CN202331254U - Current-voltage conversion circuit with over-current protection circuit module - Google Patents
Current-voltage conversion circuit with over-current protection circuit module Download PDFInfo
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- CN202331254U CN202331254U CN2011203654358U CN201120365435U CN202331254U CN 202331254 U CN202331254 U CN 202331254U CN 2011203654358 U CN2011203654358 U CN 2011203654358U CN 201120365435 U CN201120365435 U CN 201120365435U CN 202331254 U CN202331254 U CN 202331254U
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Abstract
The utility model discloses a current-voltage conversion circuit with an over-current protection circuit module. The current-voltage conversion circuit comprises an input current, a load resistor, a first operational amplifier, an over-current protection module and output voltage signals, wherein the over-current protection module comprises a second operational amplifier, an MOS (Metal Oxide Semiconductor) transistor and a resistance voltage divider, an inphase input end of the second operational amplifier is connected with the resistance voltage divider, an antiphase input end of the second operational amplifier is connected with one end of the load resistor, and an output end of the second operational amplifier is connected with a grid electrode of the MOS transistor. Thus, according to the current-voltage conversion circuit with the over-current protection circuit module, the accurate current protection for the current-voltage conversion circuit is achieved through the over-current protection circuit module comprising the operational amplifiers, the MOS transistor and the resistance voltage divider, and the response is rapid.
Description
Technical field
The utility model relates to a kind of current-voltage conversion circuit that is provided with the current foldback circuit module.
Background technology
In production practices, especially on the industrial transmitter, often need some voltage signal that collects at the scene be converted into the current signal (0～20mA or 4-20mA) of standard, through twisted-pair feeder current signal is transferred to back level receiving equipment then.In the level receiving equipment of back, convert current signal into voltage signal once more, the data processing that supplies late-class circuit to be used for signal condition or to be correlated with.In traditional current-voltage conversion circuit, use receiving circuit as shown in Figure 1, wherein, "+", "-" they are the current terminal of back level receiving equipment; Rload is a pull-up resistor; Z1 is a Zener diode regulator; C1 is a filter capacitor; U1 is the voltage follower that operational amplifier constitutes; Resistance R 1 is the current-limiting protection resistance of Zener diode regulator Z1; Resistance R 2 is the input end protective resistance of U1.Input current signal, for electric current loop current signal Iin flows into from "+" end, the pull-up resistor Rload that flows through carries out the conversion of current-voltage, forms load voltage Vload:
Vload＝Iin?x?Rload
Flow out from "-" end at last.Operational amplifier U1 receives load voltage Vload as its in-phase end " IN+ " input signal, through after the impedance conversion, at the final voltage signal Vout of output terminal " out " output.
In order to protect the circuit elements device in the pull-up resistor Rload receiving port afterwards; Need add the current foldback circuit of forming by resistance R 1 and Zener diode regulator Z1, the load voltage Vload that the upper safety limit value that its protection value is current signal Iin forms at the back on pull-up resistor at pull-up resistor.When current signal surpasses upper safety limit; Load voltage Vload will be higher than the voltage protection value of Zener diode regulator Z1, makes Zener diode regulator Z1 reverse breakdown, so; Load voltage Vload is limited in the voltage breakdown of Zener diode regulator Z1, thereby realizes the protection to late-class circuit.
Because the operating characteristic of Zener diode regulator itself causes traditional Zener current foldback circuit to exist certain shortcoming.Zener is to utilize its inner breakdown region to have the characteristic work of burning voltage, and stable voltage is the magnitude of voltage at Zener stabilivolt two ends when operate as normal.This magnitude of voltage has bigger discreteness, different and different with stabilivolt working current and temperature; Even the Zener diode regulator of same model, also there is the deviation about 10% in the voltage stabilizing value of the Zener of different batches.Therefore, in the holding circuit of receiving equipment, use Zener to carry out overcurrent protection, there is the deviation more than 10% in its current value upper safety limit to I haven't seen you for ages, for the application scenario of the accurate overcurrent protection of needs, can't satisfy need of work.
Summary of the invention
The purpose of the utility model is to overcome the defective of prior art, proposes a kind of improved current-voltage conversion circuit that is provided with the current foldback circuit module, and it has accurate overcurrent protection and is swift in response.
For realizing above-mentioned purpose; The utility model proposes following technical scheme: a kind of current-voltage conversion circuit that is provided with the current foldback circuit module; Comprise input current, pull-up resistor, first operational amplifier, overcurrent protection module and output voltage signal; It is characterized in that: said overcurrent protection module comprises second operational amplifier, MOS transistor and resitstance voltage divider; The in-phase input end of said second operational amplifier connects said resitstance voltage divider, and the inverting input of said second operational amplifier links to each other with an end of said pull-up resistor, and the output terminal of said second operational amplifier links to each other with the grid of said MOS transistor.
Aptly, said resitstance voltage divider be connected circuit working power and " " between, and comprise two each other first resistance and second resistance of series connection, the in-phase input end of said second operational amplifier is connected between said first resistance and second resistance.
