CN107704006A - A kind of drive circuit of electronic device - Google Patents

Abstract

The invention provides a driving circuit of an electronic device, including a voltage conversion and stabilization unit, a waveform generation unit and a drive unit, wherein the input end of the voltage conversion and stabilization unit is used to receive input power; the input end of the waveform generation unit is coupled to a voltage Transform the output end of the voltage stabilizing unit, and the output end of the waveform generating unit provides a signal with periodic waveform changes; the signal input end of the driving unit is coupled to the output end of the waveform generating unit, and the power input end of the driving unit is used to receive the input power, drive The output of the unit is used to provide drive power for electronic devices. The beneficial effects of the present invention: the working voltage range is wide, and can meet the working voltage range requirements of 1.8-36V at the same time; there are no extra components around, the production and debugging are simple and easy, and the cost is saved; at the same time, the driving circuit of the present invention has a certain resistance to power ground Reverse connection function, reverse connection between the power supply below 18V and the ground wire will not cause damage to the circuit.

Description

A drive circuit for an electronic device

technical field

The invention relates to the field of electronic driving chips, in particular to a driving circuit of an electronic device.

Background technique

The existing buzzer driving circuit is often driven by discrete components, which has the disadvantages of large circuit size and inconvenient production and debugging. In addition, there is also the shortcoming that the working voltage range is too narrow, which is generally limited to below 5V.

Contents of the invention

Aiming at one or more problems in the prior art, the object of the present invention is to provide a driving circuit for an electronic device (such as a buzzer) that has a wide operating voltage range, does not require external components, or operates stably and reliably.

In order to solve the above problems, one aspect of the present invention proposes:

A drive circuit for an electronic device, including a voltage conversion and stabilization unit, a waveform generation unit and a drive unit, wherein

The input terminal of the voltage conversion and stabilization unit is used to receive the input power;

The input end of the waveform generation unit is coupled to the output end of the voltage conversion and stabilization unit, and the output end of the waveform generation unit provides a signal with periodic waveform changes;

The signal input end of the driving unit is coupled to the output end of the waveform generating unit, the power input end of the driving unit is used to receive input power, and the output end of the driving unit is used to provide driving power for electronic devices.

Optionally, the electronic device is a buzzer.

Optionally, the voltage conversion and stabilization unit includes a first current source TC1 and a bandgap reference source, the input terminal of the first current source TC1 receives an input power supply, and the output terminal is coupled to a bandgap reference source, and the bandgap The output terminal of the reference source is coupled to the input terminal of the waveform generating unit.

Optionally, the first current source TC1 includes PNP transistors P2 and P3, NPN transistors N1 and N2, field effect transistor J1 and resistor R1; wherein the emitters of the transistors P2 and P3 receive input power, and the bases are coupled to each other. Connected and used as the bias current output terminal; the collector of the transistor P2 is coupled to the collector of the transistor N1, the collector of the transistor P3 is coupled to the collector of the transistor N2, the bases of the transistors N1 and N2 are connected, and the emitter of the transistor N1 The emitter of the triode N2 is grounded through the resistor R1; the drain of the field effect transistor J1 receives the input power, the source is coupled to the collectors of the triode P3 and N2, and the gate is grounded.

Optionally, the bandgap reference source includes a PNP transistor P1, an NPN transistor N3-N6, resistors R2-R5, and a capacitor C1, wherein the emitter of the transistor P1 receives the input power, and the base is coupled to the bias current The output end, the collector is coupled to one end of resistors R2, R3, R5 and the collector of transistor N6, and is used as the output end of the bandgap reference source; the other end of resistor R3 is coupled to the collector of transistor N4, and the other end of resistor R2 is coupled to Connect one end of the capacitor C1, the collector of the transistor N3 and the base of the transistor N5, the bases of the transistors N3 and N4 are connected, the emitter of the transistor N4 is grounded through the resistor R4, and the other end of the resistor R5 is coupled to the other end of the capacitor C1, The collector of the transistor N5 and the base of the transistor N6, and the emitters of the transistors N3, N5, and N6 are grounded.

