CN110763994A - Automobile switch detection working circuit structure - Google Patents
Automobile switch detection working circuit structure Download PDFInfo
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- CN110763994A CN110763994A CN201911228760.7A CN201911228760A CN110763994A CN 110763994 A CN110763994 A CN 110763994A CN 201911228760 A CN201911228760 A CN 201911228760A CN 110763994 A CN110763994 A CN 110763994A
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- 238000001514 detection method Methods 0.000 title claims abstract description 29
- 239000011324 bead Substances 0.000 claims abstract description 30
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/327—Testing of circuit interrupters, switches or circuit-breakers
- G01R31/3277—Testing of circuit interrupters, switches or circuit-breakers of low voltage devices, e.g. domestic or industrial devices, such as motor protections, relays, rotation switches
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Abstract
The invention discloses an automobile switch detection working circuit structure which comprises an interface signal input end, a system detection end, a power supply voltage end, an electronic switch, an anti-static TVS (transient voltage suppressor) tube, a ground capacitor and a resistor. A topological structure based on magnetic beads is added in a connecting line between an interface signal input end and an electronic switch. The output of the interface signal input end is connected with a magnetic bead topological structure in series, the magnetic bead topological structure is connected with a ground capacitor in parallel, and the output signal of the magnetic bead topological structure enters a grid electrode of a field effect transistor after passing through a voltage division resistor structure to control the on or off of an electronic switch. The circuit structure of the invention can not only solve the problem that the cable is influenced by the radiation of the surrounding magnetic field, but also hardly consume the current of the input end, is suitable for level signals in a larger input range, and improves the integrity of interface signals and the stability of a system. The circuit structure adopts separate components, the purchase period is short, the PCB design layout is flexible, and the component cost is lower.
Description
Technical Field
The invention relates to the technical field of automotive electronics, in particular to an automotive switch detection working circuit structure which is used for detecting logical signals in the aspects of automotive instruments and central control entertainment interfaces.
Background
The automobile electronic equipment interfaces are detected by signal logic circuits, the levels of signals with different levels are different, the working frequencies are different, the processing is improper, the correction of EMC test is influenced, and meanwhile, the level of the system interface is unstable, and the normal operation of the system is influenced. Although the shielding can be performed by an auxiliary interface cable, the time and material costs are increased, the implementation is not easy, and how to design a circuit with normalization, normalization and unification becomes a technical problem.
In the existing scheme, as shown in fig. 1, a separate NPN transistor and a resistor capacitor are adopted, the circuit design is simple, signals of different levels can be reduced in voltage through a divider resistor at the front end of the transistor, and the voltage value of the divided voltage Vbe can be forward biased in the pole base of the transistor only by being larger than the conduction voltage of an inner PN junction of the transistor, so that the logic detection of an input level is realized. However, this circuit does not take into account the operation of the broadband when the interface is applied, and the input level threshold value when the interface is switched. The concrete defects are as follows:
1. the NPN triode needs certain conduction voltage and driving current when being started, the bus cable of the vehicle-mounted equipment is long, the voltage and the current of the source end are large, and if the bus cable is a power level signal, the loss caused by improper resistor selection is large; because of the influence of the temperature and the change of the input signal level, the size of the triode collector ICQ is influenced by the environment and the change of the input level, the amplification factor is changed along with the change of IBQ = [ Ui (input) -0.7V ]/R according to the static direct current working point and the environmental influence, ICQ = the amplification factor IBQ, and the loss is higher;
2. high negative and positive voltage pulse signals are injected into an interface cable line because the interface cable line is not influenced by coupling of a peripheral magnetic field, the misoperation of the circuit by high-frequency noise and the influence on a system ground, particularly the test requirement on a control signal line in an EMC test project;
3. generally, an NPN triode serving as a current type driving switch has a certain voltage withstanding range, is suitable for controlling small-signal and small-voltage switching signals in a system and is not suitable for interface circuit design occasions.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a working circuit structure for detecting an automobile switch, which can not only solve the problem that a cable is influenced by the radiation of a surrounding magnetic field, but also hardly consume the current of an input end, is suitable for level signals in a larger input range, has filtering and isolating effects on a narrow band and a wide band, and improves the integrity of interface signals and the stability of a system.
In order to achieve the purpose, the invention provides the following technical scheme:
the utility model provides an automobile switch detects work circuit structure, includes interface signal input end, system detection end, mains voltage end, electronic switch, prevents static TVS pipe, to ground electric capacity and resistance.
A topological structure based on magnetic beads is added in a connecting line between the interface signal input end and the electronic switch. The output of the interface signal input end is connected with a magnetic bead topological structure in series, the magnetic bead topological structure is connected with a ground capacitor in parallel, and the output signal of the magnetic bead topological structure enters a grid electrode of a field effect transistor after passing through a voltage division resistor structure to control the on or off of an electronic switch.
The interface signal input end outputs and is connected with an anti-static TVS tube and a ground capacitor.
The electronic switch is a field effect transistor.
And the output signals of the electronic switch are respectively connected with a power supply voltage end through a resistor and enter a system detection end through the resistor.
