CN113867462A - Current source circuit - Google Patents
Current source circuit Download PDFInfo
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- CN113867462A CN113867462A CN202111160024.XA CN202111160024A CN113867462A CN 113867462 A CN113867462 A CN 113867462A CN 202111160024 A CN202111160024 A CN 202111160024A CN 113867462 A CN113867462 A CN 113867462A
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- 230000003321 amplification Effects 0.000 claims abstract description 35
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 35
- 238000001514 detection method Methods 0.000 claims abstract description 18
- 239000003990 capacitor Substances 0.000 claims description 100
- 230000000087 stabilizing effect Effects 0.000 claims description 12
- 238000001914 filtration Methods 0.000 claims description 10
- 238000010586 diagram Methods 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 230000001360 synchronised effect Effects 0.000 description 3
- 238000002955 isolation Methods 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 230000008707 rearrangement Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
- G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
- G05F1/561—Voltage to current converters
Abstract
The invention discloses a current source circuit, comprising: the device comprises a signal acquisition module, a signal amplification module and a current control module; the current output end of the current control module is electrically connected with a load; the current control module is used for providing output current for a load; the signal acquisition module is connected with the load in parallel; the signal acquisition module is used for acquiring voltage signals at two ends of a load and current signals flowing through the load and outputting detection voltage according to the voltage signals and the current signals; the voltage input end of the signal amplification module is electrically connected with the signal acquisition module, and the voltage output end of the signal amplification module is electrically connected with the voltage feedback end of the current control module; the signal amplification module is used for amplifying the signal of the detection voltage and then outputting a feedback voltage; the current control module is also used for adjusting the output current provided for the load according to the feedback voltage, so that the application requirements of wide voltage range and low power can be met, and the cost of the current source is reduced.
Description
Technical Field
The embodiment of the invention relates to the technical field of current sources, in particular to a current source circuit.
Background
In the application of the active oxygen electrode, as the water quality difference is large all over the country, a constant-current electrode-reversing driving mode is generally adopted to ensure the service life of the electrode; however, differences in TDS of water quality in various regions cause that under the condition that the driving current is not changed, the voltage difference range is large, the power of the driver is limited, and if a power supply adapter with a large voltage range is selected, the power of the power supply adapter is also relatively high, so that great cost waste is caused.
Disclosure of Invention
The invention provides a current source circuit to realize a power supply circuit with a wide voltage range and small power.
An embodiment of the present invention provides a current source circuit, including: the device comprises a signal acquisition module, a signal amplification module and a current control module;
the current output end of the current control module is electrically connected with a load; the current control module is used for providing output current for a load;
the signal acquisition module is connected with the load in parallel; the signal acquisition module is used for acquiring voltage signals at two ends of the load and current signals flowing through the load and outputting detection voltage according to the voltage signals and the current signals;
the voltage input end of the signal amplification module is electrically connected with the signal acquisition module, and the voltage output end of the signal amplification module is electrically connected with the voltage feedback end of the current control module; the signal amplification module is used for amplifying the detection voltage and then outputting a feedback voltage;
the current control module is further configured to regulate an output current provided to the load based on the feedback voltage.
Optionally, the signal amplification module includes an operational amplifier, a first resistor, a second resistor, and a third resistor;
the non-inverting input end of the operational amplifier is electrically connected with the signal acquisition module through the first resistor; the inverting input end of the operational amplifier is grounded through the second resistor; the inverting input end of the operational amplifier is also electrically connected with the output end of the operational amplifier through the third resistor; and the output end of the operational amplifier is electrically connected with the voltage feedback end of the current control module.
Optionally, the signal amplification module further includes a fourth resistor and a first capacitor;
one end of the first capacitor is electrically connected with the output end of the operational amplifier, and the other end of the first capacitor is electrically connected with the inverting input end of the operational amplifier through the fourth resistor.
Optionally, the signal acquisition module includes a fifth resistor, a sixth resistor, a seventh resistor, and a second capacitor;
a first end of the fifth resistor is electrically connected with a current output end of the current control module, and a second end of the fifth resistor is electrically connected with a first end of the sixth resistor;
a first end of the seventh resistor floats to the ground; the first end of the seventh resistor is electrically connected with the second end of the sixth resistor and the load; a second end of the seventh resistor is grounded; the second end of the seventh resistor is electrically connected with the first end of the sixth resistor through a second capacitor, and the first end of the sixth resistor is electrically connected with the voltage output end of the signal amplification module.
