CN112242692A - Overcurrent protection circuit and power supply circuit - Google Patents
Overcurrent protection circuit and power supply circuit Download PDFInfo
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- CN112242692A CN112242692A CN201910651496.1A CN201910651496A CN112242692A CN 112242692 A CN112242692 A CN 112242692A CN 201910651496 A CN201910651496 A CN 201910651496A CN 112242692 A CN112242692 A CN 112242692A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
- H02H7/1213—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for DC-DC converters
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Abstract
The invention discloses an overcurrent protection circuit and a power supply circuit, comprising: the device comprises a first voltage stabilizing module, a second voltage stabilizing module, a control module and a switch module; the input end of the first voltage stabilizing module is respectively connected with the power signal providing end and the input end of the switch module, the output end of the first voltage stabilizing module is connected with the first input end of the control module, and the grounding end of the first voltage stabilizing module is grounded; the first input end of the second voltage stabilizing module is connected with the power signal output end; the second input end of the second voltage stabilizing module is connected with the output end of the power supply control circuit; the output end of the second voltage stabilizing module is connected with the second input end of the control module, and the grounding end of the second voltage stabilizing module is grounded; the output end of the control module is connected with the control end of the switch module; the output end of the switch module is connected with the input end of the power supply control circuit, and the grounding end of the switch module is grounded. The overcurrent protection circuit provided by the embodiment of the invention realizes the effect of effectively protecting the power supply circuit.
Description
Technical Field
The embodiment of the invention relates to the technical field of protection, in particular to an overcurrent protection circuit and a power supply circuit.
Background
The power supply circuit is a circuit for supplying power to a switching circuit or a voltage step-down device. With the rapid development of power electronic technology, electronic devices are increasingly closely related to the work and life of people, and the electronic devices cannot be separated from reliable power supply circuits.
Fig. 1 is a circuit diagram of a power supply circuit in the prior art, and referring to fig. 1, a first voltage input by a signal input terminal Vin 'is converted into a second voltage after being processed by a power supply control circuit 50', and the second voltage is output by a signal output terminal Vout ', so as to provide the second voltage for an electronic device connected to the signal output terminal Vout'.
However, in the practical use process of the power circuit, the short circuit at the signal output terminal Vout 'often affects the circuit connected to the signal input terminal Vin', and the power circuit is seriously damaged.
Disclosure of Invention
The invention provides an overcurrent protection circuit and a power supply circuit, which are used for protecting the power supply circuit.
In a first aspect, an embodiment of the present invention provides an overcurrent protection circuit, where the overcurrent protection circuit includes: the device comprises a first voltage stabilizing module, a second voltage stabilizing module, a control module and a switch module;
the input end of the first voltage stabilizing module is respectively connected with a power signal providing end and the input end of the switch module, the output end of the first voltage stabilizing module is connected with the first input end of the control module, and the grounding end of the first voltage stabilizing module is grounded;
the first input end of the second voltage stabilizing module is connected with the power signal output end; a second input end of the second voltage stabilizing module is connected with an output end of the power supply control circuit; the output end of the second voltage stabilizing module is connected with the second input end of the control module, and the grounding end of the second voltage stabilizing module is grounded;
the output end of the control module is connected with the control end of the switch module;
the output end of the switch module is connected with the input end of the power supply control circuit, and the grounding end of the switch module is grounded;
when the power signal providing end provides a power signal, the first voltage stabilizing module is used for converting the power signal into a first voltage stabilizing signal and then sending the first voltage stabilizing signal to the control module; the control module is used for outputting a first control signal through an output end of the control module according to the first voltage stabilizing signal; the switch module is switched on according to the first control signal, and the power supply signal provided by the power supply signal providing end is sent to the power supply control circuit through the switch module, so that the power supply control circuit processes the power supply signal and then outputs the processed power supply signal from the output end of the power supply control circuit;
when the current at the output end of the power supply signal is larger than a preset value, the second voltage stabilizing module is used for sending a second voltage stabilizing signal to the control module according to the current at the output end of the power supply signal; the control module is further configured to output a second control signal through an output terminal of the control module according to the second voltage stabilization signal, so that the switch module is turned off according to the second control signal.
