CN107704006B - Driving circuit of electronic device - Google Patents
Driving circuit of electronic device Download PDFInfo
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- CN107704006B CN107704006B CN201710934420.0A CN201710934420A CN107704006B CN 107704006 B CN107704006 B CN 107704006B CN 201710934420 A CN201710934420 A CN 201710934420A CN 107704006 B CN107704006 B CN 107704006B
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- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
- G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
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Abstract
The invention provides a driving circuit of an electronic device, which comprises a voltage conversion voltage stabilization unit, a waveform generation unit and a driving unit, wherein the input end of the voltage conversion voltage stabilization unit is used for receiving an input power supply; the input end of the waveform generating unit is coupled with the output end of the voltage conversion and voltage stabilization unit, and the output end of the waveform generating unit provides a signal with periodically changed waveform; the signal input end of the driving unit is coupled with the output end of the waveform generating unit, the power supply input end of the driving unit is used for receiving an input power supply, and the output end of the driving unit is used for providing a driving power supply for the electronic device. The invention has the beneficial effects that: the range of working voltage is wide, and the requirement of the range of working voltage of 1.8-36V can be met at the same time; no additional components are arranged on the periphery, the production and debugging are simple and easy, and the cost is saved; meanwhile, the driving circuit has a certain function of resisting reverse connection of the power supply and the ground, and the circuit cannot be damaged due to the reverse connection between the power supply and the ground below 18V.
Description
Technical Field
The invention relates to the field of electronic driving chips, in particular to a driving circuit of an electronic device.
Background
The existing buzzer driving circuit is often driven by discrete components, and has the defects of large circuit volume and inconvenient production and debugging. In addition, the voltage working range is too narrow, and the voltage working range is generally limited to below 5V.
Disclosure of Invention
In view of one or more problems in the prior art, it is an object of the present invention to provide an electronic device (e.g., buzzer) driving circuit with a wide operating voltage range, or without peripheral components, or with stable and reliable operation.
In order to solve the above problems, an aspect of the present invention proposes:
a driving circuit of an electronic device comprises a voltage conversion voltage stabilizing unit, a waveform generating unit and a driving unit, wherein
The input end of the voltage conversion and stabilization unit is used for receiving an input power supply;
the input end of the waveform generating unit is coupled with the output end of the voltage conversion and voltage stabilization unit, and the output end of the waveform generating unit provides a signal with periodically changed waveform;
the signal input end of the driving unit is coupled with the output end of the waveform generating unit, the power supply input end of the driving unit is used for receiving an input power supply, and the output end of the driving unit is used for providing a driving power supply for the electronic device.
Optionally, the electronic device is a buzzer.
Optionally, the voltage converting and stabilizing unit includes a first current source TC1 and a bandgap reference source, an input terminal of the first current source TC1 receives an input power supply, an output terminal of the first current source TC1 is coupled to the bandgap reference source, and an output terminal of the bandgap reference source is coupled to an input terminal of the waveform generating unit.
Optionally, the first current source TC1 includes PNP-type triodes P2 and P3, NPN-type triodes N1 and N2, a field-effect transistor J1, and a resistor R1; wherein, the emitting electrodes of the triodes P2 and P3 receive an input power supply, and the base electrodes are mutually coupled and used as a bias current output end; the collector of the triode P2 is coupled with the collector of the triode N1, the collector of the triode P3 is coupled with the collector of the triode N2, the bases of the triodes N1 and N2 are connected, the emitter of the triode N1 is grounded through the resistor R1, and the emitter of the triode N2 is grounded; the drain electrode of the field effect transistor J1 receives an input power supply, the source electrode is coupled with the collector electrodes of the triodes P3 and N2, and the grid electrode is grounded.
Optionally, the bandgap reference source includes a PNP type triode P1, NPN type triodes N3-N6, resistors R2-R5, and a capacitor C1, where an emitter of the triode P1 receives an input power, a base is coupled to the bias current output terminal, and a collector is coupled to one ends of the resistors R2, R3, and R5 and a collector of the triode N6 and serves as an output terminal of the bandgap reference source; the other end of resistance R3 is coupled triode N4's collecting electrode, resistance R2's the other end is coupled electric capacity C1's one end, triode N3's collecting electrode and triode N5's base, triode N3, N4's base links to each other, triode N4's projecting pole passes through resistance R4 ground connection, resistance R5's the other end is coupled electric capacity C1's the other end, triode N5's collecting electrode and triode N6's base, triode N3, N5, N6's projecting pole ground connection.
