A potentiometer power-off detection circuit

Abstract

The application discloses a potentiometer power-off detection circuit, which comprises a filtering module, an analog-to-digital converter and a microcontroller; an input end of the filtering module is used for being connected to a middle tap of a potentiometer; wherein the filtering module comprises an active low-pass filtering unit, a differential filtering unit and a passive low-pass filtering unit which are sequentially connected in communication; the analog-to-digital converter is connected to an output end of the passive low-pass filtering unit; the microcontroller is connected to the analog-to-digital converter and is used for receiving position information and broken wire information of the potentiometer output by the analog-to-digital converter. The potentiometer power-off detection circuit can remove high-frequency noise on the circuit, improve the signal-to-noise ratio, and reduce the common-mode noise interference between the signal and the negative power supply.

Description

Technical Field

[0001] This application relates to the field of circuit voltage detection, and more particularly to a potentiometer power-off detection circuit. Background Technology

[0002] A potentiometer is essentially a sliding rheostat. When used as a position sensor, it can be made into either a linear or rotary structure: the sliding arm moves along a resistive track, and a voltage signal proportional to the displacement is output from the midpoint tap. Due to its simple structure and low cost, the potentiometer has become the most common medium-to-low precision position detection element in industrial settings.

[0003] However, traditional potentiometer position signal detection circuits are susceptible to common-mode noise in complex industrial environments and cannot effectively detect the reliability of potentiometer sensor cables. Utility Model Content

[0004] This application provides a potentiometer power-off detection circuit, which solves the technical problem that existing detection circuits are easily affected by common-mode noise in the circuit and cannot effectively detect the cable reliability of the potentiometer sensor.

[0005] The potentiometer power-off detection circuit provided in this application embodiment includes: a filtering module, the input terminal of which is connected to the center tap of the potentiometer; wherein, the filtering module includes an active low-pass filter unit, a differential filter unit, and a passive low-pass filter unit connected in sequence; the active low-pass filter unit includes a first amplifier, a fourth resistor, and a first capacitor; the non-inverting input terminal of the first amplifier is connected to the center tap of the potentiometer; the two ends of the first capacitor are respectively connected to the output terminal and the inverting input terminal of the first amplifier; the fourth resistor is connected in parallel with the first capacitor; the differential filter unit includes a second amplifier, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a second capacitor, and a third capacitor; the two ends of the fifth resistor are respectively connected to the output terminal of the first amplifier and the non-inverting input terminal of the second amplifier; the sixth resistor... The second resistor has two ends connected to the inverting input terminal and the negative power supply of the second amplifier, respectively, and the resistance value of the sixth resistor is equal to that of the fifth resistor; the second resistor has two ends connected to the output terminal and the inverting input terminal of the second amplifier, respectively; the second capacitor is connected in parallel with the seventh resistor; one end of the eighth resistor is connected to the non-inverting input terminal of the second amplifier, the other end of the eighth resistor is grounded, and the resistance value of the eighth resistor is equal to that of the seventh resistor; the third capacitor is connected in parallel with the eighth resistor, and the capacitance of the third capacitor is equal to that of the second capacitor; an analog-to-digital converter is connected to the output terminal of the passive low-pass filter unit; and a microcontroller is connected to the analog-to-digital converter for receiving the position information and disconnection information of the potentiometer output by the analog-to-digital converter.

[0006] In one possible implementation, the passive low-pass filter unit includes a ninth resistor and a fourth capacitor; the two ends of the ninth resistor are respectively connected to the output terminal of the second amplifier and the positive input terminal of the analog-to-digital converter; one end of the fourth capacitor is connected to the positive input terminal of the analog-to-digital converter, and the other end of the fourth capacitor is grounded.

[0007] In one possible implementation, the potentiometer power-off detection circuit further includes a clamping diode, one end of which is connected to the positive input terminal of the analog-to-digital converter, and the other end of which is grounded.

[0008] In one possible implementation, the potentiometer power-off detection circuit further includes: a first resistor, one end of which is connected to a positive power supply, and the other end of which is connected to a first terminal of the potentiometer; and a second resistor, one end of which is connected to a negative power supply, and the other end of which is connected to a second terminal of the potentiometer.

[0009] In one possible implementation, the potentiometer power-off detection circuit further includes a third resistor, one end of which is connected to the center tap of the potentiometer, and the other end of which is grounded.

[0010] This application provides a potentiometer power-off detection circuit. In this potentiometer power-off detection circuit, an active low-pass filter unit and a passive low-pass filter unit can remove high-frequency noise in the circuit before and after the differential filter unit, thereby improving the signal-to-noise ratio. The differential filter unit can effectively reduce common-mode noise interference between the signal and the negative power supply. The position and disconnection information of the potentiometer can be determined by the analog-to-digital converter and the microcontroller. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of a potentiometer power-off detection circuit provided in an embodiment of this application.