Optionally, the overcurrent protection circuit further includes: a soft start reset module; the first end of the soft start reset module is connected with the enabling end of the power control circuit, the control end of the soft start reset module is connected with the output end of the control module, and the second end of the soft start reset module is grounded;
the soft start reset module is used for pulling down the voltage at the enabling end of the power control circuit to the ground potential when the signal output by the output end of the control module is a second control signal, so that the power control circuit is reset and restarted.
Optionally, the switch module includes a first switch unit and a second switch unit;
the control end of the first switch unit is connected with the output end of the control module, the input end of the first switch unit is connected with the control end of the second switch unit, and the output end of the first switch unit is grounded;
the input end of the second switch unit is connected with the power supply signal providing end, and the output end of the second switch unit is connected with the input end of the power supply control circuit.
Optionally, the first voltage stabilizing module includes: the voltage regulator comprises a voltage regulator tube, a first resistor, a second resistor, a third resistor, a fourth resistor and a first capacitor;
the first end of the first resistor is connected with the power signal providing end, and the second end of the first resistor is respectively connected with the cathode of the voltage regulator tube, the first end of the second resistor, the first end of the first capacitor and the first end of the fourth resistor;
the anode of the voltage stabilizing tube is grounded;
a second end of the second resistor is connected with the input end of the first switch unit and the control end of the second switch unit respectively;
the first end of the third resistor is grounded, and the second end of the third resistor is respectively connected with the second end of the fourth resistor and the first input end of the control module;
the second end of the first capacitor is grounded.
Optionally, the first switch unit includes an N-type transistor; the second switching unit includes a P-type transistor; alternatively, the first and second electrodes may be,
the first switching unit includes a P-type transistor; the second switching unit includes an N-type transistor.
The second voltage stabilization module includes: a fifth resistor, a sixth resistor and a seventh resistor;
the first end of the fifth resistor is connected with the power supply signal output end, and the second end of the fifth resistor is connected with the first end of the sixth resistor;
the second end of the sixth resistor is respectively connected with the first end of the seventh resistor and the second input end of the control module;
and the second end of the seventh resistor is grounded.
Optionally, the resistance of the fifth resistor is R, and R is greater than or equal to 10m Ω and less than or equal to 100m Ω.
The soft start reset module comprises: an eighth resistor and a third switching unit;
a first end of the eighth resistor is connected with an enable end of the power control circuit, and a second end of the eighth resistor is connected with an input end of the third switching unit;
the control end of the third switch unit is connected with the output end of the control module, and the output end of the third switch unit is grounded.
Optionally, the control module includes: a voltage comparator;
the positive input end of the voltage comparator is connected with the output end of the first voltage stabilizing module, the negative input end of the voltage comparator is connected with the output end of the second voltage stabilizing module, and the output end of the voltage comparator is connected with the control end of the switch module.
In a second aspect, an embodiment of the present invention further provides a power supply circuit, where the power supply circuit includes: the overcurrent protection circuit of the first aspect.
The overcurrent protection circuit provided by the embodiment of the invention comprises: the input end of the first voltage stabilizing module is respectively connected with the power signal providing end and the input end of the switch module, the output end of the first voltage stabilizing module is connected with the first input end of the control module, and the grounding end of the first voltage stabilizing module is grounded; the first input end of the second voltage stabilizing module is connected with the power signal output end; the second input end of the second voltage stabilizing module is connected with the output end of the power supply control circuit; the output end of the second voltage stabilizing module is connected with the second input end of the control module, and the grounding end of the second voltage stabilizing module is grounded; the output end of the control module is connected with the control end of the switch module; the output end of the switch module is connected with the input end of the power supply control circuit, and the grounding end of the switch module is grounded, so that when the current at the power supply signal output end is normal, a power supply signal provided by the power supply signal providing end is input into the power supply control circuit through the switch module, so that the power supply control circuit outputs the processed power supply signal from the power supply signal output end and provides power supply for a post-stage circuit connected with the power supply signal output end; when short circuit appears at the power signal output end, the second voltage stabilizing module controls the switch module to be switched off through the control module, so that when the short circuit appears at the power signal output end, the short circuit signal influences a preceding stage circuit connected with the power signal input end, the preceding stage circuit is effectively protected, and the preceding stage circuit is not influenced by the short circuit of the following stage circuit. The problem of among the prior art because power signal output end department short circuit causes the influence to the circuit that power signal input end connects, serious can cause power supply circuit's damage is solved, the effect of realization protection power supply circuit.
