CN116382405A - Pulse constant current source circuit and pulse current generation method - Google Patents
Pulse constant current source circuit and pulse current generation method Download PDFInfo
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- CN116382405A CN116382405A CN202310376362.XA CN202310376362A CN116382405A CN 116382405 A CN116382405 A CN 116382405A CN 202310376362 A CN202310376362 A CN 202310376362A CN 116382405 A CN116382405 A CN 116382405A
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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
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- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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Abstract
The invention discloses a pulse constant current source circuit and a pulse current generation method, wherein the pulse constant current source circuit comprises: the control module, the DAC, the MOS pipe, analog switch and current negative feedback circuit, the control end of DAC is connected to control module's output, analog switch's control end is connected to control module's output, analog switch's input is connected to the output of DAC, the grid of MOS pipe is connected to analog switch's output, the one end of load is connected to the drain electrode of MOS pipe, the other end of load is used for connecting power supply voltage, the source ground of MOS pipe, the source of MOS pipe is connected to current negative feedback circuit's sampling end, the grid of MOS pipe is connected to current negative feedback circuit's feedback end, under the circumstances that does not adopt high DAC, can output high-pressure high-frequency pulse current, the cost is reduced.
Description
Technical Field
The invention relates to the technical field of current sources, in particular to a pulse constant current source circuit and a pulse current generation method.
Background
In the fields of LED, semiconductor, laser driving, etc., current source driving is widely required. As shown in figure 1, the existing pulse constant current source controls a constant current loop through a DAC, the DAC can output pulse signals with various duty ratios and various amplitudes, the pulse signals are connected to a control pin of the constant current loop, and a high-power pulse current is regulated and output through a power MOS tube. The output of the pulse signal is realized by directly adopting the DAC to overturn, the output speed of the DAC is limited, the high-frequency pulse signal is difficult to output, if the high-frequency pulse signal is to be output, the requirements on the swing rate, the output refresh rate and the building time of the DAC are very high, and the high-speed DAC is required to be adopted, so that the cost is high. In addition, in general, a high-side control method is adopted for the pulse constant current source, and high-voltage pulse current is difficult to output due to the limitation of common-mode voltage.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, the invention provides a pulse constant current source circuit and a pulse current generation method, which can solve the problems that the existing current source technology is difficult to output high-voltage high-frequency pulse current and has higher cost.
According to an embodiment of the first aspect of the present invention, a pulse constant current source circuit includes: a control module; the output end of the control module is connected with the control end of the DAC; the output end of the control module is connected with the control end of the analog switch, and the output end of the DAC is connected with the input end of the analog switch; the output end of the analog switch is connected with the grid electrode of the MOS tube, the drain electrode of the MOS tube is connected with one end of the load, the other end of the load is used for being connected with power supply voltage, and the source electrode of the MOS tube is grounded; the sampling end of the current negative feedback circuit is connected with the source electrode of the MOS tube, and the feedback end of the current negative feedback circuit is connected with the grid electrode of the MOS tube; the control module generates the pulse current by a pulse current generation method, the pulse current generation method comprising the steps of: obtaining the duty cycle and frequency of the pulse current; calculating a pulse width of the pulse current according to the duty cycle and the frequency; calculating a pulse interval of the pulse current according to the duty cycle and the frequency; controlling the analog switch to close the duration of one pulse width every other duration of the pulse interval; the DAC continuously outputs a voltage control signal, the voltage control signal is input to the grid electrode of the MOS tube through the analog switch, and the conduction state of the MOS tube is controlled; and outputting the pulse current through the MOS tube.
The pulse constant current source circuit according to the embodiment of the first aspect of the invention has at least the following beneficial effects:
the pulse current is calculated according to the duty ratio and the frequency, the pulse interval of the pulse current is calculated according to the duty ratio and the frequency, a voltage control signal is continuously output through a DAC, the voltage control signal is input to the grid electrode of the MOS tube through an analog switch, the duration of every pulse interval of the analog switch is closed, the duration of one pulse width is controlled, the conduction degree of the MOS tube is controlled, and therefore the pulse current is output, and a current negative feedback circuit inputs feedback quantity to the grid electrode of the MOS tube to realize constant current output. Compared with the traditional current source technology, the pulse constant current source circuit of the embodiment of the invention can output high-frequency voltage control signals under the condition that a high-speed DAC is not adopted because the switching frequency of the analog switch can reach tens of megahertz, thereby outputting high-frequency pulse current through the MOS tube, reducing the cost, reducing common-mode voltage because the MOS tube is arranged at the low side of the load, improving the output voltage of the MOS tube and outputting high-voltage pulse current.
