CN218498820U - Signal receiving circuit and electronic equipment - Google Patents
Signal receiving circuit and electronic equipment Download PDFInfo
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- CN218498820U CN218498820U CN202222484637.5U CN202222484637U CN218498820U CN 218498820 U CN218498820 U CN 218498820U CN 202222484637 U CN202222484637 U CN 202222484637U CN 218498820 U CN218498820 U CN 218498820U
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Abstract
The embodiment of the application provides a signal receiving circuit and electronic equipment, and relates to the technical field of communication circuits. The circuit comprises a voltage following module, a first resistor, a comparison switch module and a reference voltage module. The voltage following module is connected to the first end of the comparison switch module through a first resistor, and the first end of the comparison switch module is used for connecting a current signal; the second end of the comparison switch module is electrically connected with the reference voltage module; and the third end of the comparison switch module is electrically connected with the controller. The signal receiving circuit can play a current-limiting protection role for the voltage following module when the line of the RXD signal changes due to instability. And the voltage stabilizing diode can be arranged to protect the voltage following module from being damaged by overlarge voltage and maintain stable work.
Description
Technical Field
The present application relates to the field of communications circuitry, and more particularly, to a signal receiving circuit.
Background
Communication via high and low level signals is a widely used communication method, for example, in a metering device.
The working environment of some metering instruments is complicated and changeable, such as electric meters, and the communication reliability also becomes an important point in the scheme design.
Therefore, how to design a signal receiver with high communication reliability is a technical problem to be solved.
SUMMERY OF THE UTILITY MODEL
The present application aims to provide a signal receiving circuit and an electronic device, so as to solve the technical problem of how to design a signal receiver with high communication reliability in the prior art.
In order to achieve the above purpose, the embodiments of the present application adopt the following technical solutions.
In a first aspect, an embodiment of the present application provides a signal receiving circuit, which includes a voltage following module, a first resistor, a comparison switch module, and a reference voltage module.
The voltage following module is connected to the first end of the comparison switch module through a first resistor, and the first end of the comparison switch module is used for connecting a current signal; the second end of the comparison switch module is electrically connected with the reference voltage module; and the third end of the comparison switch module is electrically connected with the controller.
The voltage following module comprises a first switch tube and a second resistor, and the signal receiving circuit further comprises a fourth resistor. The collector of the first switch tube is used for connecting a VCC power supply, the second resistor is connected between the base and the collector of the first switch tube, the emitter of the first switch tube is connected to the first end of the comparison switch module through the first resistor, and the emitter of the first switch tube is grounded through the first resistor and the fourth resistor.
Optionally, the signal receiving circuit further comprises a zener diode. The base electrode of the first switch tube is connected to the first end of the first resistor, and the voltage stabilizing diode is connected between the second end of the first resistor and the base electrode of the first switch tube.
Optionally, the comparison switch module includes a second switch tube and a fifth resistor, and the reference voltage module includes a capacitor. The base of the second switch tube is grounded through the fifth resistor, the base of the second switch tube is connected to the first end of the capacitor, and the second end of the capacitor is used for being connected with a VCC power supply.
Optionally, the reference voltage module further comprises a diode. The diode is connected between the capacitor and the fifth resistor to prevent the capacitor from discharging through the fifth resistor.
Optionally, the reference voltage module further comprises a third resistor. The base electrode of the second switch tube is connected to the first end of the capacitor through the third resistor.
Optionally, the reference voltage module further comprises at least two charging diodes. The charging diode is connected with the third resistor in parallel, so that the third resistor is short-circuited when the capacitor is charged.
Optionally, the signal receiving circuit further comprises a low voltage module. And the third end of the comparison switch module is connected to the controller through the low-voltage module.
Optionally, the low voltage module comprises a third switching tube. The emitter of the third switching tube is grounded, the base of the third switching tube is connected to the third end of the comparison switch module, the collector of the third switching tube is used for being connected with the controller and the VBB power source, and the voltage of the VBB power source is lower than the power voltage of the voltage following module and the reference voltage module. 9
In a second aspect, an embodiment of the present application provides an electronic device, which includes the signal receiving circuit described in the first aspect.