Optionally, the current control module includes a power chip, a first transistor, a second transistor, and an inductor;
the voltage feedback end of the power supply chip is electrically connected with the voltage output end of the signal amplification module, the first output end of the power supply chip is electrically connected with the control end of the first transistor, and the second output end of the power supply chip is electrically connected with the control end of the second transistor;
the first end of the first transistor is electrically connected with a first power supply; the second end of the first transistor is electrically connected with the load through the inductor; the second end of the first transistor is also electrically connected with the first end of the second transistor; a second terminal of the second transistor is grounded;
the power supply chip is used for controlling the first transistor or the second transistor to be conducted according to the feedback voltage of the voltage feedback end.
Optionally, the current control module further includes an eighth resistor, a ninth resistor, a first diode, and a second diode;
the eighth resistor is connected in series between the first output end of the power supply chip and the control end of the first transistor, the anode of the first diode is electrically connected with the control end of the first transistor, and the cathode of the first diode is electrically connected with the first output end of the power supply chip;
the ninth resistor is connected in series between the second output end of the power chip and the control end of the second transistor, the anode of the second diode is electrically connected with the control end of the second transistor, and the cathode of the second diode is electrically connected with the second output end of the power chip.
Optionally, the current control module further includes a third capacitor and a third diode;
the first end of the third capacitor is commonly connected with the second end of the first transistor and the first end of the second transistor, and the first end of the third capacitor is also electrically connected with the first input end of the power supply chip; and the second end of the third capacitor is connected with the cathode of the third diode and the second input end of the power supply chip together, and the anode of the third diode is electrically connected with a second power supply.
Optionally, the current source circuit further includes: an overvoltage protection module;
the output end of the overvoltage protection module is electrically connected with the current output end of the current control module; the control end of the overvoltage protection module is electrically connected with the voltage feedback end of the current control module;
the overvoltage protection module is used for controlling the output voltage of the current control module according to the voltage of the voltage feedback end of the current control module.
Optionally, the overvoltage protection module includes: the voltage stabilizing diode, the tenth resistor, the eleventh resistor, the fourth capacitor and the fourth diode;
the negative electrode of the voltage stabilizing diode is electrically connected with the current output end of the current control module, and the positive electrode of the voltage stabilizing diode is grounded through the tenth resistor; the anode of the voltage stabilizing diode is also grounded through the fourth capacitor; the anode of the voltage stabilizing diode is also electrically connected with the anode of the fourth diode; and the negative electrode of the fourth diode is electrically connected with the voltage feedback end of the eleventh resistance current control module.
Optionally, the current source circuit further includes a filtering module; the filtering module comprises a fifth capacitor, a sixth capacitor, a seventh capacitor and an eighth capacitor;
one end of the fifth capacitor and one end of the sixth capacitor are both electrically connected with the signal acquisition module, and the other end of the fifth capacitor and the other end of the sixth capacitor are both grounded;
one end of the seventh capacitor and one end of the eighth capacitor are both electrically connected with the signal acquisition module, and the other end of the seventh capacitor and the other end of the eighth capacitor are both grounded. .
In the trapezoidal current source circuit provided by the embodiment of the invention, when the current control module provides output current for the load, the signal acquisition module acquires voltage signals at two ends of the load and current signals flowing through the load, and outputs detection voltage to the signal amplification module according to the voltage signals and the current signals, so that the signal amplification module amplifies the detection voltage and outputs feedback voltage to the current control module, and thus the current control module, the load, the current acquisition module and the signal amplification module form a closed-loop control circuit, so that the current control module can adjust output current in real time according to the voltage signals at two ends of the load and the current signals flowing through the load, so as to meet a wider output voltage range in a smaller power range, reduce the cost of the current source circuit, and in the application of the active oxygen electrode, under the condition of smaller output power, the current source provided by the proposal can be applied to wider water quality conditions.