The system detection end is connected with a ground capacitor in parallel, and a signal of the system detection end is defaulted to be a high level, namely, the high level is kept in a normal state when the system is electrified and initialized.
And the anti-static TVS tube and the ground capacitor are connected to the equipment shell or the shell ground of the metal interface.
Preferably, the field effect transistor is a depletion type N-MOS transistor.
Preferably, the magnetic beads in the circuit structure are ferrite patch magnetic bead filters.
Preferably, the resistors in the circuit structure are all chip film resistors.
Preferably, the capacitors to ground in the circuit structure are all ceramic patch capacitors.
The invention has the following beneficial effects:
(1) the field effect transistor is selected to have smaller direct current internal resistance after being conducted, extra current is hardly needed for voltage driving, the loss is smaller, and the network level of the rear end of the field effect transistor to the ground signal after being conducted is more stable.
(2) The shell ground of the input signal is isolated from the system detection ground, and the PCB design is simple and flexible to realize.
(3) The depletion type N-MOS tube is selected to have higher input impedance and switching rate, and the switching frequency can be adjusted through the bias resistance of the input end of the tube; the switching rate can be changed by adjusting the grid capacitance of the input end, and meanwhile, the threshold voltage value of the input level signal detection can be flexibly set.
(4) The circuit structure adopts separate components, the purchase period is short, the PCB design layout is flexible, and the component cost is lower.
Drawings
Fig. 1 is a structural diagram of a circuit for detecting an operation of an automobile switch in the related art.
FIG. 2 is a diagram of the circuit design structure of the present invention.
Fig. 3 is a schematic diagram of an equivalent circuit structure when a narrowband signal is input.
Fig. 4 is a schematic diagram of an equivalent circuit structure when a broadband signal is input according to the present invention.
Fig. 5 is a technical schematic diagram of the present invention in operation.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 2 and 5, an automobile switch detection working circuit structure includes an interface signal input terminal, a system detection terminal, a power supply voltage terminal, an electronic switch, an anti-static TVS tube, a capacitance to ground, and a resistor, wherein a topological structure based on magnetic beads is added in a connection line between the interface signal input terminal and the electronic switch; the signal of the system detection terminal IO _ DET defaults to a high level, that is, the normal high level is maintained when the system is powered on and initialized.
The circuit logic connection structure is as follows:
the interface signal input end IO _ IN outputs and is connected with an anti-static TVS tube TVS and a ground capacitor CAP1 IN parallel, the interface signal input end IO _ IN outputs and is connected with a magnetic bead topological structure IN series, the magnetic bead topological structure comprises FB1 and FB2, the magnetic bead topological structure is connected with the ground capacitor CAP2 IN parallel, the electronic switch is a field effect transistor Q1, an output signal of the magnetic bead topological structure enters a grid electrode of the field effect transistor after passing through a voltage dividing resistor structure, the electronic switch is controlled to be turned on or off, a system detection end IO _ DET signal IN a default state is turned over, high-low edge change detection of the input signal is achieved, and logic detection of the signal is achieved.
The voltage dividing resistor structure comprises R1 and R2, an output signal of the electronic switch is connected with a power supply voltage end VCC through a pull-up resistor R5 respectively and enters a system detection end IO _ DET through a series resistor R3, the system detection end IO _ DET is connected with a ground capacitor CAP3 in parallel, and the anti-static TVS tube TVS and all the ground capacitors are connected to an equipment shell or a shell ground of a metal interface.
Wherein, the field effect transistor Q1 is a depletion type N-MOS transistor, and its minimum threshold voltage value of turn-on vgs (th) =1.0Vdc (full turn-on voltage 2V); the maximum voltage threshold value of the grid source work is VGS = +/-20Vdc, the typical starting rising time is Tr =2.5 ns; the forward conduction typical voltage value VSD =0.85Vdc of the body diode.
The magnetic bead in the circuit structure is a ferrite patch magnetic bead filter.
And the resistors in the circuit structure are all chip film resistors.
The capacitors to ground in the circuit structure are all ceramic chip capacitors, and have low parasitic ESR and ESL.
As shown in fig. 3, in narrowband applications, the interface cable and connector pin have equivalent resistances of X-CZ, which in combination with CAP1 form a simple low pass filter, and the magnetic bead FB1 reflects back noise absorption isolation in the frequency range.
Network signals at two ends of the circuit magnetic beads are respectively a shell ground and a system detection ground, so that noise on interface signals at the input end forms a low-impedance backflow path through CAP1, and noise on signals at the external input end flows back to the shell ground, so that influence on a system is avoided.
The magnetic beads are energy consumption devices, have a current limiting effect together with a series resistor R1, and simultaneously form a second-order filter circuit together with capacitors CAP2, R2 and FB2 at the rear end, and R1, R2 and FB2 form a voltage division circuit, so that a high-level signal at an input end is reduced to meet the requirement of a rated working voltage range of a grid electrode of a field effect transistor Q1.
In the circuit, the acquisition of the input level signal amplitude can be realized by adjusting the direct current resistance values of R1, R2, FB1 and FB 2.
The magnetic bead FB2 can also transmit the ground noise control of the system terminal to the gate terminal of the electronic switch-field effect transistor Q1 through the R2 resistor.