Compared with the prior art, the method has the following beneficial effects:
according to the signal receiving circuit and the electronic equipment, when the line of the RXD signal changes due to instability, the first resistor plays a role in current limiting protection for the voltage following module. The voltage following module can be protected from being damaged by overlarge voltage through the voltage stabilizing diode.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.
Fig. 1 is a schematic diagram of a signal receiving circuit according to an embodiment of the present disclosure;
FIG. 2 is a schematic diagram of a signal receiving circuit with a zener diode according to an embodiment of the present disclosure;
fig. 3 is a schematic diagram of a signal receiving circuit for providing a reference voltage to a capacitor according to an embodiment of the present disclosure;
fig. 4 is a schematic diagram of a signal receiving circuit of a capacitor-resistor series according to an embodiment of the present disclosure;
fig. 5 is a schematic diagram of a signal receiving circuit for accelerating charging of a diode according to an embodiment of the present disclosure;
fig. 6 is a schematic diagram of a signal receiving circuit with a low voltage module according to an embodiment of the present application;
fig. 7 is a schematic diagram of another signal receiving circuit according to an embodiment of the present disclosure.
Description of reference numerals:
the circuit comprises a voltage following module 1, a first resistor 2, a reference voltage module 3, a comparison switch module 4, a controller 5 and a low-voltage module 6.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and the described embodiments are some embodiments, but not all embodiments, of the present application. The components of the embodiments of the present application, as generally described in the figures herein, may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. 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 application. The embodiments described below and the features of the embodiments can be combined with each other without conflict.
In the description of the present application, it should be noted that the relational terms such as first and second, and the like are only used for distinguishing one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. The term "connected" is to be understood broadly, for example, as being fixedly connected, detachably connected, or integrally connected; may be directly connected or indirectly connected through an intermediate.
The existing signal receiver sometimes can not work normally or even is damaged under the condition that the working environment is more complicated and changeable.
In order to overcome the above problem, referring to fig. 1, an embodiment of the present application provides a signal receiving circuit, which includes a voltage following module 1, a first resistor 2, a comparison switch module 4, and a reference voltage module 3.
The voltage following module 1 is connected to a first end of the comparison switch module 4 through the first resistor 2, and the first end of the comparison switch module 4 is used for connecting the current signal RXD. A second terminal of the comparison switch module 4 is electrically connected to the reference voltage module 3. The third terminal of the comparison switch module 4 is used for electrically connecting with the controller 5.
The principle of the circuit is as follows: the voltage follower module 1 outputs a stable voltage, and then passes through the first resistor 2 to the first end of the comparison switch module 4. The reference voltage module 3 outputs a reference voltage to the second terminal of the comparison switch module 4. In a static state, the RXD end has no current signal, and the comparison switch module 4 outputs a signal according to the voltage value of the first end and the voltage value of the second end.
When the RXD terminal has a current signal, the first resistor 2 has a voltage division due to the current passing through the first resistor 2, resulting in a change of the voltage value at the first terminal. The voltage value of the first terminal changes and the voltage value of the second terminal does not change, so that the output signal is different from that in (3).
That is, the RXD signal can affect the signal output by the comparison switch module 4, thereby playing a role of transmitting information.
The following beneficial effects can be obtained: because the first resistor is arranged, the line of the RXD signal changes, and even if the line of the RXD signal is short-circuited, the first resistor can play a current-limiting protection role for the voltage following module.
In order to further protect the voltage following module 1, the voltage following module 1 can be connected through the voltage stabilizing diode VD1, the voltage of the voltage following module 1 is stabilized, even if the line of the RXD signal is short-circuited, the voltages at two ends, connected with the voltage stabilizing diode VD1, of the voltage following module 1 cannot exceed the working voltage of the voltage stabilizing diode VD1, and therefore the voltage following module 1 is prevented from being damaged due to the fact that the voltage is too large and overlarge current is generated.
As shown in fig. 2, the voltage follower module 1 may include a first switch tube V1 and a second resistor R2. The signal receiving circuit further includes a fourth resistor R4.