According to some embodiments of the invention, the current negative feedback circuit comprises a differential amplifier, an error amplifier and a first resistor, one end of the first resistor is connected with the load, the other end of the first resistor is grounded, the in-phase end of the differential amplifier is connected with the source electrode of the MOS tube, the reverse phase end of the differential amplifier is grounded, the output end of the differential amplifier is connected with the reverse phase end of the error amplifier, the output end of the analog switch is connected with the in-phase end of the error amplifier, and the output end of the error amplifier is connected with the gate electrode of the MOS tube.
According to some embodiments of the invention, the MOS transistor further comprises a second resistor and a switch, wherein one end of the second resistor is connected with one end of the switch, the other end of the switch is connected with the power supply voltage, and the other end of the second resistor is connected with the drain electrode of the MOS transistor.
A pulse current generating method according to an embodiment of the second aspect of the present invention includes: obtaining the duty cycle and the frequency of pulse current; calculating a pulse width of the pulse current according to the duty cycle and the frequency; calculating a pulse interval of the pulse current according to the duty cycle and the frequency; controlling the analog switch to close the duration of one pulse width every other duration of the pulse interval; the DAC continuously outputs a voltage control signal, the voltage control signal is input to the grid electrode of the MOS tube through the analog switch, and the conduction state of the MOS tube is controlled; and outputting the pulse current through the MOS tube.
The pulse current generating method according to the embodiment of the second aspect of the present invention has at least the following advantages:
the pulse current is calculated according to the duty ratio and the frequency, the pulse interval of the pulse current is calculated according to the duty ratio and the frequency, a voltage control signal is continuously output through a DAC, the voltage control signal is input to the grid electrode of the MOS tube through an analog switch, the duration of every pulse interval of the analog switch is closed, the duration of one pulse width is controlled, the conduction degree of the MOS tube is controlled, and therefore the pulse current is output, and a current negative feedback circuit inputs feedback quantity to the grid electrode of the MOS tube to realize constant current output. According to the pulse current generation method of the second aspect of the embodiment of the present invention, compared with the conventional current source technology, since the switching frequency of the analog switch can reach tens of megahertz, the high-frequency voltage control signal can be output without using a high-speed DAC, so that the high-frequency pulse current is output through the MOS transistor, the cost is reduced, and since the MOS transistor is disposed at the low side of the load, the common-mode voltage is reduced, the output voltage of the MOS transistor is improved, and the high-voltage pulse current can be output.
According to some embodiments of the invention, the pulse width is calculated by the following formula: ton=d/f, where Ton is the pulse width, D is the duty cycle, and f is the frequency.
According to some embodiments of the invention, the pulse interval is calculated by the following formula: toff= (1-D)/f, where Toff is the pulse interval, D is the duty cycle, and f is the frequency.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The invention is further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a circuit diagram of a conventional pulsed constant current source;
FIG. 2 is a circuit diagram of a pulsed constant current source circuit of the present invention;
fig. 3 is a flowchart of a pulse current generating method according to the present invention.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention.
In the description of the present invention, it should be understood that the direction or positional relationship indicated with respect to the description of the orientation, such as up, down, etc., is based on the direction or positional relationship shown in the drawings, is merely for convenience of describing the present invention and simplifying the description, and does not indicate or imply that the apparatus or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.
In the description of the present invention, plural means two or more. The description of the first and second is for the purpose of distinguishing between technical features only and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
In the description of the present invention, unless explicitly defined otherwise, terms such as arrangement, installation, connection, etc. should be construed broadly and the specific meaning of the terms in the present invention can be reasonably determined by a person skilled in the art in combination with the specific contents of the technical scheme.
As shown in fig. 2, a pulse constant current source circuit according to an embodiment of the present invention includes: the control module U4, DAC U3, MOS pipe Q1, analog switch S2 and current negative feedback circuit, the control end of DAC U3 is connected to control module U4 ' S output, analog switch S2 ' S control end is connected to control module U4 ' S output, analog switch S2 ' S input is connected to DAC U3 ' S output, MOS pipe Q1 ' S grid is connected to analog switch S2 ' S output, MOS pipe Q1 ' S one end is connected to load RL ' S drain electrode, load RL ' S the other end is used for connecting power supply voltage, MOS pipe Q1 ' S source ground, MOS pipe Q1 ' S source is connected to current negative feedback circuit ' S sampling end, MOS pipe Q1 ' S grid is connected to current negative feedback circuit ' S feedback end, control module U4 is MCU.
The control module U4 generates a pulse current by a pulse current generating method, which includes the steps of:
step S100: obtaining the duty cycle and frequency of the pulse current;
step S200: calculating the pulse width of the pulse current according to the duty ratio and the frequency;
step S300: calculating the pulse interval of the pulse current according to the duty ratio and the frequency;
step S400: the duration of one pulse width of the analog switch S2 is controlled to be closed every other pulse interval;
step S500: the DAC U3 continuously outputs a voltage control signal, the voltage control signal is input to the grid electrode of the MOS tube Q1 through the analog switch S2, and the conduction state of the MOS tube Q1 is controlled;
step S600: pulse current is output through the MOS transistor Q1.
