Noise suppression circuit

Abstract

The utility model relates to the technical field of driving circuits, and provides a noise suppression circuit, which comprises a driving control signal, a first switch unit, a second switch unit, a noise suppression unit and a load, wherein the driving control signal is input into the first end of the first switch unit, the second end of the first switch unit is connected with the first end of the second switch unit, the second end of the second switch unit is connected with a power supply, and the third end of the second switch unit is connected with the first end of the noise suppression unit. The first end of the noise suppression unit is grounded, the second end of the noise suppression unit is grounded, the load is connected with the noise suppression unit in parallel, the first end of the load is connected with the third end of the second switch unit, and the second end of the load is grounded; the noise suppression circuit can remove noise interference and accurately drive a load by using a drive control signal.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of drive circuit, more particularly, relate to a noise suppression circuit. BACKGROUND

[0002] Load refers to the electrical device or system connected to the power consumption of electric energy, common load has electromagnetic active buzzer (hereinafter referred to as buzzer) and light emitting diode (LED), wherein, the buzzer usually adopts DC voltage power supply, is widely used in various industrial and civil field electronic products, sends event reminder or fault alarm sound etc.. Its main oscillator, electromagnetic coil, magnet, vibrating diaphragm and shell etc. are composed of.When the buzzer is turned on, the oscillator in its interior generates audio frequency electric signal, the signal generates magnetic field through electromagnetic coil, and the vibrating diaphragm is periodically vibrated and sounded under the interaction of electromagnetic coil and magnet. This kind of buzzer control circuit is simple, as long as the nominal DC voltage is applied at both ends, a specific frequency sound will be emitted, and thus is widely used in various industries.

[0003] The existing buzzer drive circuit has some problems in application. First, the DC 24V power supply used in electronic products is usually converted from AC 220V AC / DC conversion from external power or DC / DC inversion from inverter. When the AC 220V input end or the inverter power input end is disturbed by external surge or fast pulse group interference signal, the DC 24V power supply will be coupled to the surge or fast pulse group interference signal through conduction. In addition, with the large application of various power electronic devices, electromagnetic interference from external space is increasing, and the DC 24V power supply is easily coupled to the surge or fast pulse group interference signal through space coupling during transmission. These interference signals usually have high voltage and narrow pulse width, so even when the drive control signal is low, the interference signal may still briefly break through the collector and emitter of the transistor, causing the buzzer to emit a short sound uncontrollably, which will disturb the user. Second, once the DC 24V power supply is applied with a sufficient strength surge signal through conduction or space coupling, the transistor may be permanently broken, causing the buzzer to emit a continuous sound uncontrollably, which will disturb the user. Third, once the DC 24V power supply is applied with a sufficient strength surge signal through conduction or space coupling for a short period of time, the coil may be deteriorated due to the heat of the internal electromagnetic coil, causing the coil to have a small conduction resistance, further causing overcurrent or short circuit failure, burning the electronic circuit, and causing serious consequences. The LED drive circuit also has the shortcomings of the above-mentioned first and second cases. UTILITY MODEL CONTENTS

[0004] The utility model discloses a drive circuit for overcoming the defects of the prior art that the drive circuit is influenced by noise interference signal and cannot accurately drive the load, and provides a noise suppression circuit capable of accurately driving the load.

[0005] To solve the above technical problems, the technical scheme of the utility model is as follows:

[0006] A kind of noise suppression circuit includes drive control signal, first switch unit, second switch unit, noise suppression unit and load;

[0007] Wherein, the drive control signal input first end of the first switch unit, the second end of the first switch unit is connected with the first end of second switch unit, the second end of the second switch unit is connected with power supply, the third end of the second switch unit is connected with the first end of the noise suppression unit, the second end of the noise suppression unit is grounded, the load is parallel with the noise suppression unit, the first end of the load is connected with the third end of the second switch unit, the second end of the load is grounded.

