CN110350473B - Control circuit, method and device - Google Patents

Control circuit, method and device Download PDF

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Publication number
CN110350473B
CN110350473B CN201810290854.6A CN201810290854A CN110350473B CN 110350473 B CN110350473 B CN 110350473B CN 201810290854 A CN201810290854 A CN 201810290854A CN 110350473 B CN110350473 B CN 110350473B
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loudspeaker
voltage
switch
circuit
comparator
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CN110350473A (en
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王会文
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ZTE Corp
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ZTE Corp
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Priority to PCT/CN2019/077982 priority patent/WO2019192298A1/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/20—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage

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  • Circuit For Audible Band Transducer (AREA)

Abstract

The embodiment of the invention provides a control circuit, a method and a device, wherein the control circuit comprises: an overvoltage protection circuit comprising a comparator and a switch, the switch coupled between a speaker and a preceding stage of the overvoltage protection circuit; the comparator is coupled to collect the voltage of the loudspeaker and compare the voltage with a received reference voltage, and when the voltage of the loudspeaker is greater than or equal to the reference voltage, the comparator controls a switch to disconnect the communication line between the front-stage circuit and the loudspeaker. Therefore, when the loudspeaker is in an overvoltage state, the communication line between the front-stage circuit and the loudspeaker is disconnected, and the loudspeaker is protected.

Description

Control circuit, method and device
Technical Field
The present invention relates to electronic technologies, and in particular, to a control circuit, a method and an apparatus.
Background
A Speaker (Speaker, SPK) is a core module of an automobile sound system as an electroacoustic transducer. In an automobile audio system, the speaker may have abnormal conditions such as overvoltage, short circuit, and disconnection, which not only affect the normal operation of the speaker, but also may cause the speaker to become overheated or directly damage the speaker.
At present, in an on-vehicle Speaker protection mechanism, no other effective solution is available except that an offset detector is embedded to protect the safety of a loudspeaker.
Disclosure of Invention
In view of this, an embodiment of the present invention provides a control circuit, including: an overvoltage protection circuit comprising a comparator and a switch, the switch coupled between a speaker and a preceding stage of the overvoltage protection circuit;
the comparator is coupled to collect a voltage of a speaker and compare the voltage with a received reference voltage, and when the voltage of the speaker is greater than or equal to the reference voltage, the comparator controls a switch to disconnect a communication line between the pre-stage circuit and the speaker.
According to the technical scheme, when the loudspeaker is in an overvoltage state, the communication line between the front-stage circuit and the loudspeaker is disconnected, and the loudspeaker is protected.
The embodiment of the invention also provides a control method, which comprises the following steps:
when the state of the loudspeaker needs to be detected, judging whether the loudspeaker is in an overvoltage state;
when the loudspeaker is not in an overvoltage state, an enabling signal is sent to the detection circuit, and the voltage on the positive pole line or the voltage on the negative pole line of the loudspeaker is read through the detection circuit so as to judge the state of the loudspeaker.
According to the technical scheme, the state of the loudspeaker can be judged by acquiring the voltage on the positive line or the negative line of the loudspeaker at regular time or in real time as required, and the fault of the loudspeaker can be found in time.
The embodiment of the invention also provides various control devices, which comprise: the control system comprises a memory, a processor and a program stored on the memory and capable of running on the processor, wherein the program realizes the control method when being executed by the processor.
An embodiment of the present invention further provides an electronic device, where the control circuit further includes a controller configured to execute the control method.
The embodiment of the invention also provides a computer-readable storage medium storing computer-executable instructions, and the computer-executable instructions realize the control method when being executed.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the example serve to explain the principles of the invention and not to limit the invention.
Fig. 1 is a schematic structural diagram of a control circuit according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a framework of an overvoltage protection circuit according to a second embodiment of the present invention;
fig. 3 is a schematic circuit diagram of an overvoltage protection circuit according to a second embodiment of the present invention;
fig. 4 is a schematic diagram of a detection circuit according to a third embodiment of the present invention;
fig. 5 is a circuit schematic diagram of a detection circuit according to a third embodiment of the present invention;
fig. 6 is a block diagram of a car audio system according to a fourth embodiment of the present invention;
fig. 7 is a schematic structural diagram of an overvoltage protection circuit according to a fourth embodiment of the present invention;
fig. 8 is a schematic flowchart of a control method according to a fifth embodiment of the present invention;
fig. 9 is a schematic flowchart of a speaker protection and state detection method according to a sixth embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the embodiments and features of the embodiments in the present application may be arbitrarily combined with each other without conflict.
The steps illustrated in the flow charts of the figures may be performed in a computer system such as a set of computer-executable instructions. Also, while a logical order is shown in the flow diagrams, in some cases, the steps shown and/or described may be performed in an order different than here.
Abnormal excursions can place the speaker at risk of becoming overheated or directly damage the speaker. In the related art, an offset detection function may be embedded in an automotive power amplifier device, and if an offset is detected, a speaker protection control signal or command is issued. However, firstly, the offset detection protection mechanism can only protect the safety of the speaker in the abnormal offset scene of the speaker, but cannot automatically protect the safety of the speaker when the speaker is in an overvoltage state, and further cannot detect the short circuit or open circuit state of the speaker. Second, the offset detection protection mechanism must require a control Unit in the car audio system, such as an MCU (micro control Unit), to turn on the audio power amplifier in the proper sequence, and the speaker protection mechanism may not work if the MCU directly turns on the amplifier to play mode without enough set time for the amplifier to stabilize.
Also, the electronic modules and loads inside the automobile are numerous and constitute a complex electronic environment together with each other. The automotive electronics modules are connected by wire harnesses, and there may be different conditions at the interface to the module connector. Typical automotive battery voltages range from 9V to 16V, with the nominal voltage of the automotive battery at 12V when the engine is off; when the engine works, the battery voltage is about 14.4V. However, transient voltages of ± 100V may be reached under different conditions. Excessive transient voltages may cause the electronic modules to operate abnormally or even to be damaged. Because the electronic control units in the automobile are more and more, the data transmission quantity of each electronic control unit is increased in multiple, the automobile wire harness is required to have a better information transmission function, and the design of the automobile wire harness is more and more complex. For automobiles with more electrical equipment, the automobile wire harnesses are more and messy. In the production test process, even in the use process of a user, mixed insertion and wrong insertion or damage of a wire harness cause short circuit and open circuit, so that an electronic module in an automobile can be damaged, even a circuit system of the whole automobile can be influenced, and the driving safety is threatened.
Based on this, the application provides a control circuit, a method and a device, which can protect the safety of the loudspeaker when the loudspeaker is in an overvoltage state. Further, the state of the loudspeaker can be detected, the fault of the loudspeaker can be determined in time, and the fault reason can be located. The present invention will be described in detail with reference to specific examples.
Example one
Fig. 1 is a schematic structural diagram of a control circuit according to an embodiment of the present invention; as shown in fig. 1, the control circuit comprises an overvoltage protection circuit comprising a comparator and a switch coupled between a speaker and a preceding stage of the overvoltage protection circuit;
the comparator is coupled to collect a voltage of a speaker and compare the voltage with a received reference voltage, and when the voltage of the speaker is greater than or equal to the reference voltage, the comparator controls the switch to be opened to disconnect a communication line between the pre-stage circuit and the speaker.