The duty ratio and the frequency of the pulse current are obtained, the pulse width of the pulse current is calculated according to the duty ratio and the frequency, the pulse interval of the pulse current is calculated according to the duty ratio and the frequency, a voltage control signal is continuously output through the DAC U3 and is input to the grid electrode of the MOS tube Q1 through the analog switch S2, the duration of the pulse interval is closed by the analog switch S2, the duration of one pulse width is closed, the conduction degree of the MOS tube Q1 is controlled, the pulse current is output, and the current negative feedback circuit inputs the feedback quantity to the grid electrode of the MOS tube Q1 to realize constant current output. Compared with the traditional current source technology, the pulse constant current source circuit according to the embodiment of the invention can output high-frequency voltage control signals under the condition that the high-speed DAC U3 is not adopted because the frequency of the switch S1 of the analog switch S2 can reach tens of megahertz, thereby outputting high-frequency pulse current through the MOS tube Q1, reducing the cost, reducing the common mode voltage because the MOS tube Q1 is arranged at the low side of the load RL, improving the output voltage of the MOS tube Q1 and outputting high-voltage pulse current.
As shown in fig. 2, the current negative feedback circuit includes a differential amplifier U1, an error amplifier U2 and a first resistor R1, one end of the first resistor R1 is connected to a load RL, the other end of the first resistor R1 is grounded, the in-phase end of the differential amplifier U1 is connected to the source of the MOS transistor Q1, the opposite-phase end of the differential amplifier U1 is grounded, the output end of the differential amplifier U1 is connected to the opposite-phase end of the error amplifier U2, the output end of the analog switch S2 is connected to the in-phase end of the error amplifier U2, and the output end of the error amplifier U2 is connected to the gate of the MOS transistor Q1. The voltage control signal output by the DAC U3 is input to the in-phase end of the error amplifier U2 through the analog switch S2, the differential amplifier U1 obtains voltage feedback quantity through the first resistor R1 and inputs the voltage feedback quantity to the inverting end of the error amplifier U2, and the error amplifier U2 outputs an error signal to the grid electrode of the MOS tube Q1 after comparing the voltage control signal and the voltage feedback quantity, so that the conduction degree of the MOS tube Q1 is controlled, and the pulse current output by the MOS tube Q1 is high in precision.
As shown in fig. 2, the device further includes a second resistor R2 and a switch S1, wherein one end of the second resistor R2 is connected to one end of the switch S1, the other end of the switch S1 is connected to a power supply voltage, and the other end of the second resistor R2 is connected to a drain electrode of the MOS transistor Q1. When the MOS transistor Q1 is turned off, a leakage current generally exists, and when the output pulse current is not needed, the MOS transistor Q1 is turned off, the switch S1 is closed, and the leakage current is prevented from flowing through the load RL.
As shown in fig. 3, the pulse current generating method according to an embodiment of the present invention includes the steps of:
step S100: obtaining the duty cycle and frequency of the pulse current;
step S200: calculating the pulse width of the pulse current according to the duty ratio and the frequency;
step S300: calculating the pulse interval of the pulse current according to the duty ratio and the frequency;
step S400: the duration of one pulse width of the analog switch S2 is controlled to be closed every other pulse interval;
step S500: the DAC U3 continuously outputs a voltage control signal, the voltage control signal is input to the grid electrode of the MOS tube Q1 through the analog switch S2, and the conduction state of the MOS tube Q1 is controlled;
step S600: pulse current is output through the MOS transistor Q1.
In the step, the duty ratio and the frequency of the pulse current are obtained, the pulse width of the pulse current is calculated according to the duty ratio and the frequency, the pulse interval of the pulse current is calculated according to the duty ratio and the frequency, a voltage control signal is continuously output through the DAC U3 and is input to the grid electrode of the MOS tube Q1 through the analog switch S2, the duration of every other pulse interval of the analog switch S2 is equal to the duration of one pulse width, the conduction degree of the MOS tube Q1 is controlled, so that the pulse current is output, and the current negative feedback circuit inputs the feedback quantity to the grid electrode of the MOS tube Q1 to realize constant current output. Compared with the traditional current source technology, the frequency of the switch S1 of the analog switch S2 can reach tens of megahertz, and a high-frequency voltage control signal can be output under the condition that a high-speed DAC U3 is not adopted, so that high-frequency pulse current is output through the MOS tube Q1, the cost is reduced, the common-mode voltage is reduced due to the fact that the MOS tube Q1 is arranged at the low side of the load RL, the output voltage of the MOS tube Q1 is improved, and the high-voltage pulse current can be output.
