CN216133358U - High-precision constant-current source module - Google Patents
High-precision constant-current source module Download PDFInfo
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- CN216133358U CN216133358U CN202121440800.7U CN202121440800U CN216133358U CN 216133358 U CN216133358 U CN 216133358U CN 202121440800 U CN202121440800 U CN 202121440800U CN 216133358 U CN216133358 U CN 216133358U
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Abstract
The utility model aims to provide a high-precision constant current source module which has high current, low differential pressure, low ripple wave, quick dynamic response and capability of outputting a pulse-shaped constant current source. The voltage-controlled constant current source module comprises a power input module and a voltage-controlled constant current source module, wherein the input end of the power input module is connected with an external power supply, the voltage-controlled constant current source module comprises a first operational amplifier, a field-effect tube group and a switch field-effect tube which are sequentially connected, the positive input end of the first operational amplifier receives control voltage, the output end of the first operational amplifier is connected with the grids of a plurality of high-power field-effect tubes contained in the field-effect tube group, the output end of the power input module is connected with the drain electrodes of the plurality of high-power field-effect tubes, the input of the switch field-effect tube is connected with the source electrodes of the plurality of high-power field-effect tubes, the output end of the switch field-effect tube is connected with a load, and the control end of the switch field-effect tube receives PWM signals. The utility model is applied to the technical field of constant current source modules.
Description
Technical Field
The utility model is applied to the technical field of constant current source modules, and particularly relates to a high-precision constant current source module for an open-short circuit test.
Background
The principle of the open-short circuit test in the electronic industry is to input a very small current to two points to be detected, then read the voltage between the two points, calculate the resistance value between the two points by utilizing R = V/I, and judge whether the two points belong to a short circuit or an open circuit according to the obtained resistance. If the two points are in a short circuit state, if the input current cannot be controlled, the power supply is inevitably burnt. Therefore, a constant current source is required to output a constant current value regardless of the output load. The constant current source is a power source capable of supplying a constant current to a load, and therefore the application range of the constant current source is very wide and is indispensable in many cases. For example, when a battery is charged by a general charger, the charging current is reduced as the terminal voltage of the battery gradually increases. In order to ensure constant-current charging, the output voltage of the charger must be increased at any time, but the output voltage of the charger does not need to be adjusted after the constant-current source charging is adopted, so that the labor intensity is reduced, and the production efficiency is improved. Constant current sources are also widely used in measurement circuits, such as measurement and classification of resistor values, measurement of cable resistance, etc., and the more stable the current, the more accurate the measurement.
Constant current source designs in use today in the market use a similar scheme: (1) the constant current diode is directly used, but the constant current diode is used as a constant current source, so that the application is less in practice, the constant current characteristic is not very good due to the constant current characteristic of the constant current diode, the current specification is less, and the price is high; (2) the triode is used for forming a constant current source, the two triodes of the same type are used, the BE voltage relatively stable to the triodes is used as a reference, the current value is I = Ube/R, the constant current source is simple and easy to operate, the current value can BE freely controlled, no special element is used, and the cost is reduced. The defects are that the BE voltage of triodes of different models is not a fixed value, and even if the types are the same, the BE voltage has certain individual difference, and meanwhile, under different working currents, the voltage also has certain fluctuation. And therefore are not suitable for the requirements of a precise constant current source.
SUMMERY OF THE UTILITY MODEL
The utility model aims to overcome the defects of the prior art and provides a high-precision constant current source module which has high current, low differential pressure, low ripple and quick dynamic response and can output a pulse-shaped constant current source.
The technical scheme adopted by the utility model is as follows: the voltage-controlled constant current source module comprises a power input module and a voltage-controlled constant current source module, wherein the input end of the power input module is connected with an external power supply, the voltage-controlled constant current source module comprises a first operational amplifier, a field-effect tube group and a switch field-effect tube which are sequentially connected, the positive input end of the first operational amplifier receives control voltage, the output end of the first operational amplifier is connected with the grids of a plurality of high-power field-effect tubes contained in the field-effect tube group, the output end of the power input module is connected with the drain electrodes of the plurality of high-power field-effect tubes, the input of the switch field-effect tube is connected with the source electrodes of the plurality of high-power field-effect tubes, the output end of the switch field-effect tube is connected with a load, and the control end of the switch field-effect tube receives PWM signals.
