CN103837732B - Passive current detection circuit - Google Patents
Passive current detection circuit Download PDFInfo
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- CN103837732B CN103837732B CN201410108884.2A CN201410108884A CN103837732B CN 103837732 B CN103837732 B CN 103837732B CN 201410108884 A CN201410108884 A CN 201410108884A CN 103837732 B CN103837732 B CN 103837732B
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- pnp pipe
- output
- optical coupler
- circuit
- detection circuit
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Abstract
The present invention, which will provide a kind of output channel circuit that is used for, has as little as 1mA test limits and the up to passive current detection circuit of 400mA electric currents tolerance, the control signal other end, which is received, including solid-state relay one end connects the emitter stage of the first PNP pipe and the emitter stage of the second PNP pipe, the base stage of first PNP pipe, the output end that the base stage of second PNP pipe is connected as this circuit with the colelctor electrode of the second PNP pipe, the colelctor electrode of first PNP pipe connects the first input end of optical coupler by resistance, second input termination circuit voltage of optical coupler, first output end output electric current measure signal of optical coupler, the second output end and the 3rd output head grounding of optical coupler.
Description
Technical field
It is more particularly to a kind of to be applied to industrial control system and safety signal system the present invention relates to electronic circuit field
In output current detection circuit.
Background technology
Industrial control system and safety signal system are for example：In the industries such as aviation electronics, railway signal, nuclear power, controller
The opening and closing to outside controlled signal are realized by switching output channel.To determine true output situation and the leakage of port
Size of current, typically detects circuit in output port design current.To ensure that detection circuit does not cause security implication, one to output
As require detection circuit use passive design.
As shown in figure 1, being a kind of common output channel circuit design, the electric path control deivce 1, optical coupler 3, current limliting electricity
Resistance 6.1 and the grade of current sampling resistor 6.2 composition.When output channel output current makes the both end voltage of sampling resistor 6.2 be higher than threshold value
When, optical coupler 3 is opened, so as to reach the purpose of current detecting.The circuit can realize less current detecting limit, but when passage electricity
When flowing larger, sampling resistor power, pressure drop are all very big, have a strong impact on output function.It is in parallel even in current sampling resistor two ends
Zener does voltage clamping, can not also avoid power consumption larger on current sampling resistor, and the situation for being not suitable for high current is used.Separately
A kind of general design is to realize current detecting, but high cost, bulky using electromagnetic conversion device, be not appropriate for multichannel,
The use situation that PCB is installed.
The content of the invention
Being used for output channel circuit the technical problem to be solved in the present invention is to provide one kind has as little as 1mA test limits (low
To 1mA) and up to 400mA electric currents are tolerated（Up to 400mA）Passive current detection circuit.
In order to solve the above technical problems, the passive output current detection circuit of the present invention, including：The one end of solid-state relay 2
Receive the control signal other end and connect the emitter stage of the first PNP pipe 4 and the emitter stage of the second PNP pipe 5, the base of the first PNP pipe 4
The output terminals A that pole, the base stage of the second PNP pipe 5 are connected as this circuit with the colelctor electrode of the second PNP pipe 5, the collection of the first PNP pipe 4
Electrode connects the first input end 7 of optical coupler 3 by resistance 6, and the second input 8 of optical coupler 3 meets circuit voltage VCC, optocoupler
The output electric current measure signal of the first output end 9 of device 3, the second output end 10 of optical coupler 3 and the 3rd output end 11 are grounded, and first
The PNP pipe 5 of PNP pipe 4 and second can be using the completely the same device of device parameter performance.
The passive output current detection circuit of the present invention can be applied to including but not limited to safety signal system, work
The fields such as industry control system.The first PNP pipe 4, the second PNP pipe 5, the and of resistance 6 are determined according to the need for output channel design parameter
The device parameter performance of optical coupler 3.
Second PNP pipe 5 is connected into " diode " in circuit, i.e., its base stage and colelctor electrode link together, it is ensured that
Second PNP pipe 5 is necessarily in conducting state.Set the first PNP pipe 4 and the formation matching of the second PNP pipe 5 it is good to pipe, first
The base stage of PNP pipe 4 is connected with the base stage of the second PNP pipe 5, the emitter stage phase of the emitter stage of the first PNP pipe 4 and the second PNP pipe 5
Connection, it is believed that both base currents are identical, the emitter stage and its base stage of the second PNP pipe 5 are connected.Such a connected mode makes first
The colelctor electrode output of PNP pipe 4 is with the colelctor electrode output identical " ability " with the second PNP pipe 5.