Optionally, the waveform generating unit includes a triangle wave generating unit and a waveform converting unit coupled to the triangle wave generating unit, the triangle wave generating unit includes a second small current source TC2, resistors R6 to R8, capacitors C2 and C3, a diode D1 and a first comparator IC1, wherein an input end of the second small current source TC2 is coupled to an output end of the voltage converting and stabilizing unit, and an output end of the second small current source is coupled to one end of the resistor R6, the capacitor C2 and 4 pins of an output of the first comparator IC 1; the other end of the resistor R6 is coupled with one end of the capacitor C3 and the inverted input pin 1 of the first comparator IC 1; one end of the resistor R7 is coupled with the output end of the voltage conversion and voltage stabilization unit, and the other end of the resistor R7 is coupled with one end of the resistor R8, the anode of the diode D1 and the non-inverting input pin 2 of the first comparator IC 1; the other end of the diode D1 is coupled with an output pin 5 of the first comparator IC 1; the other ends of the capacitors C2 and C3 and the resistor R8 are grounded.
Optionally, the waveform conversion unit includes resistors R9 and R10 and a second comparator IC2; one end of the resistor R9 is coupled to the output end of the voltage conversion and voltage stabilization unit, and the other end is coupled to one end of the resistor R10 and the inverted 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 of the second comparator IC2 is coupled to the signal input end of the driving unit; the other end of the resistor R10 is grounded.
Optionally, the driving unit includes a signal current amplifier IC3, an amplifier Q1 and a follow current tube D2, where pin 1 of the signal current amplifier IC3 is coupled to the output end of the waveform generating unit, pin 2 receives an input power supply, pin 4 is grounded, and pin 3 is coupled to the base of the amplifier Q1; the collector of the amplifier Q1 is coupled with the anode of the follow current tube D2, and is used as the output end to be coupled with the signal input end of the electronic device, and the emitter is grounded; the cathode of the follow current tube D2 is coupled to the input power source.
Optionally, the driving unit further includes a zener diode DZ, the zener diode DZ is connected in series with the freewheeling tube D2, and a cathode of the zener diode DZ is coupled to a cathode of the freewheeling tube D2.
Optionally, the circuit is integrated and packaged in a chip, and pin 1 of the chip is used for receiving an input power supply, pin 2 is used for grounding, and pin 3 is connected to an output end of the driving unit and used for providing a driving power supply for the electronic device.
Another aspect of the present invention provides a driving system of an electronic device, comprising the driving circuit and the buzzer as described in any one of the above cases.
The invention has the beneficial effects that: the working voltage range is wide, and the requirement of the working voltage range of 1.8-36V can be met simultaneously; no additional components are arranged on the periphery, so that the production and debugging are simple and easy, and the cost is saved; meanwhile, the driving circuit has a certain function of resisting reverse connection of the power supply and the ground, and the circuit cannot be damaged due to the reverse connection between the power supply and the ground below 18V.
Drawings
Fig. 1 is a schematic diagram of a conventional simple buzzer driving circuit.
Fig. 2 is a schematic diagram of a unit composition and a coupling relationship of a driving circuit according to an embodiment of the 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 voltage stabilizing unit in fig. 2 according to a preferred embodiment of the present invention.
Fig. 5 is a circuit diagram and a waveform diagram of a triangle wave generating unit according to an embodiment of the invention.
Fig. 6 is a circuit diagram and a waveform diagram of the triangle wave generating unit in fig. 2 according to a preferred embodiment of the present invention.
Fig. 7 is a circuit diagram of the triangle wave generating unit and the waveform converting circuit in fig. 2 according to a preferred embodiment of the present invention.
Fig. 8 is a circuit coupling diagram of a driving circuit according to an embodiment of the invention.
Fig. 9 is a circuit coupling diagram of another embodiment of the driving circuit of the invention.
Fig. 10 is a diagram of an exemplary application of a driving circuit according to an embodiment of the present invention.
Detailed Description
For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.
The description in this section is for several exemplary embodiments only, and the present invention is not limited only to the scope of the embodiments described. It is within the scope of the present disclosure and claims to replace some of the features of the prior art with others that are the same or similar.
"coupled" in this specification includes direct connection and also includes indirect connection, such as connection through some active device, passive device, or electrically conductive medium.