The connection relationship is as follows: the collecting electrode of first switch tube V1 is used for connecting the VCC power, and second resistance R2 connects between first switch tube V1's base and collecting electrode, and first switch tube V1's projecting pole passes through first resistance 2 to be connected in the first end of comparison switch module 4, and first switch tube V1's projecting pole still passes through first resistance 2 and fourth resistance R4 ground connection.
The voltage following function is realized through the first switch tube V1 and the second resistor R2, other devices are not needed, and the design is simple and reliable.
The first switch tube V1 may be a triode, and operates in an amplification region rather than a saturation region, i.e., the emitter voltage of the first switch tube V1 follows the collector voltage.
As shown in fig. 2, the base of the first switching tube V1 is connected to the first end of the first resistor 2, and the zener diode VD1 is connected between the second end of the first resistor 2 and the base of the first switching tube V1. In this case, the voltage regulator VD1 may protect the voltage follower module 1, and the principle is: when the slave at the RXD end works abnormally or is short-circuited to generate a large load, the maximum value of the current flowing through the first switch tube V1 is I max ＝V vd1 R1, wherein V vd1 The voltage stabilizing value of the voltage stabilizing diode VD1 is R1, which is the resistance value of the first resistor 2.
It can be seen that the maximum value of the current flowing through the first switching tube V1 is limited by the voltage stabilizing value, and it is ensured that the first switching tube V1 is not burnt out due to the overpower.
As shown in fig. 3, the comparison switch module 4 may include a second switch tube V2 and a fifth resistor R5, and the reference voltage module 3 includes a capacitor C1. The base of the second switch tube V2 is grounded through a fifth resistor R5, the base of the second switch tube V2 is connected to the first end of the capacitor C1, and the second end of the capacitor C1 is used for being connected with a VCC power supply.
The voltage comparison function is realized through the second switching tube V2, other devices are not needed, and the design is simple and reliable.
The working principle of the second switching tube V2 is as follows:
(1) in a static state, the RXD end has no current, the voltage from the voltage following module 1 is finally grounded through the first resistor 2, the collector and the base of the second switch tube V2 and the fifth resistor R5, and a certain voltage difference is formed between the collector and the base of the second switch tube V2. This voltage difference causes the second switching transistor V2 to operate in saturation.
(2) When there is current at the RXD end, the voltage from the voltage following module 1 is in current connection with the RXD end through the first resistor 2, and at this time, the first resistor 2 generates a voltage difference, so that when the voltage from the voltage following module 1 reaches the collector of the second switching tube V2 through the first resistor 2, the voltage is reduced, and further the voltage difference formed between the collector and the base of the second switching tube V2 is reduced and is smaller than the on-state voltage of the second switching tube V2, namely, the voltage difference enables the second switching tube V2 to work in an off state.
(3) It can be seen that the voltage difference formed between the collector and the base of the second switching tube V2 is different when there is no current or there is current at the RXD terminal, so that the second switching tube V2 is switched from the on state to the off state, and different voltages are output, thereby transmitting information.
The working principle of the capacitor C1 is as follows: in (2) of the operation principle of the second switching tube V2, when there is current at the terminal RXD, the voltage from the voltage following module 1 reaching the collector of the second switching tube V2 through the first resistor 2 decreases, but since the voltage of the capacitor C1 does not change abruptly, the voltage of the base of the capacitor C1 connected to the second switching tube V2 does not change abruptly, so that the voltage difference formed between the collector and the base of the second switching tube V2 changes only with the change of the collector of the second switching tube V2.
Capacitor C1 connects GND and also can realize, but even VCC has obvious advantage, and the produced ripple of power VCC itself will not produce the interference to whole loop, if connect GND then can introduce the ripple of power VCC, reduce the circuit interference killing feature promptly capacitor C1 both ends all use VCC as the reference.
It can be seen from the working principle of the capacitor C1 that the voltage of the capacitor C1 cannot suddenly change, which plays a key role in stable transmission of signals. To further stabilize the voltage of the capacitor C1, a third resistor R3 as in fig. 4 may be provided. The base of the second switch tube V2 is connected to the first end of the capacitor C1 through a third resistor R3.