Therefore, when the voltage of the loudspeaker is greater than or equal to the reference voltage, namely the loudspeaker is in an overvoltage state, the connection between the front-stage circuit and the loudspeaker is disconnected, and the safety of the loudspeaker is protected; the front stage circuit includes a power amplification circuit, or other various circuits connected to the speaker.
In this embodiment, it is possible to determine whether the speaker is in the overvoltage state by detecting whether only the voltage of the positive electrode of the speaker is greater than or equal to the reference voltage thereof or only the voltage of the negative electrode of the speaker is greater than or equal to the reference voltage thereof. However, overvoltage may exist on both the positive and negative electrodes of the speaker, so the following description will be given in detail by taking the example of simultaneously detecting the positive and negative electrodes of the speaker as an example:
specifically, the comparator comprises a first comparator and a second comparator, the switch comprises a first switch and a second switch, the output end of the first comparator is coupled with the first switch, and the output end of the second comparator is coupled with the second switch;
the input end of the first comparator is coupled with the anode of the loudspeaker to collect anode voltage and receive first reference voltage, and when the anode voltage is greater than or equal to the first reference voltage, the first comparator outputs a disconnection control signal to the first switch;
the input end of the second comparator is coupled with the negative electrode of the loudspeaker so as to collect negative electrode voltage and receive second reference voltage, and when the negative electrode voltage is larger than or equal to the second reference voltage, the second comparator outputs a disconnection control signal to the second switch.
Wherein the first switch and the second switch may be initially set to a conductive state. The control signal may be high or low, and the first switch and the second switch may be set to be in an off state when receiving the low level and to be in an on state when receiving the high level. When the first comparator judges that the anode voltage is greater than or equal to the first reference voltage, the first comparator outputs a low level to the first switch to disconnect the first switch, and when the anode voltage is less than the first reference voltage, the first comparator outputs a high level to the first switch to connect the first switch. Similarly, when the second comparator determines that the cathode voltage is greater than or equal to the second reference voltage, a low level is output to the second switch to turn off the second switch, and when the cathode voltage is less than the second reference voltage, a high level is output to the second switch to turn on the second switch. Of course, those skilled in the art may set different rules as needed to control the switch to be turned off or on to achieve the purpose of turning off or on the communication line between the front stage circuit and the speaker. Therefore, as long as either the anode or the cathode of the loudspeaker is in an overvoltage state, the corresponding switch is disconnected, and the effect of protecting the safety of the loudspeaker is achieved.
In this embodiment, the output terminals of the first comparator and the second comparator are further coupled to a controller respectively;
when the positive voltage is greater than or equal to the first reference voltage, the first comparator outputs an overvoltage identification signal to the controller;
when the cathode voltage is greater than or equal to the second reference voltage, the second comparator outputs an overvoltage identification signal to the controller.
In this case, the overvoltage identification signal may be active low, for example, with the first comparator and the first switch. The output terminal of the first comparator is coupled to both the first switch and a pin of the controller, for example, a GPIO pin of the MCU. When the positive voltage is greater than or equal to the first reference voltage, the output end of the first comparator outputs a low level, the first switch receives the low level and is in a disconnected state, the GPIO pin receives the low level, and the controller judges that the loudspeaker is in an overvoltage state.
In this way, once the speaker is in an overvoltage state, the speaker can be reported to the controller, and the controller may be a microcontroller MCU (or a single chip microcomputer) of a circuit system, or a CPU, or a digital Signal processor dsp (digital Signal processing), or a Field-Programmable logic Array FPGA (Field-Programmable Gate Array), or the like. The following description will be given by taking the controller as an MCU, but not limited to the MCU.
In this embodiment, the two comparators may report the over-voltage identification signal to the controller through an and circuit, and the and circuit may be composed of two diodes, for example, the cathodes of the two diodes are connected together and then connected to a certain pin of the MCU, and the two diodes constitute the and circuit. A certain pin of the MCU may be a GPIO pin, for example, when there is no over-voltage identification signal, the GPIO pin is at a high level, and when any one of the comparators outputs the over-voltage identification signal (the low level is active), the GPIO pin is pulled low, so that the MCU captures the over-voltage identification signal.
In this embodiment, to perform the switching function, the switch may be an NMOS transistor, a PMOS transistor, or other devices with the switching function. In order to perform the voltage comparison function, the comparator may be a single-limit voltage comparator, a double-limit voltage comparator, or other components with the voltage comparison function.
In this embodiment, it is preferable that the first switch includes a first NMOS transistor, the second switch includes a second NMOS transistor, and the first comparator and the second comparator are both single-limit voltage comparators for detailed description:
specifically, the output end of the first comparator is coupled to the first NMOS transistor, one input end is coupled to the positive electrode of the speaker to collect the positive voltage of the speaker, the other input end receives the first reference voltage, and when the positive voltage is greater than or equal to the first reference voltage, the first comparator outputs a turn-off control signal to the first NMOS transistor;
the output end of the second comparator is coupled to the second NMOS tube, one input end of the second comparator is coupled to the negative electrode of the loudspeaker to collect negative electrode voltage, the other input end of the second comparator receives the second reference voltage, and when the negative electrode voltage is larger than or equal to the second reference voltage, the second comparator controls to output a disconnection control signal to the second NMOS tube.
Wherein the off control signal may be active low.
The G pole of the first NMOS transistor may be coupled to the output terminal of the first comparator, the S pole is coupled to the front stage circuit, and the D pole is coupled to the anode of the speaker. The G pole of the second NMOS transistor may be coupled to the output terminal of the second comparator, the S pole is coupled to the pre-stage circuit, and the D pole is coupled to the negative electrode of the speaker.
In this embodiment, the control circuit further includes: a third switch (VT1) coupled to a switch of the overvoltage protection circuit;
the third switch is used for receiving a control signal and outputting a disconnection control signal to the switch.
The switch of the overvoltage protection circuit can be controlled to be switched off or switched on by the comparator, and can also be directly controlled to be switched off or switched on by the controller.
Specifically, the first switch and the second switch may be coupled to a controller through a third switch, and the third switch may be configured to receive a control signal from the controller and output an off control signal to a switch of the overvoltage protection circuit, and disconnect a communication line between the front stage circuit and the speaker. Taking the example of the controller controlling to turn off the first switch, the control signal may be high level. The third switch is configured to be in a conducting state after receiving the high level from the controller, and to output the low level to the first switch, turning off the first switch. The process of the controller controlling the second switch to be turned off is similar to the above, and is not described in detail.
Specifically, the third switch may be further configured to receive a control signal from a controller and output a conduction control signal to a switch of the overvoltage protection circuit, so as to conduct the preceding stage circuit and a communication line of the speaker. Take the controller to control the first switch to be turned on as an example: the control signal may be a low level, and the third switch is configured to be in an off state after receiving the low level from the controller, and output a high level to the first switch, turning on the first switch. The process of controlling the second switch to be turned on by the controller is similar to the above process, and is not described in detail.
