Constant current source circuit and constant current source device

Abstract

The utility model discloses a constant current source circuit and a constant current source device, and the constant current source circuit comprises a power module which is used for providing an input current; the voltage reference module comprises a voltage reference unit and a first feedback unit, the first feedback unit is connected to the voltage reference unit, the voltage reference unit is used for providing a reference voltage, and the first feedback unit is used for generating a first constant voltage according to the reference voltage; and the constant current module is connected to the power supply module and the first feedback unit, and the constant current module is used for converting the input current into a first constant current according to the first constant voltage. The voltage reference unit is adopted to generate the reference voltage, the first feedback unit is adopted to generate the constant first constant voltage according to the reference voltage, and the constant current module converts the input current provided by the power supply module into the first constant current according to the first constant voltage, so that the first constant current is only associated with the reference voltage; even if the circuit temperature changes or the load changes, stable constant current output can be maintained.

Description

Technical Field

[0001] The utility model relates to the technical field of circuits, in particular to a constant current source circuit and a constant current source device. Background Art

[0002] With the continuous development of electronic technology, constant current source output devices play an increasingly important role in the electronic field. A constant current source output device is a power supply device that can provide a constant current. It can maintain a stable output current under different load conditions, so it is widely used in many fields such as instruments, battery testing, and electronic measurement. In the existing constant current source devices, the output current is prone to drift at different temperatures, the output is very unstable, and it is relatively sensitive to load changes. When the load changes, it is easy to cause fluctuations in the output current, resulting in unstable current output and poor overall constant current effect. Summary of the Utility Model

[0003] Embodiments of the utility model provide a constant current source circuit and a constant current source device, which solve the problem of unstable constant current output of the existing constant current source device.

[0004] In a first aspect, embodiments of the utility model provide a constant current source circuit, which includes:

[0005] A power supply module for providing an input current;

[0006] A voltage reference module includes a voltage reference unit and a first feedback unit. The first feedback unit is connected to the voltage reference unit. The voltage reference unit is used to provide a reference voltage, and the first feedback unit is used to generate a first constant voltage according to the reference voltage.

[0007] A constant current module is connected to the power supply module and the first feedback unit. The constant current module is used to convert the input current into a first constant current according to the first constant voltage.

[0008] In the constant current source circuit provided by the embodiments of the utility model, the constant current module includes a second feedback unit and a precision resistor unit. The precision resistor unit is connected to the power supply module and the first feedback unit, and the second feedback unit is connected to the first feedback unit and the precision resistor unit. Wherein, the precision resistor unit is used to generate a feedback voltage according to the first constant voltage, and the second feedback unit is used to generate the first constant current according to the feedback voltage.

[0009] In the constant current source circuit provided by the embodiment of the present utility model, the second feedback unit includes a first operational amplifier and a first triode. The precision resistor unit includes at least one first precision resistor. One end of the first precision resistor is connected to the power supply module and the first feedback unit, and the other end is connected to the collector of the first triode and the inverting input terminal of the first operational amplifier. The non-inverting input terminal of the first operational amplifier is connected to the first feedback unit, and the output terminal is connected to the base of the first triode.

[0010] In the constant current source circuit provided by the embodiment of the present utility model, the precision resistor unit further includes at least one second precision resistor with a resistance value smaller than that of the first precision resistor. The second feedback unit further includes a first MOS transistor. One end of the second precision resistor is connected to the power supply module and the first feedback unit, and the other end is connected to the inverting input terminal of the first operational amplifier and the drain of the first MOS transistor. The gate of the first MOS transistor is connected to the output terminal of the first operational amplifier.

[0011] In the constant current source circuit provided by the embodiment of the present utility model, the constant current module further includes a first analog switch and a second analog switch. The input terminal of the first analog switch is connected to the first precision resistor and the second precision resistor, and the output terminal is connected to the inverting input terminal of the first operational amplifier. The input terminal of the second analog switch is connected to the base of the first triode and the gate of the first MOS transistor, and the output terminal is connected to the output terminal of the first operational amplifier.

[0012] In the constant current source circuit provided by the embodiment of the present utility model, there are multiple first precision resistors. The constant current module further includes a third analog switch. The input terminal of the third analog switch is connected to the multiple first precision resistors, and the output terminal of the third analog switch is connected to the inverting input terminal of the first operational amplifier.

