阅读说明：本技术 一种可调微安级恒流源电路、激发光源及其控制方法 (Adjustable microampere constant current source circuit, excitation light source and control method thereof ) 是由 王君 张文松 于 2021-07-09 设计创作，主要内容包括：本发明属于激发光源控制电路及控制方法,为解决广泛应用的恒流源输出电流较大,操作困难,导致无法满足高精度和高可靠性的要求,精度更高的脉冲恒流源价格昂贵、电路结构复杂的问题,提供一种可调微安级恒流源电路、激发光源及其控制方法,包括运算放大器A、场效应管T和采样电阻R3,运算放大器A的同相输入端与外部单片机的DAC模块相连,运算放大器A的使能端与外部单片机相连,场效应管T的栅极与运算放大器A的输出端相连,源极与运算放大器A的反相输入端相连,漏极与待调节部件相连,采样电阻R3的一端与供电电源相连,另一端连接于场效应管T的源极和运算放大器A的反相输入端之间,激发光源即将外部待调节部件换为LED灯。(The invention belongs to an excitation light source control circuit and a control method, and aims to solve the problems that the widely used constant current source has larger output current, is difficult to operate, cannot meet the requirements of high precision and high reliability, and has higher precision, and a pulse constant current source has high price and a complex circuit structure, and provides an adjustable microampere constant current source circuit, an excitation light source and a control method thereof, wherein the adjustable microampere constant current source circuit comprises an operational amplifier A, a field-effect tube T and a sampling resistor R3, the non-inverting input end of the operational amplifier A is connected with a DAC module of an external singlechip, the enabling end of the operational amplifier A is connected with the external singlechip, the grid electrode of the field-effect tube T is connected with the output end of the operational amplifier A, the source electrode is connected with the inverting input end of the operational amplifier A, the drain electrode is connected with a part to be adjusted, one end of the sampling resistor R3 is connected with a power supply, the other end is connected between the source electrode of the field-effect tube T and the inverting input end of the operational amplifier A, the excitation light source is to replace the external part to be regulated into an LED lamp.)

1. An adjustable microampere constant current source circuit is characterized in that: the device comprises an operational amplifier A, a field effect transistor T and a sampling resistor R3;

the non-inverting input end of the operational amplifier A is connected with a DAC module of an external singlechip and used for receiving the adjustable voltage of the DAC module; the enabling end of the operational amplifier A is connected with an external singlechip and is used for receiving a high-level or low-level control signal sent by the singlechip;

the grid electrode of the field effect tube T is connected with the output end of the operational amplifier A, the source electrode of the field effect tube T is connected with the inverting input end of the operational amplifier A, and the drain electrode of the field effect tube T is connected with an external component to be regulated;

one end of the sampling resistor R3 is connected with a power supply, and the other end is connected with the source electrode of the field effect transistor T.

2. The adjustable microampere-level constant current source circuit of claim 1, wherein: also included is a capacitor C1;

one end of the capacitor C1 is connected with a power supply, and the other end is connected with the non-inverting input end of the operational amplifier A.

3. The adjustable microampere-level constant current source circuit of claim 1, wherein: also included is a resistor R1;

one end of the resistor R1 is connected with a power supply, and the other end is connected with the enabling end of the operational amplifier A.

4. The adjustable microampere-level constant current source circuit of claim 1, wherein: also included is a capacitor C2;

one end of the capacitor C2 is grounded, and the other end is connected to the power supply end of the operational amplifier.

5. The adjustable microampere-level constant current source circuit of claim 1, wherein: also included is a resistor R4;

one end of the resistor R4 is connected with a power supply, and the other end is connected with the output end of the operational amplifier A.

6. An excitation light source, comprising: comprising an LED lamp, and the adjustable microampere-level constant current source circuit of any one of claims 1-5;

the anode of the LED lamp is connected with the drain electrode of the field effect tube T in the adjustable microampere constant current source circuit, and the cathode of the LED lamp is grounded.

7. An excitation light source according to claim 6, wherein: also included is a resistor R2;

the resistor R2 is connected in parallel with the LED lamp.