The switch of the overvoltage protection circuit can receive the control signal of the controller and the control signal of the comparator at the same time, and there is no control conflict between the two control signals, because the line through which the switch receives the control signal output by the controller and the line through which the switch receives the control signal output by the comparator can be arranged together, taking the first switch as an example, the following description is given: when the controller outputs a low level to the first switch through the third switch, if the output of the first comparator is a high level (the loudspeaker is not in an overvoltage state) at the moment, the low level can be pulled down to be the high level, and the output of the first switch is still the low level; when the controller outputs high level to the first switch through the third switch, if the output of the comparator is low level (the loudspeaker is in an overvoltage state) at the moment, the high level can not pull down the low level, and the output of the first switch is still low level. The process of receiving the control signal by the second switch is similar to the above and is not described again. As shown in fig. 1, the control circuit not only includes an overvoltage protection circuit, but also includes a detection circuit;
the detection circuit is respectively coupled with the power supply voltage and the positive pole and the negative pole of the loudspeaker;
the detection circuit receives an enable signal and switches on a power supply voltage and the anode of the loudspeaker and grounds the cathode of the loudspeaker based on the enable signal, and outputs a voltage on the anode line of the loudspeaker. Or the detection circuit receives the enabling signal, switches on the power supply voltage and the cathode of the loudspeaker based on the enabling signal, grounds the anode of the loudspeaker and outputs the voltage on the line of the cathode of the loudspeaker.
In this embodiment, the detection circuit may receive an enable signal from the controller and output a voltage on the positive line or the negative line of the speaker to the controller.
Specifically, the detection circuit may be coupled to an ADC pin of the controller to output a voltage on the speaker positive or negative line to the controller. Therefore, the controller can acquire the voltage on the positive line or the negative line of the loudspeaker at regular time or in real time as required to judge the state of the loudspeaker and find the fault of the loudspeaker in time. The speaker states include short circuit, open circuit (open circuit), and the like.
Before the loudspeaker state detection is carried out, the controller outputs an opening control signal to a switch in the overvoltage protection circuit through a third switch so as to open a communication line between the loudspeaker and a preceding stage circuit of the overvoltage protection circuit, and the effect of isolating the detection circuit from the preceding stage circuit is achieved. The front stage circuit of the loudspeaker comprises a power amplification circuit or other circuits connected with the loudspeaker through an overvoltage protection circuit.
Specifically, the controller firstly judges whether the loudspeaker is in an overvoltage state, if so, the next action is not carried out, namely, the switch of the overvoltage protection circuit is not controlled to be turned off, and the detection circuit is not enabled; if not, the controller controls to open the switch of the overvoltage protection circuit and enable the detection circuit to detect the state of the loudspeaker.
In this embodiment, the pin for outputting the control signal to the third switch and the pin for outputting the enable signal to the detection circuit may be the same pin or different pins.
Specifically, when the pin for outputting the control signal to the third switch and the pin for outputting the enable signal to the detection circuit are the same pin, the control signal and the enable signal are the same signal, for example, when the signal is at a high level, the third switch is configured to receive the high level and be in a conducting state and output a low level, i.e., an off control signal to the switch of the overvoltage protection circuit; meanwhile, the detection circuit is configured to receive a high level in an enabled state. Other settings may be made by those skilled in the art, such as setting the control signal and enable signal active low, as desired.
Specifically, when the pin through which the controller outputs the control signal to the third switch and the pin through which the controller outputs the enable signal to the detection circuit are not the same pin, the controller outputs the control signal to the third switch and outputs the enable signal to the detection circuit, respectively; or the controller outputs the disconnection control signal to the switch of the overvoltage protection circuit directly through one pin and outputs the enable signal to the detection circuit through the other pin instead of through the third switch.
In this embodiment, after finishing detecting the state of the speaker, the controller further outputs a disable signal to the detection circuit to disconnect the line connection between the supply voltage and the positive pole of the speaker and disconnect the negative pole of the speaker from ground. After finishing detecting the state of the loudspeaker, the controller can also output a conduction control signal to the switch of the overvoltage protection circuit through the third switch to conduct the link between the preceding stage circuit and the loudspeaker.
In order to control and disconnect the switch in the overvoltage protection circuit, the third switch can be an NMOS (N-channel metal oxide semiconductor) tube, a PMOS (P-channel metal oxide semiconductor) tube and other components with the function of controlling and disconnecting the switch.
Specifically, the third switch (VT1) includes a sixth NMOS transistor (VT 1). And the G pole of the sixth NMOS tube is connected with the controller, the D pole of the sixth NMOS tube is connected with the switch of the overvoltage protection circuit, and the S pole of the sixth NMOS tube is grounded.
In this embodiment, the detection circuit includes a voltage divider circuit and a fourth switch (VT 6);
when the detection circuit is used for outputting the voltage on the positive line of the loudspeaker, the voltage division circuit is coupled between the power supply voltage and the positive pole and the negative pole of the loudspeaker, and the voltage division circuit switches on the power supply voltage and the positive pole of the loudspeaker and grounds the negative pole of the loudspeaker when receiving the enabling signal;
one end of the fourth switch is coupled to a positive electrode circuit of the loudspeaker, one end of the fourth switch is coupled to a power supply voltage, and the fourth switch outputs the voltage on the positive electrode circuit of the loudspeaker when the voltage division circuit receives the enabling signal.
In this embodiment, the detection circuit includes a voltage divider circuit and a fourth switch (VT 6);
when the detection circuit outputs the voltage on the negative electrode line of the loudspeaker, the detection circuit comprises a voltage division circuit and a fourth switch (VT 6);
the voltage division circuit is coupled between a power supply voltage and the anode and the cathode of the loudspeaker, and the voltage division circuit switches on the power supply voltage and the cathode of the loudspeaker and grounds the anode of the loudspeaker when receiving the enabling signal; one end of the fourth switch is coupled to the negative pole circuit of the loudspeaker, and the other end of the fourth switch is coupled to the power supply voltage; and the fourth switch outputs the voltage on the negative pole line of the loudspeaker when the voltage division circuit receives the enabling signal.
In this embodiment, the fourth switch may be configured to output the voltage on the positive line or the negative line to the controller. For example, the ADC pin of the MCU may be connected to the fourth switch, and the voltage on the positive line of the SPK is read to determine the state of the SPK, such as short circuit, open circuit (open circuit), etc.
In this embodiment, the fourth switch includes a fifth NMOS transistor (VT 6). Specifically, the G pole of the fifth NMOS tube is connected with the power supply voltage, the S pole is connected with the controller, and the D pole is connected with the positive electrode line of the loudspeaker. Wherein the S pole can be connected with an ADC pin of the controller. The detection circuit may further include a resistor (R4, R7) coupled between the fourth switch and the ADC pin. Therefore, the resistor forms an ADC conditioning circuit, so that the voltage collected by the ADC is within the sampling range of the ADC.
