CN214409119U - Current sampling circuit and electronic equipment - Google Patents
Current sampling circuit and electronic equipment Download PDFInfo
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- CN214409119U CN214409119U CN202023169024.XU CN202023169024U CN214409119U CN 214409119 U CN214409119 U CN 214409119U CN 202023169024 U CN202023169024 U CN 202023169024U CN 214409119 U CN214409119 U CN 214409119U
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Abstract
The application discloses current sampling circuit and electronic equipment. The current sampling circuit includes: the first sampling resistor inputs a current signal of the power supply circuit; the input end of the first-stage operational amplifier circuit is coupled with the first sampling resistor and is used for amplifying the current signal; and the input end of the second-stage operational amplifier circuit is coupled with the output end of the first-stage operational amplifier circuit and is used for amplifying the current signal amplified by the first-stage operational amplifier circuit. In this way, the cost of the current sampling circuit can be reduced and the current identification degree can be improved.
Description
Technical Field
The present application relates to the field of power electronics technologies, and in particular, to a current sampling circuit and an electronic device.
Background
The power panel of the existing electronic device, for example, the power panel of the series wall breaking machine, usually adopts an isolated flyback power (as shown in fig. 1), which outputs multiple paths of direct current or adopts a buck-boost circuit, the power is realized by adopting a common input line L/N mode, and current sampling is performed through a current transformer L, because the size of the current transformer L is large, the size of the whole power panel is large, the cost is high, and the current identification degree is low.
SUMMERY OF THE UTILITY MODEL
The technical problem that this application mainly solved is how to reduce the cost of current sampling circuit and improve the electric current discernment degree.
In order to solve the technical problem, the application adopts a technical scheme that: a current sampling circuit is provided. The current sampling circuit includes: the first sampling resistor inputs a current signal of the power supply circuit; the input end of the first-stage operational amplifier circuit is coupled with the first sampling resistor and is used for amplifying the current signal; and the input end of the second-stage operational amplifier circuit is coupled with the output end of the first-stage operational amplifier circuit and is used for amplifying the current signal amplified by the first-stage operational amplifier circuit.
In order to solve the technical problem, the application adopts a technical scheme that: an electronic device is provided. The electronic device includes: the current sampling circuit is coupled with the power supply circuit and is used for sampling a current signal of the power supply circuit.
The beneficial effects of the embodiment of the application are that: the current sampling circuit of the embodiment of the application comprises: the circuit comprises a first sampling resistor, a first-stage operational amplifier circuit and a second-stage operational amplifier circuit; the first sampling resistor inputs a current signal of the power supply circuit; the input end of the first-stage operational amplifier circuit is coupled with the first sampling resistor and is used for amplifying the current signal; the input end of the second-stage operational amplifier circuit is coupled with the output end of the first-stage operational amplifier circuit and is used for amplifying the current signal amplified by the first-stage operational amplifier circuit. In this way, the current sampling circuit is realized by adopting the sampling resistor and the operational amplifier circuit, and compared with the traditional current sampling circuit realized by adopting a current transformer (which has larger volume and low consistency, and the current signal is only used for judging the on-off state of a loop), the volume of the current sampling circuit can be obviously reduced, so that the volumes of a power panel and electronic equipment can be reduced, and the cost of the power panel and the electronic equipment can be reduced; in the embodiment of the application, the two-stage operational amplifier circuit is adopted to amplify the current signal of the power supply circuit, and the operational amplifier circuit can be ensured to normally work and meet the requirement for current signal amplification through the matching arrangement of the amplification factors of the two-stage operational amplifier circuit; therefore, the current signal amplifying method and device can meet the requirement for amplifying the current signal of the power supply circuit, and improve the current identification degree.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a schematic diagram of a current sampling circuit;
FIG. 2 is a schematic diagram of an embodiment of a current sampling circuit according to the present application;
FIG. 3 is a schematic diagram of the circuit structure of the current sampling circuit of the embodiment of FIG. 2;
fig. 4 is a schematic structural diagram of an embodiment of an electronic device according to the present application.