Drawings
Fig. 1 is a schematic structural diagram of a current source circuit according to an embodiment of the present invention;
FIG. 2 is a comparison diagram of output signals of a current source circuit according to an embodiment of the present invention;
FIG. 3 is a comparison diagram of output signals of another current source circuit according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of another current source circuit according to the present invention;
fig. 5 is a schematic structural diagram of another current source circuit provided in the embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Fig. 1 is a schematic structural diagram of a current source circuit according to an embodiment of the present invention, and as shown in fig. 1, the current source circuit includes: the device comprises a signal acquisition module 10, a signal amplification module 20 and a current control module 30; the current output end of the current control module 30 is electrically connected with the load 40; the current control module 30 is used for providing output current for the load 40 and the signal acquisition module 10; the signal acquisition module 10 is connected in parallel with the load 40; the signal acquisition module 10 is configured to acquire a voltage signal at two ends of the load 40 and a current signal flowing through the load 40, and output a detection voltage according to the voltage signal and the current signal; the voltage input end of the signal amplification module 20 is electrically connected with the signal acquisition module 10, and the voltage output end of the signal amplification module 20 is electrically connected with the voltage feedback end of the current control module 30; the signal amplification module 20 is configured to amplify the detection voltage and output a feedback voltage; the current control module 30 is also configured to regulate the output current provided to the load 40 based on the feedback voltage.
Specifically, assume that the output current provided by current control module 30 is IOThe current flowing through the signal acquisition module 10 is IRThe current flowing through the load is ILBecause of the shunting action of the signal acquisition module 10 and the load 40, a part of the output current provided by the current control module 30 flows through the signal acquisition module 10, and a part of the output current flows through the load 40, and the current signal flowing through the load 40 generates voltage on the load 40, because the signal acquisition module 10 is connected in parallel with the load 40, the signal acquisition module 10 can acquire the voltage signals at two ends of the load 40; meanwhile, since the current signal flowing through the load 40 flows from the negative terminal of the load 40 to the signal collection module 10, the signal collection module 10 can collect the current signal flowing through the load 40. The signal acquisition module 10 outputs a detection voltage to the signal amplification module 20 according to the acquired voltage signal and current signal, and the signal amplification module 20 amplifies the detection voltage and outputs a feedback voltage to the voltage of the current control module 30And a feedback terminal, which enables the current control module 30 to adjust the output current provided to the load 40 according to the received feedback voltage to form a closed-loop control circuit, so that the current control module can control the output current according to the voltage signal and the current signal at two ends of the load 40, and further control the current signal flowing through the load 40, so that the current signal can be in a trapezoidal change with a certain slope with the load voltage.
For example, fig. 2 is a comparison graph of output signals of a current source circuit provided by an embodiment of the present invention, as shown in fig. 2, as the voltage signal increases, the output current (shown by a dotted line in the figure) of a constant current source in the prior art remains constant, while the current signal output by the current source provided by the embodiment of the present invention decreases in a trapezoidal manner (shown by a solid line in the figure) as the voltage signal increases, and has an inverse proportional relationship with a certain slope of the voltage signal.
Fig. 3 is a comparison diagram of an output signal of another current source circuit according to an embodiment of the present invention, as shown in fig. 3, the output power (shown by a dotted line in the diagram) of a constant current source in the prior art increases linearly with the increase of the output voltage, and the current source according to an embodiment of the present invention maintains a steady state (shown by a solid line in the diagram) after the output power increases gently to a certain value with the increase of the output voltage because the output current decreases with the increase of the output voltage, and can have a larger output voltage range with a smaller output power than the constant current source; alternatively, when the output power is the same, the voltage use range can be expanded to reduce the power configuration standard of the current source and thus reduce the cost when a wider output voltage range is satisfied.
In the trapezoidal current source circuit provided by the embodiment of the invention, when the current control module provides output current for the load, the signal acquisition module acquires voltage signals at two ends of the load and current signals flowing through the load, and outputs detection voltage to the signal amplification module according to the voltage signals and the current signals, so that the signal amplification module amplifies the detection voltage and outputs feedback voltage to the current control module, and thus the current control module, the load, the current acquisition module and the signal amplification module form a closed-loop control circuit, so that the current control module can adjust output current in real time according to the voltage signals at two ends of the load and the current signals flowing through the load, so as to meet a wider output voltage range in a smaller power range, reduce the cost of the current source circuit, and in the application of the active oxygen electrode, under the condition of smaller output power, the current source provided by the proposal can be applied to wider water quality conditions.
Optionally, fig. 4 is a schematic structural diagram of another current source circuit according to an embodiment of the present invention, and as shown in fig. 4, the signal amplifying module 20 includes an operational amplifier 21, a first resistor R1, a second resistor R2, and a third resistor R3; the non-inverting input end of the operational amplifier 21 is electrically connected with the voltage output end of the current collection module 10 through a first resistor R1; the inverting input terminal of the operational amplifier 21 is grounded through a second resistor R2; the inverting input terminal of the operational amplifier 21 is also electrically connected to the output terminal of the operational amplifier 21 through a third resistor R3; the output of the operational amplifier 21 is electrically connected to the voltage feedback terminal of the current control module 30.