[0008] Compared with prior art, the beneficial effects of the technical scheme of the utility model are:

[0009] When the drive control signal is the signal for driving the first switch unit to be conducted, the first switch unit is conducted, the voltage difference between the first end of the second switch unit and the second end of the second switch unit makes the second switch unit be conducted, and the load is driven;When the drive control signal is the signal for making the first switch unit not conduct, if there is noise signal interference that can drive the load, the noise suppression unit suppresses the noise signal, the first switch unit is not conducted, and the voltage difference between the first end of the second switch unit and the second end of the second switch unit fails to make the second switch unit be conducted, and the load is not driven;If there is no noise signal interference, the first switch unit is not conducted, and the load is not driven;The noise suppression circuit can remove the influence of noise on drive control signal, and accurately drive the load. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 It is the first kind of structure schematic view of noise suppression circuit for embodiment 1;

[0011] Figure 2 It is the second kind of structure schematic view of noise suppression circuit for embodiment 1. DETAILED DESCRIPTION

[0012] The drawings are only for example illustration, and can not be understood as the limitation to the patent of the utility model;

[0013] In order to better illustrate the embodiment, some components of the drawings can be omitted, enlarged or reduced, and do not represent the size of actual product.

[0014] It will be appreciated by those skilled in the art that certain known structures and their descriptions can be omitted in the drawings.

[0015] The technical scheme of the utility model will be further described below with reference to the drawings and embodiments.

[0016] Embodiment 1

[0017] The embodiment provides a noise suppression circuit, Figure 1 The first structure diagram of the noise suppression circuit provided by the embodiment is shown in the figure, Figure 1 1 represents the first end, 2 represents the second end, and 3 represents the third end.

[0018] As Figure 1 shown, the embodiment provides a noise suppression circuit, which comprises a driving control signal, a first switching unit, a second switching unit, a noise suppression unit and a load.

[0019] The first end of the first switching unit is connected to the driving control signal, the second end of the first switching unit is connected to the first end of the second switching unit, the second end of the second switching unit is connected to a power supply, the third end of the second switching unit is connected to the first end of the noise suppression unit, the second end of the noise suppression unit is grounded, the load is connected in parallel with the noise suppression unit, the first end of the load is connected to the third end of the second switching unit, and the second end of the load is grounded.

[0020] In the specific implementation process, when the driving control signal is a signal for driving the first switching unit to be conductive, the first switching unit is conductive, the voltage difference between the first end of the second switching unit and the second end of the second switching unit makes the second switching unit conductive, and the load is driven.

[0021] When the driving control signal is a signal for making the first switching unit not conductive, if there is a noise signal interference capable of driving the load, the noise suppression unit suppresses the noise signal, the first switching unit is not conductive, the voltage difference between the first end of the second switching unit and the second end of the second switching unit fails to make the second switching unit conductive, and the load is not driven; if there is no noise signal interference, the first switching unit is not conductive, and the load is not driven.

[0022] The circuit uses the noise suppression unit to suppress noise signal interference when the driving control signal is a signal for making the first switching unit not conductive, and does not affect the normal driving of the load by the driving control signal when the driving control signal is a signal for driving the first switching unit to be conductive, so that the load can be accurately driven without noise interference.

[0023] The driving control signal is from a microcontroller as an example.

[0024] In an alternative embodiment, the noise suppression unit comprises a capacitor and a TVS tube.

[0025] The capacitor and the TVS tube are connected in parallel, the positive pole of the capacitor and the first end of the TVS tube are connected together as the first end of the noise suppression unit and the third end of the second switch unit, and the negative pole of the capacitor and the second end of the TVS tube are connected together as the second end of the noise suppression unit and grounded.

[0026] In an alternative embodiment, the first switch unit comprises an optocoupler and a resistor R2, the optocoupler comprises a light emitting diode and a photo triode, the anode of the light emitting diode receives the driving control signal as the first end of the first switch unit, the cathode of the light emitting diode is grounded, the base of the photo triode is optically coupled with the light emitting diode, the emitter of the photo triode is grounded, and the collector of the photo triode is connected with the first end of the second switch unit through the resistor R2.