Drawings
FIG. 1 is a circuit diagram of a prior art power supply circuit;
fig. 2 is a schematic structural diagram of an overcurrent protection circuit according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of another over-current protection circuit provided in an embodiment of the present invention;
fig. 4 is a schematic structural diagram of another over-current protection circuit provided in the embodiment of the present invention;
fig. 5 is a schematic structural diagram of a power supply circuit according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Fig. 2 is a schematic structural diagram of an overcurrent protection circuit according to an embodiment of the present invention, and referring to fig. 2, the overcurrent protection circuit includes: a first voltage stabilization module 10, a second voltage stabilization module 20, a control module 30, and a switch module 40; the input end of the first voltage stabilizing module 10 is connected to the power signal providing end Vin and the input end of the switch module 40, respectively, the output end of the first voltage stabilizing module 10 is connected to the first input end of the control module 30, and the ground end of the first voltage stabilizing module 10 is grounded; a first input end of the second voltage stabilization module 20 is connected with a power signal output end Vout; a second input end of the second voltage stabilizing module 20 is connected with an output end of the power control circuit 50; the output end of the second voltage stabilizing module 20 is connected with the second input end of the control module 30, and the ground end of the second voltage stabilizing module 20 is grounded; the output end of the control module 30 is connected with the control end of the switch module 40; the output end of the switch module 40 is connected with the input end of the power control circuit 50, and the grounding end of the switch module 40 is grounded; when the power signal providing terminal Vin provides a power signal, the first voltage stabilizing module 10 is configured to convert the power signal into a first voltage stabilizing signal and send the first voltage stabilizing signal to the control module 30; the control module 30 is configured to output a first control signal through an output end of the control module 30 according to the first voltage stabilization signal; the switch module 40 is turned on according to the first control signal, and the power signal provided by the power signal providing terminal Vin is sent to the power control circuit 50 through the switch module 40, so that the power control circuit 50 processes the power signal and outputs the processed power signal from the output terminal of the power control circuit 50; when the current at the power signal output terminal Vout is greater than the preset value, the second voltage stabilization module 20 is configured to convert the voltage at the power signal output terminal Vout into a second stabilized voltage signal and send the second stabilized voltage signal to the control module 30; the control module 30 is further configured to output a second control signal through an output terminal of the control module 30 according to the second regulated signal, so that the switch module 40 is turned off according to the second control signal.
The overcurrent protection circuit can be applied to a power supply circuit, for example, to perform overcurrent protection on the power supply circuit. The power supply circuit may include, for example, a power supply control circuit, and the power supply control circuit may process a power supply signal input thereto, and then supply power to a subsequent stage circuit connected to an output terminal of the power supply control circuit by the processed power supply signal. The power control circuit can comprise a power controller, an MOS (metal oxide semiconductor) tube, an inductor, a capacitor and the like, for example, a power signal is input through the input end of the power control circuit, so that the power controller controls the MOS tube to be turned on or off according to the power signal to realize the processing of the power signal, and power is supplied to a rear-stage circuit connected to the output end of the power control circuit. In the prior art, an overcurrent detection unit is generally used for detecting the current at the output end of a power supply control circuit, and when the current at the output end of the power supply control circuit is greater than a current preset value set in the overcurrent detection unit, a preceding stage circuit connected with the input end of the power supply control circuit is protected by switching off the output of a power supply controller and further switching off an MOS transistor. However, if the instantaneous overcurrent at the output end of the power supply control circuit is large, the MOS transistor of the voltage chopper is instantaneously broken down, and the instantaneous current of the subsequent power supply cannot be cut off only by switching off the output of the power supply controller, so that the power supply circuit is damaged, and the power supply circuit cannot be effectively protected. The overcurrent protection circuit adopted by the embodiment can quickly cut off the switch module, and effectively protects the front-stage circuit from being influenced by the rear-stage short circuit.