Optionally, the waveform generating unit includes a triangular wave generating unit and a waveform conversion unit coupled to the triangular wave generating unit, and the triangular wave generating unit includes a second small current source TC2, resistors R6-R8, capacitors C2, C3, diode D1 and The first comparator IC1, wherein the input terminal of the second small current source TC2 is coupled to the output terminal of the voltage conversion and stabilization unit, and the output terminal is coupled to the resistor R6, one end of the capacitor C2 and the output pin 4 of the first comparator IC1; the resistor R6 The other end of the capacitor C3 is coupled to one end of the capacitor C3 and the inverting input pin 1 of the first comparator IC1; one end of the resistor R7 is coupled to the output end of the voltage conversion and stabilization unit, and the other end is coupled to one end of the resistor R8, the anode of the diode D1 and The non-inverting input pin 2 of the first comparator IC1; the other end of the diode D1 is coupled to the output pin 5 of the first comparator IC1; the other end of the capacitors C2, C3 and the resistor R8 is grounded.

Optionally, the waveform conversion unit includes resistors R9, R10 and a second comparator IC2; wherein one end of the resistor R9 is coupled to the output end of the voltage conversion and stabilization unit, and the other end is coupled to one end of the resistor R10 and the second comparator IC2 the inverting input terminal of the second comparator IC2; the non-inverting input terminal of the second comparator IC2 is coupled to the output pin 4 of the first comparator IC1, and the output terminal is used to couple to the signal input terminal of the driving unit; the other end of the resistor R10 is grounded.

Optionally, the drive unit includes a signal current amplifier IC3, an amplifier Q1 and a freewheeling tube D2, wherein pin 1 of the signal current amplifier IC3 is coupled to the output end of the waveform generating unit, pin 2 receives the input power, pin 4 is grounded, and pin 3 is connected to the output terminal of the waveform generating unit. The pin is coupled to the base of the amplifier Q1; the collector of the amplifier Q1 is coupled to the positive pole of the freewheeling tube D2, and is used as an output terminal to couple to the signal input terminal of the electronic device, and the emitter is grounded; the negative pole of the freewheeling tube D2 is coupled to the input power supply.

Optionally, the drive unit further includes a Zener diode DZ, the Zener diode DZ is connected in series with the flywheel D2, and the cathode of the Zener diode DZ is coupled to the cathode of the freewheel D2.

Optionally, the circuit is integrated and packaged in a chip, and pin 1 of the chip is used to receive input power, pin 2 is used for grounding, and pin 3 is connected to the output end of the drive unit for providing drive power for electronic devices.

Another aspect of the present invention provides a drive system for electronic devices, including the drive circuit and buzzer as described in any of the above cases.

The beneficial effects of the present invention: the working voltage range is wide, and can meet the working voltage range requirements of 1.8-36V at the same time; there are no extra components around, the production and debugging are simple and easy, and the cost is saved; at the same time, the driving circuit of the present invention has a certain resistance to power ground Reverse connection function, reverse connection between the power supply below 18V and the ground wire will not cause damage to the circuit.

Description of drawings

FIG. 1 is a schematic diagram of an existing simple buzzer driving circuit.

FIG. 2 is a schematic diagram of unit composition and coupling relationship of a driving circuit according to an embodiment of the present invention.

FIG. 3 is a circuit diagram of a bandgap reference circuit according to an embodiment of the present invention.

FIG. 4 is a circuit diagram of the voltage converting and stabilizing unit in FIG. 2 in a preferred embodiment of the present invention.

5 is a circuit diagram and a schematic diagram of generated waveforms of a triangular wave generating unit according to an embodiment of the present invention.

FIG. 6 is a circuit diagram and a schematic diagram of generated waveforms of the triangular wave generating unit in FIG. 2 in a preferred embodiment of the present invention.

FIG. 7 is a circuit diagram of a triangular wave generating unit plus a waveform conversion circuit in FIG. 2 in a preferred embodiment of the present invention.

FIG. 8 is a schematic diagram of circuit coupling of an embodiment of the driving circuit of the present invention.

FIG. 9 is a schematic diagram of circuit coupling of another embodiment of the driving circuit of the present invention.

FIG. 10 is a typical application diagram of a driving circuit according to an embodiment of the present invention.

Detailed ways

In order to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only to further illustrate the features and advantages of the present invention, rather than limiting the claims of the present invention.

The description in this part is only for several typical embodiments, and the present invention is not limited to the scope of the description of the embodiments. The mutual replacement of the same or similar prior art means and some technical features in the embodiments is also within the scope of the description and protection of the present invention.

"Coupling" in the specification includes direct connection and indirect connection, such as connection through some active devices, passive devices or electrically conductive media.