Detailed Description
The present application will be described in further detail with reference to the following drawings and examples. It is to be noted that the following examples are only illustrative of the present application, and do not limit the scope of the present application. Likewise, the following examples are only some examples and not all examples of the present application, and all other examples obtained by a person of ordinary skill in the art without any inventive step are within the scope of the present application.
The present application firstly proposes a current sampling circuit, as shown in fig. 2 and fig. 3, fig. 2 is a schematic structural diagram of an embodiment of the current sampling circuit of the present application; fig. 3 is a schematic circuit diagram of the current sampling circuit in the embodiment of fig. 2. The current sampling circuit 10 of the present embodiment includes: the first sampling resistor 110, the first stage operational amplifier circuit 120 and the second stage operational amplifier circuit 130; the first sampling resistor 110 inputs a current signal of the power supply circuit 20; the input terminal of the first stage operational amplifier circuit 120 is coupled to the first sampling resistor 110, and is configured to amplify the current signal; the input terminal of the second stage operational amplifier circuit 130 is coupled to the output terminal of the first stage operational amplifier circuit 120, and is configured to amplify the current signal amplified by the first stage operational amplifier circuit 120.
The operational amplifier circuit of the present application is a circuit including an operational amplifier (hereinafter, referred to as an operational amplifier), and has characteristics such as infinite input impedance, output impedance approaching zero, infinite open loop gain, infinite common mode rejection ratio, and infinite bandwidth, and thus can improve electrical stability of a current sampling circuit and simplify the circuit.
The operational amplifier has the characteristics of 'virtual short' and 'virtual disconnection', wherein the 'virtual short' means that when the operational amplifier is analyzed to be in a linear state, the same-direction input end and the reverse-direction input end can be regarded as equipotential; the term "virtual break" refers to that when the operational amplifier is analyzed to be in a linear state, the same-direction input end and the reverse-direction input end can be regarded as equivalent open circuits.
The first sampling resistor 110 of this embodiment is an equivalent resistor formed by connecting a plurality of resistors in parallel, and the resistor may be a resistor, a constantan wire, an alloy resistor, or the like. Of course, in other embodiments, the first sampling resistor may also be a single resistor, an equivalent resistor formed by connecting a plurality of resistors in series, or an equivalent resistor formed by connecting a plurality of resistors in series and in parallel; the plurality described herein includes two or more.
Compared with the conventional current sampling circuit implemented by using a current transformer (which has a large volume and low consistency, and the current signal is only used for loop on-off judgment), the current sampling circuit 10 implemented by using the first sampling resistor 110, the first-stage operational amplifier circuit 120 and the second-stage operational amplifier circuit 130 in the embodiment has the advantages that the volume of the current sampling circuit 10 can be obviously reduced, so that the volumes of a power panel and electronic equipment can be reduced, and the costs of the power panel and the electronic equipment can be reduced; in addition, in the embodiment, the first operational amplifier circuit 120 and the second operational amplifier circuit 130 are adopted to amplify the current signal of the power supply circuit 20, and the first operational amplifier circuit 120 and the second operational amplifier circuit 130 can be ensured to normally work and meet the requirement for current signal amplification by the cooperation of the amplification factors of the first operational amplifier circuit 120 and the second operational amplifier circuit 130; therefore, the present embodiment can satisfy the requirement for amplification of the current signal of the power supply circuit 20, and improve the current discrimination.
Optionally, in this embodiment, the amplification factor of the second stage operational amplifier circuit 130 is greater than the amplification factor of the first stage operational amplifier circuit 120, a first input terminal of the first stage operational amplifier circuit 120 is connected to a supply voltage, a second input terminal of the first stage operational amplifier circuit is coupled to the first sampling resistor 110, and a difference between a voltage of the output terminal and the supply voltage is greater than a voltage threshold.
In the actual operation of the operational amplifier, the supply voltage of the operational amplifier is determined by the operating voltage range of the operational amplifier and the voltage range of the processed signal, some operational amplifiers cannot work with a single power supply or the input voltage and the output voltage cannot be too close to 0v when the single power supply works, and similarly, the input voltage and the output voltage cannot be too close to the maximum voltage of the power supply voltage because the input voltage and the output voltage are both close to the saturation region of the operational amplifier, which is nonlinear; the wider the supply voltage, the wider the range of voltages allowed for input and output; usually, the difference between the input voltage and the output voltage of the operational amplifier and the power supply voltage is larger than a voltage threshold (generally 0.9v-2.1v) so that the operational amplifier normally works (linear operation).