Specifically, the first resistor R1 is an isolation resistor, so as to prevent the operational amplifier 21 from being impacted or even damaged when the front-end circuit of the non-inverting input terminal of the operational amplifier is short-circuited. If the detection voltage output by the voltage output terminal of the current collecting module 10 is U1, the feedback voltage U2 amplified by the operational amplifier should be: u2 ═ [ (R3/R2) +1] × U1. Illustratively, the resistance of the first resistor R1 is preferably 1K Ω, the resistance of the second resistor R2 is preferably 2K Ω, and the resistance of the third resistor R3 is preferably 18K Ω, so that the signal amplification module 20 can amplify the detection voltage U1 output by the voltage output terminal of the current collection module 10 by 10 times. Illustratively, a fourteenth resistor R14 is further connected in series between the output terminal of the operational amplifier 21 and the voltage feedback terminal of the current control module 30, and the resistance of the fourteenth resistor R14 is preferably 1K Ω for isolation protection.
Optionally, with continued reference to fig. 4, the signal amplifying module 20 further includes a fourth resistor R4 and a first capacitor C1; one end of the first capacitor C1 is electrically connected to the output terminal of the operational amplifier 21, and the other end of the first capacitor C1 is electrically connected to the inverting input terminal of the operational amplifier 21 through the fourth resistor R4.
Specifically, the first capacitor C1 and the fourth resistor R4 can compensate the frequency of the feedback loop of the operational amplifier 21, improve the stability of the circuit, reduce the phase difference between the detection voltage and the feedback voltage, and synchronize the frequency of the detection voltage and the feedback voltage.
Optionally, with continued reference to fig. 4, the current collecting module 10 includes a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, and a second capacitor C2; a first end of the fifth resistor R5 is electrically connected with the current output end of the current control module 30, and a second end of the fifth resistor R5 is electrically connected with a first end of the sixth resistor R6; a first end of the seventh resistor R7 floats to the ground; the first end of the seventh resistor R7 is also electrically connected with the second end of the sixth resistor R6 and the load 40; a second end of the seventh resistor R7 is grounded; the second end of the seventh resistor R7 is further electrically connected to the first end of the sixth resistor R6 through the second capacitor C2, and the first end of the sixth resistor R6 is further electrically connected to the voltage output terminal of the signal amplifying module 20.
Specifically, assume that a connection node of the fifth resistor R5 and the current control module 30 is a first node a, a connection node of the fifth resistor R5, the sixth resistor R6 and the second capacitor C2 is a second node b, a connection node of the sixth resistor R6, the seventh resistor R7 and the load 40 is a third node C, and a connection node of the seventh resistor R7 and the second capacitor C2 is a fourth node d; the current provided by the current control module 30 and flowing through the signal acquisition module 10 flows from the first node a through the fifth resistor R5, the sixth resistor R6 and the seventh resistor R7 to the ground GND, and it is preferable that the resistance of the seventh resistor R7 is much smaller than the resistances of the fifth resistor R5 and the sixth resistor R6, for example, the resistance of the fifth resistor R5 is preferably 300K Ω, the resistance of the sixth resistor R6 is preferably 1K Ω, and the resistance of the seventh resistor R7 is preferably 0.033 Ω; then the voltage across the seventh resistor R7 is negligible at this time, and the voltage Uab across the fifth resistor R5 and the voltage Ubc across the sixth resistor R6 are equal to the voltage across the load 40, so that the input voltage at the non-inverting input terminal of the operational amplifier 21 includes the voltage Ubc across the sixth resistor R6; in addition, the current signal flowing through the load 40 is transmitted to the signal collection module 10 through the third node c, since the resistance of the sixth resistor R6 is much larger than that of the seventh resistor R7, and the resistance of the fifth resistor R5 between the second node b and the first node a is larger, and the impedance of the operational amplifier 21 electrically connected to the second node b is also much larger than that of the seventh resistor R7, the direct current transmitted from the third node c to the second node b through the sixth resistor R6 at this time is very small, so the voltage Ucb formed by the current of the load 40 on the sixth resistor R6 is negligible, the input voltage Uin at the non-inverting input end of the operational amplifier 21 is the voltage Ubc generated by the current flowing through the signal collection module 10 on the sixth resistor R6 provided by the current control module 30, and the voltage Ucd generated by the current flowing through the load 40 on the seventh resistor R7, that is Uin + Ucd, and the output voltage U4/R3 of the operational amplifier 21 is feedback voltage [ (U24) + R3 ], the current control module 30 regulates the output current based on the feedback voltage U2. The sixth resistor R6 and the second capacitor C2 form an RC filter circuit for filtering out ac components in the electrical signal transmitted to the operational amplifier 21.
