CN218675758U - Current detection circuit - Google Patents
Current detection circuit Download PDFInfo
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- CN218675758U CN218675758U CN202223330482.6U CN202223330482U CN218675758U CN 218675758 U CN218675758 U CN 218675758U CN 202223330482 U CN202223330482 U CN 202223330482U CN 218675758 U CN218675758 U CN 218675758U
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- operational amplifier
- resistance
- current detection
- detection circuit
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Abstract
The utility model discloses a current detection circuit, including first operational amplifier U1, first resistance R1, second resistance R2, third resistance R3, fourth resistance R4, fifth resistance R5, first electric capacity C1 and second electric capacity C2, third resistance R3's second end is connected with the reference voltage module, is connected with the sampling module between first resistance R1's second end and second resistance R2's second end, and MCU chip and second electric capacity C2's first end is connected to fifth resistance R5's second end. The utility model discloses a sampling module acquisition circuit voltage, the voltage of gathering through reference voltage module lifting sampling module, the negative feedback circuit who constitutes through first operational amplifier U1 is with the voltage amplification who gathers, judge the electric current size of gathering through the MCU chip, just turn-off the circuit when the electric current is greater than the setting value, the realization is to the protection of circuit, the current detection circuit who constitutes through each device has reduced manufacturing cost, each part can be changed alone after damaging simultaneously, cost of maintenance is reduced.
Description
Technical Field
The utility model belongs to the technical field of the detection circuitry, especially, relate to a current detection circuit.
Background
Various defects may occur in the use process of the fingerprint lock in the market at present, wherein the short circuit defect may cause serious consequences, so the short circuit overcurrent protection is particularly important.
The short-circuit protection of a circuit is usually realized by using an integrated current chip in the existing fingerprint lock, but the integrated chip is usually expensive, so that the production cost is higher, and when the integrated chip breaks down, the integrated current chip needs to be integrally replaced, so that the maintenance cost of the fingerprint lock is higher.
Therefore, a current detection circuit for a fingerprint lock is needed to reduce the production and maintenance costs of the fingerprint lock.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a current detection circuit to solve the current technical problem that uses integrated chip to carry out the fingerprint lock production of circuit short-circuit protection and cost of maintenance are high.
In order to achieve the above object, the present invention provides a current detection circuit, which comprises:
the utility model provides a current detection circuit, includes first operational amplifier U1, first resistance R1, second resistance R2, third resistance R3, fourth resistance R4, fifth resistance R5, first electric capacity C1 and second electric capacity C2, the positive input end of first operational amplifier U1 connects first electric capacity C1's first end first resistance R1's first end with third resistance R3's first end, first operational amplifier U1's negative pole input end is connected first electric capacity C1's second end second resistance R2's first end with fourth resistance R4's first end, first operational amplifier U1's output is connected fourth resistance R4's second end and fifth resistance R5's first end, third resistance R3's second end is connected with the reference voltage module, be connected with the sampling module between first resistance R1's second end and second resistance R2's the second end, fifth resistance R5's second end with the second end of second capacitance C2 chip, the second end of MCU 2 of second capacitance C2, the second end of MCU chip ground connection.
Preferably, the reference voltage module includes a second operational amplifier U2, a sixth resistor R6, a seventh resistor R7 and a third capacitor C3, the sixth resistor R6 is connected between the positive terminal and the positive terminal of the power supply of the second operational amplifier U2, the positive terminal of the second operational amplifier U2 is grounded through the seventh resistor R7, the output terminal and the negative terminal of the second operational amplifier U2 are short-circuited, and the output terminal of the second operational amplifier U2 is grounded through the third capacitor C3.
Preferably, the sampling module is a power resistor, the resistance of the power resistor is 0.01 ohm, and two ends of the power resistor are connected to the second ends of the first resistor R1 and the second resistor R2 through a differential line.
Preferably, the amplification factor of the first operational amplifier U1 is 20 times.
Preferably, the positive power supply terminals of the first operational amplifier U1 and the second operational amplifier U2 are both connected to a +3.3V dc power supply, and the negative power supply terminals of the first operational amplifier U1 and the second operational amplifier U2 are both grounded.
The utility model discloses a current detection circuit has following advantage: the sampling module is used for collecting circuit voltage, the sampling module is used for lifting the voltage collected by the sampling module, the collected voltage is amplified through a negative feedback circuit formed by the first operational amplifier U1, the collected current is judged through the MCU chip, the circuit is turned off when the current is greater than a set value, the circuit is protected, the production cost is reduced through a current detection circuit formed by each device, meanwhile, each component can be independently replaced after being damaged, and the maintenance cost is reduced.
Drawings
Fig. 1 is a schematic structural diagram of a current detection circuit according to the present invention;
fig. 2 is a schematic diagram of the circuit structure of the reference voltage module of the present invention.
Detailed Description
In order to better understand the purpose, structure and function of the present invention, the following description of the current detection circuit of the present invention is made in detail with reference to the accompanying drawings.