Because the amplification factor of the operational amplifier is determined by the voltage dividing resistor of the input end, if the amplification factor is larger, the voltage division of the feedback resistor is larger, so that the power supply bias voltage of the input voltage and the output voltage of the operational amplifier is smaller, namely the difference value between the input voltage and the output voltage of the operational amplifier and the power supply voltage of the power supply is smaller than a voltage threshold value, and the operational amplifier works nonlinearly; therefore, the amplification factor of the first stage operational amplifier circuit 120 of the embodiment is small, so that the input voltage and the output voltage of the operational amplifier have large power bias, and the difference between the input voltage and the output voltage and the power supply voltage is greater than the voltage threshold, so that the first stage operational amplifier circuit 120 and the second stage operational amplifier circuit 130 can work linearly.
The second-stage operational amplifier circuit 130 has a large amplification factor, and can meet the requirement for current signal amplification.
As can be seen from the above analysis, in the present embodiment, the two-stage operational amplifier circuit is used to replace the existing current transformer to sample the current signal of the power supply circuit 20, so that the normal operation of the current sampling circuit 10 and the current signal amplification requirement can be ensured.
Optionally, one end of the first sampling resistor 110 of this embodiment is coupled to the power supply circuit 20, and the first stage operational amplifier circuit 120 further includes: the first operational amplifier 121 has a same-direction input terminal connected to a reference voltage, and an opposite-direction input terminal of the first operational amplifier 121 is coupled to the other terminal of the first sampling resistor 110.
The non-inverting input terminal of the first operational amplifier 121 may be further coupled to one terminal of the first sampling resistor 110, the first sampling resistor 110 converts the current signal of the power supply circuit 20 into voltage information, and the first operational amplifier 121 amplifies the terminal voltage of the first sampling resistor 110.
The first stage operational amplifier circuit 120 of this embodiment further includes: the first voltage-dividing resistor R1, the second voltage-dividing resistor R2, the third voltage-dividing resistor R3 and the fourth voltage-dividing resistor R4; one end of the first voltage dividing resistor R1 is coupled to one end of the first sampling resistor 110, and the other end of the first voltage dividing resistor R1 is coupled to the inverting input terminal of the first operational amplifier 121; one end of the second voltage-dividing resistor R2 is coupled to the inverting input terminal of the first operational amplifier 121, and the other end of the second voltage-dividing resistor R2 is coupled to the output terminal of the first operational amplifier 121; one end of the third voltage dividing resistor R3 is coupled to one end of the first sampling resistor 110, and the other end of the third voltage dividing resistor R3 is coupled to the unidirectional input terminal of the first operational amplifier 121; one end of the fourth voltage dividing resistor R4 is coupled to the unidirectional input terminal of the first operational amplifier 121, and the other end is grounded.
As can be seen from the "virtual-off" characteristic of the first operational amplifier 121, the current passing through the first voltage-dividing resistor R1 is equal to the current passing through the second voltage-dividing resistor R2, and similarly, the current passing through the fourth voltage-dividing resistor R4 is equal to the current passing through the third voltage-dividing resistor R3, so that (V1-V-)/R1 is (V-Vo)/R2; (V2-V +)/R3 ═ V +/R4; as can be seen from the "virtual short" characteristic of the first operational amplifier 121, V + ═ V —; it can be seen that the amplification factor of the first operational amplifier 121 is related to the first voltage-dividing resistor R1, the second voltage-dividing resistor R2, the third voltage-dividing resistor R3 and the fourth voltage-dividing resistor R4, and the amplification factor of the first operational amplifier 121 can be set by adjusting the resistance values of the first voltage-dividing resistor R1, the second voltage-dividing resistor R2, the third voltage-dividing resistor R3 and the fourth voltage-dividing resistor R4.