Aptly, the drain electrode of said MOS transistor connect " ".
Aptly, said current-voltage conversion circuit also comprises the 3rd resistance, and an end of said the 3rd resistance is connected the in-phase input end of said first operational amplifier, and the other end links to each other with the source class of said MOS transistor.
Aptly, said current-voltage conversion circuit also comprises filter capacitor, said filter capacitor be connected said the 3rd resistance the other end and " " between.
Aptly, said pull-up resistor is connected between the positive and negative terminals of said input current,
Aptly, the inverting input of said first operational amplifier links to each other with its output terminal, and said output terminal is exported said output voltage signal.
Compared with prior art; The current foldback circuit module that the current-voltage conversion circuit of the utility model is formed through operational amplifier, MOS transistor and resitstance voltage divider realizes accurate overcurrent protection and is swift in response; Entire circuit also has the advantage of simple and stable in addition, and is good in practical effect.
Description of drawings
Fig. 1 is the schematic diagram that is provided with the current-voltage conversion circuit of current foldback circuit module of the prior art.
Fig. 2 is the schematic diagram of the current-voltage conversion circuit that is provided with the current foldback circuit module of the utility model.
Embodiment
The accompanying drawing that will combine the utility model below carries out clear, complete description to technical scheme among the utility model embodiment.
The utility model provides a kind of current-voltage conversion circuit that is provided with overcurrent protection module; It is used for the electric current loop receiving circuit of back level equipment; Thereby can carry out the circuit that accurate overcurrent protection ensures back level equipment receiving circuit security, the practical implementation circuit is as shown in Figure 2.The above-mentioned current-voltage conversion circuit that is provided with overcurrent protection module has been cancelled the overcurrent protection module of being made up of resistance R 1 and Zener diode regulator Z1 described in the background technology, and has been changed new overcurrent protection module into.Particularly, the current foldback circuit of the utility model loop comprises the current terminal "+" of back level receiving equipment and voltage follower and the above-mentioned new overcurrent protection module that "-", pull-up resistor Rload, filter capacitor C1, the first operational amplifier U1 constitute.Wherein the 3rd resistance R 2 is the input end protective resistance of the first operational amplifier U1; Input current signal, promptly electric current loop current signal Iin flows into from "+" end, and the pull-up resistor Rload that flows through carries out the conversion of current-voltage, forms load voltage Vload:
Vload＝Iin?x?Rload
Flow out from "-" end at last.The first operational amplifier U1 receives load voltage Vload as its in-phase end " IN+ " input signal, through after the impedance conversion, at the final voltage signal Vout of its output terminal " out " output.
Above-mentioned new overcurrent protection module comprises the second operational amplifier U2, metal oxide semiconductor transistor Q1 and resitstance voltage divider.Wherein, metal oxide semiconductor transistor Q1 is called for short MOS transistor, and conducting when low level drives ends during high level; Vcc is the working power of receiving circuit.Resitstance voltage divider be connected working power Vcc and " " between; And comprise first resistance R 3 and second resistance R 4; Wherein, the upper end of first resistance R 3 is connected with working power Vcc, and its lower end is connected with the in-phase input end " IN+ " of second resistance R, 4 upper ends and the second operational amplifier U2.Second resistance R, 4 lower ends with " " be connected.The inverting input of the second operational amplifier U2 " IN-" is connected with the upper end of pull-up resistor Rload, and its output terminal " OUT " is connected with the grid G of MOS transistor Q1.The source S of MOS transistor Q1 is connected with the left end of resistance R 2, and its drain D with " " be connected.
Like this, working power Vcc constitutes voltage comparator circuit form, its in-phase input end " IN+ " obtain setting voltage Vset from the resitstance voltage divider of forming by first, second resistance R 3, R4, Vset=R4/ (R3+R4) xVcc.Through selecting first, second resistance R 3, the R4 of different resistance value ratios, can obtain required setting voltage Vset.
During the receiving circuit operate as normal, the electric current I in pull-up resistor Rload that flows through forms load voltage Vload, and this load voltage signal is delivered to first, second operational amplifier U1, U2 simultaneously.The first operational amplifier U1 is still as voltage follower, load voltage signal Vload is carried out impedance conversion after, level circuit output voltage signal Vout backward.After the second operational amplifier U2 inverting input " IN-" receives load voltage Vload signal; Vset compares with in-phase end " IN+ " input signal; Less than setting voltage Vset, show promptly that current signal need not carry out overcurrent protection less than the safety value upper limit at this moment like the voltage Vload after the current electric current loop current signal conversion; Therefore operational amplifier U2 output terminal " out " is exported high level, and MOS transistor Q1 ends.When electric current loop current signal Iin surpasses the higher limit of operate as normal; Be Vload＞Vset, the second operational amplifier U2 output low level, MOS transistor Q1 conducting; Some MOS transistor Q1 that flows through of input current signal; Make through the electric current on the pull-up resistor Rload to reduce, load voltage Vload reduces, thereby the circuit elements device of level behind the pull-up resistor Rload is protected.Can know through foregoing description, the utility model provides a kind of improved current-voltage conversion circuit that is provided with the current foldback circuit module, it has accurate overcurrent protection, is swift in response, the advantage of circuit simple and stable, and is good in practical effect.