As shown in fig. 1, a current detection circuit includes a first operational amplifier U1, a first resistor R1 of 1 kilo-ohm, a second resistor R2 of 1 kilo-ohm, a third resistor R3 of 20 kilo-ohm, a fourth resistor R4 of 20 kilo-ohm, a first capacitor C1 of 1 kilo-ohm, a fifth resistor R5 of 10nF, and a second capacitor C2 of 100pF, a positive power supply terminal of the first operational amplifier U1 is connected to a +3.3V dc power supply, a negative power supply terminal is grounded, a positive input terminal of the first operational amplifier U1 is connected to a first terminal of the first capacitor C1, a first terminal of the first resistor R1 and a first terminal of the third resistor R3, a negative input terminal of the first operational amplifier U1 is connected to a second terminal of the first capacitor C1, a first terminal of the second resistor R2 and a first terminal of the fourth resistor R4, an output terminal of the first operational amplifier U1 is connected to a second terminal of the fourth resistor R4 and a first terminal of the fifth resistor R5, a second terminal of the second resistor R2 and a first terminal of the fourth resistor R4, a second terminal of the third resistor R3 is connected to a first terminal of the second resistor R2, a second terminal of the sampling resistor R2, a differential resistor R2 is connected between the second sampling resistor R1, a second terminal of the sampling resistor R2 sampling module is connected to a second sampling resistor R2, a differential resistor R2, a first sampling module, a first resistor R2 is connected between the second terminal of the second sampling resistor R1, a differential resistor R2 sampling module, a differential resistor R2 is connected between the second resistor R2, and a first sampling module, and a second resistor R2 sampling module is connected between the sampling module, and a first resistor R2.
During the use, 0.01 ohm's sampling resistance can reduce the influence to the circuit, the voltage that sampling resistance gathered is raised 1.65V back by reference voltage module, negative feedback circuit by first operational amplifier U1 enlargies 20 times, later send to the MCU chip, make MCU collection voltage value that can be better, judge the electric current through the MCU chip, when the current value is greater than the setting value, MCU chip control circuit cuts off, the current detection to the fingerprint lock has been realized, the probability that the fingerprint lock breaks down because of the short circuit has been reduced, negative feedback circuit through first operational amplifier U1 compares with integrated chip and has reduced manufacturing cost, can realize the change alone of each part simultaneously, the cost of maintenance that the fingerprint is many is reduced.
In order to ensure the accuracy of the collected voltage and reduce the influence on the circuit voltage, the smaller the sampling resistor is, the better is, but the relatively smaller the collected voltage is, therefore as shown in fig. 2, the reference voltage module includes a second operational amplifier U2, a sixth resistor R6 of 50 kilo-ohm, a seventh resistor R7 of 50 kilo-ohm, and a third capacitor C3 of 0.1uF, the sixth resistor R6 is connected between the positive terminal and the positive input terminal of the power supply of the second operational amplifier U2, the positive input terminal of the second operational amplifier U2 is further grounded through the seventh resistor R7, the output terminal and the negative input terminal of the second operational amplifier U2 are shorted, and the output terminal of the second operational amplifier U2 is further grounded through the third capacitor C3.
During the use, the positive terminal of the power supply of second operational amplifier U2 is connected with +3.3V DC power supply, and the negative pole end ground connection makes the output of second operational amplifier U2 exportable + 1.65V's voltage, raises the voltage that sampling resistor gathered through this voltage, and second operational amplifier U2 builds the constitution inverter circuit simultaneously, can promote the stability of voltage.
It is to be understood that the present invention has been described with reference to certain embodiments, and that various changes or equivalents may be substituted for elements thereof by those skilled in the art without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present application are intended to be covered by the present invention.
Claims (5)
1. A current sensing circuit, comprising:
the sampling circuit comprises a first operational amplifier U1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first capacitor C1 and a second capacitor C2, wherein the positive input end of the first operational amplifier U1 is connected with the first end of the first capacitor C1, the first end of the first resistor R1 and the first end of the third resistor R3, the negative input end of the first operational amplifier U1 is connected with the second end of the first capacitor C1, the first end of the second resistor R2 and the first end of the fourth resistor R4, the output end of the first operational amplifier U1 is connected with the second end of the fourth resistor R4 and the first end of the fifth resistor R5, the second end of the third resistor R3 is connected with a reference voltage module, a sampling module is connected between the second end of the first resistor R1 and the second end of the second resistor R2, and the second end of the second capacitor C2 is connected with the chip and the ground.
2. The current detection circuit according to claim 1, wherein the reference voltage module includes a second operational amplifier U2, a sixth resistor R6, a seventh resistor R7, and a third capacitor C3, the sixth resistor R6 is connected between the positive terminal and the positive terminal of the power supply of the second operational amplifier U2, the positive terminal of the second operational amplifier U2 is further grounded through the seventh resistor R7, the output terminal of the second operational amplifier U2 is shorted with the negative terminal, and the output terminal of the second operational amplifier U2 is further grounded through the third capacitor C3.
3. The current detection circuit according to claim 1, wherein the sampling module is a power resistor, the resistance of the power resistor is 0.01 ohm, and two ends of the power resistor are connected to the second ends of the first resistor R1 and the second resistor R2 through a differential line.
4. The current detection circuit of claim 1, wherein the amplification factor of the first operational amplifier U1 is 20 times.
5. The current detection circuit according to claim 2, wherein positive power supply terminals of the first operational amplifier U1 and the second operational amplifier U2 are both connected to a +3.3V dc power supply, and negative power supply terminals of the first operational amplifier U1 and the second operational amplifier U2 are both grounded.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202223330482.6U CN218675758U (en) | 2022-12-12 | 2022-12-12 | Current detection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202223330482.6U CN218675758U (en) | 2022-12-12 | 2022-12-12 | Current detection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN218675758U true CN218675758U (en) | 2023-03-21 |
Family
ID=85550063
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202223330482.6U Active CN218675758U (en) | 2022-12-12 | 2022-12-12 | Current detection circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN218675758U (en) |
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2022
- 2022-12-12 CN CN202223330482.6U patent/CN218675758U/en active Active
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