8. A method for controlling an excitation light source according to claim 6 or 7, comprising the steps of:

s1, sending a high level signal or a low level signal to the enable end of the operational amplifier A through the external singlechip, and if sending the low level signal, simultaneously inputting a voltage U to the non-inverting input end of the operational amplifier A through the DAC module of the external singlechip_DACStep S2 is executed; if a high-level signal is sent, no signal is transmitted between a DAC (digital-to-analog converter) module of the external single chip and the non-inverting input end of the operational amplifier A, and the LED lamp is in a light-off state;

s2, controlling the input voltage U from the DAC module of the external single chip to the non-inverting input terminal of the operational amplifier A_DACThe control of the power supply current of the LED lamp is realized; the current of the LED lamp is equal to the current of the field effect transistor T, and the current I of the field effect transistor T is (U-U)_DAC) and/R3, wherein U is a power supply voltage.

Technical Field

The invention belongs to an excitation light source control circuit and a control method, and particularly relates to an adjustable microampere constant current source circuit, an excitation light source and a control method thereof.

Background

At present, the output current of the widely-used constant current source is large, the current needs to be adjusted by using a knob when being adjusted, the adjustment value is not fixed every time, so that the operation is difficult, and the constant current source cannot meet the requirements of high precision and high reliability when a system is tested. The pulse constant current source with higher precision in the market generally controls the MOS tube by the output PWM of the microcontroller, and is often expensive and complicated in circuit structure.

Disclosure of Invention

The invention provides an adjustable microampere constant current source circuit, an excitation light source and a control method thereof, aiming at solving the technical problems that the requirements of high precision and high reliability cannot be met due to large output current and difficult operation of the existing widely-used constant current source, and a pulse constant current source with higher precision is expensive and has a complex circuit structure.

In order to achieve the purpose, the invention provides the following technical scheme:

an adjustable microampere constant current source circuit is characterized by comprising an operational amplifier A, a field effect transistor T and a sampling resistor R3;

the non-inverting input end of the operational amplifier A is connected with a DAC module of an external singlechip and used for receiving the adjustable voltage of the DAC module; the enabling end of the operational amplifier A is connected with an external singlechip and is used for receiving a high-level or low-level control signal sent by the singlechip;

the grid electrode of the field effect tube T is connected with the output end of the operational amplifier A, the source electrode of the field effect tube T is connected with the inverting input end of the operational amplifier A, and the drain electrode of the field effect tube T is connected with an external component to be regulated;

one end of the sampling resistor R3 is connected with a power supply, and the other end is connected with the source electrode of the field effect transistor T.

Further, a capacitor C1 may also be included; one end of the capacitor C1 is connected with the power supply, and the other end of the capacitor C1 is connected with the non-inverting input end of the operational amplifier A and is used for filtering the input voltage signal of the DAC module of the singlechip.

Further, a resistor R1 may also be included; one end of the resistor R1 is connected with a power supply, and the other end of the resistor R1 is connected with the enabling end of the operational amplifier A, so that the resistor R1 can be used as a pull-up resistor, and when the operational amplifier A is electrified, misoperation caused by unstable voltage is avoided.

Further, a capacitor C2 may be included as a decoupling capacitor of the operational amplifier a; one end of the capacitor C2 is grounded, and the other end is connected to the power supply end of the operational amplifier a.

Further, the device also comprises a resistor R4; one end of the resistor R4 is connected with a power supply, the other end of the resistor R4 is connected with the output end of the operational amplifier A, the resistor R4 and the resistor R1 have similar functions and can be used as a pull-up resistor, and when the operational amplifier A is electrified, misoperation caused by unstable voltage is avoided.

The invention also provides an excitation light source which is characterized by comprising an LED lamp and the adjustable microampere constant current source circuit;

the anode of the LED lamp is connected with the drain electrode of the field effect tube T in the adjustable microampere constant current source circuit, and the cathode of the LED lamp is grounded.

Further, the excitation light source further comprises a resistor R2; the resistor R2 is connected with the LED lamp in parallel to suppress the dark current of the LED lamp.