A buzzer is a common sounding element, and a direct current voltage (active buzzer) or a square wave (passive buzzer) is applied to two ends of the buzzer to sound. As shown in fig. 1, in a conventional driving circuit of a buzzer, a transistor Q1 functions as a switch, and a high level of a base electrode of the transistor makes the transistor conduct in saturation, so that the buzzer sounds; and the base electrode low level turns off the triode, and the buzzer stops sounding. In addition, since the buzzer is essentially an inductive element, the current cannot be transient, and therefore a freewheeling diode is necessary to provide freewheeling. Otherwise, a spike voltage of several tens of volts may be generated across the buzzer, possibly damaging the transistor and disturbing other parts of the overall circuit system.
The existing buzzer driving circuit or driving chip is not easy to install and debug due to the incomplete design and the need of coupling extra discrete components in use.
In view of this, as shown in fig. 2, the present invention provides a driving circuit, which includes a voltage converting and voltage stabilizing unit, a waveform generating unit and a driving unit, wherein an input terminal of the voltage converting and voltage stabilizing unit is used for receiving an input power; the input end of the waveform generating unit is coupled with the output end of the voltage conversion and voltage stabilization unit, and the output end of the waveform generating unit provides a signal with periodically changed waveform; the signal input end of the driving unit is coupled with the output end of the waveform generating unit, the power supply input end of the driving unit is used for receiving an input power supply, and the output end of the driving unit is used for providing a driving power supply for the electronic device.
By adopting the design, the whole drive circuit has clear and complete functions, is not required to be coupled with additional peripheral components during use, is simple and easy to produce and debug, and saves the cost.
In an embodiment of the present invention, the voltage converting and stabilizing unit includes a first small current source TC1 and a bandgap reference source, wherein an input terminal of the first small current source TC1 receives an input power source, an output terminal of the first small current source TC1 is coupled to the bandgap reference source, and an output terminal of the bandgap reference source is coupled to an input terminal of the waveform generating unit.
The technical solution of the present invention is further described in detail by the following specific embodiments with reference to the accompanying drawings.
Fig. 3 is a circuit diagram of a universal bandgap reference source according to an embodiment of the present invention. This circuit includes three second type triode N7, N8 and N9, resistance R6, R7 and R8, wherein the output of current source is coupled to resistance R6 and R7's one end, the other end of resistance R6 is coupled triode N7's collecting electrode, resistance R7's the other end is coupled triode N8's collecting electrode and triode N9's base, triode N7, N8's base and triode N7's collecting electrode link to each other, triode N8's projecting pole passes through resistance R8 ground connection, triode N9's collecting electrode is coupled the output of band gap reference source, triode N7, N9's projecting pole ground connection. Wherein, the first and the second end of the pipe are connected with each other,
wherein Ie7, ie8, ae7 and Ae8 are respectively the emitter current and the effective emitter area of N7 and N8 tubes,
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 Base current of N9 transistor, ic9 collector current of N9 transistor, beta is amplification factor of NPN transistor, and V BE9 Is a negative temperature coefficient, and Δ V BE For positive temperature coefficient, theoretically, adjusting the ratio of Ae7, ae8 and R7, R8 can achieve the zero temperature coefficient of Vref.
However, the above circuit has the following disadvantages: the redundant current generated by the starting and bias circuit Io is absorbed by the N9 tube, namely the Ic9 is absorbed along with the N9 tubeIo is changed, and the magnitude of Ie9 is equal to the base current I of N9 tube B9 Having a direct relationship, I B9 The change in magnitude causes the voltage of the two segments of R7 to change. This results in Vref varying with changes in Io, i.e., vref current linearity is poor.
Therefore, in order to improve the current linearity and stability of the bandgap reference source, the bandgap reference source in the previous embodiment is further improved by the present invention, and a more preferable voltage converting and voltage stabilizing unit is provided.
In a preferred embodiment, the voltage converting and stabilizing unit comprises a bipolar band-gap reference unit, a current source unit and a redundant current absorbing unit, wherein the current source unit and the redundant current absorbing unit are coupled with the band-gap reference unit; the current source unit is used for providing a current source for the band gap reference unit; the band-gap reference unit is used for providing band-gap reference voltage; the redundant current absorption unit is used for absorbing redundant current in the current source and improving the linearity and stability of current output by the band-gap reference source circuit. Wherein the transistors in the bipolar bandgap reference unit are bipolar transistors.