Optionally, with continued reference to fig. 4, the current control module further includes a power chip 31, a first transistor T1, a second transistor T2, and an inductor L; a voltage feedback terminal ADJ of the power chip 31 is electrically connected to a voltage output terminal of the signal amplification module 20, a first output terminal HO of the power chip 31 is electrically connected to a control terminal of the first transistor T1, and a second output terminal LO of the power chip 31 is electrically connected to a control terminal of the second transistor T2; a first terminal of the first transistor T1 is electrically connected to the first power supply V1; a second terminal of the first transistor T1 is electrically connected to the signal output module 40 through the inductor L; the second terminal of the first transistor T1 is also electrically connected to the first terminal of the second transistor T2; a second terminal of the second transistor T2 is grounded; the power chip 31 is configured to control the first transistor T1 or the second transistor T2 to be turned on according to the feedback voltage of the voltage feedback terminal ADJ.
Specifically, the power chip 31 can adjust the pulse widths of the output signals of the first output terminal HO and the second output terminal LO according to the feedback voltage of the voltage feedback terminal ADJ, for example, compare the feedback voltage of the voltage feedback terminal ADJ with a reference voltage, and if the feedback voltage is smaller than the reference voltage, control the time for the first output terminal HO to output an active level a little longer, so that the voltage provided by the first power supply V1 can be transmitted to the inductor L through the first transistor T1, and the current output to the first output terminal a is gradually increased through the inductor L; or, when the feedback voltage is greater than the reference voltage, the time for controlling the second output terminal LO to output the active level is a little longer, that is, the second transistor T2 is turned on, and at this time, the potential of the first terminal of the second transistor T2 is pulled low and approaches to the ground, so that the current output to the first output terminal a is gradually reduced through the inductor L; thus, the current control module 30 can synchronously adjust the magnitude of the output current according to the feedback voltage. For example, the control terminal of the first transistor T1 may be a gate, the first terminal is a source, and the second terminal is a drain; the control terminal of the second transistor T2 may be a gate, the first terminal is a source, and the second terminal is a drain; the voltage supplied by the first power supply V1 is preferably 24V.
Optionally, with continued reference to fig. 4, the current control module 30 further includes an eighth resistor R8, a ninth resistor R9, a first diode D1, and a second diode D2; the eighth resistor R8 is connected in series between the first output terminal HO of the power chip 31 and the control terminal of the first transistor T1, the anode of the first diode D1 is electrically connected to the control terminal of the first transistor T1, and the cathode of the first diode D1 is electrically connected to the first output terminal HO of the power chip 31; the ninth resistor R9 is connected in series between the second output terminal LO of the power chip 31 and the control terminal of the second transistor T2, the anode of the second diode D2 is electrically connected to the control terminal of the second transistor T2, and the cathode of the second diode D2 is electrically connected to the second output terminal of the power chip 31.
Specifically, the eighth resistor R8 and the ninth resistor R9 are used for limiting current, and the first diode D1 and the second diode D2 are respectively used for increasing the switching rate of the first transistor T1 and the second transistor T2, reducing the switching power consumption of the first transistor T1 and the second transistor T2, and reducing heat generation.
Optionally, with continued reference to fig. 4, the current control module 30 further includes a third capacitor C3, a third diode D3; a first end of the third capacitor C3 is commonly connected to the second end of the first transistor T1 and the first end of the second transistor T2, and a first end of the third capacitor C3 is electrically connected to the first input terminal VS of the power chip 31; a second end of the third capacitor C3 is commonly connected to a cathode of the third diode D3 and the second input terminal VB of the power chip 31, and an anode of the third diode D3 is electrically connected to the second power supply V2.