Alternatively, the resistance of the first divider resistor R1 is equal to the resistance of the third divider resistor R3, and the resistance of the second divider resistor R2 is equal to the resistance of the fourth divider resistor R4. Therefore, the amplification factor of the first operational amplifier 121 is R2/R1, which can simplify the calculation of the amplification factor of the first stage operational amplifier circuit 120.
Optionally, in this embodiment, the resistance of the third voltage dividing resistor R3 may be set to be equal to the resistance of the fourth voltage dividing resistor R4, so as to provide 1/2 power bias to the unidirectional input terminal of the first operational amplifier 121, so that the difference between the voltage at the unidirectional input terminal of the first operational amplifier 121 and the power supply voltage is greater than a voltage threshold (generally 0.9v-2.1v), so that the first operational amplifier 121 operates normally.
The first stage operational amplifier circuit 120 of this embodiment is an inverse phase amplifier circuit of the first operational amplifier 121, and in other embodiments, the first stage operational amplifier circuit of this application may also be implemented by using a same phase amplifier circuit of the first operational amplifier, and the like.
Optionally, the first stage operational amplifier circuit 120 of the present embodiment further includes a first capacitor C1, one end of which is coupled to one end of the first voltage dividing resistor R1, and the other end of which is grounded; the first capacitor C1 is used for blocking dc at the inverting input terminal of the first operational amplifier 121.
Optionally, the first stage operational amplifier circuit 120 of the present embodiment further includes a second capacitor C2, one end of which is coupled to one end of the second voltage-dividing resistor R2, and the other end of which is coupled to the other end of the second voltage-dividing resistor R2; the second capacitor C2 is used for dc blocking of the second voltage-dividing resistor R2.
Optionally, the first stage operational amplifier circuit 120 of the present embodiment further includes a third capacitor C3, one end of which is coupled to one end of the fourth voltage-dividing resistor R4, and the other end of which is coupled to the other end of the fourth voltage-dividing resistor R4; the third capacitance C3 is used for power supply decoupling filtering.
Optionally, the second stage operational amplifier circuit 130 of this embodiment includes: the sampling circuit comprises a second sampling resistor R5, a second operational amplifier 131, a fifth voltage-dividing resistor R6, a sixth voltage-dividing resistor R7, a seventh voltage-dividing resistor R8 and an eighth voltage-dividing resistor R9; one end of the second sampling resistor R5 is coupled to the output terminal of the first stage operational amplifier circuit 120, and the other end of the second sampling resistor R5 is grounded; one end of the fifth voltage-dividing resistor R6 is coupled to the other end of the second sampling resistor R5, and the other end of the fifth voltage-dividing resistor R6 is coupled to the inverting input terminal of the second operational amplifier 131; one end of the sixth voltage-dividing resistor R7 is coupled to the inverting input terminal of the second operational amplifier 131, and the other end of the sixth voltage-dividing resistor R7 is coupled to the output terminal of the second operational amplifier 131; one end of the seventh voltage-dividing resistor R8 is coupled to one end of the second sampling resistor R5, and the other end of the seventh voltage-dividing resistor R8 is coupled to the non-inverting input terminal of the second operational amplifier 131; one end of the eighth voltage dividing resistor R9 is coupled to the inverting input terminal of the second operational amplifier 131, and the other end of the eighth voltage dividing resistor R9 is grounded.
Specifically, one end of the second sampling resistor R5 is coupled to the output end of the first operational amplifier 121.
The second sampling resistor R5 is configured to convert a current signal output by the first operational amplifier 121 into a voltage signal, and the second operational amplifier 131 amplifies a terminal voltage of the second sampling resistor R5 and then converts the amplified voltage signal into a current signal to obtain a sampled current.
The second sampling resistor R5 of the present embodiment is a single resistor, which may be a resistor, a constantan wire, an alloy resistor, or the like. Of course, in other embodiments, the second sampling resistor may also be an equivalent resistor formed by connecting a plurality of resistors in parallel, an equivalent resistor formed by connecting a plurality of resistors in series, or an equivalent resistor formed by connecting a plurality of resistors in series and parallel;
the amplification factor of the second operational amplifier 131 is related to the fifth voltage-dividing resistor R6, the sixth voltage-dividing resistor R7, the seventh voltage-dividing resistor R8, and the eighth voltage-dividing resistor R9, and the amplification factor of the second operational amplifier 131 can be set by adjusting the resistance values of the fifth voltage-dividing resistor R6, the sixth voltage-dividing resistor R7, the seventh voltage-dividing resistor R8, and the eighth voltage-dividing resistor R9.
