Dual parallel circuit with adjustable current ratio and current adjusting method thereof

Abstract

The application provides a double-path parallel circuit capable of adjusting current proportion and a current adjusting method thereof, and relates to the technical field of linear constant current control. The circuit comprises a first constant current circuit, a second constant current circuit and a current adjusting circuit. The first constant current circuit and the second constant current circuit are connected in parallel. The reference end of the current adjusting circuit is connected with the output end of the first constant current circuit. The output end of the current adjusting circuit is connected with the output end of the second constant current circuit, and the output end of the current adjusting circuit is also connected with the reference end of the second constant current circuit. The current adjusting circuit is used for adjusting the current proportion of the first constant current circuit and the second constant current circuit. The application can adjust the current proportion of two parallel constant current circuits.

Description

Technical Field

[0001] This application relates to the field of linear constant current control technology, specifically to a dual-parallel circuit with an arbitrarily adjustable current ratio and its current regulation method. Background Technology

[0002] In linear LED driver applications, it is sometimes necessary to connect the outputs of two constant current circuits in parallel to provide a higher output current capability. However, in the current technical solution, two identical circuits are directly connected in parallel, with each circuit bearing half of the total load, making it impossible to control the current ratio borne by each circuit. Summary of the Invention

[0003] This invention provides a dual-parallel circuit with arbitrarily adjustable current ratio and a current adjustment method thereof, which can adjust the current ratio of two parallel constant current circuits to any value.

[0004] The present invention provides a dual-parallel circuit with an adjustable current ratio, comprising: a first constant current circuit, a second constant current circuit, and a current adjustment circuit;

[0005] The first constant current circuit and the second constant current circuit are connected in parallel. The reference terminal of the current regulating circuit is connected to the output terminal of the first constant current circuit. The output terminal of the current regulating circuit is connected to the output terminal of the second constant current circuit, and the output terminal of the current regulating circuit is also connected to the reference terminal of the second constant current circuit. The current regulating circuit is used to adjust the current ratio of the first constant current circuit and the second constant current circuit.

[0006] Optionally, the current regulation circuit includes a current mirror.

[0007] Optionally, the difference coefficient of the current mirror is 1:K, where K is a preset value, and the difference coefficient is used to adjust the current ratio of the first constant current circuit and the second constant current circuit.

[0008] Optionally, the first constant current circuit includes a first power transistor, a first operational amplifier, a first reference voltage, and a resistor; the first operational amplifier is used to adjust the current of the first power transistor so that the current of the first power transistor is equal to the ratio of the first reference voltage to the resistor.

[0009] Optionally, the second constant current circuit includes a second power transistor, a second operational amplifier, a second reference voltage, and the resistor; the second operational amplifier is used to adjust the current of the second power transistor so that the current of the second power transistor is equal to the ratio of the second reference voltage to the resistor.

[0010] Optionally, the current mirror includes a first MOSFET and a second MOSFET.

[0011] The present invention also provides a current regulation method, wherein the method applies the aforementioned dual-path parallel circuit with arbitrarily adjustable current ratio, and the method includes:

[0012] The current regulation circuit obtains the output current of the first constant current circuit and the second constant current circuit.

[0013] The output current of the first constant current circuit and the second constant current circuit are adjusted according to the preset adjustment coefficient in the current adjustment circuit.

[0014] Optionally, the preset adjustment coefficient includes the difference coefficient of the current mirror.

[0015] This invention provides a dual-parallel circuit with arbitrarily adjustable current ratio, comprising: a first constant current circuit, a second constant current circuit, and a current regulating circuit; the current regulating circuit has a preset adjustment coefficient; the first and second constant current circuits are connected in parallel, the reference terminal of the current regulating circuit is connected to the output terminal of the first constant current circuit; the output terminal of the current regulating circuit is connected to the output terminal of the second constant current circuit, and the output terminal of the current regulating circuit is also connected to the reference terminal of the second constant current circuit; the current regulating circuit is used to adjust the current ratio of the first and second constant current circuits. In other words, this invention, by setting up a current regulating circuit, can achieve arbitrary current ratio adjustment for two parallel constant current circuits. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of a dual-parallel circuit structure with an adjustable current ratio provided by the present invention.

[0018] Figure 2 These are the Bode plots of the first and second control loops provided by this invention;

[0019] Figure 3 This is a schematic diagram showing the relationship between the current ratio of the first constant current circuit and the second constant current circuit provided by the present invention and K.

[0020] Figure 4 This is a flowchart of the current regulation method provided by the present invention. Detailed Implementation

[0021] The purpose of this invention is to provide a dual-parallel circuit with an adjustable current ratio and a current regulation method thereof, which allows the current flowing through each of the two parallel paths to be arbitrarily set while keeping the total output current constant, thereby meeting various special working conditions or requirements.