According to the scheme, the field effect tube group is used as an adjusting unit in the circuit, the field effect tube is adopted for control, the voltage linear control current is easier to realize, the requirement that the output current can reach 2A at most can be met, and the voltage approximately linear control current can be well realized. When the field effect transistor works in a saturation region, the leakage current is approximate to the current set by the control voltage, and the leakage current is unchanged as long as the control voltage is unchanged. In order to output the pulse-shaped constant current source, the utility model adopts the mode that the PWM signal controls the switching field effect transistor to cause high-low level conversion, thereby forming square wave pulse, regulating and controlling the frequency and the duty ratio of the PWM signal and realizing the purpose of regulating the time frequency of the output pulse. The positive input end of the first operational amplifier is connected with a DAC circuit on an external controller, and the DAC circuit outputs control voltage to the positive input end of the first operational amplifier to set output voltage.
Preferably, the power input module comprises a buck switching regulator of type LT3680EMSE and a linear regulator of type SC1592 IMTR.
Preferably, the voltage-controlled constant current source module further comprises a second operational amplifier and a sampling resistor, the sampling resistor is connected between the output end of the field-effect tube group and the switching field-effect tube, the positive input end and the negative input end of the second operational amplifier are respectively connected to the two ends of the sampling resistor, and the output end of the second operational amplifier is connected to the negative input end of the first operational amplifier.
According to the scheme, the second operational amplifier is used as a voltage follower to sample the voltages at two ends of the sampling resistor, so that the output current of the voltage-controlled constant current source module is obtained. And feeding back a voltage value through an output end of the second operational amplifier to the first operational amplifier. Causing the first operational amplifier to perform output control.
Further preferably, the second operational amplifier is an operational amplifier chip with a model number of LT1800C 854.
Preferably, a plurality of the high-power field effect transistors are field effect transistors with the model number being SPD28N 03.
Preferably, the first operational amplifier is an operational amplifier chip with model number LT1800C 854.
Preferably, the high-precision constant current source electrical module further comprises a high-voltage side switch and a MOSFET driver with model number ADP3654ARDZ, and output ends of the high-voltage side switch and the MOSFET driver are connected with a control end of the switching field effect transistor.
According to the scheme, the high-voltage side switch and the MOSFET driver output and PWM signals to the switching field effect transistor for control.
Drawings
FIG. 1 is a system block diagram of the present invention;
FIG. 2 is a circuit schematic of the power input module;
fig. 3 is a circuit schematic diagram of the voltage-controlled constant current source module.
Detailed Description
As shown in fig. 1 to fig. 3, in this embodiment, the present invention includes a power input module 1 and a voltage-controlled constant current source module 2, an input end of the power input module 1 is connected to an external power supply, the voltage-controlled constant current source module 2 includes a first operational amplifier U15, a field-effect tube group and a switching field-effect tube Q3 which are connected in sequence, a positive input end of the first operational amplifier U15 is connected to a DAC circuit of an external control module, the DAC circuit outputs a control voltage of 0 to 2.5V to the first operational amplifier U15, an output end of the first operational amplifier U15 is connected to gates of two high-power field-effect tubes Q5/Q1 included in the field-effect tube group, an output end of the power input module 1 is connected to drains of the two high-power field-effect tubes Q5/Q1, an input of the switching field-effect tube Q3 is connected to sources of the two high-power field-effect tubes Q5/Q1, the output end of the switching field effect transistor Q3 is connected with a load, and the control end of the switching field effect transistor Q3 receives a PWM signal. A plurality of high-power field effect transistors Q5/Q1 are field effect transistors with the model number of SPD28N 03. The first operational amplifier U15 is an operational amplifier chip model LT1800C 854.
In this embodiment, the power input module 1 includes a buck switching regulator U14 of model LT3680EMSE and a linear regulator U32 of model SC1592 IMTR.