Optionally, in this embodiment, the resistance of the fifth voltage-dividing resistor R6 is equal to the resistance of the seventh voltage-dividing resistor R8, and the resistance of the sixth voltage-dividing resistor R7 is equal to the resistance of the eighth voltage-dividing resistor R9. Therefore, the amplification factor of the second operational amplifier 131 is R7/R6, which can simplify the calculation of the amplification factor of the second stage operational amplifier circuit 130.
Optionally, the second stage operational amplifier circuit 130 of this embodiment further includes: one end of a fourth capacitor C4, one end of a fourth capacitor C4 is coupled to one end of the sixth voltage-dividing resistor R7, and the other end of the fourth capacitor C4 is coupled to the other end of the sixth voltage-dividing resistor R7; the fourth capacitor C4 is used for dc blocking of the sixth voltage-dividing resistor R7.
Optionally, the second stage operational amplifier circuit 130 of this embodiment further includes: one end of a fifth capacitor C5, one end of a fifth capacitor C5 is coupled to one end of the eighth voltage-dividing resistor R9, and the other end of the fifth capacitor C5 is grounded; the fifth capacitance C5 is used for power supply decoupling filtering.
The amplification factors of the first stage operational amplifier circuit 120 and the second stage operational amplifier circuit 130 may be set to be different by setting the resistances of the first voltage-dividing resistor R1, the second voltage-dividing resistor R2, the third voltage-dividing resistor R3 and the fourth voltage-dividing resistor R4 to be at least partially different from the resistances of the fifth voltage-dividing resistor R6, the sixth voltage-dividing resistor R7, the seventh voltage-dividing resistor R8 and the eighth voltage-dividing resistor R9.
Optionally, the current sampling circuit 10 of this embodiment further includes: and a clamping circuit 150, coupled to the output terminal of the second stage operational amplifier circuit 130, for limiting the output voltage of the output terminal of the second stage operational amplifier circuit 130 to be less than or equal to the supply voltage of the power supply circuit 20, so as to avoid damaging other circuits, such as an ADC circuit, coupled to the current sampling circuit 10 on the power board.
Optionally, the clamp circuit 150 of the present embodiment includes: a first resistor R10, a sixth capacitor C6 and a diode D; one end of the first resistor R10 is coupled to the output end of the second stage operational amplifier circuit 130; one end of a sixth capacitor C6 is coupled to the other end of the first resistor R10, and the other end of the sixth capacitor C6 is grounded; the anode of the diode D is coupled to the other end of the first resistor R10, and the cathode of the diode D is connected to the supply voltage VCC 1.
Specifically, one end of the first resistor R10 is coupled to the output end of the second operational amplifier 131.
In other embodiments, the clamp circuit of the present application may also be implemented by using a hybrid circuit of a voltage dividing resistor and a voltage stabilizing diode.
In an application scenario, the supply voltage of the power supply circuit 20 is +12 v; the terminal voltage at one end of the first sampling resistor 110 is +12 v; the terminal voltage of one end of the third voltage dividing resistor R3 is +12 v; the cathode of the diode D is connected with a power supply voltage VCC1 to be +12 v; the supply voltages VCC2, VCC3 of the first operational amplifier 121 may be +12v, -12v, respectively, and the amplification factor of the first operational amplifier 121 may be 2.
This embodiment adopts doublestage single channel mode to carry out current signal sampling, and first-order fortune is put circuit 120 and is carried out the syntropy input that the 121 was put to the partial pressure input first fortune altogether 12V, and the magnification is less, and the output of 121 is put as the input that 131 was put to the second fortune, and the second fortune is put 131 the magnification higher, realizes the non-current sampling of keeping apart altogether 12V power scheme, and more traditional mutual-inductor current sampling scheme, its is with low costs, and current sampling is more accurate, and the uniformity is better.