Specifically, referring to fig. 2, when the current at the power signal output terminal Vout is normal, the power signal providing terminal Vin inputs the power signal, and the first voltage stabilizing module 10 converts the power signal into a first voltage stabilizing signal and sends the first voltage stabilizing signal to the control module 30. When the control module 30 receives the first voltage-stabilizing signal, it outputs a first control signal through its output terminal according to the first voltage-stabilizing signal, so that the switch module 40 is turned on according to the first control signal. At this time, the power signal provided by the power signal providing terminal Vin reaches the power control circuit 50 through the switch module 40. The power control circuit 50 processes the power signal and outputs the processed power signal from the output terminal of the power control circuit 50, for example, the power control circuit 50 may step down the power signal, and the power signal is stepped down by the power control circuit 50, and then output from the power signal output terminal Vout after passing through the second voltage stabilizing module 20, so as to supply power to the subsequent circuit connected to the power signal output terminal Vout. When the current at the power signal output terminal Vout is greater than a preset value, for example, a short circuit occurs at the power signal output terminal Vout, the second voltage stabilizing module 20 converts the current at the power signal output terminal Vout into a second voltage stabilizing signal and sends the second voltage stabilizing signal to the control module 30; the control module 30 outputs a second control signal through the output terminal of the control module 30 according to the second voltage-stabilizing signal, so that the switch module 40 is turned off according to the second control signal, and when a short circuit occurs at the power signal output terminal Vout, the short circuit signal affects a preceding stage circuit connected to the power signal input terminal Vin, thereby effectively protecting the preceding stage circuit from the short circuit of the following stage circuit.
The overcurrent protection circuit provided by the embodiment of the invention comprises: the input end of the first voltage stabilizing module is respectively connected with the power signal providing end and the input end of the switch module, the output end of the first voltage stabilizing module is connected with the first input end of the control module, and the grounding end of the first voltage stabilizing module is grounded; the first input end of the second voltage stabilizing module is connected with the power signal output end; the second input end of the second voltage stabilizing module is connected with the output end of the power supply control circuit; the output end of the second voltage stabilizing module is connected with the second input end of the control module, and the grounding end of the second voltage stabilizing module is grounded; the output end of the control module is connected with the control end of the switch module; the output end of the switch module is connected with the input end of the power supply control circuit, and the grounding end of the switch module is grounded, so that when the current at the power supply signal output end is normal, a power supply signal provided by the power supply signal providing end is input into the power supply control circuit through the switch module, so that the power supply control circuit outputs the processed power supply signal from the power supply signal output end and provides power supply for a post-stage circuit connected with the power supply signal output end; when short circuit appears at the power signal output end, the second voltage stabilizing module controls the switch module to be switched off through the control module, so that when the short circuit appears at the power signal output end, the short circuit signal influences a preceding stage circuit connected with the power signal input end, the preceding stage circuit is effectively protected, and the preceding stage circuit is not influenced by the short circuit of the following stage circuit. The problem of among the prior art because power signal output end department short circuit causes the influence to the circuit that power signal input end connects, serious can cause power supply circuit's damage is solved, the effect of realization protection power supply circuit.
On the basis of the above technical solution, optionally, fig. 3 is a schematic structural diagram of an overcurrent protection circuit provided in an embodiment of the present invention, and referring to fig. 3, the overcurrent protection circuit further includes: a soft start reset module 60; a first end of the soft start reset module 60 is connected with an enabling end of the power control circuit 50, a control end of the soft start reset module 60 is connected with an output end of the control module 30, and a second end of the soft start reset module 60 is grounded; the soft-start reset module 60 is configured to pull down the voltage at the enable terminal of the power control circuit 50 to the ground potential when the signal output by the output terminal of the control module 30 is the second control signal, so as to reset and restart the power control circuit 50.
If the instantaneous overcurrent at the output end of the power supply control circuit is larger, the MOS tube of the voltage chopping is instantaneously broken down, the output of the power supply controller is only cut off, so that the instantaneous current of the rear-stage power supply cannot be cut off, and even if the MOS tube is not broken down, the power supply controller loses the soft start effect of the output voltage because the front-stage input power supply is not cut off after the short circuit of the rear-stage circuit disappears. Therefore, according to the technical scheme, the preceding-stage circuit is effectively protected, the power supply control circuit can be rapidly restarted after the short circuit phenomenon disappears on the basis that the preceding-stage circuit is not influenced by the short circuit of the subsequent-stage circuit, and the power supply control circuit is rapidly restarted so as to work again.