In addition, the present invention also provides a method for controlling the excitation light source, which is characterized by comprising the following steps:

s1, sending a high level signal or a low level signal to the enable end of the operational amplifier A through the external singlechip, and if sending the low level signal, simultaneously inputting a voltage U to the non-inverting input end of the operational amplifier A through the DAC module of the external singlechip_DACStep S2 is executed; if a high-level signal is sent, no signal is transmitted between a DAC (digital-to-analog converter) module of the external single chip and the non-inverting input end of the operational amplifier A, and the LED lamp is in a light-off state;

s2, controlling the input voltage U from the DAC module of the external single chip to the non-inverting input terminal of the operational amplifier A_DACThe control of the power supply current of the LED lamp is realized; the current of the LED lamp is equal to the current of the field effect transistor T, and the current I of the field effect transistor T is (U-U)_DAC) and/R3, wherein U is a power supply voltage.

Compared with the prior art, the invention has the beneficial effects that:

1. the adjustable microampere constant current source circuit sends a high level signal or a low level signal through the enabling end of the operational amplifier A, realizes a pulse constant current source or a direct current constant current source, controls the working state of the whole circuit and controls whether an external part to be adjusted works or not according to the working state; according to the input of the external single chip microcomputer DAC module, the adjustable voltage is controlled, so that the output current is adjusted with high precision, and the output current of microampere level can be output. The circuit of the invention has simple structure, easy realization and low manufacturing cost.

2. The invention also comprises a capacitor C1 which can filter the voltage signal sent by the external singlechip DAC module to the operational amplifier A.

3. The invention also comprises a resistor R1 as a pull-up resistor, which can avoid malfunction caused by unstable voltage when the circuit is powered on.

4. The invention also comprises a capacitor C2 which can be used as a decoupling capacitor of the operational amplifier A to avoid causing parasitic oscillation.

5. The invention also comprises a resistor R4 which has the same function as the resistor R1 and is used as a pull-up resistor, so that misoperation caused by unstable voltage when the circuit is electrified can be avoided.

6. The excitation light source can effectively realize the on-off control of the LED lamp in the excitation light source by utilizing the adjustable microampere constant current source circuit, can control the brightness of the LED lamp through microampere current output of the constant current source circuit, and ensures the precision and the reliability of the excitation light source at higher cost performance through a simple circuit structure.

7. The LED lamp also comprises a resistor R2, so that the dark current of the LED lamp can be suppressed.

8. The invention also provides a control method of an excitation light source, based on the adjustable microampere constant current source circuit, the excitation light source is controlled, the external singlechip sends a high-level or low-level signal to the enabling end of the operational amplifier A to control the on and off of the LED and the like, and the external singlechip DAC module is controlled to input voltage U of the non-inverting input end of the operational amplifier A_DACThe LED lamp can be controlled by using the mode of controlling the enabling end of the operational amplifier A, the reliability is higher, and microampere can be realized under high precisionAnd controlling the stage current.

Drawings

Fig. 1 is a schematic circuit diagram of an excitation light source according to an embodiment of the invention.

Detailed Description

The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention and the accompanying drawings, and it is obvious that the described embodiments do not limit the present invention.

As shown in fig. 1, the present invention provides an excitation light source, which controls an LED lamp by using the adjustable microampere-level constant current source circuit of the present invention, and the following describes a specific embodiment of the present invention by using an embodiment of the excitation light source of the present invention:

as shown in fig. 1, an excitation light source includes an operational amplifier a, a field effect transistor T, a sampling resistor R3, a capacitor C1, a resistor R1, a capacitor C2, a resistor R2, and a resistor R4. Wherein, the pin No. 3 of the non-inverting input end of the operational amplifier A is connected with the DAC module of the external singlechip for receiving the adjustable voltage of the DAC module, the voltage can be adjusted by digital, the pin No. 8 of the enable end of the operational amplifier A is connected with the external singlechip for receiving the high level or low level control signal sent by the singlechip, one end of a capacitor C1 for filtering is connected with a power supply, the other end is connected between the non-inverting input end of the operational amplifier A and the DAC module, one end of a resistor R1 used as a pull-up resistor is connected with the power supply, the other end is connected between the enable end of the operational amplifier A and the external singlechip, when the power is on, the misoperation caused by unstable voltage is avoided, one end of a capacitor C2 used as a decoupling capacitor of the operational amplifier A is grounded, the other end is connected between the pin No. 7 of the operational amplifier A and the power supply, one end of a resistor R4 used as a pull-up resistor is connected with the power supply, the other end of the operational amplifier A is connected between the output end of the operational amplifier A and the grid electrode of the field effect transistor T, the No. 1 pin and the No. 5 pin of the operational amplifier A are empty pins, and the No. 4 pin is grounded. The grid electrode of the field effect transistor T is connected with the pin No. 6 of the output end of the operational amplifier A, the source electrode of the field effect transistor T is connected with the pin No. 2 of the inverting input end of the operational amplifier A, and the drain electrode of the field effect transistor T is connected with the LED lamp. One end of the sampling resistor R3 is connected with a power supply, and the other end is connected between the source electrode of the field effect transistor T and the inverting input end of the operational amplifier A.