Assuming that from output channel circuit output current be I0, the DC current gain of the second PNP pipe 5 is hFE, the second PNP pipe 5
Collector current is IC, then have：
IO=IC+IB+IBAnd IC=hFE*IB
I.e.：
IO=IC+2*IB/hFE
Due to hFEIt is larger, therefore IO≈IC, therefore draw, the colelctor electrode output of the first PNP pipe 4 has and output channel circuit
Output identical " ability ".So if there is output current, then almost identical electric current can pass through the PNP of optical coupler 3 and the first
Pipe 4, produces current detection signal.
When channel current is larger, the LED sides of optical coupler 3 are likely to be broken, and place 6 metering functions of resistance.Assuming that defeated
It is U to go out channel circuit output maximum voltagemax, the resistance of resistance 6 is R6, flow through the electric current I of optical coupler 3LED sidesF：
IF≤(UMAX-0.7-UF)/R6
Because colelctor electrode-emitter voltage drop at the first PNP pipe 4 and the second PNP pipe 5 only has 0.7V or so, optical coupler 3
LED sides electric current IFAlso in uA ranks, therefore whole detection circuit power consumption is extremely low, and output function is not influenceed substantially.
The present invention by select the optocoupler optical coupler 3 of different model, different resistance resistance 6, it is possible to adjust electric current inspection
Survey threshold value and tolerance threshold.Detection circuit is simultaneously not introduced into extra power supply, it is to avoid because component failure causes power supply to scurry into passage,
It ensure that detection circuit does not influence safety.
Brief description of the drawings
The present invention is further detailed explanation with embodiment below in conjunction with the accompanying drawings：
Fig. 1 is a kind of existing output channel circuit.
Fig. 2 is passive current detection circuit principle schematic of the invention.
Fig. 3 is the schematic diagram of one embodiment of the invention.
Description of reference numerals
Controller 1
Solid-state relay 2
Optical coupler 3
First PNP pipe 4
Second PNP pipe 5
Resistance 6
Current-limiting resistance 6.1
Current sampling resistor 6.2
Optical coupler first input end 7,
The second input of optical coupler 8
The input 9 of optical coupler the 3rd
The input 10 of optical coupler the 4th
The first output end of optical coupler 11
Circuit voltage VCC
External voltage VDD
Circuit output end A
Embodiment
As shown in figure 3, one embodiment of the invention, including：Controller 1 outputs control signals to the one end of solid-state relay 2, separately
The emitter stage of one end connection the first PNP pipe 4 of connection and the emitter stage of the second PNP pipe 5, the base stage of the first PNP pipe 4, the second PNP pipe
The output terminals A that 5 base stage is connected as this circuit with the colelctor electrode of the second PNP pipe 5, the colelctor electrode of the first PNP pipe 4 passes through resistance
The first input end 7 of 6 connection optical couplers 3, the 3rd input 9 of optical coupler 3 meets circuit voltage VCC, the first output of optical coupler 3
11 output electric current measure signals are held, the second input 10 of optical coupler 3 and the 4th input 11 are grounded.
In the present embodiment, solid-state relay 2 uses PVG612AS；First PNP pipe 4 and the second PNP pipe 5BC807-40, light
Coupling device 3 uses TLP124, and resistance 6 uses 7.5K Ω resistance, output channel rated voltage 24V.When output channel is opened, pole is loaded
Hour, output channel electric current is minimum, and the electric current for flowing through detection optical coupler LED sides is also minimum, it is impossible to turn on optical coupler output end；
When electric current becomes larger, due to aforementioned principles, the conducting of optical coupler output end, electric current is detected；When channel current is very big, by
In output channel voltage 24V, current-limiting resistance 7.5k, then optical coupler LED ends electric current is not more than（24-0.7-1）/ 7.5k=3mA,
Optocoupler can't be damaged.
The present invention is described in detail above by embodiment and embodiment, but these are not constituted pair
The limitation of the present invention.Without departing from the principles of the present invention, those skilled in the art can also make many deformations and change
Enter, these also should be regarded as protection scope of the present invention.