Fig. 4 is a circuit coupling diagram according to an embodiment of the present invention. The band-gap reference unit comprises three second-type triodes N3, N4 and N5, resistors R2, R3 and R4, wherein one ends of the resistors R2 and R3 are coupled with the output end of the band-gap reference unit, the other end of the resistor R3 is coupled with the collector electrode of the triode N4, the other end of the resistor R2 is coupled with the collector electrode of the triode N3 and the base electrode of the triode N5, the base electrodes of the triodes N3 and N4 are connected with the collector electrode of the triode N4, the emitter electrode of the triode N4 is grounded through the resistor R4, the collector electrode of the triode N5 is coupled with the output end of the band-gap reference unit, and the emitter electrodes of the triodes N3 and N5 are grounded.
As a preferred embodiment, the excess current absorbing unit includes a second type transistor N6, a collector of the transistor N6 is coupled to the output terminal of the current source unit, a base of the transistor N6 is coupled to a collector of the transistor N5, and an emitter of the transistor N is grounded.
As a further preferred embodiment, the current linearity and stability of the output terminal are further improved, and the 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, the other end of the resistor R5 is coupled to one end of the capacitor C1 and 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 transistor P1 and a current bias circuit, wherein an emitter of the first type transistor P1 is coupled to the input power source, a base thereof is coupled to the current bias circuit, and a collector thereof is used for providing a current source.
As a preferred embodiment, the current bias circuit includes a start-up circuit and a bias circuit for low voltage start-up.
The starting circuit comprises a field effect transistor J1 and a second type triode N2, wherein the drain electrode of the field effect transistor J1 is coupled with an input power supply, the source electrode of the field effect transistor J1 is coupled with the collector electrode and the base electrode of the triode N2, the grid electrode of the field effect transistor J1 is grounded, and the emitting electrode of the triode N2 is grounded.
The bias circuit comprises a first type triode P2, a P3, a second type triode N1 and a resistor R1, wherein emitting electrodes of the triodes P2 and P3 are coupled with an input power supply, base electrodes of the triodes P2 and P3 are connected with a collecting electrode of the triode P2, a collecting electrode of the triode N1 is coupled with a collecting electrode of the triode P2, the base electrode is coupled with a base electrode and a collecting electrode of the triode N2, the emitting electrode is grounded through the resistor R1, and the collecting electrode of the triode P3 is coupled with a source electrode of a field effect tube J1 and a collecting electrode and a base electrode of the triode N2.
In the bandgap reference cell of the 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 N3 tube, ic3 is the collector current of N3 tube, beta is the amplification factor of NPN tube, where Ie3, ie4, ae3, ae4 are respectivelyEmitter currents and effective emitter areas of the N3 and N4 tubes are adjusted, the emitter area ratio of the N3 and N4 tubes and the resistance ratio of the R3 and R4 tubes are adjusted, and the reference voltage Vref with a theoretical zero temperature coefficient can be obtained.
Meanwhile, the redundant current Ip coming down from the P1 tube is finally absorbed by the N6 tube, when the collector current of the P1 tube changes, the base current Ib6 of the N6 tube changes, but the variation amount has a small proportion to the collector current Ic5 of the N5 tube, and the variation amount can be ignored when reflecting to the base current Ib5 of the N5 tube, so the final Vref is insensitive to the change of the collector current Ic6 of the N6 tube, and the current linearity and stability of the Vref are greatly improved.
On the other hand, the J1 tube is a JFET tube and is connected to a power ground through the N2 tube, the JFET tube can be started only by about 0.1V, the starting voltage of the N2 tube is about 0.6V, so that the current starts to exist when the power is connected to the power supply and is used as a starting signal, the whole circuit is started, and normal starting under low power voltage is realized.
Meanwhile, the collector of the P1 tube is used as an output end to output constant current. The voltage of the band-gap reference source is set at 1.25V, and the saturation voltage drop of the P1 tube is generally about 0.25V, so that when the voltage of the connected power supply of the whole circuit is 1.5V, the stable 1.25V reference voltage can be provided. Meanwhile, stable band-gap reference voltage can be provided for the waveform generating unit between 1.5V and 36V of input power supply voltage, and the working stability of the whole driving circuit is ensured.