The present application further provides an electronic device, as shown in fig. 4, fig. 4 is a schematic structural diagram of an embodiment of the electronic device of the present application. The electronic device 40 of the present embodiment includes: the current sampling circuit 10 is coupled to the power supply circuit 20, and the current sampling circuit 10 is configured to sample a current signal of the power supply circuit 20.
The current sampling circuit 10 of the present embodiment may participate in the above embodiments, and is not described herein.
The electronic device 30 of the present embodiment may be a household appliance device or the like; such as a wall breaking machine, a cooking machine, etc., and is not particularly limited. The current sampling circuit can be used in a single power supply circuit.
In this embodiment, the current sampling circuit 10 is implemented by using the first sampling resistor 110, the first stage operational amplifier circuit 120 and the second stage operational amplifier circuit 130, and compared with a current sampling circuit implemented by using a conventional current transformer (which has a large volume and low consistency, and a current signal is only used for loop on-off judgment), the volume of the current sampling circuit 10 can be significantly reduced, so that the volumes of a power panel and electronic equipment can be reduced, and therefore, the costs of the power panel and the electronic equipment can be reduced; in addition, in the embodiment, the first operational amplifier circuit 120 and the second operational amplifier circuit 130 are adopted to amplify the current signal of the power supply circuit 20, and the first operational amplifier circuit 120 and the second operational amplifier circuit 130 can be ensured to normally work and meet the requirement for current signal amplification by the cooperation of the amplification factors of the first operational amplifier circuit 120 and the second operational amplifier circuit 130; therefore, the present embodiment can satisfy the requirement for amplification of the current signal of the power supply circuit 20, and improve the current discrimination.
Further, the electronic device 40 of the embodiment further includes a main control circuit 50, and the main control circuit 50 is coupled to the output terminal of the current sampling circuit 10, and is configured to perform subsequent processing and control according to the sampling current of the current sampling circuit 10.
The main control circuit 50 of the present embodiment at least includes an MCU and an Analog-to-Digital Converter (ADC) circuit, wherein an output end of the current sampling circuit 10 is coupled to the ADC circuit, and the ADC circuit is configured to convert the sampling current output by the current sampling circuit 10 into a binary Digital signal of the current; the MCU is coupled with the ADC circuit and is used for carrying out subsequent processing and control according to the sampling current of the current sampling circuit 10; ADcur is a binary digital signal of current, R is an equivalent resistance value of the first sampling resistor 110, and Iout is a sampling current.
In other embodiments, to improve the current signal identification range of the current sampling circuit and improve the current signal identification accuracy, the current sampling circuit may be provided with at least two amplifying circuits, and the amplifying circuits include a first stage operational amplifier circuit and a second stage operational amplifier circuit, where the circuit structures and principles of the first stage operational amplifier circuit and the second stage operational amplifier circuit may refer to the above embodiments.
The input end of each amplifying circuit is coupled with the first sampling resistor, and each amplifying circuit amplifies the current signals to obtain at least two paths of amplified current signals; the main control circuit is respectively coupled with the output end of each amplifying circuit and the power supply circuit, and is used for selecting one circuit from at least two amplified current signals as sampling current according to the magnitude of the current signal of the power supply circuit; wherein, the amplification factors of at least two amplifying circuits are different.
In actual work, when an amplifying circuit with a large amplification factor is used for amplifying a large current signal, current overflow is easy to cause, and when an amplifying circuit with a small amplification factor is used for amplifying a small current signal, the amplified current is still small and is difficult to identify; in this embodiment, at least two amplifying circuits are used to obtain at least two paths of amplified current signals, and the main control circuit is used to select one of the at least two paths of amplified current signals as a sampling current according to the magnitude of the current signal of the power supply circuit, that is, the amplifying circuit with a suitable amplification factor is used to select the amplified current signal as the sampling current according to the magnitude of the current signal of the power supply circuit. For example, when the current signal of the power supply circuit is small, the main control circuit obtains the current signal amplified by the amplifying circuit with a large amplification factor as the sampling current, and when the current signal of the power supply circuit is large, the current signal amplified by the amplifying circuit with a small amplification factor is obtained as the sampling current, so that not only can the current overflow be avoided, but also the problems that the current signal is small and cannot be identified can be solved.