Specifically, the third capacitor C3 is used to provide a driving floating voltage source for the first transistor T1 and a conducting condition for the first transistor T1. Illustratively, when the second transistor T2 is in a conducting state, the first terminal of the third capacitor C3 is grounded through the second transistor T2, and the second power supply V2 charges the third capacitor C3 through the third diode D3; the voltage supplied by the second power supply V2 is preferably 12V. When the first transistor T1 is turned on, the voltage of 24V provided by the first power supply V1 is transmitted to the first terminal of the third capacitor C3, and the voltage at the second terminal of the third capacitor C3 is 24V +12V — 36V. The potential (24V) at the first terminal and the potential (36V) at the first terminal of the third capacitor C3 are fed back to the power chip 31 through the first input terminal VS and the second input terminal VB, respectively, so that the power chip 31 can control the first output terminal HO to output a level signal sufficient to turn on the first transistor T1 according to the voltage signals at the first input terminal VS and the second input terminal VB.
For example, the power chip 31 is preferably a step-down synchronous rectification constant-voltage output control chip EG1186, each ground terminal GND of the chip EG1186 is grounded, and the external capacitor terminal CT is grounded through a ninth capacitor C9 (preferably 820 pF); the power supply terminal VDD of the PWM control part is electrically connected with a second power supply V2; the driving power supply input end VCC is electrically connected with a second power supply V2; the driving power input terminal VCC is also grounded through a tenth capacitor C10 (preferably 1 μ F), the PWM low-voltage output terminal OUT is grounded through a twelfth resistor R12 (preferably 2K Ω), and the pin HIN is grounded through an eleventh capacitor C11 (preferably 1 nF); the pin LIN is grounded through a thirteenth resistor R13 (preferably 10K Ω) and an eleventh capacitor C11 connected in series; the SD pin is electrically connected with an external pulse signal terminal S, and is also grounded through a fourteenth resistor R14 (preferably 20K omega) and a twelfth capacitor C12 (preferably 1nF) respectively; the FB pin is suspended; in addition, the first power supply V1 is also grounded through a thirteenth capacitor C13 (preferably 1 μ F) and a fourteenth capacitor C14 (preferably 470 μ F), respectively; the second power supply V2 is also grounded through a fifteenth capacitor C15 (preferably 1 μ F) and a sixteenth capacitor C16 (preferably 10 μ F), respectively; the voltage feedback terminal ADJ is also connected to ground via a seventeenth capacitor C17, preferably 10 pF.
In an exemplary manner, the first and second electrodes are,the internal reference voltage of the chip EG1186 is 1.35V, and therefore when the feedback voltage received by the voltage feedback terminal ADJ is lower than 1.35V, it indicates that the output current is low, and the PWM module of the chip EG1186 controls the on-time of the first transistor T1 to be longer than the on-time of the second transistor T2, so that the output current is kept constant; when the feedback voltage U2 received by the voltage feedback terminal ADJ is higher than 1.35V, which indicates that the output current is large, the PWM module of the chip EG1186 controls the on-time of the second transistor T2 to be longer than the on-time of the first transistor T1, so that the output current is kept constant; if the feedback voltage U2 is 1.35V, the first transistor T1 and the second transistor T2 are controlled to be turned on at a normal frequency. When the feedback voltage U2 is 1.35V, according to U2 ═ [ (R3/R2) +1]As can be seen, the detected voltage Uin of the current collection module 10 is 0.135V. Illustratively, if the voltage across the load 40, i.e., Uad, is 19V, then Ucd ═ Uin-Ubc ═ Uin-Uad [ -R6/(R5 + R6)]When the current I flows through the load 40, i.e., 0.135V to 19V (1K/301K) 0.07187VLIcd Ucd/R7 0.07187V/0.033R 2.18A; based on the same principle, if the voltage across the load 40, Uad, is 10V, the current I flowing through the load 40LIs 3.08A; if the voltage across the load 40, Uad, is 2V, the current I flowing through the load 40LIs 3.89A; it is evident that the output current decreases inversely proportionally with increasing output voltage.
Optionally, fig. 5 is a schematic structural diagram of another current source circuit provided in the embodiment of the present invention, and as shown in fig. 5, the current source circuit further includes an overvoltage protection module 50; the output end of the overvoltage protection module 60 is electrically connected with the current output end of the current control module 30; the control end of the overvoltage protection module 50 is electrically connected with the voltage feedback end of the current control module 30; the overvoltage protection module 50 is used for controlling the output voltage of the current control module 30 according to the voltage at the voltage feedback end of the current control module 30.