[0013] In the constant current source circuit provided by the embodiment of the present utility model, the first feedback unit includes a second operational amplifier, a second triode, a sampling resistor, and a load resistor. The non-inverting input terminal of the second operational amplifier is connected to the voltage reference unit, the inverting input terminal is connected to the emitter of the second triode and one end of the sampling resistor, the output terminal is connected to the base of the second triode, the other end of the sampling resistor is grounded, the emitter of the second triode is connected to one end of the load resistor, the power supply module is connected to the other end of the load resistor, and the constant current module is connected between the collector of the second triode and the load resistor.

[0014] In the constant current source circuit provided by the embodiment of the present utility model, the voltage reference unit includes a voltage stabilizing chip and at least one voltage dividing resistor. One end of the voltage dividing resistor is connected to the voltage stabilizing chip, and the other end is grounded. The non-inverting input terminal of the second operational amplifier is connected between the voltage dividing resistor and the ground.

[0015] In the constant current source circuit provided by the embodiment of the present utility model, the constant current source circuit further includes a current output module. The current output module is connected to the constant current module. Wherein, the current output module is used to connect to a load to output the first constant current to the load for use.

[0016] In a second aspect, the embodiment of the present utility model further provides a constant current source device, and the constant current source device includes the constant current source circuit described in the first aspect above.

[0017] The embodiment of the present utility model provides a constant current source circuit and a constant current source device. The constant current source circuit includes a power supply module, a voltage reference module, and a constant current module. The power supply module is used to provide an input current. The voltage reference module includes a voltage reference unit and a first feedback unit. The first feedback unit is connected to the voltage reference unit. The voltage reference unit is used to provide a reference voltage, and the first feedback unit is used to generate a first constant voltage according to the reference voltage. The constant current module is connected to the power supply module and the first feedback unit. The constant current module is used to convert the input current provided by the power supply module into a first constant current according to the first constant voltage. The constant current source circuit provided by the embodiment of the present application uses a voltage reference unit to generate a reference voltage, and uses a first feedback unit to generate a constant first constant voltage according to the reference voltage. The constant current module then converts the input current provided by the power supply module into a first constant current according to the first constant voltage, so that the first constant current is only related to the reference voltage. Even if the circuit temperature changes or the load changes, a stable constant current output can be maintained. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained according to these drawings without creative efforts.

[0019] Figure 1 It is a structural block diagram of the constant current source circuit provided by the embodiment of the present utility model;

[0020] Figure 2 It is a structural block diagram of the constant current source circuit provided by the embodiment of the present utility model;

[0021] Figure 3The circuit diagram of the constant current source circuit provided by the embodiment of the present invention;

[0022] The reference signs in the figure are as follows:

[0023] 10. Power supply module; 20. Voltage reference module; 21. Voltage reference unit; 22. First feedback unit; 30. Constant current module; 31. Second feedback unit; 32. Precision resistor unit; 40. Current output module. Detailed implementation manners

[0024] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0025] The directional terms mentioned in the present invention, such as "upper", "lower", "front", "rear", "left", "right", "inner", "outer", "side", etc., are only with reference to the directions in the attached drawings. Therefore, the directional terms used are for explaining and understanding the present invention, rather than for limiting the present invention. In addition, in the drawings, structures that are similar or the same are denoted by the same reference signs.

[0026] Please refer to Figures 1 to 3 , the embodiment of the present invention shows a constant current source circuit. In this embodiment, the constant current source circuit includes a power supply module 10, a voltage reference module 20, and a constant current module 30; the power supply module 10 is used to provide an input current; the voltage reference module 20 includes a voltage reference unit 21 and a first feedback unit 22, the first feedback unit 22 is connected to the voltage reference unit 21, the voltage reference unit 21 is used to provide a reference voltage, and the first feedback unit 22 is used to generate a first constant voltage according to the reference voltage; the constant current module 30 is connected to the power supply module 10 and the first feedback unit 22, and the constant current module 30 is used to convert the input current into a first constant current according to the first constant voltage.

