Current detection circuit for measuring micro current

Abstract

The utility model discloses a current detection circuit for measuring micro current, comprising an amplification circuit and a comparator circuit, the amplification circuit comprises an operational amplifier A1, an operational amplifier A2, an operational amplifier A3, a resistor R1, a resistor R2, a resistor RF, a resistor RG, a resistor RF *, a resistor R1 * and a resistor R2 *; the output end of the operational amplifier A1 is connected with a resistor R1 in series, the resistor R1 is respectively connected with the non-inverting input end of the resistor R2 and the non-inverting input end of the operational amplifier A3, and a resistor RF is connected between the output end of the operational amplifier A1 and the inverting input end of the operational amplifier A1 in series; the output end of the operational amplifier A1 is connected in series with a resistor R1 *; the comparator circuit comprises a comparator 1, a comparator 2, a resistor R15, a resistor R16, a resistor R45 and a resistor R46. According to the utility model, the micro current is amplified in a multi-stage manner, and finally reaches an order of magnitude which can be easily detected, so that the monitoring of the micro current is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of current detection circuits, in particular to a current detection circuit for measuring tiny currents. Background Art

[0002] A current detection circuit is a detection circuit that can read the current value of a specific node in a circuit, which can help engineers better detect the working status of the circuit.

[0003] The current detection circuit in the prior art can detect a limited current range. For the tiny current of some small circuits, the detection circuit is prone to have the problem of insufficient detection accuracy. Utility Model Content

[0004] The utility model aims to provide a current detection circuit for measuring tiny currents, so as to solve the problems in the prior art.

[0005] To achieve the above object, the utility model provides the following technical solution: a current detection circuit for measuring a small current, comprising an amplifier circuit and a comparator circuit,

[0006] The amplifying circuit includes an operational amplifier A1, an operational amplifier A2, an operational amplifier A3, a resistor R1, a resistor R2, a resistor R F , resistor R G , resistor R F* , resistor R 1* , resistor R 2* The output end of the operational amplifier A1 is connected in series with a resistor R1, and the resistor R1 is connected to the resistor R2 and the same-direction input end of the operational amplifier A3 respectively, and a resistor R is connected in series between the output end of the operational amplifier A1 and the reverse input end of the operational amplifier A1. F The output terminal of the operational amplifier A1 is connected in series with a resistor R 1* , the resistor R 1* Respectively with the resistor R 2* The output terminal of the operational amplifier A1 is connected to the inverting input terminal of the operational amplifier A3, and a resistor R is connected in series between the output terminal of the operational amplifier A1 and the inverting input terminal of the operational amplifier A1. F* , the resistor R 2* The two ends are respectively connected to the inverting input terminal of the operational amplifier A3 and the output terminal of the operational amplifier A1;

[0007] The comparator circuit includes a comparator 1, a comparator 2, a resistor R15, a resistor R16, a resistor R45 and a resistor R46.

[0008] Preferably, the resistor R1 and the resistor R 1* The resistance values ​​of the resistor R2 and the resistor R 2*The resistance value is the same as that of the resistor R F and resistor R F* The resistance value is the same.

[0009] Preferably, the resistance values ​​of the resistor R16, the resistor R45 and the resistor R46 are all 1 kilo-ohm; and the resistance value of the resistor R15 is all 10 kilo-ohm.

[0010] Preferably, the operational amplifier A1, the operational amplifier A2 and the operational amplifier A3 are all MCP6H04 operational amplifiers.

[0011] Compared with the prior art, the beneficial effect of the present invention is that the tiny current will be amplified through multiple stages and finally reach an order of magnitude that can be detected relatively easily, thereby realizing the monitoring of the tiny current. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0013] Figure 1 It is the amplification circuit diagram of the utility model;

[0014] Figure 2 It is a comparator circuit diagram of the utility model;

[0015] Figure 3 It is the overall circuit diagram of the utility model;

[0016] Figure 4 It is a flow chart of the utility model. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model. Therefore, the following detailed description of the embodiments of the utility model provided in the drawings is not intended to limit the scope of the utility model for which protection is claimed, but merely represents selected embodiments of the utility model.

[0018] See also Figure 1-3 In an embodiment of the utility model, a current detection circuit for measuring a tiny current includes an amplifier circuit and a comparator circuit.