The buzzer is a common sound-generating component, which can be sounded by applying a DC voltage (active buzzer) or a square wave (passive buzzer) to both ends of it. As shown in Figure 1, the existing buzzer drive circuit, the triode Q1 acts as a switch, and the high level of the base makes the triode conduct in saturation, making the buzzer sound; while the low level of the base makes the triode Off, the buzzer stops sounding. In addition, since the buzzer is essentially an inductive element, its current cannot be transient, so there must be a freewheeling diode to provide freewheeling. Otherwise, a spike voltage of tens of volts will be generated at both ends of the buzzer, which may damage the triode and interfere with other parts of the entire circuit system.

Due to the imperfect design of the existing buzzer drive circuit or drive chip, it is generally necessary to couple additional discrete components during use, resulting in inconvenient installation and debugging.

In view of this, as shown in Figure 2, the present invention provides a kind of driving circuit, comprises voltage conversion voltage stabilization unit, waveform generation unit and driving unit, wherein the input terminal of voltage conversion voltage stabilization unit is used to receive input power; Waveform generation unit The input end of the drive unit is coupled to the output end of the voltage conversion and stabilization unit, and the output end of the waveform generation unit provides a signal with a periodic waveform change; the signal input end of the drive unit is coupled to the output end of the waveform generation unit, and the power input end of the drive unit is used for In order to receive the input power, the output end of the driving unit is used to provide driving power for the electronic device.

With this design, the entire drive circuit has clear and complete functions, and no additional peripheral components need to be coupled during use, making production and debugging easy and cost-saving.

As a preferred implementation, in an embodiment of the present invention, the voltage conversion and stabilization unit includes a first small current source TC1 and a bandgap reference source, wherein the input end of the first small current source TC1 receives the input power supply, and the output end is coupled to the bandgap A reference source, the output end of the bandgap reference source is coupled to the input end of the waveform generating unit.

The technical solution of the present invention will be described in further detail below through specific embodiments in conjunction with the accompanying drawings.

FIG. 3 is a schematic circuit diagram of a general-purpose bandgap reference source according to an embodiment of the present invention. The circuit includes three second-type transistors N7, N8 and N9, resistors R6, R7 and R8, wherein one end of the resistors R6 and R7 is coupled to the output terminal of the current source, and the other end of the resistor R6 is coupled to the collector of the transistor N7, The other end of the resistor R7 is coupled to the collector of the transistor N8 and the base of the transistor N9, the bases of the transistors N7 and N8 are connected to the collector of the transistor N7, the emitter of the transistor N8 is grounded through the resistor R8, and the collector of the transistor N9 is coupled to the ground. Connect to the output terminal of the bandgap reference source, and the emitters of the transistors N7 and N9 are grounded. in,

In the formula, Ie7, Ie8, Ae7, and Ae8 are the emitter current and effective emitter area of N7 and N8 tubes respectively,

Vref＝V _BE9 +(ΔV _BE /R8+I _B9 )*R7

I _B9 =Ic9/β

ΔI _B9 = ΔIc9/β = ΔIo/β

ΔVref=ΔI _B9 *R7=(ΔIo/β)*R7

In the formula, I _B9 is the base current of the N9 tube, Ic9 is the collector current of the N9 tube, β is the magnification of the NPN tube, V _BE9 is the negative temperature coefficient, and ΔV _BE is the positive temperature coefficient, so theoretically adjust Ae7 , Ae8 and the ratio of R7, R8 can realize the zero temperature coefficient of Vref.

However, the above circuit also has the following disadvantages: the excess current from the start-up and bias circuit Io is completely absorbed by the N9 tube, that is, Ic9 will change with the change of Io, and the size of Ie9 is related to the base current I _B9 of the N9 tube. Direct relationship, the change of the size of I _B9 will cause the voltage of the two sections of R7 to change. This causes Vref to change with the change of Io, that is, the current linearity of Vref is not good.

Therefore, in order to improve the current linearity and stability of the bandgap reference source, the present invention further improves the bandgap reference source in the previous embodiment, and provides a more preferable voltage converting and stabilizing unit.

In a preferred embodiment, the voltage conversion and stabilization unit includes a bipolar bandgap reference unit, and also includes a current source unit and an excess current sink unit coupled to the bandgap reference unit; the current source unit is used for The bandgap reference unit provides a current source; the bandgap reference unit is used to provide a bandgap reference voltage; the excess current sink unit is used to absorb excess current in the current source, improving the current linearity and stability of the bandgap reference source circuit output sex. Wherein the transistors in the bipolar bandgap reference unit are bipolar transistors.