[0027] In an alternative embodiment, the second switch unit comprises a P-channel enhancement mode MOS tube and a resistor R4, the gate of the P-channel enhancement mode MOS tube is connected with the second end of the first switch unit as the first end of the second switch unit, the source of the P-channel enhancement mode MOS tube is connected with the first end of the resistor R4, the second end of the resistor R4 is connected with the power supply as the second end of the second switch unit, and the drain of the P-channel enhancement mode MOS tube is connected with the first end of the noise suppression unit as the third end of the second switch unit.

[0028] As an example, when the second switch unit is a P-channel enhancement mode MOS tube, if the driving control signal is high, the first switch unit is turned on; if the driving control signal is low, the first switch unit is not turned on.

[0029] In an alternative embodiment, the driving control signal comprises a low level and a high level, when the driving control signal is low, the driving control signal is a signal for turning off the first switch unit; when the driving control signal is high, the driving control signal is a signal for turning on the first switch unit.

[0030] Embodiment 2

[0031] This embodiment is an improvement on the noise suppression circuit proposed in Embodiment 1.

[0032] Figure 2 The second structure diagram of the noise suppression circuit proposed in this embodiment.

[0033] The embodiment provides a noise suppression circuit, which comprises a driving control signal, a first switch unit, a second switch unit, a noise suppression unit and a load.

[0034] The driving control signal is input into a first end of the first switch unit, a second end of the first switch unit is connected with a first end of the second switch unit, a second end of the second switch unit is connected with a power supply, a third end of the second switch unit is connected with a first end of the noise suppression unit, a second end of the noise suppression unit is grounded, the load is connected in parallel with the noise suppression unit, a first end of the load is connected with the third end of the second switch unit, and a second end of the load is grounded.

[0035] As shown in Figure 2 In an optional embodiment, the noise suppression circuit further comprises a first overload protection unit, the first overload protection unit comprises a PNP type triode and a resistor R3, a collector of the PNP type triode is connected with the second end of the first switch unit, an emitter of the PNP type triode is connected with the power supply, a base of the PNP type triode is connected with the second end of the second switch unit, and a first end and a second end of the resistor R3 are respectively connected with the collector and the emitter of the PNP type triode.

[0036] In an optional embodiment, the noise suppression circuit further comprises a second overload protection unit, the second overload protection unit comprises a diode, a cathode of the diode is connected with the power supply, and an anode of the diode is connected with the third end of the second switch unit.

[0037] In an optional embodiment, the noise suppression circuit further comprises a resistor R5, a first end of the resistor R5 is connected with the third end of the second switch unit, and a second end of the resistor R5 is grounded.

[0038] In an optional embodiment, the load comprises an LED or a buzzer.

[0039] As an exemplary illustration, in addition to the LED and the buzzer, other loads capable of being driven by using low level and high level as the driving control signal can also use the circuit provided in the application, and in actual application, the parameters of the components in the circuit can be appropriately adjusted.

[0040] In an optional embodiment, the driving control signal is input into the first end of the first switch unit via a resistor R1.

[0041] It can be understood that the noise suppression circuit of the embodiment improves the noise suppression circuit of the embodiment 1, and the optional items in the above-mentioned embodiment 1 are also applicable to the embodiment, and thus are not repeatedly described herein.

[0042] Embodiment 3

[0043] This embodiment proposes a specific implementation example based on the noise suppression circuits proposed in Embodiments 1 and 2.

[0044] like Figure 2 As shown, Figure 2 In this circuit, Buzzer_ctl is the control signal (drive control signal) from the microcontroller, R1, R2, R3, R4, and R5 are current-limiting resistors, Q1 is a PNP transistor, Q2 is a P-channel enhancement-mode MOSFET, D1 is a reverse-connection protection diode, C1 is a filter capacitor, VB1 is a bidirectional transient voltage suppressor (TVS transistor), and Buzzer is the buzzer. The presence of filter capacitor C1 absorbs interference signals, and TVS transistor VB1 can quickly bypass interference signals across the buzzer, thus preventing the buzzer from emitting uncontrolled, brief beeps. The current-limiting resistor R4 is connected in series with MOSFET Q2. If a high-voltage pulse interference signal is coupled to the DC 24V power supply, resistor R4 can effectively limit the spike current flowing through MOSFET Q2, thereby protecting MOSFET Q2 from permanent breakdown and preventing the buzzer from emitting uncontrolled, continuous beeps. If the electromagnetic coil overheats and deteriorates, causing its on-resistance to decrease, the current flowing through resistor R4 and MOSFET Q2 will increase. This will also increase the voltage drop across resistor R4. When the current exceeds the preset overcurrent value, a certain voltage difference will be reached between the emitter and base of transistor Q1, causing Q1 to conduct. The saturation voltage drop V between the emitter and collector will then increase. CE The voltage is approximately 0.3V, which clamps the gate potential of MOSFET Q2 to around DC (24-0.3)V, thereby quickly turning off MOSFET Q2 and achieving overcurrent or short-circuit protection for the circuit, protecting the subsequent circuits.