In this embodiment, when the detection circuit outputs the voltage on the positive line of the speaker, the voltage dividing circuit includes a pull-up resistor coupled between the supply voltage and the positive line of the speaker, and a pull-down resistor coupled between the negative line of the speaker and the ground, where the pull-up resistor and the pull-down resistor are used to form a voltage dividing network together with the internal resistance of the speaker.
In this embodiment, in order to perform the voltage dividing function, the voltage dividing circuit may be an NMOS transistor, a PMOS transistor, a resistor, or other components with the voltage dividing function. In order to output voltage, the fourth switch may be an NMOS transistor, a PMOS transistor, or other device with a voltage output function.
Specifically, the voltage division circuit further comprises two PMOS tubes (VT3, VT5) which are coupled between the supply voltage and the positive electrode of the loudspeaker and respectively located on each side of the pull-up resistor, and a third NMOS tube (VT4) which is coupled between the negative electrode of the loudspeaker and the pull-down resistor, wherein the two PMOS tubes are connected in parallel and then connected in series with a fourth NMOS tube, and the fourth NMOS tube is used for receiving an enable signal and conducting the two PMOS tubes based on the enable signal to connect the supply voltage and the positive electrode of the loudspeaker; the third NMOS tube (VT4) is used for receiving an enabling signal to enable the negative pole of the loudspeaker to be grounded.
The third NMOS tube and the two PMOS tubes in the voltage division circuit can play a role in preventing high voltage.
Both the NMOS transistor and the PMOS transistor in the circuit can be configured with diodes.
In this embodiment, the detection circuit may further couple a current limiting resistor (R2, R3) to the output line of the power supply voltage for current limiting, and may couple a capacitor for filtering.
In this embodiment, the overvoltage protection circuit in the control circuit can protect the speaker from being in an overvoltage state, and further, the detection circuit in the control circuit detects the state of the speaker to find out a speaker fault.
The following describes the present invention in detail by taking an overvoltage protection circuit and a detection circuit as examples.
Example two
The embodiment of the invention also provides an overvoltage protection circuit which comprises a switch and a comparator.
Fig. 2 is a schematic diagram of a framework of an overvoltage protection circuit according to a second embodiment of the present invention, and as shown in fig. 2, the overvoltage protection circuit includes a comparator and a switch.
The comparator comprises a first comparator and a second comparator, the switch comprises a first switch and a second switch, the output end of the first comparator is coupled with the first switch, and the output end of the second comparator is coupled with the second switch;
the input end of the first comparator is coupled with the anode of the loudspeaker to collect anode voltage and receive first reference voltage, and when the anode voltage is greater than or equal to the first reference voltage, the first comparator outputs a disconnection control signal to the first switch;
the input end of the second comparator is coupled with the negative electrode of the loudspeaker so as to collect negative electrode voltage and receive second reference voltage, and when the negative electrode voltage is larger than or equal to the second reference voltage, the second comparator outputs a disconnection control signal to the second switch.
Specifically, the first switch and the second switch may be initially set to a conductive state. The control signal may be high or low, and the first switch and the second switch may be set to be in an off state when receiving the low level and to be in an on state when receiving the high level. When the first comparator judges that the anode voltage is greater than or equal to the first reference voltage, the first comparator outputs a low level to the first switch to disconnect the first switch, and when the anode voltage is less than the first reference voltage, the first comparator outputs a high level to the first switch to connect the first switch. Similarly, when the second comparator determines that the cathode voltage is greater than or equal to the second reference voltage, a low level is output to the second switch to turn off the second switch, and when the cathode voltage is less than the second reference voltage, a high level is output to the second switch to turn on the second switch. Of course, those skilled in the art may set different rules as needed to control the switch to be turned off or on to achieve the purpose of turning off or on the communication line between the front stage circuit and the speaker.
Therefore, as long as either the anode or the cathode of the loudspeaker is in an overvoltage state, the corresponding switch is disconnected, and the effect of protecting the safety of the loudspeaker is achieved.
Meanwhile, at the moment of overvoltage, the two comparators can report overvoltage identification signals to the controller respectively.
In this embodiment, the output terminals of the first comparator and the second comparator may be further coupled to a controller respectively;
when the positive voltage is greater than or equal to the first reference voltage, the first comparator outputs an overvoltage identification signal to the controller;
when the cathode voltage is greater than or equal to the second reference voltage, the second comparator outputs an overvoltage identification signal to the controller.
In this case, the overvoltage identification signal may be active low, for example, with the first comparator and the first switch. The output terminal of the first comparator is coupled to both the first switch and a pin of the controller, for example, a GPIO pin of the MCU. When the positive voltage is greater than or equal to the first reference voltage, the output end of the first comparator outputs a low level, the first switch receives the low level and is in a disconnected state, the GPIO pin receives the low level, and the controller judges that the loudspeaker is in an overvoltage state.
In this way, once the speaker is in an overvoltage state, the speaker can be reported to the controller, and the controller may be a microcontroller MCU (or a single chip microcomputer) of a circuit system, or a CPU, or a digital Signal processor dsp (digital Signal processing), or a Field-Programmable logic Array FPGA (Field-Programmable Gate Array), or the like. The following description will be given by taking the controller as an MCU, but not limited to the MCU.
In this embodiment, the two comparators may report the over-voltage identification signal to the controller through an and circuit, and the and circuit may be composed of two diodes, for example, the cathodes of the two diodes are connected together and then connected to a certain pin of the MCU, and the two diodes constitute the and circuit. A certain pin of the MCU may be a GPIO pin, for example, when there is no over-voltage identification signal, the GPIO pin is at a high level, and when any one of the comparators outputs the over-voltage identification signal (the low level is active), the GPIO pin is pulled low, so that the MCU captures the over-voltage identification signal.
In this embodiment, to perform the switching function, the switch may be an NMOS transistor, a PMOS transistor, or other devices with the switching function. In order to perform the voltage comparison function, the comparator may be a single-limit voltage comparator, a double-limit voltage comparator, or other components with the voltage comparison function.
Fig. 3 is a schematic circuit diagram of an over-voltage protection circuit according to a second embodiment of the present invention, as shown in fig. 3,
in this embodiment, an integrated double N MOS transistor VT9 and two single-limit comparators COM _1 and COM _2 constitute an overvoltage protection circuit, the power supply voltages of the two single-limit comparators COM _1 and COM _2 are VCC _ PROT, and the reference voltages of the two single-limit comparators COM _1 and COM _2 correspond to VREF1 and VREF2, respectively. R10 and R11 form a conditioning network of a reference voltage VREF1, so that the non-inverting input end of the comparator COM _1 has a proper reference voltage value, R8 and R9 form a voltage division network of the SPK positive voltage, and the input voltage of the inverting input end of the comparator COM _1 is in a measuring range; similarly, R14 and R15 form a conditioning network of the reference voltage VREF2, so that the non-inverting input terminal of the comparator COM _2 has a suitable reference voltage value, and R12 and R13 form a voltage dividing network of the SPK cathode voltage, so that the input voltage of the inverting input terminal of the comparator COM _2 is within the range of the measurement range. The diode VD1 and VD2 are connected together and then connected to a certain GPIO pin of the MCU, the pin is configured to be in a pull-up input mode (PU mode) and in a low-level interrupt capture mode, then the VD1 and the VD2 form an AND gate circuit, the GPIO pin is in a high level when no overvoltage identification signal exists, when any comparator outputs an overvoltage identification signal (the low level is effective), the GPIO is pulled down, and the MCU captures the overvoltage identification signal. The capacitance of this part acts as a filter.
