CN203117828U - High-precision adjustable weak current output circuit - Google Patents
High-precision adjustable weak current output circuit Download PDFInfo
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- CN203117828U CN203117828U CN 201320142282 CN201320142282U CN203117828U CN 203117828 U CN203117828 U CN 203117828U CN 201320142282 CN201320142282 CN 201320142282 CN 201320142282 U CN201320142282 U CN 201320142282U CN 203117828 U CN203117828 U CN 203117828U
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- operational amplifier
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Abstract
The utility model discloses a high-precision adjustable weak current output circuit comprising voltage input port, a second-order active filter, a voltage/current conversion circuit and an output port used for outputting weak currents, wherein the voltage input port, the second-order active filter, the voltage/current conversion circuit and the output port are sequentially connected. The second-order active filter comprises a second-order filter and a first operational amplifier. The voltage/current conversion circuit comprises a second operational amplifier and a plurality of resistors connected with the second operational amplifier. The output end of the first operational amplifier is connected with a positive input end of the second operational amplifier, and a negative input end of the second operational amplifier is connected with a reference voltage circuit. The current output circuit is simple, high in precision and easy to adjust. By means of the second-order active filter, voltage after filtering passes the voltage/current conversion circuit so that the currents from microampere to milliampere are obtained.
Description
Technical field
The utility model relates to a kind of electric current export technique field, relates in particular to the adjustable Weak current output circuit of a kind of high precision.
Background technology
Current signal is not subjected to its antijamming capability of variation while of extraneous load strong, impel it in a lot of fields application to be arranged all, for example sensor field belongs to Weak current control field, the 4-20mA output device belongs to the medium current application, electric car charger belongs to high-power electric current application, yet present current output circuit complexity, and precision is low, adjustability is not strong.
Summary of the invention
The utility model provides a kind of high precision adjustable Weak current output circuit in order to solve the prior art above shortcomings; Current output circuit is simple, the precision height, is easy to regulate, and carries out second-order active filter by the voltage to PWM form or stable form, and filtered voltage obtains from microampere order to milliampere level electric current through the voltage/current translation circuit.
The purpose of this utility model is to adopt following technical proposals to realize:
The adjustable Weak current control circuit of a kind of high precision, comprise successively the voltage input that connects Port input interface, second-order active filter device, voltage/current conversion circuit, be used for the Port output port of output Weak current, described second-order active filter device comprises second order filter, first operational amplifier; Described voltage/current conversion circuit comprises second operational amplifier, reaches a plurality of resistance that are connected with second operational amplifier, the output terminal of first operational amplifier connects the positive input terminal of second operational amplifier, and the negative input end of second operational amplifier is connected with reference voltage circuit.
Described second order filter comprises resistance R 3, polar capacitor C1, resistance R 4, the polar capacitor C2 that is connected, wherein, polar capacitor C1 connects back, in parallel with resistance R 4 with polar capacitor C2, connect the connecting line place ground connection of polar capacitor C1, polar capacitor C2 again with resistance R 3; Second order filter is connected with the first operational amplifier positive input terminal, and the negative input end of first operational amplifier is connected with output terminal.
Described reference voltage circuit comprises resistance R 1, rheochord VR1, the resistance R 2 that is in series, resistance R 1 other end ground connection wherein, resistance R 2 another termination 5V direct supplys.
Described a plurality of resistance comprises resistance R 5, resistance R 7, resistance R 6, resistance R 8, resistance R 9, wherein the front end of resistance R 6 is connected with first operational amplifier output terminal, the rear end is connected with the positive input terminal of second operational amplifier, resistance R 5 one ends are connected with the negative input end of second operational amplifier, the other end is connected with the rheochord VR1 of reference voltage circuit, resistance R 7 one ends are connected with the negative input end of second operational amplifier, the other end is connected with the output terminal of second operational amplifier, resistance R 9 one ends are connected with the output terminal of second operational amplifier, the other end is connected with the Port output port, resistance R 8 one ends be connected with the Port output port, the other end is connected with the positive input terminal of second operational amplifier, first operational amplifier, second operational amplifier passes through positive and negative 5V power supply respectively to positive-negative power end 4,11 power supplies.
Described Port input port voltage signal is voltage signal or pwm signal.