The working principle of the third resistor R3 is as follows: in the working principle (2) of the second switching tube V2, since the voltage from the voltage following module 1 to the base of the second switching tube V2 is reduced, the capacitor C1 is in a discharging state, and the third resistor R3 plays a role in slowing down the discharging of the capacitor C1, so that the voltage of the capacitor C1 is more stable.
Due to the third resistor R3, when the voltage from the voltage follower module 1 to the base of the second switch tube V2 is recovered, the charging process of the capacitor C1 is also slowed down by the third resistor R3. To avoid this disadvantage, a diode VD2 as in fig. 5 may be provided.
The working principle of the diode VD2 is as follows:
(1) when the RXD end has current, the voltage of the capacitor C1 is in a discharging state because the voltage from the voltage following module 1 reaching the base electrode of the second switching tube V2 is reduced, and the voltage of the capacitor C1 is reduced after a short time. The capacitor C1 is not discharged through the diode VD2, and thus the diode VD2 acts to block the voltage variation of the capacitor C1.
(2) When the communication circuit is restored to the state that no current exists at the RXD end, namely the voltage of the base electrode of the second switching tube V2 is restored to the voltage which is not reduced because the RXD current flows through the first resistor 2, at the moment, the capacitor C1 can be quickly charged through the diode VD2, namely the diode VD2 is used for short-circuiting the third resistor R3, and a slower way of charging from the third resistor R3 is avoided. The third resistor R3 also plays a role in filtering ripple signals, and the anti-interference capability of the circuit is improved.
The diode VD2 of fig. 5 may be provided in two, or more. Two or more diodes are connected in parallel, so that the condition of a circuit with RXD large current signals can be met through larger current, or the capacitor C1 can be charged more quickly.
The signal received by the controller 5 may be a voltage and a current lower than the current of the RXD terminal, as shown in FIG. 6, and the signal receiving circuit further comprises a low voltage module 6. The third terminal of the comparison switch module 4 is connected to the controller 5 through the low voltage module 6.
In one embodiment, as shown in fig. 7, the low voltage module 6 is implemented by the third switching tube V3 in fig. 7. The emitter of the third switching tube V3 is grounded, the base of the third switching tube V3 is connected to the third end of the comparison switch module 4, the collector of the third switching tube V3 is used for being connected with the controller 5 and the VBB power source, and the voltage of the VBB power source is lower than the power voltage VCC of the voltage following module 1 and the reference voltage module 3. The supply voltages of the voltage follower block 1 and the reference voltage block 3 may be the same VCC. The controller 5 is an MCU. The circuit has the following advantages: the anti-interference capability is strong; the used analog devices are common analog devices, so that the cost is low and the purchase is convenient; the PCB layout space is saved; the compatibility is strong, and the flexible adjustment can be realized according to the use requirement; the application scene is wide.
The working principle of fig. 7 is:
1. when the circuit is in a static state, the voltage at RXD is equal to the voltage of VCC after being reduced by V1, namely VCC-0.7V, and the states of each device are as follows: v1 is used as a voltage follower and operates in an amplification state, the voltage stabilizing diode VD1 is cut off at the moment, V2 is in a saturation state, the base electrode of V2 is connected with R5, and the voltage Vb of the base electrode of V2 is VCC-1.4V at the moment, namely VCC is the voltage after voltage reduction through V1 and V2. The voltage difference between VCC and 1.4V is between R5 and C1, when VCC charges C1 through C1, R3 and R5, when C1 is fully charged, the voltage between two ends is
VCC-(VCC-1.4V)＝1.4V
Since the voltage difference between the collector and the base of V2 is 0.7V, and V2 is in a saturated state, the base voltage of V3 reaches the working voltage through R7, V3 is in saturated conduction, and the MCU receives low level.