The excitation light source is an adjustable microampere constant current source circuit which controls the change of current through voltage and is suitable for the condition that the system has higher requirements on the output current and the precision. In another embodiment of the constant current source circuit of the present invention, the capacitor C1, the resistor R1, the capacitor C2 and the resistor R4 may be configured according to actual use requirements, and specific parameter values thereof may be adjusted as needed. In another embodiment of the excitation light source of the present invention, a resistor R2 may be connected in parallel with the LED lamp for suppressing the dark current of the LED lamp.

The invention adopts a field effect transistor T, so that the voltage control current is easier to realize, when the No. 8 pin of the operational amplifier A is in a low level, the operational amplifier A is used as a voltage follower (isolating front and back ends), at the moment, the voltage of the No. 3 pin at the non-inverting input end of the operational amplifier A is equal to the voltage of the No. 2 pin at the inverting input end of the operational amplifier A, and the current I at the field effect transistor T is equal to (U-U)_DAC) and/R3, wherein U is a power supply voltage. The DAC module of the external single chip microcomputer inputs adjustable voltage control current I, so that a voltage-controlled constant current source is realized, the external single chip microcomputer controls the No. 8 pin with high and low levels, the LED lamp is controlled to be on or off, a pulse constant current source can be realized, and if the external single chip microcomputer enables the No. 8 pin to be always at the low level, a direct current constant current source can be realized. The specific control method comprises the following steps:

step 1: sending a high level signal or a low level signal to an enabling end of the operational amplifier A through an external single chip microcomputer, and simultaneously inputting a voltage U to a non-inverting input end of the operational amplifier A through a DAC (digital-to-analog converter) module of the external single chip microcomputer if the high level signal or the low level signal is sent_DACStep S2 is executed; if a high-level signal is sent, no signal is transmitted between a DAC (digital-to-analog converter) module of the external single chip and the non-inverting input end of the operational amplifier A, and the LED lamp is in a light-off state;

step 2: negative feedback is formed between the source electrode of the field effect transistor T and the inverting input end of the operational amplifier A, so that the operational amplifierA is used as a voltage follower to isolate the front end and the back end of the voltage follower, and the current I at the field effect tube T is equal to (U-U)_DAC)/R3；

And step 3: the current of the LED lamp is equal to that of the field effect tube T, and the input voltage U from the DAC module of the external singlechip to the non-inverting input end of the operational amplifier A is controlled_DACAnd the LED lamp is controlled.

An example of the use of the present invention is as follows:

the digital/analog converter in the external single chip microcomputer can convert 12-bit digital data into voltage 3.3V for output, if U (i.e. VCC) is 5V, R3 is 10 Ω, when the DAC module inputs 3.3V, the constant current source outputs current: i ═ 0.17A, (5-3.3)/10A; the adjustable precision of the DAC module is as follows:

3.3/4095V is 0.00080586V, and the adjustable current precision is as follows: 0.00080586/R3-0.000080586A-0.080586 mA. Therefore, by selecting a proper DAC module and R3 resistance, the adjustable constant current source with higher precision can be realized.

The above description is only an embodiment of the present invention, and is not intended to limit the scope of the present invention, and all equivalent structural changes made by using the contents of the present specification and the drawings, or applied directly or indirectly to other related technical fields, are included in the scope of the present invention.