[0019] The amplifying circuit includes an operational amplifier A1, an operational amplifier A2, an operational amplifier A3, a resistor R1, a resistor R2, a resistor R F , resistor R G , resistor R F* , resistor R 1* , resistor R 2* The output end of the operational amplifier A1 is connected in series with a resistor R1, and the resistor R1 is connected to the resistor R2 and the same-direction input end of the operational amplifier A3 respectively, and a resistor R is connected in series between the output end of the operational amplifier A1 and the reverse input end of the operational amplifier A1. F The output terminal of the operational amplifier A1 is connected in series with a resistor R 1* , the resistor R 1* Respectively with the resistor R 2* The output terminal of the operational amplifier A1 is connected to the inverting input terminal of the operational amplifier A3, and a resistor R is connected in series between the output terminal of the operational amplifier A1 and the inverting input terminal of the operational amplifier A1. F* , the resistor R 2* The two ends are connected to the inverting input end of the operational amplifier A3 and the output end of the operational amplifier A1 respectively; the resistor R1 and the resistor R 1* The resistance values ​​of the resistor R2 and the resistor R 2* The resistance value is the same as that of the resistor R F and resistor R F* The resistance values ​​are the same; the operational amplifier A1, the operational amplifier A2 and the operational amplifier A3 all adopt the MCP6H04 operational amplifier;

[0020] The comparator circuit includes comparator 1, comparator 2, resistor R15, resistor R16, resistor R45 and resistor R46; the resistance values ​​of the resistor R16, resistor R45 and resistor R46 are all 1 kilo-ohm; the resistance value of the resistor R15 is all 10 kilo-ohm.

[0021] like Figure 3 , the amplification factor of each level is set to 100. Considering that excessive amplification may burn out the chip, diodes are required to limit the voltage.

[0022] like Figure 4 , the measured current flows through the sampling resistor and is converted into a measured voltage, which is amplified by a multi-stage amplifier. Each stage is compared with the 150mV of the comparator to obtain the level state of the comparator. According to the level state of the comparator, it is known which level of amplified voltage should be read, and the measured voltage is calculated to obtain the real current value. If the comparator state is 00, the third level measurement voltage should be read, and if the comparator state is 10, the second level measurement voltage should be read.

[0023] This current measurement circuit not only has a current detection accuracy of 1uA, but also a maximum measurement frequency of 300kHz. It can detect not only DC current but also AC current of a certain frequency.

[0024] Finally, it should be noted that the above description is only a preferred embodiment of the utility model and is not intended to limit the utility model. Although the utility model is described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions recorded in the above embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A current detection circuit for measuring a small current, characterized in that: Including amplifier circuit and comparator circuit, The amplifying circuit includes an operational amplifier A1, an operational amplifier A2, an operational amplifier A3, a resistor R1, a resistor R2, a resistor R F , resistor R G , resistor R F* , resistor R 1* , resistor R 2* The output end of the operational amplifier A1 is connected in series with a resistor R1, and the resistor R1 is connected to the resistor R2 and the same-direction input end of the operational amplifier A3 respectively, and a resistor R is connected in series between the output end of the operational amplifier A1 and the reverse input end of the operational amplifier A1. F The output terminal of the operational amplifier A1 is connected in series with a resistor R 1* , the resistor R 1* Respectively with the resistor R 2* The output terminal of the operational amplifier A1 is connected to the inverting input terminal of the operational amplifier A3, and a resistor R is connected in series between the output terminal of the operational amplifier A1 and the inverting input terminal of the operational amplifier A1. F* , the resistor R 2* The two ends are respectively connected to the inverting input terminal of the operational amplifier A3 and the output terminal of the operational amplifier A1; The comparator circuit includes a comparator 1, a comparator 2, a resistor R15, a resistor R16, a resistor R45 and a resistor R46.

2. A current detection circuit for measuring a small current according to claim 1, characterized in that: The resistor R1 and the resistor R 1* The resistance values ​​of the resistor R2 and the resistor R 2* The resistance value is the same as that of the resistor R F and resistor R F* The resistance value is the same.

3. A current detection circuit for measuring tiny current according to claim 1, characterized in that: The resistance values ​​of the resistor R16, the resistor R45 and the resistor R46 are all 1 kilo-ohm; the resistance value of the resistor R15 is all 10 kilo-ohm.

4. A current detection circuit for measuring tiny current according to claim 1, characterized in that: The operational amplifier A1, operational amplifier A2 and operational amplifier A3 are all MCP6H04 operational amplifiers.

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