The main control circuit of this embodiment may obtain the magnitude of the current signal of the power supply circuit through the detection circuit, or may directly obtain the magnitude of the current signal of the power supply circuit from the power supply system, which is not limited specifically. The magnitude of the current signal may be quantitative or qualitative.
In an application scenario, the MCU acquires a current signal from the power supply circuit, acquires at least two adcurs from the ADC circuit, selects one ADcur as a binary digital signal of the sampling current according to the magnitude of the current signal of the power supply circuit, and performs subsequent processing or control on the binary digital signal of the sampling current. Specifically, the MCU acquires a current signal from the power supply circuit, compares the current signal of the power supply circuit with a current threshold, and selects ADcur corresponding to an amplifying circuit with a large amplification factor as a binary digital signal of the sampling current if the current signal of the power supply circuit is smaller than the current threshold so as to amplify a small current signal with a high amplification factor and improve the current identification degree; if the current signal of the power supply circuit is larger than or equal to the current threshold, the MCU selects ADcur corresponding to the amplifying circuit with the more effective amplification factor as a binary digital signal of the sampling current so as to amplify the large current signal with the lower amplification factor and avoid current overflow.
Different from the prior art, the current sampling circuit of the embodiment of the application includes: the circuit comprises a first sampling resistor, a first-stage operational amplifier circuit and a second-stage operational amplifier circuit; the first sampling resistor inputs a current signal of the power supply circuit; the input end of the first-stage operational amplifier circuit is coupled with the first sampling resistor and is used for amplifying the current signal; the input end of the second-stage operational amplifier circuit is coupled with the output end of the first-stage operational amplifier circuit and is used for amplifying the current signal amplified by the first-stage operational amplifier circuit. In this way, the current sampling circuit is realized by adopting the sampling resistor and the operational amplifier circuit, and compared with the traditional current sampling circuit realized by adopting a current transformer (which has larger volume and low consistency, and the current signal is only used for judging the on-off state of a loop), the volume of the current sampling circuit can be obviously reduced, so that the volumes of a power panel and electronic equipment can be reduced, and the cost of the power panel and the electronic equipment can be reduced; in the embodiment of the application, the two-stage operational amplifier circuit is adopted to amplify the current signal of the power supply circuit, and the operational amplifier circuit can be ensured to normally work and meet the requirement for current signal amplification through the matching arrangement of the amplification factors of the two-stage operational amplifier circuit; therefore, the current signal amplifying method and device can meet the requirement for amplifying the current signal of the power supply circuit, and improve the current identification degree.
The above description is only an embodiment of the present application, and not intended to limit the scope of the present application, and all equivalent mechanisms or equivalent processes performed by the present application and the contents of the appended drawings, or directly or indirectly applied to other related technical fields, are all included in the scope of the present application.
Claims (10)
1. A current sampling circuit, comprising:
the first sampling resistor inputs a current signal of the power supply circuit;
the input end of the first-stage operational amplifier circuit is coupled with the first sampling resistor and is used for amplifying the current signal;
and the input end of the second-stage operational amplifier circuit is coupled with the output end of the first-stage operational amplifier circuit and is used for amplifying the current signal amplified by the first-stage operational amplifier circuit.
2. The current sampling circuit of claim 1, wherein the amplification of the second stage operational amplifier circuit is greater than the amplification of the first stage operational amplifier circuit;
the first input end of the first-stage operational amplifier circuit is connected with a power supply voltage, the second input end of the first-stage operational amplifier circuit is coupled with the first sampling resistor, and the difference value between the voltage of the output end and the power supply voltage is larger than a voltage threshold value.