For example, when the current at the power signal output terminal Vout is greater than a preset value, for example, a short circuit occurs at the power signal output terminal Vout, the second voltage regulation module 20 converts the current at the power signal output terminal Vout into a second voltage regulation signal and sends the second voltage regulation signal to the control module 30; the control module 30 outputs a second control signal through the output terminal of the control module 30 according to the second voltage-stabilizing signal, so that the switch module 40 is turned off according to the second control signal, and the short-circuit signal is prevented from affecting the preceding stage circuit connected to the power signal input terminal Vin when the short-circuit occurs at the power signal output terminal Vout. Meanwhile, since the control terminal of the soft-start reset module 60 is connected to the output terminal of the control module 30, when the signal output by the output terminal of the control module 30 is the second control signal, the soft-start reset module 60 may pull down the voltage at the enable terminal of the power control circuit 50 to the ground potential according to the second control signal. Therefore, after the short circuit phenomenon at the power signal output end Vout disappears, the power control circuit 50 can be quickly reset and restarted, and the power control circuit 50 can work normally again.
According to the technical scheme, when the short circuit phenomenon occurs at the output end of the power supply signal, the voltage at the enabling end of the power supply control circuit is pulled down to the grounding potential through the soft start reset module, so that the power supply control circuit is reset and restarted, and the power supply control circuit can work normally again.
On the basis of the above technical solution, optionally, fig. 4 is a schematic structural diagram of an overcurrent protection circuit provided in an embodiment of the present invention, and referring to fig. 4, a switch module 40 includes a first switch unit T1 and a second switch unit T2; the control end of the first switch unit T1 is connected with the output end of the control module 30, the input end of the first switch unit T1 is connected with the control end of the second switch unit T2, and the output end of the first switch unit T1 is grounded; an input terminal of the second switch unit T2 is connected to the power signal providing terminal Vin, and an output terminal of the second switch unit T2 is connected to an input terminal of the power control circuit 50.
Here, the first and second switching units T1 and T2 may be different types of transistors, for example. Illustratively, the first switching unit T1 may include, for example, an N-type transistor; the second switching unit T2 may include, for example, a P-type transistor; alternatively, the first switching unit T1 may include, for example, a P-type transistor; the second switching unit T2 may include, for example, an N-type transistor. Fig. 4 is exemplarily illustrated only in that the first switching unit T1 includes an N-type transistor and the second switching unit T2 includes a P-type transistor.
It should be noted that the present embodiment does not specifically limit the types of the first switch unit T1 and the second switch unit T2, as long as the first switch unit T1 and the second switch unit T2 can be turned on or off according to the control signal output by the control module, so that the power signal input from the power signal providing terminal Vin is normally output when the current at the power signal output terminal Vout is normal, and the first-stage circuit is protected from the short circuit of the second-stage circuit when the current at the power signal output terminal Vout is abnormal.
On the basis of the above technical solution, optionally, with continued reference to fig. 4, the first voltage stabilization module 10 includes: a voltage regulator tube D, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4 and a first capacitor C1; a first end of the first resistor R1 is connected with the power signal providing end Vin, and a second end of the first resistor R1 is respectively connected with a cathode of the voltage regulator tube D, a first end of the second resistor R2, a first end of the first capacitor C1 and a first end of the fourth resistor R4; the anode of the voltage-stabilizing tube D is grounded; a second end of the second resistor R2 is connected to the input end of the first switch unit T1 and the control end of the second switch unit T2, respectively; a first end of the third resistor R3 is grounded, and a second end of the third resistor R3 is connected to a second end of the fourth resistor R4 and a first input end of the control module 30; the second terminal of the first capacitor C1 is set to ground.
The first resistor R1 includes a current-limiting resistor, and when the voltage provided by the power signal providing terminal Vin is large, the current is limited by the first resistor R1, so that the voltage regulator tube D is prevented from being damaged by large current. The voltage regulator tube D stabilizes the voltage provided by the power signal providing terminal Vin at a constant value, and prevents the control module 30 from being damaged by a large voltage. The first capacitor C1 further stabilizes the voltage provided by the power signal terminal Vin at a constant value, preventing the control module 30 from being damaged by a larger voltage. The second resistor R2 is used for dividing voltage, and when the first switch unit T1 is turned on, if the second resistor R2 is not provided, the cathode voltage of the zener diode D is the ground voltage. The third resistor R3 and the fourth resistor R4 comprise adjustable resistors, and the voltage of the first input terminal of the control module can be controlled by adjusting the resistance values of the third resistor R3 and the fourth resistor R4, so that the control module can output a first control signal according to the voltage of the first input terminal.