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] A typical constant current circuit consists of an operational amplifier, a power NMOS transistor, and a resistor R. The resistor is connected in series with the source of the NMOS transistor, and the other end of the resistor is grounded. The negative input of the operational amplifier is connected to the source of the NMOS transistor, the positive input is connected to the reference voltage vref, and the output is connected to the control terminal of the NMOS transistor. Through the above connection relationship, a constant current circuit is formed. The output current of the constant current circuit is equal to the reference voltage vref divided by the resistor R. To output different currents, the resistor R or the vref voltage can be changed.

[0024] In this way, the outputs of the two constant current circuits can be directly connected in parallel without affecting each other, and the total output current is equal to the sum of the two. Based on the above principle, this invention adds a current regulation circuit. The two inputs of the regulation circuit are the sampling signals of the output currents of the first and second constant current circuits, respectively. The sampling ratios can be the same or different. The current regulation circuit calculates the difference between the sampled currents and outputs it to the reference terminal of the second constant current circuit. By using the difference coefficient of the current regulation circuit, arbitrary control of the ratio of the output currents of the first and second constant current circuits can be achieved.

[0025] The following is combined Figures 1-4 This invention describes a dual-parallel circuit with arbitrarily adjustable current ratio and its current regulation method.

[0026] Figure 1 This is a schematic diagram of a dual-path parallel circuit structure with adjustable current ratio provided by the present invention, as shown below. Figure 1 As shown, a dual-parallel circuit with an adjustable current ratio includes: a first constant current circuit, a second constant current circuit, and a current regulation circuit.

[0027] The first constant current circuit and the second constant current circuit are connected in parallel. The reference terminal of the current regulating circuit is connected to the output terminal of the first constant current circuit. The output terminal of the current regulating circuit is connected to the output terminal of the second constant current circuit, and the output terminal of the current regulating circuit is also connected to the reference terminal of the second constant current circuit. The current regulating circuit is used to adjust the current ratio of the first constant current circuit and the second constant current circuit.

[0028] This invention adds a current regulation circuit to the traditional constant current circuit. The figure shows two identical constant current circuits (the first constant current circuit and the second constant current circuit) connected in parallel. The corresponding output currents are the first output current IOUT1 and the second output current IOUT2. They can be directly connected together or separately connected to different load terminals. The sum of the first output current IOUT1 and the second output current IOUT2 ​​is constant and equal to the first reference voltage vref divided by the resistance Rs. The current regulation circuit needs to sample the current in the first power transistor P1 and the second power transistor P2 through the first sampling point and the second sampling point, respectively. The current regulation circuit can be a 1:K current mirror. The sampled current of the first power transistor P1 flows into the reference terminal of the current regulation circuit, and the sampled current of the second power transistor P2 flows into the output terminal of the current regulation circuit. Therefore, they will perform a difference operation at the output terminal of the current regulation circuit, and the result is equal to IOUT1*K – IOUT2. The output terminal is connected to the reference terminal of the second constant current circuit. The voltage of this reference terminal is denoted as the second reference voltage vrefx. The current regulation circuit and the second constant current circuit together constitute the second control loop, and the first constant current circuit becomes the first control loop. The output of the current regulation circuit controls the reference terminal of the second control loop to adjust the current ratio in the first constant current circuit and the second constant current circuit. The first control loop is used to set the total current. Figure 2 The diagram shows the loop bandwidth relationship between the second control loop and the first control loop when they are working simultaneously. It can be seen from the figure that the feature of this invention is that the bandwidth of the second control loop is much smaller than that of the first control loop. This ensures the stability of the overall loop and allows for free setting of the current ratio between the two loops.

[0029] In one specific embodiment, the current regulation circuit includes a current mirror.

[0030] In one specific embodiment, the difference coefficient of the current mirror is 1:K (i.e., the coefficient on one side is 1, and the coefficient on the other side is K), where K is a preset value. The difference coefficient is used to adjust the current ratio of the first constant current circuit and the second constant current circuit. The relationship between the current ratio of the first constant current circuit and the second constant current circuit and K is as follows: Figure 3 As shown.

[0031] In one specific embodiment, the first constant current circuit includes a first power transistor P1, a first operational amplifier A1, a first reference voltage vref1, and a resistor Rs; the first operational amplifier A1 is used to adjust the current of the first power transistor P1 so that the current of the first power transistor P1 is equal to the ratio of the first reference voltage vref1 to the resistor Rs.

[0032] In one specific embodiment, the second constant current circuit includes a second power transistor P2, a second operational amplifier A2, a second reference voltage vref2, and the resistor Rs; the second operational amplifier A2 is used to adjust the current of the second power transistor P2 so that the current of the second power transistor P2 is equal to the ratio of the second reference voltage vref2 and the resistor Rs.