[0045] This invention proposes a safe and reliable noise suppression circuit. The circuit design is simple and reliable, compatible with multiple voltage levels, and has good resistance to surge or fast pulse group interference. It can eliminate surge or fast pulse group interference signals coupled to the DC24V power supply through conduction or spatial coupling, preventing the buzzer from emitting short or continuous sounds uncontrollably. It can also eliminate the problem of internal electromagnetic coil overheating and coil degradation caused by external surge signal coupling, avoiding serious consequences such as overcurrent or short circuit faults. In the event of an overcurrent or short circuit fault, the circuit can provide immediate protection. This circuit is not only suitable for buzzer loads but also for LED loads, effectively solving problems such as abnormal LED flickering caused by interference signals.

[0046] The power supply voltage of the power supply mentioned in the embodiment is DC 24V, but in fact, as long as the parameters of the components in the circuit are properly adjusted, the circuit can still be used for other different voltage levels. The circuit can be widely used in various technical fields in civil and industrial fields, and if the technology is popularized, it will have good economic and practical effects.

[0047] Figure 2 The resistor R5 and the diode D1 in the circuit form an anti-reverse connection protection circuit. If the positive and negative lines of the DC 24V power supply are connected in reverse, the current will flow through R5 and D1, thereby protecting the circuit. In addition, when the Buzzer_ctl signal output is low, R5 will also quickly discharge the charge on C1 and stabilize the voltage across the buzzer at 0V, ensuring that the buzzer does not abnormally sound. The bidirectional TVS tube VB1 is connected in parallel across the buzzer and is used to bypass transient high voltage, which can stabilize the interference signal applied across the buzzer within the normal voltage range.

[0048] The buzzer noise suppression circuit can eliminate the surge or fast pulse group interference signal coupled to the DC 24V power supply through the conduction method, and can eliminate the surge or fast pulse group interference signal coupled to the DC 24V power supply through the space coupling method, so that the buzzer will not be uncontrollably emitted for a short time. The circuit can also eliminate the problem of triode breakdown caused by external surge signal coupling, and avoid the buzzer from being uncontrollably emitted for a long time. Moreover, the circuit can eliminate the problem of coil degradation caused by internal electromagnetic coil heating caused by external surge signal coupling, and avoid causing overcurrent or short circuit failure and serious consequences. In case of overcurrent or short circuit failure, the circuit can also immediately protect.

[0049] Normally, the buzzer can be controlled to sound or be silent by setting the output of the Buzzer_ctl signal. When the Buzzer_ctl signal output is low, no current flows through the LED side of the optocoupler O1, and the collector and emitter of the transistor side of the optocoupler O1 are not conductive. The emitter of the transistor side of the optocoupler O1 is connected to the common terminal of the DC 24V power supply, and the collector of the transistor side is connected to the DC 24V through current-limiting resistors R2 and R3. At this time, no sufficient negative voltage is formed between the gate G and the source S of the P-channel enhancement-mode MOS transistor Q2, so Q2 is not conductive, no current flows through the buzzer, and the buzzer remains silent. At this time, the transistor Q1 is also not conductive. When the Buzzer_ctl signal output is high, current flows through the LED side of the optocoupler O1, and the collector and emitter of the transistor side of the optocoupler O1 begin to conduct. Due to the voltage division of the resistor R2, a sufficient negative voltage is formed between the gate G and the source S of the MOS transistor Q2, and current begins to flow between the source and the drain of the MOS transistor Q2. The current passes through the buzzer, causing the buzzer to sound. At this time, the current flowing through the buzzer is normal, and the voltage drop generated by the current-limiting resistor R4 is not large, so the transistor Q1 is not conductive at this time.