EXAMPLE III
The embodiment of the invention also provides a detection circuit. Fig. 4 is a schematic diagram of a detection circuit according to a third embodiment of the present invention, as shown in fig. 4,
the detection circuit is respectively coupled with the power supply voltage and the positive pole and the negative pole of the loudspeaker;
the detection circuit receives an enable signal and switches on a supply voltage and the anode of the speaker and grounds the cathode of the speaker based on the enable signal, and outputs a voltage on the anode line of the speaker.
Or the detection circuit receives the enabling signal, switches on the power supply voltage and the cathode of the loudspeaker based on the enabling signal, grounds the anode of the loudspeaker and outputs the voltage on the line of the cathode of the loudspeaker.
In this embodiment, the detection circuit may receive an enable signal from the controller and output a voltage on the positive line or the negative line of the speaker to the controller.
Specifically, the detection circuit may be coupled to an ADC pin of the controller to output a voltage on the speaker positive or negative line to the controller. Therefore, the controller can acquire the voltage on the positive line or the negative line of the loudspeaker at regular time or in real time as required to judge the state of the loudspeaker and find the fault of the loudspeaker in time. The speaker states include short circuit, open circuit (open circuit), and the like.
Before the loudspeaker state detection is carried out, the controller outputs an opening control signal to a switch in the overvoltage protection circuit through a third switch so as to open a communication line between the loudspeaker and a preceding stage circuit of the overvoltage protection circuit, and the effect of isolating the detection circuit from the preceding stage circuit is achieved. The front stage circuit of the loudspeaker comprises a power amplification circuit or other circuits connected with the loudspeaker through an overvoltage protection circuit.
Specifically, the controller firstly judges whether the loudspeaker is in an overvoltage state, if so, the next action is not carried out, namely, the switch of the overvoltage protection circuit is not controlled to be turned off, and the detection circuit is not enabled; if not, the controller controls to open the switch of the overvoltage protection circuit and enable the detection circuit to detect the state of the loudspeaker.
In this embodiment, the pin for outputting the control signal to the third switch and the pin for outputting the enable signal to the detection circuit may be the same pin or different pins.
Specifically, when the pin for outputting the control signal to the third switch and the pin for outputting the enable signal to the detection circuit are the same pin, the control signal and the enable signal are the same signal, for example, when the signal is at a high level, the third switch is configured to receive the high level and be in a conducting state and output a low level, i.e., an off control signal to the switch of the overvoltage protection circuit; meanwhile, the detection circuit is configured to receive a high level in an enabled state. Other settings may be made by those skilled in the art, such as setting the control signal and enable signal active low, as desired.
Specifically, when the pin through which the controller outputs the control signal to the third switch and the pin through which the controller outputs the enable signal to the detection circuit are not the same pin, the controller outputs the control signal to the third switch and outputs the enable signal to the detection circuit, respectively.
In order to control and disconnect the switch in the overvoltage protection circuit, the third switch can be an NMOS (N-channel metal oxide semiconductor) tube, a PMOS (P-channel metal oxide semiconductor) tube and other components with the function of controlling and disconnecting the switch.
Specifically, the third switch (VT1) includes a sixth NMOS transistor (VT 1). And the G pole of the sixth NMOS tube is connected with the controller, the D pole of the sixth NMOS tube is connected with the switch of the overvoltage protection circuit, and the S pole of the sixth NMOS tube is grounded.
In this embodiment, the detection circuit includes a voltage divider circuit and a fourth switch (VT 6);
when the detection circuit is used for outputting the voltage on the positive line of the loudspeaker, the voltage division circuit is coupled between the power supply voltage and the positive pole and the negative pole of the loudspeaker, and the voltage division circuit switches on the power supply voltage and the positive pole of the loudspeaker and grounds the negative pole of the loudspeaker when receiving the enabling signal;
one end of the fourth switch is coupled to the positive line of the loudspeaker, one end of the fourth switch is coupled to the power supply voltage, and the fourth switch outputs the voltage on the positive line of the loudspeaker when the voltage dividing circuit receives the enabling signal.
In this embodiment, the detection circuit includes a voltage divider circuit and a fourth switch (VT 6);
when the detection circuit outputs the voltage on the negative electrode line of the loudspeaker, the detection circuit comprises a voltage division circuit and a fourth switch (VT 6);
the voltage division circuit is coupled between a power supply voltage and the anode and the cathode of the loudspeaker, and the voltage division circuit switches on the power supply voltage and the cathode of the loudspeaker and grounds the anode of the loudspeaker when receiving the enabling signal; one end of the fourth switch is coupled to the negative pole circuit of the loudspeaker, and the other end of the fourth switch is coupled to the power supply voltage; and the fourth switch outputs the voltage on the negative pole line of the loudspeaker when the voltage division circuit receives the enabling signal.
In this embodiment, the fourth switch may be configured to output the voltage on the positive line or the negative line to the controller. For example, the ADC pin of the MCU may be connected to the fourth switch, and the voltage on the positive line of the SPK is read to determine the state of the SPK, such as short circuit, open circuit (open circuit), etc.
In this embodiment, the fourth switch includes a fifth NMOS transistor (VT 6). Specifically, the G pole of the fifth NMOS tube is connected with the power supply voltage, the S pole is connected with the controller, and the D pole is connected with the positive electrode line of the loudspeaker. Wherein the S pole can be connected with an ADC pin of the controller. The detection circuit may further include a resistor (R4, R7) coupled between the fourth switch and the ADC pin. Therefore, the resistor forms an ADC conditioning circuit, so that the voltage collected by the ADC is within the sampling range of the ADC.
In this embodiment, when the detection circuit outputs the voltage on the positive line of the speaker, the voltage dividing circuit includes a pull-up resistor (R6) coupled between the power supply voltage and the positive line of the speaker, and a pull-down resistor (R5) coupled between the negative line of the speaker and the ground, and the pull-up resistor and the pull-down resistor are used to form a voltage dividing network together with the internal resistance of the speaker.
In this embodiment, in order to perform the voltage dividing function, the voltage dividing circuit may be an NMOS transistor, a PMOS transistor, a resistor, or other components with the voltage dividing function. In order to output voltage, the fourth switch may be an NMOS transistor, a PMOS transistor, or other device with a voltage output function.
Specifically, the voltage division circuit further comprises two PMOS tubes (VT3, VT5) which are coupled between a supply voltage and a positive electrode of the loudspeaker and are respectively positioned on each side of the pull-up resistor, and a third NMOS tube (VT4) which is coupled between a negative electrode of the loudspeaker and the pull-down resistor, wherein the two PMOS tubes are connected in parallel and then are connected in series with a fourth NMOS tube, and the fourth NMOS tube is used for receiving an enable signal and conducting the two PMOS tubes based on the enable signal to connect the supply voltage and the positive electrode of the loudspeaker; the third NMOS tube (VT4) is used for receiving an enabling signal to enable the negative pole of the loudspeaker to be grounded.