In one embodiment, as shown in fig. 4, the current source circuit may also be referred to as a first current source TC1, and the bandgap reference unit and the excess current sinking unit may be referred to as a bandgap reference source, such that the voltage transforming and voltage stabilizing unit includes the first current source TC1 and the bandgap reference source, an input terminal of the first current source TC1 is coupled to the input power source, an output terminal of the first current source is coupled to the bandgap reference source, and an output terminal of the bandgap reference source is coupled to an input terminal of the waveform generating unit. The first current source TC1 comprises first type triodes P1, P2 and P3, second type triodes N1 and N2, a field effect tube J1 and a resistor R1; wherein, the emitting electrodes of the triodes P2 and P3 receive an input power supply, and the base electrodes are mutually coupled and used as a bias current output end; an emitting electrode of the triode P1 receives an input power supply, a base electrode of the triode P1 is coupled with a bias current output end, and a collector electrode of the triode P1 is used as an output end of the first current source TC 1; the collector of the triode P2 is coupled with the collector of the triode N1, the collector of the triode P3 is coupled with the collector of the triode N2, the bases of the triodes N1 and N2 are connected, the emitter of the triode N1 is grounded through the resistor R1, and the emitter of the triode N2 is grounded; the drain electrode of the field effect transistor J1 receives an input power supply, the source electrode is coupled with the collector electrodes of the triodes P3 and N2, and the grid electrode is grounded. The band-gap reference source comprises second type triodes N3-N6, resistors R2-R5 and a capacitor C1, wherein one ends of the resistors R2, R3 and R5 and a collector of the triode N6 are coupled with an output end of the first current source TC1 and are used as an output end of the band-gap reference source; the other end of the resistor R3 is coupled with the collector of the triode N4, the other end of the resistor R2 is coupled with one end of the capacitor C1, the collector of the triode N3 and the base of the triode N5, the bases of the triodes N3 and N4 are connected, the emitting electrode of the triode N4 is grounded through the resistor R4, the other end of the resistor R5 is coupled with the other end of the capacitor C1, the collector of the triode N5 and the base of the triode N6, and the emitting electrodes of the triodes N3, N5 and N6 are grounded.
In a preferred embodiment of the present invention, the waveform generating unit includes a triangle wave generating unit and a waveform converting unit coupled to the triangle wave generating unit, wherein the triangle wave generating unit is configured to generate a periodic triangle wave signal, and the waveform converting unit is configured to convert the triangle 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 the general triangular wave generating unit according to an embodiment of the invention.
The triangular wave generating unit includes a second current source TC2 receiving an input power, a capacitor C3 coupled between an output terminal of the current source TC2 and a power ground, resistors R4 and R5 connected in series for providing a reference voltage, and a comparator IC2 and a diode D2. The first end of the resistor R4 is coupled to the input power source, 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 pin of the comparator IC2 is coupled to the output terminal of the current source TC2, the non-inverting input terminal 2 pin is coupled to the second terminal of the resistor R4, the output terminal 4 pin is coupled to the output terminal of the current source TC2 and serves as the output terminal of the waveform generating circuit, and the output terminal 5 pin is coupled to the first terminal of the resistor R5 through the diode D2 arranged in the reverse direction.
The principle is as follows: when the capacitor C3 is charged to the peak voltage Vp, the comparison IC2 is turned over, the 4 pins and the 5 pins of the comparison IC2 start to source current, namely the pin IC2 is lowered to 0.7V, the capacitor C3 starts to discharge, theoretically, when the C3 is lowered to the valley voltage Vg (0.7V), the comparison IC2 is turned over again, the 4 pins and the 5 pins are cut off, and the capacitor C3 starts to charge again. This is a period of oscillation of the triangular wave.
The disadvantages of this design are: the 4-pin discharge rate of the IC2 is fast, and the IC2 has a certain delay, so that the valley value Vg of the triangular wave has a certain overdischarge, and the valley value Vg of the triangular wave fluctuates.
In order to overcome the above-mentioned drawbacks, the triangular wave generating unit of the present invention is further improved to provide a triangular wave generating circuit, comprising:
a current source, an input end of which receives an input power supply;
the first capacitor is coupled between the output end of the current source and the power ground;
the comparison unit is provided with a first input end, a second input end and an output end, wherein the first input end is used for receiving a periodically-changed signal, the second input end is used for receiving a reference voltage, and the output end is used for providing a triangular wave;
a first resistor, a first end of which is coupled to the output end of the current source, and a second end of which is coupled to the first input end of the comparison unit; and
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 for fully discharging the first capacitor.
As a preferred embodiment, the triangular waveform generating circuit further includes a reference voltage circuit, which includes a second resistor and a third resistor, wherein a first end of the second resistor is coupled to the input power source, a second end of the second resistor is coupled to a first end of the third resistor and serves as a reference voltage output end, and a second end of the third resistor is grounded.