The beneficial effects of the utility model:
1. circuit of the present utility model at first passes through the second-order active filter circuit, no matter the PWM form still is that the voltage signal of stable form all can obtain the current signal that changes with voltage ratio when sending into signal, has widened the applicability of system.
2. circuit increases reference voltage circuit and carries out the reference point adjusting, can overcome the Weak current deviation that the operational amplifier inconsistency is brought, and has strengthened reliability and the adaptability of system.
3. circuit can obtain the Weak current of microampere order, and the precision height is for the control of little electric current provides a kind of thinking; Circuit also can obtain milliampere medium current of level simultaneously, and this electric current not only provides a kind of thinking for the 4-20mA current output device, and this electric current can also be as the driving stage of the big electric current output of charging system for electric automobile simultaneously.
4. circuital current and input voltage are linear, thus do not need electric current is measured again, owing to adopt hardware to realize fully, so this circuit wide accommodation, cost are low.
Description of drawings
Fig. 1 is the structural drawing of the utility model embodiment.
Embodiment
Below in conjunction with drawings and Examples the utility model is described further.
In conjunction with Fig. 1, the adjustable Weak current control circuit of a kind of high precision, comprise successively the voltage input that connects Port input interface, second-order active filter device, voltage/current conversion circuit, be used for the Port output port of output Weak current, described second-order active filter device comprises second order filter, first operational amplifier; Described voltage/current conversion circuit comprises second operational amplifier, reaches a plurality of resistance that are connected with second operational amplifier, the negative input end 2 that the output terminal 7 of first operational amplifier connects positive input terminal 3, the second operational amplifiers of second operational amplifier is connected with reference voltage circuit.
Described second order filter comprises resistance R 3, polar capacitor C1, resistance R 4, the polar capacitor C2 that is connected, wherein, polar capacitor C1 connects back, in parallel with resistance R 4 with polar capacitor C2, connect the connecting line place ground connection of polar capacitor C1, polar capacitor C2 again with resistance R 3; Second order filter is connected with the first operational amplifier positive input terminal 5, and the negative input end 6 of first operational amplifier is connected with output terminal 7.
Described reference voltage circuit comprises resistance R 1, rheochord VR1, the resistance R 2 that is in series, resistance R 1 other end ground connection wherein, resistance R 2 another termination 5V direct supplys.
Described a plurality of resistance comprises resistance R 5, resistance R 7, resistance R 6, resistance R 8, resistance R 9, wherein the output terminal 7 of first operational amplifier connects the positive input terminal 3 of second operational amplifier through resistance R 6, the negative input end 2 of second operational amplifier is connected with the rheochord VR1 of reference voltage circuit through resistance R 5, resistance R 7 one ends are connected with the negative input end 2 of second operational amplifier, the other end is connected with the output terminal 1 of second operational amplifier, resistance R 9 one ends are connected with the output terminal 1 of second operational amplifier, the other end is connected with the Port output port, resistance R 8 one ends be connected with the Port output port, the other end is connected first operational amplifier with the positive input terminal 3 of second operational amplifier, second operational amplifier passes through positive and negative 5V power supply respectively to positive-negative power end 4,11 power supplies.
Described Port input port voltage signal is voltage signal or pwm signal.
Accompanying drawing 1 is schematic diagram of the present utility model, the adjustable Weak current output circuit of this high precision comprises for the Port1 port of voltage input, operational amplifier 1, operational amplifier 2, is used for the Port2 port that electric current is exported, voltage signal obtains voltage signal stably through the second-order active filter circuit, voltage signal changes into the current signal of linear ratio with it through the voltage/current conversion circuit with voltage signal.
The principle analysis of the utility model patent is as follows:
Embodiment 1,
When input voltage signal is pwm signal, when the PWM dutycycle is 0%, the output end voltage of operational amplifier 1 is U1, dutycycle is 100% o'clock, and the output end voltage of operational amplifier 1 is U2, and the dutycycle of supposing pwm signal is K%, then this moment the second-order active filter circuit the * K/100 of output voltage U=(U2-U1), suppose by resistance R 1, slide rheostat VR1, the reference voltage output voltage values that resistance R 2 constitutes is U', and operational amplifier 2 output end voltages are U
o, the negative input end voltage of operational amplifier 2 is U
-, the positive input terminal voltage of operational amplifier 2 is U
+, the Port2 port voltage is U
*, the circuit output current is I, the characteristics that are operated in linear zone " empty short ", " empty disconnected " according to the amplifier amplifier can obtain equation:
(U'-U
-)/R5＝(U
--U
o)/R7 （1）
(U-U
+)/R6＝(U
+-U
*)/R8 （2）
U
+＝U
- （3）
I＝(U
O-U
*)/R9+(U
+-U
*)/R8 （4）
Work as R5=R6, R7=R8, R5/R6/R7/R8〉〉 during R9, abbreviation can get I=(U-U')/R9*R7/R5.