In this embodiment, the voltage-controlled constant current source module 2 further includes a second operational amplifier U16 and a sampling resistor R73, the sampling resistor R73 is connected between the output end of the fet group and the switching fet Q3, the positive input end and the negative input end of the second operational amplifier are respectively connected to the two ends of the sampling resistor R73, and the output end of the second operational amplifier U16 is connected to the negative input end of the first operational amplifier U15. The second operational amplifier U16 is an operational amplifier chip model LT1800C 854. The sampling resistor R73 is wound by constantan wire, and the resistance value changes little with the temperature.
In this embodiment, the high-precision constant current source electrical module further includes a high-side switch and a MOSFET driver U17 with model number ADP3654ARDZ, and an output terminal of the high-side switch and the MOSFET driver U17 is connected to a control terminal of the switching fet Q3.
Claims (7)
1. The utility model provides a high accuracy constant current source module which characterized in that: the power supply comprises a power input module (1) and a voltage-controlled constant current source module (2), wherein the input end of the power input module (1) is connected with an external power supply, the voltage-controlled constant current source module (2) comprises a first operational amplifier (U15), a field-effect tube group and a switch field-effect tube (Q3) which are sequentially connected, the positive input end of the first operational amplifier (U15) receives control voltage, the output end of the first operational amplifier (U15) is connected with the grids of a plurality of first high-power field-effect tubes (Q5) and a plurality of second high-power field-effect tubes (Q1) contained in the field-effect tube group, the output end of the power input module (1) is connected with the drains of a plurality of first high-power field-effect tubes (Q5) and a plurality of second high-power field-effect tubes (Q1), and the input of the switch field-effect tube (Q3) is connected with the sources of a plurality of first high-power field-effect tubes (Q5) and a plurality of second high-power field-effect tubes (Q1) And the output end of the switching field effect transistor (Q3) is connected with a load, and the control end of the switching field effect transistor (Q3) receives a PWM signal.
2. The high-precision constant current source module according to claim 1, wherein: the power input module (1) comprises a buck switching regulator (U14) with the model number LT3680EMSE and a linear regulator (U32) with the model number SC1592 IMTR.
3. The high-precision constant current source module according to claim 1, wherein: the voltage-controlled constant current source module (2) further comprises a second operational amplifier (U16) and a sampling resistor (R73), wherein the sampling resistor (R73) is connected between the output end of the field-effect tube group and the switch field-effect tube (Q3), the positive input end and the negative input end of the second operational amplifier (U16) are respectively connected with the two ends of the sampling resistor (R73), and the output end of the second operational amplifier (U16) is connected with the negative input end of the first operational amplifier (U15).
4. A high precision constant current source module according to claim 3, wherein: the second operational amplifier (U16) is an operational amplifier chip with model number LT1800C 854.
5. The high-precision constant current source module according to claim 1, wherein: the first power field effect transistors (Q5) and the second power field effect transistors (Q1) are field effect transistors with the model number of SPD28N 03.
6. The high-precision constant current source module according to claim 1, wherein: the first operational amplifier (U15) is an operational amplifier chip with model number LT1800C 854.
7. The high-precision constant current source module according to claim 1, wherein: the high-precision constant current source electrical module further comprises a high-voltage side switch and a MOSFET driver (U17) with the model number of ADP3654ARDZ, and the output ends of the high-voltage side switch and the MOSFET driver (U17) are connected with the control end of the switch field effect transistor (Q3).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121440800.7U CN216133358U (en) | 2021-06-28 | 2021-06-28 | High-precision constant-current source module |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121440800.7U CN216133358U (en) | 2021-06-28 | 2021-06-28 | High-precision constant-current source module |
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| Publication Number | Publication Date |
|---|---|
| CN216133358U true CN216133358U (en) | 2022-03-25 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202121440800.7U Active CN216133358U (en) | 2021-06-28 | 2021-06-28 | High-precision constant-current source module |
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| CN (1) | CN216133358U (en) |
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2021
- 2021-06-28 CN CN202121440800.7U patent/CN216133358U/en active Active
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