[0027] In specific implementation, the constant current source circuit can be used alone as a standard constant current source for a load, or can be used in combination with a resistance and capacitance measurement circuit, etc. In this embodiment, the constant current source circuit mainly consists of a power supply module 10, a voltage reference module 20, and a constant current module 30. The power supply module 10 serves as the voltage and current source of the constant current source circuit. The power supply module 10 provides an input current, such as Figure 3As shown, the power supply module 10 is specifically designed using a low-dropout linear regulator U7, which can provide a stable input current. The input current provided by the power supply module 10 serves as the current source for the constant current of the constant current source circuit, and the magnitude of the input current can be designed within a suitable range according to the actual requirements of the circuit. The voltage reference module 20 mainly consists of a voltage reference unit 21 and a first feedback unit 22. The first feedback unit 22 is connected to the voltage reference unit 21 and the constant current module 30. The voltage reference unit 21 is mainly used to provide a reference voltage for the first feedback unit 22, such as Figure 3 As shown, the voltage reference unit 21 is specifically designed using a voltage regulator chip U6 to provide a stable reference voltage, and the first feedback unit 22 is specifically an operational amplifier feedback circuit, which can generate a first constant voltage through feedback according to the reference voltage provided by the voltage reference unit 21. The constant current module 30 can convert the first constant voltage provided by the power supply module 10 into a first constant current according to the first constant voltage generated by the voltage reference module 20. That is, the constant current module 30 uses the first constant voltage generated by the voltage reference module 20 as a reference standard for current conversion, and converts the input current according to this standard to obtain the first constant current. The load is mainly connected to the constant current module 30 to use the first constant current. Since the reference voltage is a stable voltage provided by the voltage reference unit 21, the magnitude of the reference voltage directly determines the magnitude of the first constant voltage. Therefore, the magnitude of the first constant voltage is only related to the voltage reference unit 21. Only the impedance change of the voltage reference unit 21 itself will affect the input of the first feedback unit 22 and thus affect the first constant voltage. The change of the load or the temperature change will not affect the feedback function of the first feedback unit 22, and the first constant voltage remains constant. Then, the constant current module 30 converts the input current provided by the power supply module 10 into the first constant current according to the first constant voltage, which is constant, thereby effectively achieving constant current.

[0028] The constant current source circuit provided in this embodiment uses a voltage reference unit to generate a reference voltage, and uses a first feedback unit to generate a constant first constant voltage according to the reference voltage. The constant current module then converts the input current provided by the power supply module into the first constant current according to the first constant voltage, so that the first constant current is only related to the reference voltage and has nothing to do with the connected load. Even if the circuit temperature changes or the load changes, a stable constant current output can be maintained.

[0029] In one embodiment, referring to Figures 1 to 3, the voltage reference module 20 includes a voltage reference unit 21 and a first feedback unit 22. The first feedback unit 22 is connected to the voltage reference unit 21 and the constant current module 30. Among them, the voltage reference unit 21 is used to provide a reference voltage, and the first feedback unit 22 is used to generate the first constant voltage according to the reference voltage. In a specific implementation, the voltage reference module 20 is mainly composed of a voltage reference unit 21 and a first feedback unit 22. The first feedback unit 22 is connected to the voltage reference unit 21 and the constant current module 30. The voltage reference unit 21 is mainly used to provide a reference voltage for the first feedback unit 22, such as Figure 3 shown, the voltage reference unit 21 is specifically designed by using a voltage regulator chip U6 to provide a stable reference voltage, and the first feedback unit 22 is specifically an operational amplifier feedback circuit, which can generate a first constant voltage through a feedback effect according to the reference voltage provided by the voltage reference unit 21. Therefore, the magnitude of the first constant voltage is related to the voltage reference unit 21, and the magnitude of the reference voltage affects the magnitude of the first constant voltage. Therefore, by changing the reference voltage, the magnitude of the desired first constant voltage can be adjusted, and thus the purpose of adjusting the first constant current can be achieved.