Embodiment 2,
When input signal is the voltage form signal, suppose that input voltage is U, then the output voltage of operational amplifier 1 is U, other structure and principle and PWM form input voltage analysis classes seemingly do not repeat them here.
Though above-mentionedly by reference to the accompanying drawings the embodiment of utility model is described; but be not the restriction to the utility model protection domain; one of ordinary skill in the art should be understood that; on the basis of the technical solution of the utility model, those skilled in the art do not need to pay various modifications that creative work can make or distortion still in protection domain of the present utility model.
Claims (5)
1. adjustable Weak current control circuit of high precision, it is characterized in that, comprise successively the voltage input that connects Port input interface, second-order active filter device, voltage/current conversion circuit, be used for the Port output port of output Weak current, described second-order active filter device comprises second order filter, first operational amplifier; Described voltage/current conversion circuit comprises second operational amplifier, reaches a plurality of resistance that are connected with second operational amplifier, the output terminal of first operational amplifier connects the positive input terminal of second operational amplifier, and the negative input end of second operational amplifier is connected with reference voltage circuit.
2. the adjustable Weak current control circuit of high precision as claimed in claim 1, it is characterized in that, described second order filter comprises resistance R 3, polar capacitor C1, resistance R 4, the polar capacitor C2 that is connected, wherein, polar capacitor C1 connects back, in parallel with resistance R 4 with polar capacitor C2, connect the connecting line place ground connection of polar capacitor C1, polar capacitor C2 again with resistance R 3; Second order filter is connected with the first operational amplifier positive input terminal, and the negative input end of first operational amplifier is connected with output terminal.
3. the adjustable Weak current control circuit of high precision as claimed in claim 1, it is characterized in that, described reference voltage circuit comprises resistance R 1, rheochord VR1, the resistance R 2 that is in series, resistance R 1 other end ground connection wherein, resistance R 2 another termination 5V direct supplys.
4. the adjustable Weak current control circuit of high precision as claimed in claim 1, it is characterized in that, described a plurality of resistance comprises resistance R 5, resistance R 7, resistance R 6, resistance R 8, resistance R 9, wherein the front end of resistance R 6 is connected with first operational amplifier output terminal, the rear end is connected with the positive input terminal of second operational amplifier, resistance R 5 one ends are connected with the negative input end of second operational amplifier, the other end is connected with the rheochord VR1 of reference voltage circuit, resistance R 7 one ends are connected with the negative input end of second operational amplifier, the other end is connected with the output terminal of second operational amplifier, resistance R 9 one ends are connected with the output terminal of second operational amplifier, the other end is connected with the Port output port, resistance R 8 one ends be connected with the Port output port, the other end is connected with the positive input terminal of second operational amplifier, first operational amplifier, second operational amplifier passes through positive and negative 5V power supply respectively to positive-negative power end 4,11 power supplies.
5. the adjustable Weak current control circuit of high precision as claimed in claim 1 is characterized in that, described Port input port voltage signal is voltage signal or pwm signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320142282 CN203117828U (en) | 2013-03-26 | 2013-03-26 | High-precision adjustable weak current output circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320142282 CN203117828U (en) | 2013-03-26 | 2013-03-26 | High-precision adjustable weak current output circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203117828U true CN203117828U (en) | 2013-08-07 |
Family
ID=48898157
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201320142282 Expired - Fee Related CN203117828U (en) | 2013-03-26 | 2013-03-26 | High-precision adjustable weak current output circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN203117828U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103149960A (en) * | 2013-03-26 | 2013-06-12 | 山东大学 | High-precision adjustable type miniature current control circuit |
-
2013
- 2013-03-26 CN CN 201320142282 patent/CN203117828U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103149960A (en) * | 2013-03-26 | 2013-06-12 | 山东大学 | High-precision adjustable type miniature current control circuit |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20130807 Termination date: 20160326 |