As a preferred embodiment, the comparing unit includes a comparator and a diode, wherein an inverting input terminal of the comparator is coupled to the second terminal of the first resistor, a non-inverting input terminal of the comparator is coupled to the output terminal of the reference voltage circuit, and an output terminal of the comparator is coupled to the output terminal of the current source, and the diode is reversely disposed and coupled to the output terminal of the reference voltage circuit.
By adopting the design, the resistor and the capacitor are arranged on the periodic signal input end circuit of the comparison unit, so that the discharge condition of the original capacitor is improved, the original capacitor can be fully discharged, the valley value of the triangular wave can be reduced to 0 level through full discharge, the peak-to-peak voltage of the triangular wave is increased, the consistency of the circuit is improved, and the temperature characteristic of the circuit is improved.
The triangular wave waveform generating circuit described above will be described in further detail with reference to the drawings and specific embodiments.
Fig. 6 is a schematic diagram of a circuit coupling relationship and a waveform generation of the triangle wave generating circuit according to a preferred embodiment. The triangular wave generating circuit specifically comprises:
the current source TC2 receives an input power supply, and the first capacitor C1 is coupled between the output end of the current source TC2 and a power ground; the first end of the resistor is coupled to the output end of the current source TC2, and the second end of the resistor is coupled to the first resistor R1 of the first input end of the comparison unit; a second capacitor C2 coupled between the second terminal of the first resistor R1 and a power ground, and a comparison unit having a first input terminal, a second input terminal and an output terminal. The first input end of the comparison unit is used for receiving a periodically-changed signal, the second input end of the comparison unit is used for receiving a reference voltage, and the output end of the comparison unit is used for providing a triangular wave; the first resistor R1 and the second capacitor C2 are used to fully discharge the first capacitor C1.
In addition, the circuit further comprises a second resistor R2 and a third resistor R3, wherein a first end of the second resistor R2 is coupled to the input power source, a second end of the second resistor R2 is coupled to a first end of the third resistor R3 and serves as a reference voltage output end, and a second end of the third resistor R3 is grounded.
As a preferred embodiment, the comparing unit specifically includes a comparator IC1 and a diode D1, wherein a pin of an inverting input terminal 1 of the comparator IC1 is coupled to the second terminal of the first resistor R1, and a pin of a non-inverting input terminal 2 is coupled to the output terminal of the reference voltage circuit; the pin 4 of the output end of the comparator IC1 is coupled with the output end of the current source and is used as the output end of the waveform generating circuit, and the pin 5 of the output end is coupled with the output end of the reference voltage circuit through the diode D1 which is reversely arranged.
The advantages of this design are as follows: a resistor R1 and a capacitor C2 are added in a discharge loop, and when the pin 1 of the comparator IC1 detects the potential of the pin C1, the delay exists, so that the capacitor C1 can be fully discharged. Therefore, the valley value of the generated triangular wave can be reduced to 0 level through full discharge, the peak voltage of the triangular wave is increased, and the consistency of the circuit is improved. Meanwhile, the wave trough reaches the level 0, so that fluctuation is not generated along with the change of the power supply voltage and the temperature, and the temperature characteristic of the circuit is further improved.
On the other hand, as shown in fig. 7, in the above embodiment, the waveform converting unit preferably includes resistors R4 and R5 and a second comparator IC2; one end of the resistor R4 is coupled with the output end of the voltage conversion and voltage stabilization unit, and the other end of the resistor R4 is coupled with one end of the resistor R5 and the inverted 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 of the second comparator IC2 is coupled to the signal input end of the driving unit; the other end of the resistor R5 is grounded.
Fig. 8 is a schematic circuit diagram showing the entire driving circuit to which the above preferred embodiment is applied. The driving unit comprises a signal current amplifier IC3, an amplifier Q1 and a follow current tube D2, wherein a pin 1 of the signal current amplifier IC3 is coupled with the output end of the waveform generating unit, a pin 2 receives an input power supply, a pin 4 is grounded, and a pin 3 is coupled with the base electrode of the amplifier Q1; the collector of the amplifier Q1 is coupled with the anode of the follow current tube D2, and is used as the output end to be coupled with the signal input end of the electronic device, and the emitter is grounded; the cathode of the follow current tube D2 is coupled to the input power source.
In the circuit, when the power supply is reversely connected with the GND, a diode characteristic is formed between the GND and the 3 pins, the withstand voltage is about 0.7V, the conventional freewheel diode withstand voltage is only 0.7V, and therefore the reverse withstand voltage between the GND and the power supply is only 1.4V. When the voltage of the reverse connection is relatively large, the circuit is easy to damage.