[0030] Furthermore, referring to Figure 3, the first feedback unit 22 includes a second operational amplifier U2, a second triode Q2, a sampling resistor R2, and a load resistor R1. The non-inverting input terminal of the second operational amplifier U2 is connected to the voltage reference unit 21, the inverting input terminal is connected to the emitter of the second triode Q2 and one end of the sampling resistor R2, the output terminal is connected to the base of the second triode Q2, the other end of the sampling resistor R2 is grounded, the emitter of the second triode Q2 is connected to one end of the load resistor R1, the power supply module 10 is connected to the other end of the load resistor R1, and the constant current module 30 is connected between the collector of the second triode Q2 and the load resistor R1. In a specific implementation, the first feedback unit 22 is mainly composed of a second operational amplifier U2, a second triode Q2, a sampling resistor R2, and a load resistor R1. The non-inverting input terminal of the second operational amplifier U2 is connected to the voltage reference unit 21 mainly to receive a reference voltage. The inverting input terminal of the second operational amplifier U2 is connected to the emitter of the second triode Q2 and one end of the sampling resistor R2. The output terminal of the second operational amplifier U2 is connected to the base of the second triode Q2. The other end of the sampling resistor R2 is grounded. The emitter of the second triode Q2 is connected to one end of the load resistor R1. The power supply module 10 is connected to the other end of the load resistor R1. The constant current module 30 is connected between the collector of the second triode Q2 and the load resistor R1. Thus, the second operational amplifier U2, the second triode Q2, the sampling resistor R2, and the load resistor R1 jointly form a feedback network. The reference voltage is input to the non-inverting input terminal of the second operational amplifier U2 as a voltage reference, and a voltage equal to the reference voltage is generated on the sampling resistor R2. This voltage generates a current on the sampling resistor R2. According to the principle that the current is the same everywhere in a series circuit, since the load resistor R1 and the sampling resistor R2 are in series, the current passing through the feedback resistor is equal to the current passing through the sampling resistor R2. According to Ohm's law, the voltage across the load resistor R1 is equal to the current flowing through the load resistor R1 multiplied by the resistance value of the load resistor R1. The voltage across the load resistor R1 is the first constant voltage. Therefore, the first constant voltage is only affected by the reference voltage and has nothing to do with the load, avoiding the change of the first constant voltage caused by the change of the load. The constant current module 30 then converts the input current provided by the power supply module 10 into a first constant current according to the first constant voltage. As long as the first constant voltage remains unchanged, the first constant current will not change, thereby realizing constant current output.

[0031] Furthermore, referring to Figure 3 , the voltage reference unit 21 includes a voltage regulator chip U6 and at least one voltage dividing resistor. One end of the voltage dividing resistor is connected to the voltage regulator chip U6, and the other end is grounded. The non-inverting input terminal of the second operational amplifier U2 is connected between the voltage dividing resistor and the ground. In a specific implementation, the voltage reference unit 21 is composed of a voltage regulator chip U6 and at least one voltage dividing resistor. Multiple voltage dividing resistors can be set, such asFigure 3 As shown, resistors R10 to R12 serve as three voltage-dividing resistors. The voltage-dividing resistors are connected in series at the output end of voltage regulator chip U6. The input end of voltage regulator chip U6 is connected to the power supply. Voltage regulator chip U6 can output a stable voltage. After the voltage is divided by the voltage-dividing resistors, a reference voltage Vref is obtained. The reference voltage Vref is input to the non-inverting input end of the second operational amplifier U2 as the reference for feedback. By changing the resistance value of the voltage-dividing resistors, the magnitude of the reference voltage Vref can be changed, and the regulation of the first constant voltage can be achieved.

[0032] In one embodiment, referring to Figure 2 and Figure 3 , the constant current module 30 includes a second feedback unit 31 and a precision resistor unit 32. The precision resistor unit 32 is connected to the power supply module 10 and the first feedback unit 22, and the second feedback unit 31 is connected to the first feedback unit 22 and the precision resistor unit 32. Among them, the precision resistor unit 32 is used to generate a feedback voltage according to the first constant voltage, and the second feedback unit 31 is used to generate the first constant current according to the feedback voltage. In a specific implementation, the constant current module 30 is mainly composed of the second feedback unit 31 and the precision resistor unit 32. The precision resistor unit 32 is connected to the power supply module 10 and the first feedback unit 22, and the second feedback unit 31 is connected to the first feedback unit 22 and the precision resistor unit 32. The precision resistor unit 32 can generate a feedback voltage according to the first constant voltage generated by the first feedback unit 22. Here, the feedback voltage is the voltage obtained by the precision resistor unit 32 dividing the first constant voltage. The first feedback unit 22 is specifically a feedback circuit, and the first constant current is generated through the feedback action by the feedback voltage generated by the precision resistor unit 32 for the load to use.