On the basis of the above technical solution, optionally, with continued reference to fig. 4, the second voltage stabilization module 20 includes: a fifth resistor R5, a sixth resistor R6 and a seventh resistor R7; a first end of the fifth resistor R5 is connected with the power supply signal output end Vout, and a second end of the fifth resistor R5 is connected with a first end of the sixth resistor R6; a second end of the sixth resistor R6 is connected to a first end of the seventh resistor R7 and a second input end of the control module 30, respectively; the second end of the seventh resistor R7 is connected to ground.
Referring to fig. 4, the power control module 50 includes a power controller 50, a first feedback resistor R9, a second feedback resistor R10, a second capacitor C2, an inductor L, a first MOS transistor T4, a second MOS transistor T5, and a third capacitor C3. A first end of the fifth resistor R5 is connected to the power signal output terminal Vout and the first end of the first feedback resistor R9, respectively, and a second end of the fifth resistor R5 is connected to the first end of the sixth resistor R6, the first end of the inductor L, and the first end of the third capacitor C3, respectively; a second end of the sixth resistor R6 is connected to a first end of the seventh resistor R7 and a second input end of the control module 30, respectively; the second end of the seventh resistor R7 is connected to ground.
Illustratively, when the power signal output terminal Vout is short-circuited, the voltage at the first end of the fifth resistor R5 does not change immediately, and the current at the first end of the fifth resistor R5 is large. When the current at the first end of the fifth resistor R5 is large, the voltage at the second end of the fifth resistor R5 becomes high, and is divided by the sixth resistor R6 and the seventh resistor R7 and then sent to the second input end of the control module 30. The control module 30 outputs a second control signal through the output terminal of the control module 30 according to the voltage signal at this time, so that the switch module 40 is turned off according to the second control signal, and the short circuit signal is prevented from affecting the front stage circuit connected to the power signal input terminal Vin when the power signal output terminal Vout is short-circuited. Meanwhile, the first feedback resistor R9 and the second feedback resistor R10 of the power control module 50 convert the large current signal of the power signal output terminal Vout into a voltage signal and feed the voltage signal back to the power controller 50, so that the power controller 50 controls the first MOS transistor T4 and the second MOS transistor T5 to be turned on or off.
On the basis of the technical scheme, optionally, the resistance value of the fifth resistor R5 is R, and R is larger than or equal to 10m omega and smaller than or equal to 100m omega.
The fifth resistor R5 may include a precise milliohm resistor, for example, having a resistance R, 10m Ω ≦ R ≦ 100m Ω. When a short circuit occurs at the power signal output end Vout, the fifth resistor R5, which is a precise milliohm resistor, can quickly raise the voltage at the second end, at this time, the raised voltage enters the control module 30 after being divided by the sixth resistor R6 and the seventh resistor R7, the control module 30 outputs a second control signal through the output end of the control module 30 according to the voltage signal at this time, so that the switch module 40 is disconnected according to the second control signal, and when a short circuit occurs at the power signal output end Vout, the short circuit signal affects the front-stage circuit connected to the power signal input end Vin.
Based on the above technical solution, optionally, with reference to fig. 4, the soft start reset module 60 includes: an eighth resistor R8 and a third switching unit T3; a first terminal of the eighth resistor R8 is connected to an enable terminal of the power control circuit 50, and a second terminal of the eighth resistor R8 is connected to an input terminal of the third switching unit T3; a control terminal of the third switching unit T3 is connected to an output terminal of the control module 30, and an output terminal of the third switching unit T3 is grounded.
The third switching unit T3 may include a transistor or a MOS transistor, for example.
Specifically, the soft-start reset module 60 uses the control signal outputted from the output terminal of the control module 30 as a switching signal, and turns on or off the third switching unit T3 according to the outputted control signal, and when the third switching unit T3 is turned on, the soft-start reset module 60 performs a reset function on the power control circuit by rapidly discharging the capacitor C2.