FIG. 4 is a schematic diagram of circuit coupling of a specific embodiment thereof. Wherein, the bandgap reference unit includes three second-type transistors N3, N4 and N5, resistors R2, R3 and R4, wherein one end of the resistors R2 and R3 is coupled to the output end of the bandgap reference unit, and the resistor R3 The other end of the resistor R2 is coupled to the collector of the transistor N4, the other end of the resistor R2 is coupled to the collector of the transistor N3 and the base of the transistor N5, the bases of the transistors N3 and N4 are connected to the collector of the transistor N4, and the emitter of the transistor N4 The resistor R4 is grounded, the collector of the transistor N5 is coupled to the output end of the bandgap reference unit, and the emitters of the transistors N3 and N5 are grounded.

As a preferred embodiment, the redundant current sink unit includes a second-type transistor N6, the collector of the transistor N6 is coupled to the output terminal of the current source unit, the base is coupled to the collector of the transistor N5, and the emitter grounded.

As a further preferred implementation, to further improve the current linearity and stability of the output terminal, the above-mentioned bandgap reference unit further includes a resistor R5 and a capacitor C1, wherein one end of the resistor R5 is coupled to the output terminal of the bandgap reference unit, and the other end is One end of the capacitor C1 is coupled to the collector of the transistor N5, and the other end of the capacitor C1 is coupled to the collector of the transistor N3 and the base of the transistor N5.

On the other hand, in this embodiment, the current source circuit includes a first-type triode P1 and a current bias circuit, wherein the emitter of the first-type triode P1 is coupled to the input power supply, and the base is coupled to the current bias circuit, The collector is used to provide a current source.

As a preferred embodiment, the current bias circuit includes a startup circuit and a bias circuit for low voltage startup.

Wherein, the start-up circuit includes a field effect transistor J1 and a second-type triode N2, wherein the drain of the field effect transistor J1 is coupled to the input power supply, the source is coupled to the collector and base of the triode N2, the gate is grounded, and the emitter of the triode N2 Pole grounded.

The bias circuit includes first-type transistors P2 and P3, second-type transistor N1, and resistor R1, wherein the emitters of the transistors P2 and P3 are coupled to the input power supply, the bases of the transistors P2 and P3 are connected to the collector of the transistor P2, The collector of the transistor N1 is coupled to the collector of the transistor P2, the base is coupled to the base and collector of the transistor N2, the emitter is grounded through the resistor R1, the collector of the transistor P3 is coupled to the source of the field effect transistor J1 and the transistor N2 collector and base.

In the bandgap reference unit of the above circuit:

Vref＝V _BE3 +(ΔV _BE /R4+I _B3 )*R3

I _B3 =Ic3/β=((Vref−V _BE5 )/R2)/β

ΔVref＝ΔI _B3 *R3≈0

In the formula, I _B3 is the base current of the N3 tube, Ic3 is the collector current of the N3 tube, and β is the magnification of the NPN tube. In the formula, Ie3, Ie4, Ae3, and Ae4 are the emitter current and effective current of the N3 and N4 tubes, respectively. Emitter area, adjusting the emitter area ratio of N3 tube and N4 tube and the resistance ratio of R3 and R4, can get the theoretical reference voltage Vref with zero temperature coefficient.

At the same time, the excess current Ip from the P1 tube is finally absorbed by N6. When the collector current of P1 changes, the base current Ib6 of the N6 tube will change, but the amount of change is compared to the collector current Ic5 of the N5 tube. The proportion is very small, and the reaction to the base current Ib5 of the N5 tube can be ignored, so the final Vref is not sensitive to the change of the collector current Ic6 of the N6 tube, which greatly improves the current linearity and stability of Vref .

On the other hand, the J1 tube is a JFET tube, which is connected to the power ground through the N2 tube. The JFET tube itself only needs about 0.1V to turn on, and the N2 tube has a turn-on voltage of about 0.6V, so the power supply is above 0.7V. There is a current at the beginning, and its current is used as a start signal, so that the whole circuit is turned on, and the normal start under low power supply voltage is realized.

At the same time, the collector of the P1 tube is used as the output terminal to output a constant current. The voltage of the bandgap reference source is set at 1.25V, and the saturation voltage drop of the P1 tube is generally around 0.25V, so when the power supply voltage of the whole circuit is 1.5V, a stable 1.25V reference voltage can be provided. At the same time, it can provide a stable bandgap reference voltage for the waveform generation unit between the input power supply voltage of 1.5V and 36V, which ensures the stability of the entire driving circuit.