Specifically, when the load 50 connected to the signal acquisition module 10 changes suddenly or the signal acquisition module 10 is disconnected from the load 50, the voltage output by the signal amplification module 20 to the voltage feedback end of the current control module 30 may increase suddenly and greatly, and the overvoltage protection module 50 may stabilize the output voltage of the current control module 30 at a set value when the load 50 connected to the signal output module 40 changes suddenly or when the signal acquisition module 10 is not connected to the load 40, so as to ensure the stability of the synchronous rectification constant current source circuit.
Alternatively, referring to fig. 5, the overvoltage protection module 50 includes: a zener diode ZD1, a tenth resistor R10, an eleventh resistor R11, a fourth capacitor C4, and a fourth diode D4; the cathode of the zener diode ZD1 is electrically connected with the current output end of the current control module 30, and the anode of the zener diode ZD1 is grounded through a tenth resistor R10; the anode of the zener diode ZD1 is also grounded through a fourth capacitor C4; the anode of the zener diode ZD1 is also electrically connected to the anode of D4 of the fourth diode; the cathode of the fourth diode D4 is electrically connected to the voltage feedback terminal of the current control module 30 through an eleventh resistor R11.
Specifically, the ninth resistor R9 is used to provide a leakage current path for the zener diode ZD1, so as to avoid the malfunction of the zener diode ZD 1; the fourth capacitor C4 is used for filtering; the fourth diode D4 is used for reverse bias cutoff of the output voltage at the first node a to avoid affecting the feedback voltage output to the voltage feedback terminal of the current control module 30, and the eleventh resistor R11 is an active current-limiting resistor for protecting the circuit. For example, if the output voltage of the selection signal output module 40 is about 15V, U is setZD1＝15-U2-UD4Approximately equals to 13.5V, and a voltage stabilizing diode ZD1 with a voltage stabilizing value of about 13.5V can be selected; in this way, when the load 50 to which the signal output module 40 is connected suddenly changes or the signal output module 40 is disconnected from the load 50, the output voltage of the output module 40 can be stabilized at 13.5V. Illustratively, the tenth resistor R10 and the eleventh resistor R11 may have the same resistance, preferably 1K Ω.
Optionally, with continued reference to fig. 5, the synchronous rectification constant current source circuit further includes a filtering module 60; the filtering module 60 includes a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, and an eighth capacitor C8; one end of the fifth capacitor C5 and one end of the sixth capacitor C6 are both electrically connected to the signal acquisition module 10, and the other end of the fifth capacitor C5 and the other end of the sixth capacitor C6 are both grounded; one end of the seventh capacitor C7 and one end of the eighth capacitor C8 are both electrically connected to the signal acquisition module 10, and the other end of the seventh capacitor C7 and the other end of the eighth capacitor C8 are both floating.
Specifically, the capacitance values of the fifth capacitor C5 and the seventh capacitor C7 may be the same, and are preferably 1 μ F, and are used for filtering out high-frequency signals; the capacitance values of the sixth capacitor C6 and the eighth capacitor C8 are preferably 470 muF, and the sixth capacitor C6 and the eighth capacitor C8 are used for filtering low-frequency signals; in addition, the capacitance values of the sixth capacitor C6 and the eighth capacitor C8 are large, so that the capacitor has an energy storage function, the switching frequency of the inductor L can be reduced, and the switching loss generated on the inductor L is reduced.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (10)
1. A current source circuit, comprising: the device comprises a signal acquisition module, a signal amplification module and a current control module;
the current output end of the current control module is electrically connected with a load; the current control module is used for providing output current for a load;
the signal acquisition module is connected with the load in parallel; the signal acquisition module is used for acquiring voltage signals at two ends of the load and current signals flowing through the load and outputting detection voltage according to the voltage signals and the current signals;
the voltage input end of the signal amplification module is electrically connected with the signal acquisition module, and the voltage output end of the signal amplification module is electrically connected with the voltage feedback end of the current control module; the signal amplification module is used for amplifying the detection voltage and then outputting a feedback voltage;
the current control module is further configured to regulate an output current provided to the load based on the feedback voltage.
2. The current source circuit of claim 1, wherein the signal amplification module comprises an operational amplifier, a first resistor, a second resistor, and a third resistor;
the non-inverting input end of the operational amplifier is electrically connected with the signal acquisition module through the first resistor; the inverting input end of the operational amplifier is grounded through the second resistor; the inverting input end of the operational amplifier is also electrically connected with the output end of the operational amplifier through the third resistor; and the output end of the operational amplifier is electrically connected with the voltage feedback end of the current control module.