[0013] Reference numerals: 100-First resistor; 200-Second resistor; 300-Third resistor; 400-Filter module; 410-Active low-pass filter unit; 411-First amplifier; 412-Fourth resistor; 413-First capacitor; 420-Differential filter unit; 421-Second amplifier; 422-Fifth resistor; 423-Sixth resistor; 424-Seventh resistor; 425-Eighth resistor; 426-Second capacitor; 427-Third capacitor; 430-Passive low-pass filter unit; 431-Ninth resistor; 432-Fourth capacitor; 500-Analog-to-digital converter; 600-Microcontroller; 700-Clamping diode. Detailed Implementation

[0014] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0015] In the description of the embodiments of this application, it should be noted that the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0016] This application provides a potentiometer power-off detection circuit, such as... Figure 1 As shown, the potentiometer power-off detection circuit includes a filter module 400, an analog-to-digital converter 500, and a microcontroller 600.

[0017] The input terminal of the filter module 400 is used to connect to the center tap of the potentiometer; wherein, the filter module 400 includes an active low-pass filter unit 410, a differential filter unit 420 and a passive low-pass filter unit 430 connected in sequence.

[0018] The active low-pass filter unit 410 includes a first amplifier 411, a fourth resistor 412, and a first capacitor 413. The non-inverting input of the first amplifier 411 is connected to the center tap of the potentiometer. The two ends of the first capacitor 413 are connected to the output and inverting input of the first amplifier 411, respectively. The fourth resistor 412 is connected in parallel with the first capacitor 413.

[0019] The active low-pass filter unit 410 eliminates high-frequency noise (such as PWM noise and electromagnetic coupling noise) introduced by the potentiometer wires, providing a low-impedance signal source for the subsequent differential filter unit 420 and improving the common-mode rejection ratio. When the active low-pass filter unit 410 is working, when the input to the non-inverting input terminal of the first amplifier 411 is a low-frequency signal, the capacitive reactance of the first capacitor 413 is relatively large, and the current enters the inverting input terminal through the fourth resistor 412; when the input to the non-inverting input terminal of the first amplifier 411 is high-frequency noise, the capacitive reactance of the first capacitor 413 decreases sharply, and the high-frequency noise component enters the inverting input terminal of the first amplifier 411 through the first capacitor 413, and the high-frequency noise is attenuated.

[0020] The differential filter unit 420 includes a second amplifier 421, a fifth resistor 422, a sixth resistor 423, a seventh resistor 424, an eighth resistor 425, a second capacitor 426, and a third capacitor 427. The two ends of the fifth resistor 422 are connected to the output of the first amplifier 411 and the non-inverting input of the second amplifier 421, respectively. The two ends of the sixth resistor 423 are connected to the inverting input of the second amplifier 421 and the negative power supply, respectively, and the resistance of the sixth resistor 423 is equal to the resistance of the fifth resistor 422. The two ends of the seventh resistor 424 are connected to the output of the second amplifier 421 and the inverting input of the second amplifier 421, respectively. The second capacitor 426 is connected in parallel with the seventh resistor 424. One end of the eighth resistor 425 is connected to the non-inverting input of the second amplifier 421, and the other end of the eighth resistor 425 is grounded. The resistance of the eighth resistor 425 is equal to that of the seventh resistor 424. The third capacitor 427 is connected in parallel with the eighth resistor 425, and the capacitance of the third capacitor 427 is equal to that of the second capacitor 426.

[0021] The analog-to-digital converter 500 is connected to the output of the passive low-pass filter unit 430 and converts the analog signal output by the passive low-pass filter unit 430 into a digital signal.

[0022] The microcontroller 600 is connected to the analog-to-digital converter 500 and is used to receive the position information and disconnection information of the potentiometer output by the analog-to-digital converter 500.

[0023] In this potentiometer power-off detection circuit, the active low-pass filter unit 410 and the passive low-pass filter unit 430 can remove high-frequency noise in the circuit before and after the differential filter unit 420, thus improving the signal-to-noise ratio. In the differential filter unit 420, since the resistance value of the sixth resistor 423 is equal to that of the fifth resistor 422, the common-mode noise at the two input terminals of the operational amplifier has the same magnitude, phase, and frequency characteristics, thereby eliminating common-mode noise at the output terminal of the second amplifier 421. The analog-to-digital converter 500 converts the analog signal into a digital signal and sends the potentiometer's position information and disconnection information to the microcontroller 600.

[0024] The passive low-pass filter unit 430 includes a ninth resistor 431 and a fourth capacitor 432. The two ends of the ninth resistor 431 are connected to the output terminal of the second amplifier 421 and the positive input terminal of the analog-to-digital converter 500, respectively. One end of the fourth capacitor 432 is connected to the positive input terminal of the analog-to-digital converter 500, and the other end of the fourth capacitor 432 is grounded.

[0025] The passive low-pass filter unit 430, as the final stage of the three-stage filtering, ensures the purity of the signal fed into the analog-to-digital converter 500. During operation, the high-frequency noise component of the passive low-pass filter unit 430 is directly shunted to ground via the ninth resistor 431 and the fourth capacitor 432, while the low-frequency signal component is transmitted to the analog-to-digital converter 500 via the ninth resistor 431. The potentiometer power-off detection circuit also includes a clamping diode 700, one end of which is connected to the positive input terminal of the analog-to-digital converter 500, and the other end of which is grounded.