On the basis of the above technical solution, optionally, with continued reference to fig. 4, the control module 30 includes: a voltage comparator; the positive input end of the voltage comparator is connected with the output end of the first voltage stabilizing module 10, the negative input end of the voltage comparator is connected with the output end of the second voltage stabilizing module 20, and the output end of the voltage comparator is connected with the control end of the switch module 40.
When the control module 30 is a voltage comparator, the accurate over-current point design can be performed by adjusting the resistances of the sixth resistor R6 and the seventh resistor R7, and the resistances of the third resistor R3 and the fourth resistor R4, so that the power circuit is protected in a targeted manner, the current at the power signal output end Vout is prevented from affecting a front-stage circuit connected to the power signal input end Vin, the front-stage circuit is effectively protected, and the front-stage circuit is not affected by a rear-stage circuit.
For understanding, the following description exemplarily shows the whole protection process of the over-current protection circuit, but does not limit the present application.
With reference to fig. 4, when the power supply at the power signal input terminal Vin is powered on, the voltage regulator D generates a stable voltage after being divided by the first resistor R1, so as to provide a forward voltage input to the positive input terminal of the voltage comparator. At this time, since the power controller 51 in the power control circuit 50 does not operate normally, the negative input terminal of the voltage comparator does not input, and the voltage comparator outputs a high level. After the voltage comparator outputs a high level, the first switch unit T1 is turned on, and at this time, the base of the second switch unit T2 is pulled to the ground, because the second switch unit T2 is a PMOS transistor, at this time, the second switch unit T2 is turned on, the voltage input at the power signal input terminal Vin is powered on by the power controller 50, the power control circuit 50 starts to work and sequentially outputs the voltage through the fifth resistor R5 of the second voltage stabilizing module 20 and the power signal output terminal Vout, and because the resistance of the fifth resistor R5 is very small, the power loss is very small at this time, and the voltage signal output by the power signal output terminal Vout is not affected. When a short circuit occurs at the power signal output terminal Vout, the voltage at the second terminal of the fifth resistor R5, which is a precision resistor, is raised, and the raised voltage enters the negative input terminal of the voltage comparator through the voltage dividing resistor set by R6 and R7, and when the voltage at the negative input terminal of the voltage comparator exceeds the voltage at the positive input terminal, the voltage comparator outputs a low level, and at this time, the first switch unit T1 (N-type transistor) is turned off, because fig. 4 exemplarily shows that the second switch unit T2 is a PMOS transistor, the source of the second switch unit T2 is raised, the second switch unit T2 is turned off, and the input power at the power signal input terminal Vin is cut off. The voltage comparator outputs low level and simultaneously makes the emitter and the collector of the third switching unit T3 conductive, and the soft start second capacitor C2 quickly drains the voltage through the eighth resistor R8. When the short circuit at the power signal output terminal Vout disappears, the soft-start reset module 60 is reset and can work normally again.
The embodiment of the invention also provides a power supply circuit, and fig. 5 is a schematic structural diagram of the power supply circuit provided by the embodiment of the invention. As shown in fig. 5, the power circuit 200 includes the over-current protection circuit 100 in the above embodiment, so that the power circuit 200 provided in the embodiment of the present invention also has the beneficial effects described in the above embodiment, and further description is omitted here.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (10)
1. An overcurrent protection circuit, comprising: the device comprises a first voltage stabilizing module, a second voltage stabilizing module, a control module and a switch module;
the input end of the first voltage stabilizing module is respectively connected with a power signal providing end and the input end of the switch module, the output end of the first voltage stabilizing module is connected with the first input end of the control module, and the grounding end of the first voltage stabilizing module is grounded;
the first input end of the second voltage stabilizing module is connected with the power signal output end; a second input end of the second voltage stabilizing module is connected with an output end of the power supply control circuit; the output end of the second voltage stabilizing module is connected with the second input end of the control module, and the grounding end of the second voltage stabilizing module is grounded;
the output end of the control module is connected with the control end of the switch module;
the output end of the switch module is connected with the input end of the power supply control circuit, and the grounding end of the switch module is grounded;
when the power signal providing end provides a power signal, the first voltage stabilizing module is used for converting the power signal into a first voltage stabilizing signal and then sending the first voltage stabilizing signal to the control module; the control module is used for outputting a first control signal through an output end of the control module according to the first voltage stabilizing signal; the switch module is switched on according to the first control signal, and the power supply signal provided by the power supply signal providing end is sent to the power supply control circuit through the switch module, so that the power supply control circuit processes the power supply signal and then outputs the processed power supply signal from the output end of the power supply control circuit;
when the current at the output end of the power supply signal is larger than a preset value, the second voltage stabilizing module is used for sending a second voltage stabilizing signal to the control module according to the current at the output end of the power supply signal; the control module is further configured to output a second control signal through an output terminal of the control module according to the second voltage stabilization signal, so that the switch module is turned off according to the second control signal.