Claims (2)
1. a kind of passive output current detection circuit, its feature includes：Solid-state relay（2）One end receives the control signal other end
Connect the first PNP pipe（4）Emitter stage and the second PNP pipe（5）Emitter stage, the first PNP pipe（4）Base stage, the second PNP pipe
（5）Base stage and the second PNP pipe（5）Colelctor electrode be connected as this circuit output end（A）, the first PNP pipe（4）Colelctor electrode
Pass through resistance（6）Connect optical coupler（3）First input end（7）, optical coupler（3）The second input（8）Connect circuit voltage
（VCC）, optical coupler（3）The first output end（9）Output electric current measure signal, optical coupler（3）The second output end（10）With
Three output ends（11）Ground connection.
2. passive output current detection circuit as claimed in claim 1, it is characterized in that：First PNP pipe（4）With the second PNP pipe
（5）Device parameter performance is completely the same.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410108884.2A CN103837732B (en) | 2014-03-21 | 2014-03-21 | Passive current detection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410108884.2A CN103837732B (en) | 2014-03-21 | 2014-03-21 | Passive current detection circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN103837732A CN103837732A (en) | 2014-06-04 |
| CN103837732B true CN103837732B (en) | 2017-07-18 |
Family
ID=50801437
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410108884.2A Active CN103837732B (en) | 2014-03-21 | 2014-03-21 | Passive current detection circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN103837732B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113972622A (en) * | 2021-10-25 | 2022-01-25 | 上海电气泰雷兹交通自动化***有限公司 | Automatic circuit overload or short circuit protection device |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1030334A (en) * | 1987-06-17 | 1989-01-11 | 富士通株式会社 | Battery feed circuit |
| JPH05196660A (en) * | 1992-01-22 | 1993-08-06 | Nec Ic Microcomput Syst Ltd | Current detection circuit |
| EP0366253B1 (en) * | 1988-10-24 | 1994-08-03 | DELCO ELECTRONICS CORPORATION (a Delaware corp.) | Noise immune current mirror circuit |
| CN1615620A (en) * | 2002-01-23 | 2005-05-11 | 皇家飞利浦电子股份有限公司 | Transmitter output stage for a two-wire bus |
| CN2810094Y (en) * | 2005-08-11 | 2006-08-23 | 深圳飞通光电股份有限公司 | Optical power control circuit (APC) for light emitter |
| CN201681118U (en) * | 2010-05-27 | 2010-12-22 | 朱晓 | Output current detection device of high voltage electric field and electric potential therapeutic apparatus |
| CN201766284U (en) * | 2010-09-20 | 2011-03-16 | 深圳新飞通光电子技术有限公司 | Light power monitoring circuit of digital light emitter |
| CN102866324A (en) * | 2012-09-12 | 2013-01-09 | 上海富欣智能交通控制有限公司 | Leakage current detection circuit for output channel |
| CN203025235U (en) * | 2012-11-21 | 2013-06-26 | 上海富欣智能交通控制有限公司 | Voltage state detection circuit of output channel |
-
2014
- 2014-03-21 CN CN201410108884.2A patent/CN103837732B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1030334A (en) * | 1987-06-17 | 1989-01-11 | 富士通株式会社 | Battery feed circuit |
| EP0366253B1 (en) * | 1988-10-24 | 1994-08-03 | DELCO ELECTRONICS CORPORATION (a Delaware corp.) | Noise immune current mirror circuit |
| JPH05196660A (en) * | 1992-01-22 | 1993-08-06 | Nec Ic Microcomput Syst Ltd | Current detection circuit |
| CN1615620A (en) * | 2002-01-23 | 2005-05-11 | 皇家飞利浦电子股份有限公司 | Transmitter output stage for a two-wire bus |
| CN2810094Y (en) * | 2005-08-11 | 2006-08-23 | 深圳飞通光电股份有限公司 | Optical power control circuit (APC) for light emitter |
| CN201681118U (en) * | 2010-05-27 | 2010-12-22 | 朱晓 | Output current detection device of high voltage electric field and electric potential therapeutic apparatus |
| CN201766284U (en) * | 2010-09-20 | 2011-03-16 | 深圳新飞通光电子技术有限公司 | Light power monitoring circuit of digital light emitter |
| CN102866324A (en) * | 2012-09-12 | 2013-01-09 | 上海富欣智能交通控制有限公司 | Leakage current detection circuit for output channel |
| CN203025235U (en) * | 2012-11-21 | 2013-06-26 | 上海富欣智能交通控制有限公司 | Voltage state detection circuit of output channel |
Also Published As
| Publication number | Publication date |
|---|---|
| CN103837732A (en) | 2014-06-04 |
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