In one embodiment, as shown in FIG. 4, the current source circuit can also be referred to as a first current source TC1, and the bandgap reference unit and the excess current sink unit can be referred to as a bandgap reference source, so that the voltage conversion and stabilization The unit includes a first current source TC1 and a bandgap reference source, the input end of the first current source TC1 is coupled to the input power supply, the output end is coupled to the bandgap reference source, and the output end of the bandgap reference source is coupled to the The input terminal of the waveform generation unit. The first current source TC1 includes first-type triodes P1, P2, P3, second-type triodes N1, N2, field effect transistor J1, and resistor R1; wherein the emitters of the triodes P2, P3 receive input power, and the bases are coupled to each other. Connected and used as the bias current output terminal; the emitter of the triode P1 receives the input power, the base is coupled to the bias current output terminal, and the collector is used as the output terminal of the first current source TC1; the collector of the triode P2 is coupled to the triode N1 The collector of the transistor P3 is coupled to the collector of the transistor N2, the bases of the transistors N1 and N2 are connected, the emitter of the transistor N1 is grounded through the resistor R1, and the emitter of the transistor N2 is grounded; the drain of the field effect transistor J1 Receive input power, the source is coupled to the collectors of transistors P3 and N2, and the gate is grounded. The bandgap reference source includes second-type transistors N3-N6, resistors R2-R5, and capacitor C1, wherein one end of resistors R2, R3, and R5 and the collector of transistor N6 are coupled to the output end of the first current source TC1, and As the output terminal of the bandgap reference source; the other end of the resistor R3 is coupled to the collector of the transistor N4, the other end of the resistor R2 is coupled to one end of the capacitor C1, the collector of the transistor N3 and the base of the transistor N5, and the transistors N3 and N4 The bases are connected, the emitter of the transistor N4 is grounded through the resistor R4, the other end of the resistor R5 is coupled to the other end of the capacitor C1, the collector of the transistor N5 and the base of the transistor N6, and the emitters of the transistors N3, N5, and N6 are grounded.

In a preferred embodiment of the present invention, the waveform generating unit includes a triangular wave generating unit and a waveform converting unit coupled to the triangular wave generating unit, wherein the triangular wave generating unit is used to generate a periodic triangular wave signal, and the waveform converting unit is used to convert the triangular wave signal into a square wave Signal.

FIG. 5 is a schematic diagram of a circuit of a general triangular wave generating unit and a triangular wave signal generated by an embodiment of the present invention.

The triangular wave generating unit includes a second current source TC2 receiving an input power supply, a capacitor C3 coupled between the output terminal of the current source TC2 and the power ground, series resistors R4 and R5 for providing a reference voltage, and a comparator IC2 and diode D2. The first end of the resistor R4 is coupled to the input power supply, the second end is coupled to the first end of the resistor R5, and serves as a reference voltage output end, and the second end of the resistor R5 is grounded. The inverting input terminal 1 of the comparator IC2 is coupled to the output terminal of the current source TC2, the non-inverting input terminal 2 is coupled to the second terminal of the resistor R4, and the output terminal 4 is coupled to the output terminal of the current source TC2, and used as a waveform The output terminal of the generating circuit, pin 5 of the output terminal is coupled to the first terminal of the resistor R5 through the diode D2 arranged in reverse.

The principle is: when the C3 capacitor is charged to the peak voltage Vp, the comparison IC2 flips over, and its 4 pins and 5 pins start to pull current, that is, the IC2 pin drops to 0.7V, and the C3 capacitor starts to discharge, theoretically C3 drops to the valley voltage Vg (0.7V), the comparator IC2 flips again, pins 4 and 5 are cut off, and the C3 capacitor starts charging again. This is a triangle wave oscillation cycle.

The disadvantage of this design is: the discharge rate of pin 4 of IC2 is fast, and there is a certain delay in IC2, so there is a certain overdischarge in the valley of the triangular wave, so that the valley Vg of the triangular wave will fluctuate.

In order to overcome the above-mentioned defects, the triangular wave generating unit in the present invention has been further improved, and the following triangular wave waveform generating circuit is provided, including:

a current source, the input terminal of which receives the input power;

The first capacitor is coupled between the output terminal of the current source and the power ground;

The comparison unit has a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is used to receive a periodically changing signal, the second input terminal is used to receive a reference voltage, and the output terminal is used to provide a triangular wave;

a first resistor, the first end of which is coupled to the output end of the current source, and the second end is coupled to the first input end of the comparison unit; and

The second capacitor is coupled between the second end of the first resistor and the power ground, wherein the first resistor and the second capacitor are used to fully discharge the first capacitor.