As shown in fig. 4, an equivalent circuit of a magnetic bead in a broadband level signal is described, when the input is the broadband level signal, no matter the redundant noise carried by an external signal or the common mode noise in the system is isolated by equivalent inductive reactance Xr1 and Xr2 of the magnetic bead, the equivalent impedance of the magnetic bead in the circuit is consistent under the same model and the same operating frequency, so that the voltage division of the level signal at the input end is not changed, particularly, the impedance increase of the magnetic resistance in the broadband signal can compensate the smaller resistance values of the resistors R1 and R2 in the equivalent circuit, and the signal level of the gate of the field effect transistor Q1 can be stabilized.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (5)
1. The utility model provides an automobile switch detects work circuit structure, includes interface signal input part, system detection end, mains voltage end, electronic switch, prevents static TVS pipe, to ground electric capacity and resistance, its characterized in that: a topological structure based on magnetic beads is added in a connecting line between the interface signal input end and the electronic switch; the output of the interface signal input end is connected with a magnetic bead topological structure in series, the magnetic bead topological structure is connected with a ground capacitor in parallel, and the output signal of the magnetic bead topological structure enters a grid electrode of a field effect transistor after passing through a voltage division resistor structure to control the on or off of an electronic switch; the interface signal input end outputs and is connected with an anti-static TVS tube and a ground capacitor in parallel, and the electronic switch is a field effect transistor; the output signals of the electronic switches are respectively connected with a power supply voltage end through resistors and enter a system detection end through the resistors; the system detection end is connected with a ground capacitor in parallel, and a signal of the system detection end is defaulted to be a high level, namely, the normal high level is kept when the system is electrified and initialized; and the anti-static TVS tube and the ground capacitor are connected to the equipment shell or the shell ground of the metal interface.
2. The automotive switch detection operating circuit structure according to claim 1, characterized in that: the field effect transistor is a depletion mode NM0S tube.
3. The automotive switch detection operating circuit structure according to claim 1, characterized in that: the magnetic bead in the circuit structure is a ferrite patch magnetic bead filter.
4. The automotive switch detection operating circuit structure according to claim 1, characterized in that: the resistors in the circuit structure are all chip film resistors.
5. The automotive switch detection operating circuit structure according to claim 1, characterized in that: the capacitors to ground in the circuit structure are all ceramic chip capacitors.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911228760.7A CN110763994A (en) | 2019-12-04 | 2019-12-04 | Automobile switch detection working circuit structure |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911228760.7A CN110763994A (en) | 2019-12-04 | 2019-12-04 | Automobile switch detection working circuit structure |
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| CN110763994A true CN110763994A (en) | 2020-02-07 |
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| CN201911228760.7A Pending CN110763994A (en) | 2019-12-04 | 2019-12-04 | Automobile switch detection working circuit structure |
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| US5629842A (en) * | 1995-04-05 | 1997-05-13 | Zero Emissions Technology Inc. | Two-stage, high voltage inductor |
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| WO2015090083A1 (en) * | 2013-12-17 | 2015-06-25 | 国家电网公司 | Control guidance detection circuit and device of charging pile |
| CN105782556A (en) * | 2016-04-26 | 2016-07-20 | 杭州电子科技大学 | Detecting and controlling circuit for hydraulic high-speed switch valve |
| CN205877386U (en) * | 2016-04-26 | 2017-01-11 | 杭州电子科技大学 | Hydraulic pressure high -speed switching valve detect and control circuit |
| CN206595545U (en) * | 2017-03-13 | 2017-10-27 | 广州市爱司凯科技股份有限公司 | A kind of laser constant-current speed-sensitive switch drive system |
| CN207601158U (en) * | 2017-12-08 | 2018-07-10 | 深圳市英威腾电气股份有限公司 | A kind of detection circuit and its microprocessor of voltage and current analog signals |
| CN207869198U (en) * | 2018-01-31 | 2018-09-14 | 刘秋平 | A kind of low-frequency filter using magnetic bead as HF switch |
| CN211505800U (en) * | 2019-12-04 | 2020-09-15 | 新阳荣乐(上海)汽车电子有限公司 | Automobile switch detection working circuit structure |
-
2019
- 2019-12-04 CN CN201911228760.7A patent/CN110763994A/en active Pending
Patent Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5629842A (en) * | 1995-04-05 | 1997-05-13 | Zero Emissions Technology Inc. | Two-stage, high voltage inductor |
| CN101113992A (en) * | 2007-07-27 | 2008-01-30 | 中兴通讯股份有限公司 | Fan testing circuit |
| WO2012118035A1 (en) * | 2011-03-02 | 2012-09-07 | 株式会社日立国際電気 | Switching circuit and imaging device using switching circuit |
| CN103533487A (en) * | 2013-09-27 | 2014-01-22 | 潍坊歌尔电子有限公司 | Wired earphone circuit with function of suppressing 217Hz noise interference |
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| CN105782556A (en) * | 2016-04-26 | 2016-07-20 | 杭州电子科技大学 | Detecting and controlling circuit for hydraulic high-speed switch valve |
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