The third NMOS tube and the two PMOS tubes in the voltage division circuit can play a role in preventing high voltage.
Both the NMOS transistor and the PMOS transistor in the circuit can be configured with diodes.
Fig. 5 is a circuit schematic diagram of a detection circuit according to a third embodiment of the present invention, as shown in fig. 5,
in this embodiment, SPK _ DET _ CTL is an enable pin of the Speaker state detection circuit, and is a turn-off pin of a switch (dual NMOS transistor) in the MCU control overvoltage protection circuit. The high level of SPK _ DET _ CTL is active, when SPK _ DET _ CTL is high, MOS transistor VT1 is turned on, SPK _ OFF _ N is low, and the double N MOS transistors in the overvoltage protection circuit are turned OFF. Meanwhile, a voltage division network consisting of resistors R5, R6 and SPK internal resistance is connected to a circuit, and the power supply voltage of the network is VCC _ DEC. The combination of a P MOS tube VT3 and a P MOS tube VT5 is adopted in a circuit connected with SPK _ P in the voltage division network to prevent overvoltage from entering the circuit from two directions, the N MOS tube VT2 and the N MOS tube VT4 are adopted in the circuit connected with SPK _ N to prevent high voltage by using a parasitic diode of the MOS tubes, the N MOS tube VT6 connected with an ADC pin SPK _ DEC _ ADC of the MCU also provides overvoltage protection for the MCU, a resistor R4 and a resistor R7 form an ADC conditioning circuit, so that the acquired voltage is within the sampling range of the ADC, the resistor R2 and the resistor R3 play a current limiting role, and the capacitors of the part play a filtering role.
Therefore, the positive electrode and the negative electrode of the SPK are respectively connected with a pull-down resistor (R5) and a pull-down resistor (R6) to form a voltage division network with the internal resistance of the SPK. The state of the SPK, such as an open circuit state, a short circuit state and the like, is interpreted by reading the voltage on the positive line of the SPK through the ADC of the MCU.
In summary, with the solutions described in the second and third embodiments of the present invention, states such as an overvoltage, a short circuit, or an open circuit (open circuit) of the SPK can be detected, and when the SPK is in the overvoltage state, the safety of the speaker is protected by disconnecting the line.
The state of the speaker can be determined by the following principles, for example:
when any end of the SPK _ P or the SPK _ N is short-circuited to the power supply, the overvoltage protection circuit acts and judges that the power supply is in an overvoltage state;
when the SPK _ P is short-circuited to the ground, the voltage of the front end of the ADC reading voltage division network is 0, namely the voltage of the drain (D pole) of the N MOS tube VT6 is 0; firstly, setting Rspk as SPK internal resistance, and then when SPK _ N is short-circuited to the ground, the drain voltage of VT6 is VCC _ DEC × Rspk/(Rspk + R6); when the SPK _ P and the SPK _ N are directly connected together and then are short-circuited to the ground, the situation is consistent with the short circuit of the SPK _ P to the ground;
when SPK _ P and SPK _ N are short, i.e. SPK _ P and SPK _ N are directly connected together, SPK is short-circuited, and then VT6 drain voltage is VCC _ DEC × R5/(R5+ R6);
when SPK is open, i.e., SPK _ P or SPK _ N is not short-circuited to power and ground and SPK is not normally connected to the line of SPK _ P and SPK _ N, the drain voltage of VT6 is VCC _ DEC.
The status of the speaker can thus be determined by reading the VT6 drain voltage through the ADC of the MCU. When the voltage of any end of SPK _ P or SPK _ N is higher than the reference voltage, the loudspeaker can be judged to be in an overvoltage state.
In addition, in the second and third embodiments, the voltage value of VCC _ DEC should be lower than the voltage of the electric battery of the automobile, and the input reference voltage of the comparator should also be lower than the voltage of the electric battery of the automobile, i.e., in the 12V automobile power supply system, VCC _ DEC/VREF1/VREF2 should be lower than 12V, and so on for other systems.
Example four
The overvoltage protection circuit and the detection circuit provided by the embodiment can be combined or independently applied to the vehicle-mounted T-BOX (telematics BOX) and other vehicle-mounted products with audio links. The following description will be made in detail by taking an automobile audio system as an example.
Fig. 6 is a block diagram of a car audio system according to a fourth embodiment of the present invention, as shown in fig. 6:
in this embodiment, the car audio system includes an audio power amplifier, an overvoltage protection circuit, a detection circuit, a Microprocessor (MCU) and a Speaker.
The Microprocessor (MCU) may be a CPU, a DSP, or an FPGA.
The audio power amplifier part is responsible for amplifying the sound source.
Wherein, the overvoltage protection circuit part:
referring to fig. 7, fig. 7 is a schematic structural diagram of an overvoltage protection circuit according to a fourth embodiment of the present invention, as shown in fig. 7, the overvoltage protection circuit includes two single-line comparators and two nmos transistors, where the two single-line comparators respectively collect voltages on a Speaker positive link and a Speaker negative link, and compare the collected voltages with respective reference voltages in real time: when the real-time voltage is not greater than the reference voltage, the N MOS tube is opened by default; when the real-time voltage is greater than the reference voltage, the comparator controls the N MOS to be turned off, and the overvoltage protection effect is achieved. Meanwhile, at the moment of overvoltage, the two comparators output two overvoltage identification signals, and the two overvoltage identification signals are reported to the MCU through an AND gate circuit consisting of two diodes. Meanwhile, the two N MOS tubes are also controlled by the controller, and the two N MOS tubes are switched off when Speaker state detection is carried out, so that the effect of isolating the detection circuit from a preceding-stage link is achieved.
Specifically, the output end of the first comparator is coupled to the first NMOS transistor, one input end is coupled to the positive electrode of the speaker to collect the positive voltage of the speaker, the other input end receives the first reference voltage, and when the positive voltage is greater than or equal to the first reference voltage, the first comparator outputs a turn-off control signal to the first NMOS transistor;
the output end of the second comparator is coupled to the second NMOS tube, one input end of the second comparator is coupled to the negative electrode of the loudspeaker to collect negative electrode voltage, the other input end of the second comparator receives the second reference voltage, and when the negative electrode voltage is larger than or equal to the second reference voltage, the second comparator controls to output a disconnection control signal to the second NMOS tube. Wherein the off control signal may be active low.
The G pole of the first NMOS transistor may be coupled to the output terminal of the first comparator, the S pole is coupled to the front stage circuit, and the D pole is coupled to the anode of the speaker. The G pole of the second NMOS transistor may be coupled to the output terminal of the second comparator, the S pole is coupled to the pre-stage circuit, and the D pole is coupled to the negative electrode of the speaker.