2. The overcurrent protection circuit of claim 1, further comprising: a soft start reset module; the first end of the soft start reset module is connected with the enabling end of the power control circuit, the control end of the soft start reset module is connected with the output end of the control module, and the second end of the soft start reset module is grounded;
the soft start reset module is used for pulling down the voltage at the enabling end of the power control circuit to the ground potential when the signal output by the output end of the control module is a second control signal, so that the power control circuit is reset and restarted.
3. The overcurrent protection circuit of claim 1, wherein the switch module comprises a first switch unit and a second switch unit;
the control end of the first switch unit is connected with the output end of the control module, the input end of the first switch unit is connected with the control end of the second switch unit, and the output end of the first switch unit is grounded;
the input end of the second switch unit is connected with the power supply signal providing end, and the output end of the second switch unit is connected with the input end of the power supply control circuit.
4. The overcurrent protection circuit of claim 3, wherein the first voltage regulation module comprises: the voltage regulator comprises a voltage regulator tube, a first resistor, a second resistor, a third resistor, a fourth resistor and a first capacitor;
the first end of the first resistor is connected with the power signal providing end, and the second end of the first resistor is respectively connected with the cathode of the voltage regulator tube, the first end of the second resistor, the first end of the first capacitor and the first end of the fourth resistor;
the anode of the voltage stabilizing tube is grounded;
a second end of the second resistor is connected with the input end of the first switch unit and the control end of the second switch unit respectively;
the first end of the third resistor is grounded, and the second end of the third resistor is respectively connected with the second end of the fourth resistor and the first input end of the control module;
the second end of the first capacitor is grounded.
5. The overcurrent protection circuit of claim 3, wherein the first switch unit comprises an N-type transistor; the second switching unit includes a P-type transistor; alternatively, the first and second electrodes may be,
the first switching unit includes a P-type transistor; the second switching unit includes an N-type transistor.
6. The overcurrent protection circuit of claim 1, wherein the second voltage regulation module comprises: a fifth resistor, a sixth resistor and a seventh resistor;
the first end of the fifth resistor is connected with the power supply signal output end, and the second end of the fifth resistor is connected with the first end of the sixth resistor;
the second end of the sixth resistor is respectively connected with the first end of the seventh resistor and the second input end of the control module;
and the second end of the seventh resistor is grounded.
7. The overcurrent protection circuit as recited in claim 6, wherein the resistance of the fifth resistor is R, R is greater than or equal to 10m Ω and less than or equal to 100m Ω.
8. The over-current protection circuit of claim 2, wherein the soft start reset module comprises: an eighth resistor and a third switching unit;
a first end of the eighth resistor is connected with an enable end of the power control circuit, and a second end of the eighth resistor is connected with an input end of the third switching unit;
the control end of the third switch unit is connected with the output end of the control module, and the output end of the third switch unit is grounded.
9. The overcurrent protection circuit of claim 1, wherein the control module comprises: a voltage comparator;
the positive input end of the voltage comparator is connected with the output end of the first voltage stabilizing module, the negative input end of the voltage comparator is connected with the output end of the second voltage stabilizing module, and the output end of the voltage comparator is connected with the control end of the switch module.
10. A power supply circuit comprising the overcurrent protection circuit as set forth in any one of claims 1 to 9.
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| CN201910651496.1A CN112242692B (en) | 2019-07-18 | 2019-07-18 | Overcurrent protection circuit and power supply circuit |
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