[0050] The resistor R5 and the diode D1 form an anti-reverse connection protection circuit. If the positive and negative lines of the DC 24V power supply are connected in reverse, current will flow through R5 and diode D1, thereby protecting the circuit. In addition, when the Buzzer_ctl signal output is low, the resistor R5 will quickly discharge the charge on C1 and stabilize the voltage across the buzzer at 0V, ensuring that the buzzer does not sound abnormally. The bidirectional TVS tube VB1 is connected in parallel across the buzzer to bypass transient high voltage, and can stabilize the interference signal applied across the buzzer within the normal voltage range.

[0051] According to the above analysis of the working principle of the circuit under normal conditions, when the Buzzer_ctl signal output is low, the buzzer remains silent. If at this time a surge or a group of fast pulse interference signals from the outside world is coupled to the DC 24V power supply through conduction or space coupling, once the coupled interference signal voltage exceeds the breakdown voltage value between the source and the drain of the MOS tube Q2, a short pulse current will flow through the MOS tube Q2, but due to the existence of the current-limiting resistor R4 and the filter capacitor C1, the interference signal is absorbed, and the TVS tube VB1 can also bypass the interference signal between the two ends of the buzzer, so that the problem of uncontrolled short-term buzzing of the buzzer will not occur. When the Buzzer_ctl signal output is high, the buzzer starts to buzz, and if there is a coupled interference signal on the DC 24V power supply at this time, the interference signal is also absorbed by the filter capacitor C1. When selecting the parameter of the capacitor C1, the capacitance value of C1 cannot be too large, otherwise the buzzer buzzing frequency will be affected. Since the Buzzer_ctl signal output is a low-frequency signal, usually between 1-5Hz, the filter capacitor does not affect the buzzing of the buzzer, but only absorbs high-frequency interference signals.

[0052] Therefore, the circuit of the present application can solve the problem of uncontrolled short-term buzzing of the buzzer, and if the load is an LED, it can solve the problem of uncontrolled short-term lighting of the LED.

[0053] Figure 2 The current-limiting resistor R4 is connected in series with the MOS tube Q2. If there is a high-voltage pulse interference signal coupled to the DC 24V power supply, the resistor R4 can effectively limit the peak current flowing through the MOS tube Q2, thereby protecting the MOS tube Q2 from being permanently broken down and avoiding the buzzer from emitting a continuous buzzing sound uncontrollably, and if the load is an LED, it can avoid the LED from lighting uncontrollably.

[0054] When the Buzzer_ctl signal output is high, the buzzer starts to buzz, and at this time if the electromagnetic coil overheats and causes coil degradation, causing the electromagnetic coil conduction resistance to decrease, the current flowing through the resistor R4 and the MOS tube Q2 will increase, and the voltage drop across the resistor R4 will also increase. When the current exceeds the preset overcurrent value, a certain voltage difference between the emitter and the base of the transistor Q1 is reached, causing the transistor Q1 to conduct, and the saturation voltage drop V CE about 0.3V, so that the gate potential of the MOS tube Q2 is clamped at DC(24-0.3)V, thereby quickly turning off the MOS tube Q2 and protecting the subsequent circuit.

[0055] Therefore, the circuit of the present embodiment can realize overcurrent or short circuit protection.

[0056] In the description of the embodiment, the load is a buzzer, if the load is changed to a light emitting diode (LED), the circuit is still applicable, and problems such as abnormal flashing of the LED caused by interference signals in the circuit can be solved.

[0057] It can be understood that the noise suppression circuit of the embodiment improves the noise suppression circuits of Embodiments 1 and 2, and the options in the above-mentioned Embodiments 1 and 2 are also applicable to the present embodiment, and therefore will not be described again here.