3. The current sampling circuit of claim 2, wherein one end of the first sampling resistor is coupled to the power supply circuit, and wherein the first stage op-amp circuit further comprises:
a first operational amplifier;
a first voltage dividing resistor, one end of which is coupled with one end of the first sampling resistor, and the other end of which is coupled with the reverse input end of the first operational amplifier;
a second voltage-dividing resistor, one end of which is coupled with the inverted input end of the first operational amplifier, and the other end of which is coupled with the output end of the first operational amplifier;
a third voltage dividing resistor, one end of which is coupled with the one end of the first sampling resistor, and the other end of which is coupled with the same-direction input end of the first operational amplifier;
and one end of the fourth voltage-dividing resistor is coupled with the equidirectional input end of the first operational amplifier, and the other end of the fourth voltage-dividing resistor is grounded.
4. The current sampling circuit of claim 3, wherein the first stage op-amp circuit further comprises:
a first capacitor having one end coupled to the one end of the first voltage dividing resistor and the other end grounded;
a second capacitor having one end coupled to the one end of the second voltage-dividing resistor and the other end coupled to the other end of the second voltage-dividing resistor;
and a third capacitor having one end coupled to the one end of the fourth voltage dividing resistor and the other end grounded.
5. The current sampling circuit of claim 3, wherein the first voltage dividing resistor has a resistance equal to that of the third voltage dividing resistor, and the second voltage dividing resistor has a resistance equal to that of the fourth voltage dividing resistor.
6. The current sampling circuit of claim 1, wherein the second stage operational amplifier circuit comprises:
one end of the second sampling resistor is coupled with the output end of the first-stage operational amplifier circuit, and the other end of the second sampling resistor is grounded;
a second operational amplifier;
a fifth voltage-dividing resistor, one end of which is coupled with the other end of the second sampling resistor, and the other end of which is coupled with the reverse input end of the second operational amplifier;
one end of the sixth divider resistor is coupled with the reverse input end of the second operational amplifier, and the other end of the sixth divider resistor is coupled with the output end of the second operational amplifier;
a seventh voltage-dividing resistor, one end of which is coupled to the one end of the second sampling resistor, and the other end of which is coupled to the equidirectional input end of the second operational amplifier;
and one end of the eighth divider resistor is coupled with the equidirectional input end of the second operational amplifier, and the other end of the eighth divider resistor is grounded.
7. The current sampling circuit of claim 6, wherein the second stage op-amp circuit further comprises:
a fourth capacitor, one end of which is coupled to the one end of the sixth voltage-dividing resistor, and the other end of which is coupled to the other end of the sixth voltage-dividing resistor;
and one end of the fifth capacitor is coupled with the one end of the eighth divider resistor, and the other end of the fifth capacitor is grounded.
8. The current sampling circuit of any one of claims 1-7, further comprising: and the clamping circuit is coupled with the output end of the second-stage operational amplifier circuit and is used for limiting the output voltage of the output end of the second-stage operational amplifier circuit to be less than or equal to the power supply voltage of the power supply circuit.
9. The current sampling circuit of claim 8, wherein the clamping circuit comprises:
one end of the first resistor is coupled with the output end of the second-stage operational amplifier circuit;
one end of the sixth capacitor is coupled with the other end of the first resistor, and the other end of the sixth capacitor is grounded;
and the anode of the diode is coupled with the other end of the first resistor, and the cathode of the diode is connected with the power supply voltage.
10. An electronic device, comprising: a power supply circuit and the current sampling circuit of any one of claims 1 to 9, the current sampling circuit being coupled to the power supply circuit, the current sampling circuit being configured to sample a current signal of the power supply circuit.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116165420A (en) * | 2023-04-20 | 2023-05-26 | 杭州瑞盟科技股份有限公司 | Current detection circuit and device |
| CN118646416A (en) * | 2024-08-09 | 2024-09-13 | 杭州飞仕得科技股份有限公司 | Electric signal sampling device |
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2020
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116165420A (en) * | 2023-04-20 | 2023-05-26 | 杭州瑞盟科技股份有限公司 | Current detection circuit and device |
| CN116165420B (en) * | 2023-04-20 | 2023-10-03 | 杭州瑞盟科技股份有限公司 | Current detection circuit and device |
| CN118646416A (en) * | 2024-08-09 | 2024-09-13 | 杭州飞仕得科技股份有限公司 | Electric signal sampling device |
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