2. When the RXD receives the current signal Ir, a voltage drop of V1= Ir multiplied by R1 is generated on R1, the level of the RXD is Vrxd = VCC-0.7V-V1 at the moment, the voltage Vb of the V2 base electrode is maintained at VCC-1.4 because the voltage at the two ends of the V2 capacitor C1 can not be suddenly changed, and the voltage difference between the V2 collector electrode and the base electrode is V2
Vrxd-Vb = VCC-0.7V-V1- (VCC-1.4V) =0.7V-V1<0.7V V2 is cut off, and at the same time, V3 does not reach the operating voltage, enters a cut-off state, and the MCU receives a high level.
Based on the foregoing embodiments, an electronic device, such as an electric meter, including the foregoing signal receiving circuit is also provided in the embodiments of the present application.
Generally speaking, this application has proposed a signal receiving circuit and electronic equipment, when the circuit of RXD signal changes because unstable, first resistance can play the current-limiting protection effect for the voltage follower module. The voltage following module can be protected from being damaged by overlarge voltage through the voltage stabilizing diode.
The above-described embodiments of the apparatus and system are merely exemplary, and some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
The above description is only for the preferred embodiments of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (9)
1. A signal receiving circuit is characterized by comprising a voltage following module, a first resistor, a comparison switch module and a reference voltage module;
the voltage following module is connected to a first end of the comparison switch module through the first resistor, and the first end of the comparison switch module is used for connecting a current signal;
the second end of the comparison switch module is electrically connected with the reference voltage module;
the third end of the comparison switch module is electrically connected with the controller;
the voltage following module comprises a first switch tube, a second resistor and a fourth resistor;
the collecting electrode of first switch tube is used for connecting the VCC power, second resistance connect in between the base and the collecting electrode of first switch tube, the projecting pole of first switch tube passes through first resistance connect in compare switch module's first end, the projecting pole of first switch tube still passes through first resistance and fourth resistance ground connection.
2. The signal receiving circuit of claim 1, wherein the signal receiving circuit further comprises a zener diode;
the base electrode of the first switch tube is connected to the first end of the first resistor, and the voltage stabilizing diode is connected between the second end of the first resistor and the base electrode of the first switch tube.
3. The signal receiving circuit of claim 1, wherein the comparison switch module comprises a second switch tube and a fifth resistor, and the reference voltage module comprises a capacitor;
the base of the second switch tube is grounded through the fifth resistor, the base of the second switch tube is connected to the first end of the capacitor, and the second end of the capacitor is used for being connected with a VCC power supply.
4. The signal receiving circuit of claim 3, wherein the reference voltage module further comprises a diode connected between the capacitor and the fifth resistor to prevent the capacitor from discharging through the fifth resistor.
5. The signal receiving circuit of claim 3, wherein the reference voltage module further comprises a third resistor, and the base of the second switch tube is connected to the first end of the capacitor through the third resistor.
6. The signal receiving circuit of claim 5, wherein the reference voltage module further comprises at least two charging diodes connected in parallel with the third resistor to short circuit the third resistor when the capacitor is charging.
7. The signal receiving circuit of claim 1, further comprising a low voltage module, wherein a third terminal of the comparator switch module is connected to the controller through the low voltage module.
8. The signal receiving circuit of claim 7, wherein the low voltage module comprises a third switch tube, an emitter of the third switch tube is grounded, a base of the third switch tube is connected to the third terminal of the comparison switch module, a collector of the third switch tube is used for connecting the controller and a VBB power source, and the VBB power source has a lower voltage than the power supply voltages of the voltage follower module and the reference voltage module.
9. An electronic device, characterized in that it comprises a signal receiving circuit according to any one of claims 1 to 8.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222484637.5U CN218498820U (en) | 2022-09-19 | 2022-09-19 | Signal receiving circuit and electronic equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222484637.5U CN218498820U (en) | 2022-09-19 | 2022-09-19 | Signal receiving circuit and electronic equipment |
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| Publication Number | Publication Date |
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| CN218498820U true CN218498820U (en) | 2023-02-17 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202222484637.5U Active CN218498820U (en) | 2022-09-19 | 2022-09-19 | Signal receiving circuit and electronic equipment |
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| CN (1) | CN218498820U (en) |
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