[0033] Further, referring to Figure 3 , the second feedback unit 31 includes a first operational amplifier U1 and a first triode Q1. The precision resistor unit 32 includes at least one first precision resistor. One end of the first precision resistor is connected to the power supply module 10 and the first feedback unit 22, and the other end is connected to the collector of the first triode Q1 and the inverting input end of the first operational amplifier U1. The non-inverting input end of the first operational amplifier U1 is connected to the first feedback unit 22, and the output end is connected to the base of the first triode Q1. In a specific implementation, the second feedback unit 31 is mainly composed of the first operational amplifier U1 and the first triode Q1. The precision resistor unit 32 is composed of at least one first precision resistor. For example, Figure 3As shown, resistors R3 to R8 are all first precision resistors. One end of the first precision resistor is connected to the power supply module 10 and the first feedback unit 22, and the other end of the first precision resistor is connected to the collector of the first triode Q1 and the inverting input terminal of the first operational amplifier U1. The non-inverting input terminal of the first operational amplifier U1 is connected to the first feedback unit 22 to receive the first constant voltage, and the first constant voltage is used as the voltage reference of the first operational amplifier U1. The output terminal of the first operational amplifier U1 is connected to the base of the first triode Q1, and the emitter of the first triode Q1 serves as the output terminal of the first constant current. As can be seen from the voltage reference module 20 of the above embodiment, a first constant voltage is generated across the load resistor R1, and the non-inverting input terminal of the first operational amplifier U1 is specifically connected to one end of the load resistor R1 in the first feedback unit 22. The input current provided by the power supply module 10 is divided into two paths after passing through the first precision resistor. The first path is output to the collector of the first triode Q1, and after passing through the first triode Q1, it can be output to the emitter of the first triode Q1. This path is the output of the first constant current. The other path is output to the inverting input terminal of the first operational amplifier U1. The inverting input terminal and the output terminal of the first operational amplifier U1 are connected by a capacitor. When the first operational amplifier U1 is in the negative feedback working state, the voltages at the non-inverting input terminal and the inverting input terminal of the first operational amplifier U1 are equal. Therefore, the voltage across the first precision resistor is equal to the first constant voltage. Thus, the current generated across the first precision resistor is the first constant voltage divided by the resistance value of the first precision resistor. This current is constant. The current generated across the first precision resistor is the first constant current. Therefore, the current output by the aforementioned first path is the first constant current, that is, the first constant current output by the emitter of the first triode Q1 is constant, and the first constant current output by the emitter of the first triode Q1 is finally provided for the load to use.

[0034] Furthermore, referring to Figure 3 , the precision resistor unit 32 further includes at least one second precision resistor whose resistance value is less than that of the first precision resistor. The second feedback unit 31 further includes a first MOS transistor Q3. One end of the second precision resistor is connected to the power supply module 10 and the first feedback unit 22, and the other end is connected to the inverting input terminal of the first operational amplifier U1 and the drain of the first MOS transistor Q3. The gate of the first MOS transistor Q3 is connected to the output terminal of the first operational amplifier U1. In a specific implementation, the first constant current generated via the first precision resistor is mainly a constant current output of a small current, usually a constant current output within 10 mA. In this embodiment, a large current constant current output loop of more than 100 mA is added. The precision resistor unit 32 further includes at least one second precision resistor, such as Figure 3As shown, the resistor R9 serves as the second precision resistor. The resistance value of the second precision resistor is much smaller than that of the first precision resistor. Generally, the resistance value of the first precision resistor is at least 100 times that of the second resistor. The second feedback unit 31 further includes a first MOS transistor Q3. One end of the second precision resistor is connected to the power supply module 10 and the first feedback unit 22. The other end of the second precision resistor is respectively connected to the inverting input terminal of the first operational amplifier U1 and the drain of the first MOS transistor Q3. The gate of the first MOS transistor Q3 is connected to the output terminal of the first operational amplifier U1, and the source of the first MOS transistor Q3 serves as the output terminal of the first constant current. The input current provided by the power supply module 10 is also divided into two paths after passing through the second precision resistor. The first path is to output to the drain of the first MOS transistor Q3, and after passing through the first MOS transistor Q3, it can be output to the source of the first MOS transistor Q3. This path is the output of the first constant current. The other path is to output to the inverting input terminal of the first operational amplifier U1. The inverting input terminal and the output terminal of the first operational amplifier U1 are connected by a capacitor. When the first operational amplifier U1 is in the negative feedback working state, the voltages of the non-inverting input terminal and the inverting input terminal of the first operational amplifier U1 are equal. Therefore, the voltage across the second precision resistor is also equal to the first constant voltage. Thus, the current generated on the second precision resistor is the first constant voltage divided by the resistance value of the second precision resistor. This current is a constant current. The current generated on the first precision resistor is the first constant current. Therefore, the current output by the aforementioned first path is the first constant current, that is, the source of the first MOS transistor Q3 outputs a constant first constant current. Since the resistance value of the second precision resistor is much smaller than that of the first precision resistor, the current flowing through the second precision resistor is much larger than the current of the first precision resistor. A large current constant current output of more than 100 mA can be achieved. The first constant current output by the source of the first MOS transistor Q3 is finally provided for the load to use.