Wherein, the Speaker detection circuit part:
the partial circuit is composed of a plurality of MOS tubes. Firstly, the MCU reads whether the overvoltage protection circuit has an overvoltage identification signal: if yes, an overvoltage state exists, and the next action is not carried out; if no over-voltage identification signal exists, the double N MOS tubes are controlled to be turned off through the MCU, and the detection circuit is enabled. Therefore, the pull-up resistor and the pull-down resistor are connected to the positive electrode and the negative electrode of the SPK respectively to form a voltage division network together with the SPK internal resistance. And finally, reading the voltage on the positive electrode of the SPK through an ADC of the MCU to judge whether the SPK is in an open circuit or short circuit state.
Wherein, the MCU part: the part is mainly responsible for identification of overvoltage signals, enabling of an SPK detection initial turn-off double N MOS tube and a detection circuit, and reading the SPK to be in an open circuit state or a short circuit state.
Wherein, the Speaker part: the method mainly converts an electric signal sent by a preceding stage audio power amplifier into an acoustic signal, and plays the acoustic signal.
EXAMPLE five
The fifth embodiment of the present invention further provides a control method, which is applied to a controller, where the controller may be a microcontroller MCU (or a single chip microcomputer) of a circuit system, or a CPU, or a digital Signal processor dsp (digital Signal processing), or a Field Programmable logic Array FPGA (Field-Programmable Gate Array), and the like. The following controller is exemplified by MCU, but not limited to MCU
Fig. 8 is a schematic flowchart of a control method according to a fifth embodiment of the present invention, and as shown in fig. 8, the control method includes:
step 801, judging whether a loudspeaker is in an overvoltage state or not when the loudspeaker state needs to be detected;
step 802, when the speaker is not in an overvoltage state, sending an enable signal to a detection circuit, and reading the voltage on the positive line or the voltage on the negative line of the speaker through the detection circuit to judge the state of the speaker.
In this embodiment, the determining whether the speaker is in the overvoltage state includes:
judging whether an overvoltage identification signal is received or not, if so, judging that the loudspeaker is in an overvoltage state, and if not, judging that the loudspeaker is not in the overvoltage state;
or actively reading the overvoltage protection signal, if the overvoltage protection signal is read, judging that the loudspeaker is in an overvoltage state, and if the overvoltage protection signal is not read, judging that the loudspeaker is not in the overvoltage state.
The overvoltage protection signal can be passively received, and the overvoltage protection signal can also be actively polled and read.
When the loudspeaker is in an overvoltage state, for example, when high-voltage impact occurs, a switch in the overvoltage protection circuit can be automatically disconnected to disconnect a connecting circuit of a power amplifier and the loudspeaker, so that the loudspeaker is protected to be safe, and the loudspeaker immediately enters a main protection state; at this time, the MCU passively receives the over-voltage identification signal or actively reads the over-voltage identification signal, and determines that the speaker is in an over-voltage state, so that the speaker does not perform any further actions, such as enabling the detection circuit.
Only when the loudspeaker is not in an overvoltage state, the MCU enables the detection circuit, and the voltage of the SPK is read by the ADC of the MCU to judge whether the SPK is in an open circuit or a short circuit or the like.
In this embodiment, before sending the enable signal to the detection circuit, the method further includes:
and outputting a control signal to the overvoltage protection circuit to open a switch in the overvoltage protection circuit.
In this way, when Speaker state detection is performed, the switch in the overvoltage protection circuit is turned off, and the detection circuit is isolated from the preceding link.
In this embodiment, the reading of the voltage of the speaker includes reading a voltage of a positive electrode of the speaker.
In this embodiment, when the voltage on the positive line of the speaker is read by the detection circuit, the method further includes:
judging the state of the loudspeaker according to the voltage on the positive line, comprising the following steps:
judging the state of the loudspeaker according to the voltage on the positive line, comprising the following steps:
when the voltage on the positive line is zero, the state of the loudspeaker is that the positive line SPK _ P of the loudspeaker is short-circuited to the ground;
when the voltage on the positive electrode line is VCC _ DEC × Rspk/(Rspk + R6), the state of the loudspeaker is that the negative electrode line SPK _ N of the loudspeaker is short-circuited to the ground, or SPK _ P and SPK _ N are directly connected together and are short-circuited to the ground;
when the voltage on the positive electrode circuit is VCC _ DEC R5/(R5+ R6), the state of the loudspeaker is that SPK _ P and SPK _ N are mutually short;
when the voltage on the positive line is the supply voltage VCC _ DEC of the loudspeaker, the state of the loudspeaker is open circuit, namely SPK _ P or SPK _ N is not short-circuited to the power supply and the ground and SPK is not normally connected to the lines of SPK _ P and SPK _ N;
wherein Rspk is the internal resistance of the loudspeaker, R6 is the pull-up resistance connected to the positive pole of the loudspeaker and forming a voltage dividing network together with the internal resistance of the loudspeaker, and R5 is the pull-down resistance connected to the negative pole of the loudspeaker and forming a voltage dividing network together with the internal resistance of the loudspeaker.
EXAMPLE six
Fig. 9 is a schematic flowchart of a speaker protection and state detection method according to a sixth embodiment of the present invention, which is applied to an automobile audio system according to a fourth embodiment of the present invention.
As shown in fig. 9, the method includes:
step 901, when the loudspeaker is subjected to high-voltage impact, the overvoltage protection circuit automatically turns off the double N MOS tubes;
when the loudspeaker is subjected to high-voltage impact, the loudspeaker can be judged to be in an overvoltage state for any one end of the loudspeaker positive electrode circuit SPK _ P or the loudspeaker negative electrode circuit SPK _ N is short-circuited with a power supply, the overvoltage protection circuit acts, the double N MOS tubes are turned off, the circuit between the power amplifier and the loudspeaker is disconnected, and the loudspeaker enters a main protection state, so that the safety of the loudspeaker is protected.
Step 902, the overvoltage protection circuit detects whether the speaker SPK has high voltage, and if so, reports an overvoltage identification signal to the MCU; if not, repeat step 902;
wherein, whether there is high voltage on the protection circuit of above-mentioned overvoltage detects speaker SPK, includes: and a comparator of the overvoltage protection circuit collects the voltage of the anode or the cathode of the loudspeaker in real time and compares the voltage with respective reference voltages. When the voltage of the anode or the cathode is greater than or equal to the respective reference voltage, namely the loudspeaker is in an overvoltage state (also can be called as a high-voltage state), reporting an overvoltage identification signal to the MCU.
Step 903, the MCU judges whether the SPK has high voltage, if so, the process is ended; if not, go to step 904;
the MCU judges whether the SPK has high voltage or not, wherein the MCU can passively receive an overvoltage protection signal, if so, the SPK is judged to have high voltage, and if not, the SPK is judged not to have high voltage; or the MCU actively trains in turn to read the overvoltage protection signal, if the overvoltage protection signal is read, the SPK is judged to have high voltage, and if the overvoltage protection signal is not read, the SPK is judged not to have high voltage.
Step 904, the MCU closes the double MOS tubes of the overvoltage protection circuit and enables the detection circuit;
the double MOS tube for closing the overvoltage protection circuit can comprise a pin level connected with the double MOS tube, and a low level is output to the double MOS tube through an NMOS tube to control the double N MOS tube in the overvoltage protection circuit to be switched off.
The enabling detection circuit can output high level to the detection circuit, the power supply voltage and the loudspeaker anode are connected through the detection circuit, and the voltage on the anode line of the loudspeaker is sampled.