Technology contents of the utility model and technical characterictic have disclosed as above; Yet those of ordinary skill in the art still maybe be based on the teaching of the utility model and announcements and are done all replacement and modifications that does not deviate from the utility model spirit; Therefore; The utility model protection domain should be not limited to the content that embodiment discloses, and should comprise various replacement and the modifications that do not deviate from the utility model, and is contained by the present patent application claim.
Claims (7)
1. current-voltage conversion circuit that is provided with the current foldback circuit module; Comprise input current, pull-up resistor, first operational amplifier, overcurrent protection module and output voltage signal; It is characterized in that: said overcurrent protection module comprises second operational amplifier, MOS transistor and resitstance voltage divider; The in-phase input end of said second operational amplifier connects said resitstance voltage divider; The inverting input of said second operational amplifier links to each other with an end of said pull-up resistor, and the output terminal of said second operational amplifier links to each other with the grid of said MOS transistor.
2. the current-voltage conversion circuit that is provided with the current foldback circuit module according to claim 1; It is characterized in that: said resitstance voltage divider be connected circuit working power and " " between; And comprising two first resistance and second resistance of series connection each other, the in-phase input end of said second operational amplifier is connected between said first resistance and second resistance.
3. the current-voltage conversion circuit that is provided with the current foldback circuit module according to claim 1 is characterized in that: the drain electrode of said MOS transistor connect " ".
4. according to claim 1 or the 3 described current-voltage conversion circuits that are provided with the current foldback circuit module; It is characterized in that: said current-voltage conversion circuit also comprises the 3rd resistance; One end of said the 3rd resistance is connected the in-phase input end of said first operational amplifier, and the other end links to each other with the source class of said MOS transistor.
5. the current-voltage conversion circuit that is provided with the current foldback circuit module according to claim 4; It is characterized in that: said current-voltage conversion circuit also comprises filter capacitor, said filter capacitor be connected said the 3rd resistance the other end and " " between.
6. the current-voltage conversion circuit that is provided with the current foldback circuit module according to claim 1 is characterized in that: said pull-up resistor is connected between the positive and negative terminals of said input current.
7. the current-voltage conversion circuit that is provided with the current foldback circuit module according to claim 1 is characterized in that: the inverting input of said first operational amplifier links to each other with its output terminal, and said output terminal is exported said output voltage signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011203654358U CN202331254U (en) | 2011-09-28 | 2011-09-28 | Current-voltage conversion circuit with over-current protection circuit module |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011203654358U CN202331254U (en) | 2011-09-28 | 2011-09-28 | Current-voltage conversion circuit with over-current protection circuit module |
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| Publication Number | Publication Date |
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| CN202331254U true CN202331254U (en) | 2012-07-11 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN2011203654358U Expired - Fee Related CN202331254U (en) | 2011-09-28 | 2011-09-28 | Current-voltage conversion circuit with over-current protection circuit module |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102394494A (en) * | 2011-09-28 | 2012-03-28 | 魏德米勒电联接国际贸易(上海)有限公司 | Current-voltage converting circuit provided with over-current protection circuit module |
| CN104374983A (en) * | 2014-10-29 | 2015-02-25 | 中国电子科技集团公司第三十六研究所 | Current monitoring circuit |
| CN106489107A (en) * | 2016-08-16 | 2017-03-08 | 深圳市汇顶科技股份有限公司 | I V modular converter |
-
2011
- 2011-09-28 CN CN2011203654358U patent/CN202331254U/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102394494A (en) * | 2011-09-28 | 2012-03-28 | 魏德米勒电联接国际贸易(上海)有限公司 | Current-voltage converting circuit provided with over-current protection circuit module |
| CN104374983A (en) * | 2014-10-29 | 2015-02-25 | 中国电子科技集团公司第三十六研究所 | Current monitoring circuit |
| CN104374983B (en) * | 2014-10-29 | 2017-12-22 | 中国电子科技集团公司第三十六研究所 | A kind of current monitoring circuit |
| CN106489107A (en) * | 2016-08-16 | 2017-03-08 | 深圳市汇顶科技股份有限公司 | I V modular converter |
| CN106489107B (en) * | 2016-08-16 | 2018-02-13 | 深圳市汇顶科技股份有限公司 | I V modular converters |
| WO2018032309A1 (en) * | 2016-08-16 | 2018-02-22 | 深圳市汇顶科技股份有限公司 | I-v conversion module |
| US10146245B2 (en) | 2016-08-16 | 2018-12-04 | Shenzhen GOODIX Technology Co., Ltd. | I-V converting module |
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Legal Events
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| 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: 20120711 Termination date: 20190928 |