In view of this, as shown in fig. 9, in a further preferred embodiment of the driving circuit of the present invention, a zener diode DZ is added in the driving unit, the zener diode DZ is connected in series with the follow current tube D2, and the cathode of the zener diode DZ is coupled to the cathode of the follow current tube D2.
After the improvement, the voltage resistance between the 3 pin and the power supply pin is improved to about 14V, so that the reverse conducting voltage resistance between GND and the power supply pin reaches about 14.7V, and the reverse damage voltage resistance reaches 18V. In addition, in practical application, after the diode DZ is connected in series, compared with the original mode of single diode freewheeling, the loudness of the same buzzer is also improved to a certain extent.
As shown in fig. 8 and fig. 9, the driving circuit of the present invention is integrally packaged in a chip, and pin 1 of the chip is used for receiving an input power, pin 2 is used for grounding, and pin 3 is connected to an output terminal of the driving unit and used for providing a driving power for an electronic device. A typical application of this is shown in figure 10. The chip has wide working voltage range, no need of additional components at the periphery, simple and easy production and debugging, low cost, certain power ground reverse connection resistance, capability of meeting the requirements of most users in the market, and good practicability and market prospect.
As shown in fig. 8, the triangle wave generating unit includes a second current source TC2, resistors R6 to R8, capacitors C2 and C3, a diode D1 and a first comparator IC1, wherein an input terminal of the second current source TC2 is coupled to an output terminal of the voltage converting and voltage stabilizing unit, and an output terminal thereof is coupled to one terminal of the resistor R6, the capacitor C2 and an output terminal of the first comparator IC1 via pin 4; the other end of the resistor R6 is coupled with one end of the capacitor C3 and the inverted input pin 1 of the first comparator IC 1; one end of the resistor R7 is coupled with the output end of the voltage conversion and voltage stabilization unit, and the other end of the resistor R7 is coupled with one end of the resistor R8, the anode of the diode D1 and the non-inverting input pin 2 of the first comparator IC 1; the other end of the diode D1 is coupled with an output pin 5 of the first comparator IC 1; the other ends of the capacitors C2 and C3 and the resistor R8 are grounded.
The waveform conversion unit comprises resistors R9 and R10 and a second comparator IC2; one end of the resistor R9 is coupled to the output end of the voltage conversion and voltage stabilization unit, and the other end is coupled to one end of the resistor R10 and the inverted 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 of the second comparator IC2 is coupled to the signal input end of the driving unit; the other end of the resistor R10 is grounded.
The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
Claims (9)
1. A driving circuit of an electronic device comprises a voltage conversion voltage stabilizing unit, a waveform generating unit and a driving unit, wherein
The input end of the voltage conversion and stabilization unit is coupled with an input power supply;
the input end of the waveform generating unit is coupled with the output end of the voltage conversion and voltage stabilization unit, and the output end of the waveform generating unit provides a signal with periodically changed waveform;
the signal input end of the driving unit is coupled with the output end of the waveform generating unit, the power supply input end of the driving unit is used for receiving an input power supply, and the output end of the driving unit is used for providing a driving power supply for the electronic device;
the voltage conversion and voltage stabilization unit comprises a first current source TC1 and a band-gap reference source, wherein the input end of the first current source TC1 is coupled with an input power supply, the output end of the first current source TC1 is coupled with the band-gap reference source, and the output end of the band-gap reference source is coupled with the input end of the waveform generation unit; the first current source TC1 comprises first type triodes P1, P2 and P3, second type triodes N1 and N2, a field effect tube J1 and a resistor R1; wherein, the emitting electrodes of the triodes P2 and P3 receive an input power supply, and the base electrodes are mutually coupled and used as a bias current output end; an emitting electrode of the triode P1 receives an input power supply, a base electrode of the triode P1 is coupled with a bias current output end, and a collector electrode of the triode P1 is used as an output end of the first current source TC 1; the collector of the triode P2 is coupled with the collector of the triode N1, the collector of the triode P3 is coupled with the collector of the triode N2, the bases of the triodes N1 and N2 are connected, the emitter of the triode N1 is grounded through the resistor R1, and the emitter of the triode N2 is grounded; the drain electrode of the field effect tube J1 receives an input power supply, the source electrode is coupled with the collector electrodes of the triodes P3 and N2, and the grid electrode is grounded; the band-gap reference source comprises second type triodes N3-N6, resistors R2-R5 and a capacitor C1, wherein one ends of the resistors R2, R3 and R5 and a collector of the triode N6 are coupled with an output end of the first current source TC1 and are used as an output end of the band-gap reference source; the other end of the resistor R3 is coupled with the collector of the triode N4, the other end of the resistor R2 is coupled with one end of the capacitor C1, the collector of the triode N3 and the base of the triode N5, the bases of the triodes N3 and N4 are connected, the emitting electrode of the triode N4 is grounded through the resistor R4, the other end of the resistor R5 is coupled with the other end of the capacitor C1, the collector of the triode N5 and the base of the triode N6, and the emitting electrodes of the triodes N3, N5 and N6 are grounded.
