage stabilizing regulator, wherein the rear end of the diode D16 is connected with a power supply, the front end of the diode D16 is connected with the rear ends of the resistor R16 and the resistor R16, the front ends of the resistor R16 and the resistor R16 are connected with the rear ends of the capacitor C16, the capacitor C16 and the input port of the three-terminal voltage stabilizing regulator, the front ends of the capacitor C16 and the capacitor C16 are grounded, the output port of the three-terminal voltage stabilizing regulator is connected with the capacitor C16, the resistor R16 and the rear end of the resistor R16, the front end of the capacitor C16 and the capacitor C16 are grounded, the front end of the resistor R16 is connected with the rear end of the PIN 16 of the operational amplifier U6851 of the PIN 16, the front end of the resistor R14 is grounded, the front end of the resistor R15 is connected with the rear end of the resistor R16 and the non-inverting input PIN3 of the operational amplifier U1A, and the front end of the resistor R16 is grounded.
6. The overload/short-circuit protection circuit of claim 5, wherein: the overload/short-circuit protection circuit also comprises a resistor R1 connected with the positive terminal of the rear-end load CN 2.
7. The overload/short-circuit protection circuit of claim 5, wherein: the overload/short-circuit protection circuit also comprises a resistor R2 connected with the negative terminal of the rear-end load CN 2.
8. The overload/short-circuit protection circuit of claim 5, wherein: the voltage reduction and stabilization circuit provides a working voltage and a reference voltage VREF1 for the operational amplifier U1A, and provides a working voltage and a reference voltage VREF2 for the operational amplifier U1B.
9. The overload/short-circuit protection circuit of claim 5, wherein: the reference voltage VREF1 at the non-inverting input of the operational amplifier U1A is used to control the maximum current of the front-end load CN 1.
10. An electronic device, characterized in that: the electronic device includes: an overload/short-circuit protection circuit according to any one of claims 1 to 9.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116365902A (en) * | 2023-05-29 | 2023-06-30 | 深圳市英能达电子有限公司 | Switching power supply circuit topology |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116365902A (en) * | 2023-05-29 | 2023-06-30 | 深圳市英能达电子有限公司 | Switching power supply circuit topology |
| CN116365902B (en) * | 2023-05-29 | 2023-08-11 | 深圳市英能达电子有限公司 | Switching power supply circuit topology |
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