Precise current source circuit

Abstract

The utility model discloses a precise current source circuit which comprises a first operational amplifier U2 and a first operational amplifier U3. The positive input end of the first operational amplifier U2 is connected with a resistor R6, and the resistor R6 is connected with an INPUT port; the output end of the first operational amplifier U2 is connected with a resistor R3 and a resistor R7; the resistor R7 is connected with the output port; the resistor R3 is connected with the negative input end of the first operational amplifier U2 and the resistor R2, and the resistor R2 is grounded; the positive input end of the first operational amplifier U3 is respectively connected with a resistor R7 and an output port; the output end of the first operational amplifier U3 is connected with a resistor R9 and the negative input end of the first operational amplifier U3; the resistor R9 is connected with the positive input end of the first operational amplifier U2 and the resistor R6; the power supply positive input end of the first operational amplifier U3 is connected with the positive electrode of a 12V power supply and the positive electrode of a capacitor C7, and the negative electrode of a capacitor C3 is grounded. The resistor R6, the resistor R2, the resistor R3 and the resistor R9 are configured to be consistent in resistance value. The circuit can output constant high-precision current.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit structures, in particular to a precision current source circuit. Background Art

[0002] With the rapid development of electronic products, performance requirements are becoming increasingly stringent. Consequently, the circuits in these products are becoming increasingly sophisticated. These precision circuits often require a constant, high-precision current to meet their operational needs. Therefore, developing a new power supply circuit structure capable of delivering a constant, high-precision current to meet the operational requirements of these precision circuits is a topic of considerable research interest for those skilled in the art. Utility Model Content

[0003] The purpose of the utility model is to provide a precision current source circuit that can be used to output a constant high-precision current to meet the working requirements of the precision circuit.

[0004] The utility model discloses a precision current source circuit, which includes:

[0005] A first operational amplifier U2, wherein the positive input terminal of the first operational amplifier U2 is connected to one end of a resistor R6, and the other end of the resistor R6 is connected to the INPUT port; the output terminal of the first operational amplifier U2 is connected to one end of a resistor R3 and one end of a resistor R7; the other end of the resistor R7 is connected to the output port; the other end of the resistor R3 is respectively connected to the negative input terminal of the first operational amplifier U2 and one end of the resistor R2, and the other end of the resistor R2 is grounded; the positive power input terminal of the first operational amplifier U2 is respectively connected to the positive electrode of a 12V power supply and the positive electrode of a capacitor C3, and the negative electrode of the capacitor C3 is grounded; the negative power input terminal of the first operational amplifier U2 is respectively connected to the negative electrode of a 12V power supply and the positive electrode of a capacitor C9, and the negative electrode of the capacitor C9 is grounded;

[0006] A first operational amplifier U3, wherein the positive input terminal of the first operational amplifier U3 is respectively connected to the other end of the resistor R7 and the output port; the output terminal of the first operational amplifier U3 is connected to one end of the resistor R9 and the negative input terminal of the first operational amplifier U3; the other end of the resistor R9 is respectively connected to the positive input terminal of the first operational amplifier U2 and one end of the resistor R6; the positive power input terminal of the first operational amplifier U3 is respectively connected to the positive electrode of the 12V power supply and the positive electrode of the capacitor C7, and the negative electrode of the capacitor C3 is grounded; the negative power input terminal of the first operational amplifier U3 is respectively connected to the negative electrode of the 12V power supply and the positive electrode of the capacitor C12, and the negative electrode of the capacitor C9 is grounded;

[0007] The resistor R6 , the resistor R2 , the resistor R3 , and the resistor R9 are configured to have the same resistance value.

[0008] By adopting this technical solution, the first operational amplifier U2 amplifies the voltage inputted at the input terminal, while the first operational amplifier U3 provides negative feedback to the first operational amplifier U2. By configuring the resistors R6, R2, R3, and R9 to have the same resistance value, the current gain outputted at the OUTPUT terminal of this circuit is simplified to I = Vinput / R7. Therefore, the resistance value of the corresponding resistor R7 can be adjusted according to the rated voltage at the ITPUT terminal, thereby achieving a constant, high-precision output current to meet the operating requirements of precision circuits.

[0009] Preferably, the first operational amplifier U2 and the first operational amplifier U3 are respectively HT1177 amplifiers.

[0010] Preferably, the resistance values ​​of the resistor R6 , the resistor R2 , the resistor R3 , and the resistor R9 are all configured to be 1 KΩ.

[0011] Preferably, the capacitor C3, the capacitor C9, the capacitor C7, and the constant capacitor C12 are configured to have the same capacitance.

[0012] Preferably, the capacitance of the capacitor C3, the capacitor C9, the capacitor C7, and the constant capacitor C12 are all configured to be 0.1 μF.

[0013] Compared with the existing technology, the utility model has the following technical advantages:

[0014] By constructing a specific negative feedback op amp loop and selecting a specific load resistor value, the utility model makes the output current I of the OUTPUT terminal equal to Vinput / R7. Therefore, the resistance value of R7 can be determined according to the load requirements and the maximum output load capacity of the HT1177. That is, by adjusting the specific resistance value of R7, a constant high-precision current can be obtained to meet the working requirements of the precision circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a structural diagram of Example 1. DETAILED DESCRIPTION

[0016] The embodiments of the present application will be described in detail with specific examples below, and other advantages and effects of the present application can be easily understood by those skilled in the art from the disclosure of the present application. The present application can also be implemented or applied in other different specific embodiments, and various modifications or changes can be made to the details in the specification without departing from the spirit of the present application.