As a preferred embodiment, the above triangular wave waveform generating circuit further includes a reference voltage circuit, including a second resistor and a third resistor, wherein the first end of the second resistor is coupled to the input power supply, and the second end is coupled to the first end of the third resistor. Terminal, and as a reference voltage output terminal, the second terminal of the third resistor is grounded.

As a preferred implementation, the comparison unit above includes a comparator and a diode, wherein the inverting input terminal of the comparator is coupled to the second terminal of the first resistor, the non-inverting input terminal is coupled to the output terminal of the reference voltage circuit, and the output terminal is coupled to The output terminal of the current source is coupled to the output terminal of the reference voltage circuit through a reversely arranged diode.

With this design, by configuring resistors and capacitors on the periodic signal input circuit of the comparison unit, the discharge of the original capacitor is improved, so that it can be fully discharged, so that the valley value of the triangular wave can be reduced to 0 level through sufficient discharge , which increases the peak-to-peak voltage of the triangular wave, improves the consistency of the circuit, and improves the temperature characteristics of the circuit at the same time.

The above-mentioned triangular wave waveform generation circuit will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

FIG. 6 is a circuit coupling relationship diagram and a schematic diagram of generated waveforms of a preferred embodiment of the above-mentioned triangular wave generating circuit. The triangular wave generating circuit specifically includes:

The current source TC2 receiving the input power is coupled to the first capacitor C1 between the output terminal of the current source TC2 and the power ground; the first terminal is coupled to the output terminal of the current source TC2, and the second terminal is coupled to the first capacitor of the comparison unit A first resistor R1 at the input terminal; a second capacitor C2 coupled between the second terminal of the first resistor R1 and the power ground, and a comparison unit having a first input terminal, a second input terminal and an output terminal. Wherein, the first input terminal of the comparison unit is used to receive a periodically changing signal, the second input terminal is used to receive a reference voltage, and the output terminal is used to provide a triangular wave; the first resistor R1 and the second capacitor C2 are used to make the first capacitor C1 is fully discharged.

In addition, it also includes a second resistor R2 and a third resistor R3, wherein the first end of the second resistor R2 is coupled to the input power supply, the second end is coupled to the first end of the third resistor R3, and serves as a reference voltage output end, and the second end The second end of the three resistors R3 is grounded.

As a preferred implementation, the above comparison unit specifically includes a comparator IC1 and a diode D1, wherein the inverting input terminal 1 of the comparator IC1 is coupled to the second terminal of the first resistor R1, and the non-inverting input terminal 2 is coupled to the reference voltage The output terminal of the circuit; the output terminal 4 of the comparator IC1 is coupled to the output terminal of the current source, and is used as the output terminal of the waveform generating circuit, and the output terminal 5 is coupled to the output terminal of the reference voltage circuit through the reversely arranged diode D1.

The advantages of this design are as follows: there is an additional resistor R1 and capacitor C2 in the discharge circuit, and there is a lag when pin 1 of comparator IC1 detects the potential of pin C1, so that capacitor C1 can be fully discharged. Therefore, the valley value of the generated triangular wave can be reduced to 0 level by fully discharging, the peak voltage of the triangular wave is increased, and the consistency of the circuit is improved. At the same time, since the trough reaches 0 level, it does not fluctuate with the change of power supply voltage and temperature, which further improves the temperature characteristics of the circuit.

On the other hand, as shown in FIG. 7, in the above embodiment, the waveform conversion unit preferably includes resistors R4, R5 and a second comparator IC2; wherein one end of the resistor R4 is coupled to the output end of the voltage conversion and stabilization unit, and the other end is coupled to Connect one end of the resistor R5 and the inverting input end of the second comparator IC2; the non-inverting input end of the second comparator IC2 is coupled to the output pin 4 of the first comparator IC1, and the output end is used to couple the signal input end of the drive unit ; The other end of the resistor R5 is grounded.

FIG. 8 is a schematic circuit diagram of the entire driving circuit using the above-mentioned preferred embodiment. Among them, the drive unit includes signal current amplifier IC3, amplifier Q1 and freewheeling tube D2, wherein pin 1 of the signal current amplifier IC3 is coupled to the output end of the waveform generating unit, pin 2 receives the input power, pin 4 is grounded, and pin 3 is coupled to the amplifier The base of Q1; the collector of the amplifier Q1 is coupled to the positive pole of the freewheeling tube D2, and is used as an output terminal to couple to the signal input terminal of the electronic device, and the emitter is grounded; the negative pole of the freewheeling tube D2 is coupled to the input power supply.