[0058] The same or similar reference signs correspond to the same or similar components;

[0059] The terms describing the positional relationship in the drawings are only used for exemplary illustration, and should not be understood as a limitation on the patent;

[0060] Obviously, the above embodiments of the utility model are only examples for clearly illustrating the utility model, and are not a limitation on the embodiments of the utility model. For ordinary skilled persons in the art, other different forms of changes or variations can be made on the basis of the above description. Here, all the embodiments need not and cannot be exhausted. Any modification, equivalent replacement and improvement, etc. made within the spirit and principle of the utility model should be included in the protection scope of the utility model claim.

Claims

1. A noise suppression circuit, characterized by comprising: The noise suppression circuit comprises a driving control signal, a first switch unit, a second switch unit, a noise suppression unit and a load. The driving control signal is input to the first end of the first switch unit, the second end of the first switch unit is connected to the first end of the second switch unit, the second end of the second switch unit is connected to a power supply, the third end of the second switch unit is connected to the first end of the noise suppression unit, the second end of the noise suppression unit is grounded, the load is connected in parallel with the noise suppression unit, the first end of the load is connected to the third end of the second switch unit, and the second end of the load is grounded.

2. The noise suppression circuit of claim 1, wherein The noise suppression unit comprises a capacitor and a TVS tube. The capacitor and the TVS tube are connected in parallel, the positive pole of the capacitor and the first end of the TVS tube are connected to the third end of the second switch unit as the first end of the noise suppression unit, and the negative pole of the capacitor and the second end of the TVS tube are grounded as the second end of the noise suppression unit.

3. The noise suppression circuit of claim 1, wherein The first switch unit comprises an optoelectronic coupler and a resistor R2, the optoelectronic coupler comprises a light-emitting diode and a photosensitive triode, the anode of the light-emitting diode receives the driving control signal as the first end of the first switch unit, the cathode of the light-emitting diode is grounded, the base of the photosensitive triode is optically coupled to the light-emitting diode, the emitter of the photosensitive triode is grounded, and the collector of the photosensitive triode is connected to the first end of the second switch unit through the resistor R2.

4. The noise suppression circuit of claim 1, wherein The second switch unit comprises a P-channel enhancement mode MOS tube and a resistor R4, the gate of the P-channel enhancement mode MOS tube is connected to the second end of the first switch unit as the first end of the second switch unit, the source of the P-channel enhancement mode MOS tube is connected to the first end of the resistor R4, the second end of the resistor R4 is connected to the power supply as the second end of the second switch unit, and the drain of the P-channel enhancement mode MOS tube is connected to the first end of the noise suppression unit as the third end of the second switch unit.

5. The noise suppression circuit of claim 4, wherein The driving control signal comprises a low level and a high level, when the driving control signal is at the low level, the driving control signal is a signal for turning off the first switch unit, and when the driving control signal is at the high level, the driving control signal is a signal for turning on the first switch unit.

6. The noise suppression circuit of claim 1, wherein The noise suppression circuit further comprises a first overload protection unit, the first overload protection unit comprises a PNP triode and a resistor R3, the collector of the PNP triode is connected to the second end of the first switch unit, the emitter of the PNP triode is connected to the power supply, the base of the PNP triode is connected to the second end of the second switch unit, and the first end and the second end of the resistor R3 are respectively connected to the collector and the emitter of the PNP triode.

7. The noise suppression circuit of claim 1, wherein The noise suppression circuit further comprises a second overload protection unit, the second overload protection unit comprises a diode, the cathode of the diode is connected to the power supply, and the anode of the diode is connected to the third end of the second switch unit.

8. A noise suppression circuit according to any one of claims 1 to 7, characterised in that, The noise suppression circuit further comprises a resistor R5, a first end of the resistor R5 is connected with the third end of the second switch unit, and a second end of the resistor R5 is grounded.

9. A noise suppression circuit according to any one of claims 1 to 7, characterised in that, The load comprises an LED or a buzzer.

10. A noise suppression circuit according to any one of claims 1 to 7, characterised in that, The drive control signal is input into the first end of the first switch unit via a resistor R1.

Images