[0035] In one embodiment, referring to Figure 3, the constant current module 30 further includes a first analog switch 33 and a second analog switch 34. The input end of the first analog switch 33 is connected to the first precision resistor and the second precision resistor, and the output end is connected to the inverting input end of the first operational amplifier U1. The input end of the second analog switch 34 is connected to the base of the first triode Q1 and the gate of the first MOS transistor Q3, and the output end is connected to the output end of the first operational amplifier U1. In a specific implementation, since the current levels of the two circuits of the first precision resistor and the second precision resistor are different, generating two different levels of first constant current through the feedback action of the first operational amplifier U1 cannot be carried out simultaneously. Therefore, in this embodiment, the first analog switch 33 and the second analog switch 34 are used to select and switch the circuits. Both the first analog switch 33 and the second analog switch 34 are multi-select-one analog switches. The two input ends of the first analog switch 33 are respectively connected to the first precision resistor and the second precision resistor, and the output end of the first analog switch 33 is connected to the inverting input end of the first operational amplifier U1. The first analog switch 33 selects one of the two circuits of the first precision resistor and the second precision resistor to be connected to the inverting input end of the first operational amplifier U1. The two input ends of the second analog switch 34 are respectively connected to the base of the first triode Q1 and the gate of the first MOS transistor Q3, and the output end of the second analog switch 34 is connected to the output end of the first operational amplifier U1. The second analog switch 34 selects one of the two circuits of the first triode Q1 and the first MOS transistor Q3 to be connected to the output end of the first operational amplifier U1. The first analog switch 33 and the second analog switch 34 are controlled by the main control chip. During actual operation and control, the first analog switch 33 and the second analog switch 34 need to synchronously switch the circuits, that is, when the first analog switch 33 selects to connect the first precision resistor circuit to the inverting input end of the first operational amplifier U1, the second analog switch 34 selects to connect the base of the first triode Q1 to the output end of the first operational amplifier U1; when the first analog switch 33 selects to connect the second precision resistor circuit to the inverting input end of the first operational amplifier U1, the second analog switch 34 selects to connect the gate of the first MOS transistor Q3 to the output end of the first operational amplifier U1. Thus, the free switching between the first precision resistor circuit and the second precision resistor circuit is realized through the first analog switch 33, and further the output switching of two different levels of first constant current is realized.

[0036] In one embodiment, referring to Figure 3, a plurality of the first precision resistors are provided, and the constant current module 30 further includes a third analog switch 35. The input end of the third analog switch 35 is connected to the plurality of first precision resistors, and the output end of the third analog switch 35 is connected to the inverting input end of the first operational amplifier U1. In a specific implementation, in order to achieve a wide range of first constant current output, a plurality of first precision resistors are provided, and the resistance values of each first precision resistor are different, so that the first precision resistors are divided into multiple paths. As Figure 3 shown, 6 first precision resistors are provided, namely resistors R3 to R8, and each path of first precision resistor represents a level of constant current output. The constant current module 30 further includes a third analog switch 35. The third analog switch 35 is a multiple-selection analog switch. The multiple input ends of the third analog switch 35 are respectively connected to each first precision resistor. The output end of the third analog switch 35 is connected to the inverting input end of the first operational amplifier U1. The third analog switch 35 is controlled by the main control chip. By the third analog switch 35, one of the multiple paths of first precision resistors is selected to be connected to the inverting input end of the first operational amplifier U1, so as to achieve different levels of first constant current output.

[0037] In one embodiment, referring to Figures 1 to 3 , the constant current source circuit further includes a current output module 40. The current output module 40 is connected to the constant current module 30. Wherein, the current output module 40 is used to connect a load to output the first constant current to the load for use. In a specific implementation, the current output module 40 is connected to the constant current module 30. As the access end of the load, it is mainly used to connect the load to output the first constant current generated by the constant current module 30 to the load for use. The load can work by using the first constant current by accessing the current output module 40. The current output module 40 can be designed as a switch, which can more conveniently control the constant current output.