In the above circuit, when the power supply and GND are reversely connected, a diode characteristic will be formed between GND and pin 3, and the withstand voltage is about 0.7V, while the conventional freewheeling diode has a withstand voltage of only 0.7V, so the distance between GND and the power supply The reverse withstand voltage is only 1.4V. When the reverse voltage is relatively large, it is easy to cause damage to the circuit.

In view of this, as shown in FIG. 9, in a further preferred embodiment of the drive circuit of the present invention, a Zener diode DZ is added in the drive unit, the Zener diode DZ is connected in series with the freewheeling tube D2, and the Zener diode DZ The negative pole of the freewheeling tube D2 is coupled to the negative pole.

After this improvement, the withstand voltage between pin 3 and the power pin is increased to about 14V, so that the reverse conduction withstand voltage from GND to the power pin reaches about 14.7V, and the reverse damage withstand voltage reaches 18V. In addition, in practical applications, after the diode DZ is connected in series, the loudness of the same buzzer is also improved to a certain extent compared with the original single diode freewheeling method.

As shown in Fig. 8 and Fig. 9, the drive circuit of the present invention is integrally packaged in a chip, and pin 1 of the chip is used to receive input power, pin 2 is used for grounding, and pin 3 is connected to the output end of the drive unit. Used to provide driving power for electronic devices. Its typical application mode is shown in Figure 10. The chip has a wide range of operating voltages, no need for additional components on the periphery, easy production and debugging, low cost, and has a certain function of anti-reverse connection of power supply, which can meet the needs of most users in the market, and has good practicability and market prospect.

As shown in Figure 8, the triangular wave generating unit includes a second current source TC2, resistors R6-R8, capacitors C2, C3, diode D1, and a first comparator IC1, wherein the input end of the second current source TC2 is coupled to a voltage conversion regulator The unit output terminal, the output terminal is coupled to the resistor R6, one end of the capacitor C2 and the output pin 4 of the first comparator IC1; the other end of the resistor R6 is coupled to one end of the capacitor C3 and the inverting input pin 1 of the first comparator IC1; One end of the resistor R7 is coupled to the output end of the voltage conversion and stabilization unit, and the other end is coupled to one end of the resistor R8, the anode of the diode D1, and the non-inverting input pin 2 of the first comparator IC1; the other end of the diode D1 is coupled to the first comparator The output pin 5 of IC1; the other end of capacitor C2, C3 and resistor R8 is grounded.

The waveform conversion unit includes resistors R9, R10 and a second comparator IC2; wherein one end of the resistor R9 is coupled to the output end of the voltage conversion and stabilization unit, and the other end is coupled to one end of the resistor R10 and the inverting input of the second comparator IC2 end; the non-inverting input end of the second comparator IC2 is coupled to the output pin 4 of the first comparator IC1, and the output end is used to couple to the signal input end of the drive unit; the other end of the resistor R10 is grounded.

The descriptions of the above embodiments are only used to help understand the method and core idea of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims (12)