[0026] The clamping diode 700 is a transient suppression diode. When the voltage across the clamping diode 700 exceeds the conduction threshold, the clamping diode 700 quickly conducts, clamping the voltage within a safe range.

[0027] The clamping diode 700 limits the voltage at the positive input terminal of the analog-to-digital converter 500, preventing overvoltage at the positive input terminal. When the positive input voltage of the analog-to-digital converter 500 exceeds the conduction threshold of the clamping diode 700, the clamping diode 700 conducts to clamp the voltage within a safe range, preventing transient high voltage from damaging the analog-to-digital converter 500.

[0028] Furthermore, the potentiometer power-off detection circuit also includes a first resistor 100 and a second resistor 200. One end of the first resistor 100 is connected to a positive power supply, and the other end of the first resistor 100 is used to connect to the first terminal of the potentiometer. One end of the second resistor 200 is connected to a negative power supply, and the other end of the second resistor 200 is used to connect to the second terminal of the potentiometer.

[0029] The first resistor 100 and the second resistor 200 enable the potentiometer power-off detection circuit to meet the requirements of different potentiometer resistance values, positive power supply, and negative power supply. Specifically, by setting the first resistor 100 and the second resistor 200 with different resistance values, the voltage at the center tap of the potentiometer can be adjusted so that the voltage at the center tap of the potentiometer is within the input voltage range of the analog-to-digital converter 500.

[0030] The potentiometer power-off detection circuit also includes a third resistor 300, one end of which is connected to the center tap of the potentiometer, and the other end of which is grounded.

[0031] When the first terminal of the potentiometer is disconnected from the positive power supply, the analog-to-digital converter 500 receives a voltage close to 0 volts. When the second terminal of the potentiometer is disconnected from the negative power supply, the analog-to-digital converter 500 receives a voltage close to the positive power supply.

[0032] The various embodiments in this specification are described in a progressive manner. For the same or similar parts between the various embodiments, please refer to each other. Each embodiment focuses on describing the differences from other embodiments.

[0033] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. A potentiometer power-off detection circuit, characterized in that, include: A filtering module, wherein the input terminal of the filtering module is used to connect to the center tap of the potentiometer; wherein the filtering module includes an active low-pass filter unit, a differential filter unit and a passive low-pass filter unit connected in sequence; The active low-pass filter unit includes a first amplifier, a fourth resistor, and a first capacitor; the non-inverting input of the first amplifier is connected to the center tap of the potentiometer; the two ends of the first capacitor are respectively connected to the output of the first amplifier and the inverting input of the first amplifier; the fourth resistor is connected in parallel with the first capacitor. The differential filter unit includes a second amplifier, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a second capacitor, and a third capacitor. The two ends of the fifth resistor are connected to the output terminal of the first amplifier and the non-inverting input terminal of the second amplifier, respectively. The two ends of the sixth resistor are connected to the inverting input terminal of the second amplifier and the negative power supply, respectively, and the resistance value of the sixth resistor is equal to that of the fifth resistor. The two ends of the seventh resistor are connected to the output terminal of the second amplifier and the inverting input terminal of the second amplifier, respectively. The second capacitor is connected in parallel with the seventh resistor. One end of the eighth resistor is connected to the non-inverting input terminal of the second amplifier, and the other end of the eighth resistor is grounded, and the resistance value of the eighth resistor is equal to that of the seventh resistor. The third capacitor is connected in parallel with the eighth resistor, and the capacitance of the third capacitor is equal to that of the second capacitor. An analog-to-digital converter, wherein the analog-to-digital converter is connected to the output of the passive low-pass filter unit; and A microcontroller, connected to the analog-to-digital converter, is used to receive the position information and disconnection information of the potentiometer output by the analog-to-digital converter.

2. The potentiometer power-off detection circuit according to claim 1, characterized in that, The passive low-pass filter unit includes a ninth resistor and a fourth capacitor; The two ends of the ninth resistor are respectively connected to the output terminal of the second amplifier and the positive input terminal of the analog-to-digital converter; One end of the fourth capacitor is connected to the positive input terminal of the analog-to-digital converter, and the other end of the fourth capacitor is grounded.

3. The potentiometer power-off detection circuit according to claim 1, characterized in that, Also includes: A clamping diode, one end of which is connected to the positive input terminal of the analog-to-digital converter, and the other end of which is grounded.

4. The potentiometer power-off detection circuit according to claim 1, characterized in that, Also includes: A first resistor, one end of which is connected to a positive power supply, and the other end of which is used to connect to the first end of the potentiometer. The second resistor has one end connected to the negative power supply and the other end connected to the second terminal of the potentiometer.

5. The potentiometer power-off detection circuit according to claim 1, characterized in that, Also includes: The third resistor has one end connected to the center tap of the potentiometer and the other end grounded.

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