[0038] In one embodiment, a constant current source device is provided. The constant current source device includes the constant current source circuit provided in the above embodiment. The constant current source circuit is integrated in the constant current source device as a constant current source. The constant current source device can provide a stable current input for a load that requires a constant current input, so that the load can work under a stable current input. Since the specific structure and working principle of the constant current source circuit have been introduced in detail in the previous specification, for the sake of simplicity of the specification, it will not be repeated here.

[0039] In the constant current source device of this embodiment, due to the adoption of the constant current source circuit provided by the embodiment of the present invention, in actual application, when the temperature changes or the load changes, the constant current output can be kept stable, and the constant current effect is better.

[0040] As described above, it is only the specific implementation manner of the present utility model, but the protection scope of the present utility model is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present utility model can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present utility model. Therefore, the protection scope of the present utility model shall be subject to the protection scope of the claims.

Claims

1. A constant current source circuit, characterized in that: include: A power module, used for providing input current; A voltage reference module, comprising a voltage reference unit and a first feedback unit, wherein the first feedback unit is connected to the voltage reference unit, the voltage reference unit is used to provide a reference voltage, and the first feedback unit is used to generate a first constant voltage according to the reference voltage; A constant current module is connected to the power module and the first feedback unit, and is used for converting the input current into a first constant current according to the first constant voltage.

2. The constant current source circuit according to claim 1, characterized in that: The constant current module includes a second feedback unit and a precision resistance unit, the precision resistance unit is connected to the power supply module and the first feedback unit, and the second feedback unit is connected to the first feedback unit and the precision resistance unit; The precision resistance unit is used to generate a feedback voltage according to the first constant voltage, and the second feedback unit is used to generate the first constant current according to the feedback voltage.

3. The constant current source circuit according to claim 2, characterized in that: The second feedback unit includes a first operational amplifier and a first transistor, the precision resistor unit includes at least one first precision resistor, one end of the first precision resistor is connected to the power module and the first feedback unit, and the other end is connected to the collector of the first transistor and the inverting input of the first operational amplifier, the non-inverting input of the first operational amplifier is connected to the first feedback unit, and the output is connected to the base of the first transistor.

4. The constant current source circuit according to claim 3, characterized in that: The precision resistor unit also includes at least one second precision resistor whose resistance is smaller than that of the first precision resistor. The second feedback unit also includes a first MOS tube. One end of the second precision resistor is connected to the power module and the first feedback unit, and the other end is connected to the inverting input end of the first operational amplifier and the drain of the first MOS tube. The gate of the first MOS tube is connected to the output end of the first operational amplifier.

5. The constant current source circuit according to claim 4, characterized in that: The constant current module also includes a first analog switch and a second analog switch, wherein the input end of the first analog switch is connected to the first precision resistor and the second precision resistor, and the output end is connected to the inverting input end of the first operational amplifier, the input end of the second analog switch is connected to the base of the first transistor and the gate of the first MOS tube, and the output end is connected to the output end of the first operational amplifier.

6. The constant current source circuit according to claim 3, characterized in that: There are multiple first precision resistors, and the constant current module also includes a third analog switch, the input end of the third analog switch is connected to the multiple first precision resistors, and the output end of the third analog switch is connected to the inverting input end of the first operational amplifier.

7. The constant current source circuit according to any one of claims 1 to 6, characterized in that: The first feedback unit includes a second operational amplifier, a second triode, a sampling resistor and a load resistor, the non-inverting input terminal of the second operational amplifier is connected to the voltage reference unit, the inverting input terminal is connected to the emitter of the second triode and one end of the sampling resistor, the output terminal is connected to the base of the second triode, the other end of the sampling resistor is grounded, the emitter of the second triode is connected to one end of the load resistor, the power supply module is connected to the other end of the load resistor, and the constant current module is connected between the collector of the second triode and the load resistor.

8. The constant current source circuit according to claim 7, characterized in that: The voltage reference unit includes a voltage stabilizing chip and at least one voltage dividing resistor, one end of the voltage dividing resistor is connected to the voltage stabilizing chip, and the other end is grounded, and the in-phase input end of the second operational amplifier is connected between the voltage dividing resistor and the ground.

9. The constant current source circuit according to any one of claims 1 to 6, characterized in that: The constant current source circuit further includes a current output module, which is connected to the constant current module, wherein the current output module is used to connect to a load to output the first constant current to the load for use.

10. A constant current source device, characterized in that: The invention comprises the constant current source circuit as described in any one of claims 1 to 9.

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