Step S200 is further described according to some embodiments of the present invention, in which the pulse width is calculated by the following formula:
Ton＝D/f
where Ton is the pulse width, D is the duty cycle, and f is the frequency.
Step S300 is further described according to some embodiments of the present invention, the pulse interval is calculated by the following formula: toff= (1-D)/f
Where Toff is the pulse interval, D is the duty cycle, and f is the frequency.
The pulse current generating method according to the embodiment of the present invention is exemplified below.
The step of outputting a pulse current with a duty cycle of 30% and a frequency of 10KHz is as follows:
step 1, calculating pulse width according to duty ratio and frequency: ton=d/f=30us;
step 2, calculating pulse intervals according to the duty ratio and the frequency: toff= (1-D)/f=70us;
step 3, controlling the closing time of the analog switch S2 to be 30us every 70us;
and 5, outputting pulse current with the duty ratio of 30% and the frequency of 10KHz through the MOS transistor Q1.
The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of one of ordinary skill in the art without departing from the spirit of the present invention.
Claims (6)
1. A pulse constant current source circuit for supplying a pulse current to a load, comprising:
a control module;
the output end of the control module is connected with the control end of the DAC;
the output end of the control module is connected with the control end of the analog switch, and the output end of the DAC is connected with the input end of the analog switch;
the output end of the analog switch is connected with the grid electrode of the MOS tube, the drain electrode of the MOS tube is connected with one end of the load, the other end of the load is used for being connected with power supply voltage, and the source electrode of the MOS tube is grounded;
the sampling end of the current negative feedback circuit is connected with the source electrode of the MOS tube, and the feedback end of the current negative feedback circuit is connected with the grid electrode of the MOS tube;
the control module generates the pulse current by a pulse current generation method, the pulse current generation method comprising the steps of:
obtaining the duty cycle and frequency of the pulse current;
calculating a pulse width of the pulse current according to the duty cycle and the frequency;
calculating a pulse interval of the pulse current according to the duty cycle and the frequency;
controlling the analog switch to close the duration of one pulse width every other duration of the pulse interval;
the DAC continuously outputs a voltage control signal, the voltage control signal is input to the grid electrode of the MOS tube through the analog switch, and the conduction state of the MOS tube is controlled;
and outputting the pulse current through the MOS tube.
2. The pulsed constant current source circuit according to claim 1, wherein: the current negative feedback circuit comprises a differential amplifier, an error amplifier and a first resistor, one end of the first resistor is connected with the load, the other end of the first resistor is grounded, the in-phase end of the differential amplifier is connected with the source electrode of the MOS tube, the opposite phase end of the differential amplifier is grounded, the output end of the differential amplifier is connected with the opposite phase end of the error amplifier, the output end of the analog switch is connected with the in-phase end of the error amplifier, and the output end of the error amplifier is connected with the grid electrode of the MOS tube.
3. The pulsed constant current source circuit according to claim 1, wherein: the MOS transistor further comprises a second resistor and a switch, one end of the second resistor is connected with one end of the switch, the other end of the switch is connected with the power supply voltage, and the other end of the second resistor is connected with the drain electrode of the MOS transistor.
4. A pulse current generation method, comprising:
obtaining the duty cycle and frequency of the pulse current;
calculating a pulse width of the pulse current according to the duty cycle and the frequency;
calculating a pulse interval of the pulse current according to the duty cycle and the frequency;
controlling the analog switch to close the duration of one pulse width every other duration of the pulse interval;
the DAC continuously outputs a voltage control signal, the voltage control signal is input to the grid electrode of the MOS tube through the analog switch, and the conduction state of the MOS tube is controlled;
and outputting the pulse current through the MOS tube.
5. The pulse current generating method of claim 4, wherein the pulse width is calculated by the following formula: ton=d/f, where Ton is the pulse width, D is the duty cycle, and f is the frequency.
6. The pulse current generating method of claim 4, wherein the pulse interval is calculated by the following formula: toff= (1-D)/f, where Toff is the pulse interval, D is the duty cycle, and f is the frequency.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310376362.XA CN116382405A (en) | 2023-04-10 | 2023-04-10 | Pulse constant current source circuit and pulse current generation method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117519396A (en) * | 2023-12-27 | 2024-02-06 | 中国科学院合肥物质科学研究院 | Load self-adaptive high-efficiency pulse constant current source and control method |
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2023
- 2023-04-10 CN CN202310376362.XA patent/CN116382405A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117519396A (en) * | 2023-12-27 | 2024-02-06 | 中国科学院合肥物质科学研究院 | Load self-adaptive high-efficiency pulse constant current source and control method |
| CN117519396B (en) * | 2023-12-27 | 2024-03-22 | 中国科学院合肥物质科学研究院 | Load self-adaptive high-efficiency pulse constant current source and control method |
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