3. The current source circuit of claim 2, wherein the signal amplification module further comprises a fourth resistor and a first capacitor;
one end of the first capacitor is electrically connected with the output end of the operational amplifier, and the other end of the first capacitor is electrically connected with the inverting input end of the operational amplifier through the fourth resistor.
4. The current source circuit according to claim 1, wherein the signal acquisition module comprises a fifth resistor, a sixth resistor, a seventh resistor and a second capacitor;
a first end of the fifth resistor is electrically connected with a current output end of the current control module, and a second end of the fifth resistor is electrically connected with a first end of the sixth resistor;
a first end of the seventh resistor floats to the ground; the first end of the seventh resistor is electrically connected with the second end of the sixth resistor and the load; a second end of the seventh resistor is grounded; the second end of the seventh resistor is electrically connected with the first end of the sixth resistor through a second capacitor, and the first end of the sixth resistor is electrically connected with the voltage output end of the signal amplification module.
5. The current source circuit according to claim 1, wherein the current control module comprises a power chip, a first transistor, a second transistor, and an inductor;
the voltage feedback end of the power supply chip is electrically connected with the voltage output end of the signal amplification module, the first output end of the power supply chip is electrically connected with the control end of the first transistor, and the second output end of the power supply chip is electrically connected with the control end of the second transistor;
the first end of the first transistor is electrically connected with a first power supply; the second end of the first transistor is electrically connected with the load through the inductor; the second end of the first transistor is also electrically connected with the first end of the second transistor; a second terminal of the second transistor is grounded;
the power supply chip is used for controlling the first transistor or the second transistor to be conducted according to the feedback voltage of the voltage feedback end.
6. The current source circuit of claim 5, wherein the current control module further comprises an eighth resistor, a ninth resistor, a first diode, and a second diode;
the eighth resistor is connected in series between the first output end of the power supply chip and the control end of the first transistor, the anode of the first diode is electrically connected with the control end of the first transistor, and the cathode of the first diode is electrically connected with the first output end of the power supply chip;
the ninth resistor is connected in series between the second output end of the power chip and the control end of the second transistor, the anode of the second diode is electrically connected with the control end of the second transistor, and the cathode of the second diode is electrically connected with the second output end of the power chip.
7. The current source circuit of claim 5, wherein the current control module further comprises a third capacitor, a third diode;
the first end of the third capacitor is commonly connected with the second end of the first transistor and the first end of the second transistor, and the first end of the third capacitor is also electrically connected with the first input end of the power supply chip; and the second end of the third capacitor is connected with the cathode of the third diode and the second input end of the power supply chip together, and the anode of the third diode is electrically connected with a second power supply.
8. The current source circuit of claim 1, further comprising: an overvoltage protection module;
the output end of the overvoltage protection module is electrically connected with the current output end of the current control module; the control end of the overvoltage protection module is electrically connected with the voltage feedback end of the current control module;
the overvoltage protection module is used for controlling the output voltage of the current control module according to the voltage of the voltage feedback end of the current control module.
9. The current source circuit of claim 1, wherein the overvoltage protection module comprises: the voltage stabilizing diode, the tenth resistor, the eleventh resistor, the fourth capacitor and the fourth diode;
the negative electrode of the voltage stabilizing diode is electrically connected with the current output end of the current control module, and the positive electrode of the voltage stabilizing diode is grounded through the tenth resistor; the anode of the voltage stabilizing diode is also grounded through the fourth capacitor; the anode of the voltage stabilizing diode is also electrically connected with the anode of the fourth diode; and the negative electrode of the fourth diode is electrically connected with the voltage feedback end of the eleventh resistance current control module.
10. The current source circuit of claim 1, further comprising a filtering module; the filtering module comprises a fifth capacitor, a sixth capacitor, a seventh capacitor and an eighth capacitor;
one end of the fifth capacitor and one end of the sixth capacitor are both electrically connected with the signal acquisition module, and the other end of the fifth capacitor and the other end of the sixth capacitor are both grounded;
one end of the seventh capacitor and one end of the eighth capacitor are both electrically connected with the signal acquisition module, and the other end of the seventh capacitor and the other end of the eighth capacitor are both grounded.
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| CN202111160024.XA CN113867462A (en) | 2021-09-30 | 2021-09-30 | Current source circuit |
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| CN202111160024.XA CN113867462A (en) | 2021-09-30 | 2021-09-30 | Current source circuit |
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