2. A drive circuit of an electronic device according to claim 1, wherein: the electronic device includes a buzzer.
3. A drive 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 with the triangular wave generating unit.
4. A driving circuit of an electronic device according to claim 3, wherein the triangular wave generating unit comprises a second current source TC2, resistors R6-R8, capacitors C2, C3, a diode D1, and a first comparator IC1, wherein an input terminal of the second current source TC2 is coupled to an output terminal of the voltage transforming and stabilizing unit, and an output terminal of the second current source TC2 is coupled to the resistor R6, one terminal of the capacitor C2, and 4 pins of an output terminal of the first comparator IC 1; the other end of the resistor R6 is coupled with one end of the capacitor C3 and the inverted input pin 1 of the first comparator IC 1; one end of the resistor R7 is coupled with the output end of the voltage conversion and voltage stabilization unit, and the other end of the resistor R7 is coupled with one end of the resistor R8, the anode of the diode D1 and the non-inverting input pin 2 of the first comparator IC 1; the other end of the diode D1 is coupled with an output pin 5 of the first comparator IC 1; the other ends of the capacitors C2 and C3 and the resistor R8 are grounded.
5. A drive circuit of an electronic device according to claim 3, characterized in that: the waveform conversion unit comprises resistors R9 and R10 and a second comparator IC2; one end of the resistor R9 is coupled to the output end of the voltage conversion and voltage stabilization unit, and the other end is coupled to one end of the resistor R10 and the inverted 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 of the second comparator IC2 is coupled to the signal input end of the driving unit; the other end of the resistor R10 is grounded.
6. A drive circuit of an electronic device according to claim 1, wherein: the driving unit comprises a signal current amplifier IC3, an amplifier Q1 and a follow current tube D2, wherein a pin 1 of the signal current amplifier IC3 is coupled with the output end of the waveform generating unit, a pin 2 receives an input power supply, a pin 4 is grounded, and a pin 3 is coupled with the base electrode of the amplifier Q1; the collector of the amplifier Q1 is coupled with the anode of the follow current tube D2, and is used as the output end to be coupled with the signal input end of the electronic device, and the emitter is grounded; the cathode of the follow current tube D2 is coupled to the input power source.
7. A drive circuit of an electronic device according to claim 6, characterized in that: the voltage stabilizing diode DZ is connected with the follow current tube D2 in series, and the negative electrode of the voltage stabilizing diode DZ is coupled with the negative electrode of the follow current tube D2.
8. A drive circuit of an electronic device according to any one of claims 1 to 7, wherein: the circuit is integrated and packaged in a chip, and a pin 1 of the chip is used for receiving an input power supply, a pin 2 of the chip is used for grounding, and a pin 3 of the chip is connected with an output end of a driving unit and used for providing a driving power supply for an electronic device.
9. A driving system of an electronic device comprising the driving circuit according to any one of claims 1 to 7 and a buzzer.
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| CN201710934420.0A CN107704006B (en) | 2017-10-10 | 2017-10-10 | Driving circuit of electronic device |
| US15/894,072 US10629180B2 (en) | 2017-10-10 | 2018-02-12 | Driving circuit for electronic device and associated system and method |
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| CN201710934420.0A CN107704006B (en) | 2017-10-10 | 2017-10-10 | Driving circuit of electronic device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108470558A (en) * | 2018-05-30 | 2018-08-31 | 杭州百隆电子有限公司 | A kind of buzzer drive circuit and drive system |
| CN110346015B (en) * | 2019-08-05 | 2024-05-28 | 杭州微联智控科技有限公司 | Electrode type water immersion detection circuit and water immersion sensor |
| CN110335579B (en) * | 2019-08-16 | 2022-01-07 | 深圳南云微电子有限公司 | Driving circuit of buzzer |
| CN113067991A (en) * | 2021-03-30 | 2021-07-02 | 中国科学院长春光学精密机械与物理研究所 | Self-defined waveform driving circuit |
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