1. A driving circuit of an electronic device, comprising a voltage conversion and voltage stabilization unit, a waveform generation unit and a driving unit, wherein The input terminal of the voltage conversion and stabilization unit is coupled to the input power supply; The input end of the waveform generation unit is coupled to the output end of the voltage conversion and stabilization unit, and the output end of the waveform generation unit provides a signal with periodic waveform changes; The signal input end of the driving unit is coupled to the output end of the waveform generating unit, the power input end of the driving unit is used to receive input power, and the output end of the driving unit is used to provide driving power for electronic devices. 2. The driving circuit of the electronic device according to claim 1, wherein the electronic device comprises a buzzer. 3. The driving circuit of an electronic device according to claim 1, wherein the voltage conversion and stabilization unit includes a first current source TC1 and a bandgap reference source, and the input terminal of the first current source TC1 is coupled to Input power supply, the output terminal is coupled to the bandgap reference source, and the output terminal of the bandgap reference source is coupled to the input terminal of the waveform generating unit. 4. The driving circuit of an electronic device as claimed in claim 3, wherein: said first current source TC1 comprises first type triodes P1, P2, P3, second type triodes N1, N2, field effect transistor J1 and Resistor R1; the emitters of transistors P2 and P3 receive input power, the bases are coupled to each other, and serve as bias current output terminals; the emitter of transistor P1 receives input power, the base is coupled to bias current output terminals, and the collector As the output terminal of the first current source TC1; the collector of the transistor P2 is coupled to the collector of the transistor N1, the collector of the transistor P3 is coupled to the collector of the transistor N2, the bases of the transistors N1 and N2 are connected, and the emitter of the transistor N1 The emitter of the triode N2 is grounded through the resistor R1; the drain of the field effect transistor J1 receives the input power, the source is coupled to the collectors of the triode P3 and N2, and the gate is grounded. 5. The drive circuit of the electronic device as claimed in claim 3, characterized in that: said bandgap reference source comprises second type triodes N3-N6, resistors R2-R5 and capacitor C1, wherein resistors R2, R3, R5 One end and the collector of the transistor N6 are coupled to the output end of the first current source TC1, and serve as the output end of the bandgap reference source; the other end of the resistor R3 is coupled to the collector of the transistor N4, and the other end of the resistor R2 is coupled to the capacitor C1 One end, the collector of the transistor N3 and the base of the transistor N5, the bases of the transistors N3 and N4 are connected, the emitter of the transistor N4 is grounded through the resistor R4, and the other end of the resistor R5 is coupled to the other end of the capacitor C1 and the collector of the transistor N5 The electrodes and the base of the transistor N6, and the emitters of the transistors N3, N5, and N6 are grounded. 6. The driving circuit of an electronic device according to claim 1, wherein the waveform generating unit comprises a triangular wave generating unit and a waveform converting unit coupled to the triangular wave generating unit. 7. The driving circuit of the electronic device as claimed in claim 6, wherein the triangular wave generating unit comprises a second current source TC2, resistors R6-R8, capacitors C2, C3, diode D1 and a first comparator IC1, wherein the second The input end of the current source TC2 is coupled to the output end of the voltage conversion and stabilization unit, and the output end is coupled to the resistor R6, one end of the capacitor C2 and the output pin 4 of the first comparator IC1; the other end of the resistor R6 is coupled to one end of the capacitor C3 and The inverting input pin 1 of the first comparator IC1; one end of the resistor R7 is coupled to the output end of the voltage conversion and stabilization unit, and the other end is coupled to one end of the resistor R8, the anode of the diode D1 and the non-inverting input pin 2 of the first comparator IC1 ; The other end of the diode D1 is coupled to the output pin 5 of the first comparator IC1; the other end of the capacitors C2, C3 and the resistor R8 is grounded. 8. The driving circuit of an electronic device as claimed in claim 6, wherein the waveform conversion unit includes resistors R9, R10 and a second comparator IC2; wherein one end of the resistor R9 is coupled to the output end of the voltage conversion and stabilization unit , the other end is coupled to one end of the resistor R10 and the inverting input end of the second comparator IC2; the non-inverting input end of the second comparator IC2 is coupled to the output pin 4 of the first comparator IC1, and the output end is used to couple the drive unit The signal input terminal; the other end of the resistor R10 is grounded. 9. The driving circuit of an electronic device as claimed in claim 1, wherein the driving unit comprises a signal current amplifier IC3, an amplifier Q1 and a freewheeling tube D2, wherein pin 1 of the signal current amplifier IC3 is coupled to the waveform generating unit The output terminal of the output terminal, pin 2 receives the input power, pin 4 is grounded, and pin 3 is coupled to the base of the amplifier Q1; the collector of the amplifier Q1 is coupled to the positive pole of the freewheeling tube D2, and is used as an output terminal to couple to the signal input terminal of the electronic device, and the emitter grounding; the cathode of the freewheeling tube D2 is coupled to the input power supply. 10. The driving circuit of an electronic device as claimed in claim 9, further comprising a Zener diode DZ, the Zener diode DZ is connected in series with the freewheeling tube D2, and the negative pole of the Zener diode DZ is coupled to Connect to the negative pole of the flow tube D2. 11. The driving circuit of an electronic device according to any one of claims 1-10, wherein the circuit is integrated and packaged in a chip, and pin 1 of the chip is used to receive input power, and pin 2 is used for grounding , Pin 3 is connected to the output terminal of the drive unit, which is used to provide drive power for electronic devices. 12. A driving system for an electronic device, comprising the driving circuit and a buzzer according to any one of claims 1-10.