[0033] In one specific embodiment, the current mirror includes a first MOSFET M1 and a second MOSFET M2.

[0034] The present invention also discloses the following technical effects:

[0035] When one of the constant current circuits is insufficient to provide the corresponding current (such as insufficient voltage margin, open circuit, or other unexpected situations), the other circuit can supplement the insufficient part to ensure that the total output current is constant.

[0036] In this invention, when both constant current circuits can provide sufficient current, the current ratio is determined by a preset ratio.

[0037] In practical applications, this invention allows one of the first and second control loops to be used as the main path and the other as the auxiliary path. Under normal circumstances, the main path carries most of the current and can be a path with good heat dissipation and high precision. When the power supply voltage changes, the temperature changes, or other abnormal conditions occur, the auxiliary path can serve as a supplementary output.

[0038] The current regulation method provided by the present invention is described below. The current regulation method described below can be referred to in correspondence with the dual parallel circuit with arbitrarily adjustable current ratio described above.

[0039] A current regulation method, such as Figure 4 As shown, it includes:

[0040] Step 401: Obtain the output current of the first constant current circuit and the second constant current circuit.

[0041] Step 402: Adjust the output current of the first constant current circuit and the second constant current circuit according to the current adjustment circuit.

[0042] In one specific embodiment, the output current of the first constant current circuit and the second constant current circuit is adjusted according to the difference coefficient of the current mirror.

[0043] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0044] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dual-channel parallel circuit with an adjustable current ratio, characterized in that, include: The circuit consists of a first constant current circuit, a second constant current circuit, and a current regulation circuit. The first constant current circuit and the second constant current circuit are connected in parallel. The reference terminal of the current regulating circuit is connected to the output terminal of the first constant current circuit. The output terminal of the current regulating circuit is connected to the output terminal of the second constant current circuit, and the output terminal of the current regulating circuit is also connected to the reference terminal of the second constant current circuit. The reference terminal of the current regulating circuit refers to the input terminal of the current regulating circuit. The first constant current circuit includes a first power transistor. The second constant current circuit includes a second power transistor, a second operational amplifier, and a second resistor. The first terminal of the second resistor is grounded, and the second terminal of the second resistor serves as the reference terminal of the second constant current circuit and is connected to the non-inverting input of the second operational amplifier. The current regulating circuit is used to adjust the current ratio of the first constant current circuit and the second constant current circuit so that the total output current of the dual-path parallel circuit is constant. The current regulating circuit includes a current mirror with a difference coefficient of 1:K, where K is a preset value. The difference coefficient is used to adjust the current ratio of the first constant current circuit and the second constant current circuit. The sampling current IOUT1 of the first power transistor of the first constant current circuit flows into the reference terminal of the current regulating circuit, and the sampling current IOUT2 ​​of the second power transistor of the second constant current circuit flows into the output terminal of the current regulating circuit. Thus, the difference operation IOUT1 * K – IOUT2 ​​is performed at the output terminal of the current regulating circuit. The bandwidth of the second control loop formed by the second constant current circuit and the current regulating circuit is less than the bandwidth of the first control loop formed by the first constant current circuit.

2. The dual-channel parallel circuit with arbitrarily adjustable current ratio according to claim 1, characterized in that, The first constant current circuit further includes a first operational amplifier and a first resistor. The first end of the first resistor is grounded, and the second end of the first resistor provides a first reference voltage and is connected to the non-inverting input terminal of the first operational amplifier. The first operational amplifier is used to adjust the current of the first power transistor so that the current of the first power transistor is equal to the ratio of the first reference voltage to the first resistor.

3. The dual-channel parallel circuit with arbitrarily adjustable current ratio according to claim 1, characterized in that, The second terminal of the second resistor provides a second reference voltage, and the second operational amplifier is used to adjust the current of the second power transistor so that the current of the second power transistor is equal to the ratio of the second reference voltage to the second resistor.

4. The dual-channel parallel circuit with arbitrarily adjustable current ratio according to claim 1, characterized in that, The current mirror includes a first MOSFET and a second MOSFET.

5. A current regulation method, characterized in that, The method employs the dual-path parallel circuit with arbitrarily adjustable current ratio as described in any one of claims 1-4, and the method includes: Obtain the output current of the first constant current circuit and the second constant current circuit; The output current of the first constant current circuit and the second constant current circuit is adjusted according to the current adjustment circuit.

6. The current regulation method according to claim 5, characterized in that, The adjustment of the output current of the first constant current circuit and the second constant current circuit according to the current adjustment circuit includes: The output current of the first constant current circuit and the second constant current circuit are adjusted according to the difference coefficient of the current mirror.

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