[0017] Embodiment 1, please refer to Figure 1 :

[0018] A precise current source circuit comprises:

[0019] The positive input end of the first operational amplifier U2 is connected to one end of the resistor R6, and the other end of the resistor R6 is connected to the INPUT port; the output end of the first operational amplifier U2 is connected to one end of the resistor R3 and one end of the resistor R7; the other end of the resistor R7 is connected to the output port; the other end of the resistor R3 is respectively connected to the negative input end of the first operational amplifier U2 and one end of the resistor R2, and the other end of the resistor R2 is grounded; the power supply positive input end of the first operational amplifier U2 is respectively connected to the positive pole of the 12V power supply and the positive pole of the capacitor C3, and the negative pole of the capacitor C3 is grounded; the power supply negative input end of the first operational amplifier U2 is respectively connected to the negative pole of the 12V power supply and the positive pole of the capacitor C9, and the negative pole of the capacitor C9 is grounded;

[0020] The positive input end of the first operational amplifier U3 is respectively connected to the other end of the resistor R7 and the output port; the output end of the first operational amplifier U3 is connected to one end of the resistor R9 and the negative input end of the first operational amplifier U3; the other end of the resistor R9 is respectively connected to the positive input end of the first operational amplifier U2 and one end of the resistor R6; the power supply positive input end of the first operational amplifier U3 is respectively connected to the positive pole of the 12V power supply and the positive pole of the capacitor C7, and the negative pole of the capacitor C3 is grounded; the power supply negative input end of the first operational amplifier U3 is respectively connected to the negative pole of the 12V power supply and the positive pole of the capacitor C12, and the negative pole of the capacitor C9 is grounded; in this example: the first operational amplifier U2 and the first operational amplifier U3 are selected as HT1177 amplifiers. The resistor R6, the resistor R2, the resistor R3 and the resistor R9 are configured to have the same resistance value, and each has a value of 1kΩ.

[0021] By adopting this technical scheme:

[0022] Based on the above current structure, the output current of the output end can be calculated by the following formula:

[0023] I=Vinput*(R9 / R6+R3*R9 / R2*R6) / (R7*(1+R9 / R6)

[0024] When the resistor R6 , the resistor R2 , the resistor R3 , and the resistor R9 are configured to have the same resistance value, the above formula is simplified to: I=Vinput / R7 .

[0025] Therefore, by adjusting the resistor R7 value according to the Vinput voltage, a constant and precise current value can be obtained at the OUTPUT terminal, meeting the working requirements of the corresponding precision circuit.

[0026] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they will still fall within the scope of protection of the present invention.

Claims

1. A precision current source circuit, characterized in that: include: A first operational amplifier U2, wherein a positive input terminal of the first operational amplifier U2 is connected to one end of a resistor R6, and the other end of the resistor R6 is connected to an INPUT port; The output end of the first operational amplifier U2 is connected to one end of the resistor R3 and one end of the resistor R7; the other end of the resistor R7 is connected to the output port; the other end of the resistor R3 is respectively connected to the negative input end of the first operational amplifier U2 and one end of the resistor R2, and the other end of the resistor R2 is grounded; the positive power input end of the first operational amplifier U2 is respectively connected to the positive electrode of the 12V power supply and the positive electrode of the capacitor C3, and the negative electrode of the capacitor C3 is grounded; the negative power input end of the first operational amplifier U2 is respectively connected to the negative electrode of the 12V power supply and the positive electrode of the capacitor C9, and the negative electrode of the capacitor C9 is grounded; A first operational amplifier U3, wherein the positive input terminal of the first operational amplifier U3 is respectively connected to the other end of the resistor R7 and the output port; the output terminal of the first operational amplifier U3 is connected to one end of the resistor R9 and the negative input terminal of the first operational amplifier U3; the other end of the resistor R9 is respectively connected to the positive input terminal of the first operational amplifier U2 and one end of the resistor R6; the positive power input terminal of the first operational amplifier U3 is respectively connected to the positive electrode of the 12V power supply and the positive electrode of the capacitor C7, and the negative electrode of the capacitor C3 is grounded; the negative power input terminal of the first operational amplifier U3 is respectively connected to the negative electrode of the 12V power supply and the positive electrode of the capacitor C12, and the negative electrode of the capacitor C9 is grounded; The resistor R6 , the resistor R2 , the resistor R3 , and the resistor R9 are configured to have the same resistance value.

2. The precision current source circuit according to claim 1, characterized in that: The first operational amplifier U2 and the first operational amplifier U3 are respectively HT1177 amplifiers.

3. The precision current source circuit according to claim 2, characterized in that: The resistance values ​​of the resistor R6 , the resistor R2 , the resistor R3 , and the resistor R9 are all configured to be 1 KΩ.

4. The precision current source circuit according to claim 3, characterized in that: The capacitor C3 , the capacitor C9 , the capacitor C7 , and the capacitor C12 are configured to have the same capacitance.

5. The precision current source circuit according to claim 4, characterized in that: The capacitance of the capacitor C3 , the capacitor C9 , the capacitor C7 , and the capacitor C12 are all configured to be 0.1 μF.

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