Step 905, reading the sampling voltage of the detection circuit by an ADC pin of the MCU;
wherein the sampling voltage is the voltage of the anode of the loudspeaker.
Step 906, judging the state of the SPK according to the sampling voltage and reporting the state;
the judging the state of the SPK according to the sampling voltage may include:
when the sampling voltage is 0, SPK _ P is shorted to ground, or SPK _ P and SPK _ N are directly connected together and then shorted to ground,
when the sampling voltage is VCC _ DEC × Rspk/(Rspk + R6), SPK _ N is short-circuited to ground;
when the sampling voltage is VCC _ DEC R5/(R5+ R6), SPK _ P and SPK _ N are mutually short-circuited; namely SPK _ P and SPK _ N are directly connected together, and SPK is short-circuited;
when the sampling voltage is VCC _ DEC, the SPK is open circuit, namely SPK _ P or SPK _ N is not short-circuited to power supply and ground and SPK is not normally connected to the circuit of SPK _ P and SPK _ N;
VCC _ DEC is the power supply voltage of the loudspeaker, Rspk is the SPK internal resistance, R5 is the pull-down resistor, R6 is the pull-up resistor, and the resistors R5, R6 and the SPK internal resistance form a voltage division network and are connected to the circuit.
Step 907 exits the detection state.
Wherein exiting the detection state may include: the method can comprise the steps of pulling down the pin level connected with the double MOS tubes, outputting a high level to the double MOS tubes through one NMOS tube, and switching on the double N MOS tubes in the overvoltage protection circuit. The method can also comprise the following steps: and pulling down the pin level of the detection circuit, outputting a low level to the detection circuit, and disconnecting the power supply voltage from the anode of the loudspeaker through the detection circuit.
An embodiment of the present invention further provides a control device, where the control device includes: the control system comprises a memory, a processor and a program stored on the memory and capable of running on the processor, wherein the program realizes the control method when being executed by the processor.
An embodiment of the present invention further provides an electronic device, which includes the control circuit described above, and further includes a controller configured to execute the control method described above.
The embodiment of the invention also provides a computer-readable storage medium storing computer-executable instructions, and the computer-executable instructions realize the control method when being executed.
Although the embodiments of the present invention have been described above, the above description is only for the convenience of understanding the present invention, and is not intended to limit the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (14)

1. A control circuit, comprising: an overvoltage protection circuit comprising a comparator and a switch, the switch coupled between a speaker and a preceding stage of the overvoltage protection circuit;
the comparator is coupled to collect the voltage of the loudspeaker and compare the voltage with the received reference voltage, and when the voltage of the loudspeaker is greater than or equal to the reference voltage, the comparator controls the switch to disconnect the communication line of the front-stage circuit and the loudspeaker;
the comparator comprises a first comparator and a second comparator, the switch comprises a first switch and a second switch, the output end of the first comparator is coupled with the first switch, and the output end of the second comparator is coupled with the second switch;
the input end of the first comparator is coupled with the anode of the loudspeaker to collect anode voltage and receive first reference voltage, and when the anode voltage is greater than or equal to the first reference voltage, the first comparator outputs a disconnection control signal to the first switch;
the input end of the second comparator is coupled with the negative electrode of the loudspeaker so as to collect negative electrode voltage and receive second reference voltage, and when the negative electrode voltage is greater than or equal to the second reference voltage, the second comparator outputs a disconnection control signal to the second switch;
wherein the control circuit further comprises: a detection circuit;
the detection circuit is respectively coupled with the power supply voltage and the anode and the cathode of the loudspeaker;
the detection circuit receives an enable signal, switches on a power supply voltage and the anode of the loudspeaker and grounds the cathode of the loudspeaker based on the enable signal, and outputs a voltage on the anode line of the loudspeaker;
wherein the detection circuit comprises a voltage divider circuit and a fourth switch (VT 6);
the voltage division circuit is coupled between a power supply voltage and the anode and the cathode of the loudspeaker, and the voltage division circuit switches on the power supply voltage and the anode of the loudspeaker and grounds the cathode of the loudspeaker when receiving the enabling signal; one end of the fourth switch is coupled to the positive electrode circuit of the loudspeaker, and the other end of the fourth switch is coupled to the power supply voltage; the fourth switch outputs the voltage on the positive line of the loudspeaker when the voltage division circuit receives the enabling signal;
the voltage division circuit further comprises two PMOS tubes (VT3, VT5) which are coupled between the supply voltage and the positive electrode of the loudspeaker and are respectively positioned at each side of the pull-up resistor, and a third NMOS tube (VT4) which is coupled between the negative electrode of the loudspeaker and the pull-down resistor, wherein the two PMOS tubes are connected in parallel and then are connected in series with a fourth NMOS tube, and the fourth NMOS tube is used for receiving an enabling signal and conducting the two PMOS tubes based on the enabling signal to switch on the supply voltage and the positive electrode of the loudspeaker; the third NMOS tube (VT4) is used for receiving an enabling signal to enable the negative pole of the loudspeaker to be grounded.
2. The control circuit of claim 1,
the output ends of the first comparator and the second comparator are further used for being coupled with a controller;
when the positive voltage is greater than or equal to the first reference voltage, the first comparator outputs an overvoltage identification signal to the controller;
when the cathode voltage is greater than or equal to the second reference voltage, the second comparator outputs an overvoltage identification signal to the controller.
3. The control circuit of claim 1,
the first switch and the second switch are coupled with a controller, and based on a control signal sent by the controller, the communication lines of the front stage circuit and the loudspeaker are disconnected.
4. The control circuit of claim 1, wherein the first switch comprises a first NMOS transistor, the second switch comprises a second NMOS transistor, and the first comparator and the second comparator are both single-limit voltage comparators;
the output end of the first comparator is coupled to the first NMOS tube, the inverting input end of the first comparator is coupled to the positive pole of the loudspeaker to collect the positive voltage of the loudspeaker, the non-inverting input end of the first comparator receives the first reference voltage, and when the positive voltage is larger than or equal to the first reference voltage, the first comparator outputs a disconnection control signal to the first NMOS tube;
the output end of the second comparator is coupled to the second NMOS tube, the inverting input end of the second comparator is coupled to the negative electrode of the loudspeaker to collect negative voltage, the non-inverting input end of the second comparator receives the second reference voltage, and when the negative voltage is larger than or equal to the second reference voltage, the second comparator controls to output a disconnection control signal to the second NMOS tube.
5. The control circuit of claim 1, further comprising: a third switch (VT1) coupled to a switch of the overvoltage protection circuit;
the third switch is used for receiving a control signal and outputting a disconnection control signal to the switch.
6. The control circuit of claim 5,
the third switch (VT1) includes a sixth NMOS transistor (VT 1).
7. The control circuit of claim 1,
when the detection circuit outputs the voltage on the positive line of the loudspeaker, the voltage division circuit comprises a pull-up resistor coupled between the power supply voltage and the positive electrode of the loudspeaker and a pull-down resistor coupled between the negative electrode of the loudspeaker and the ground, and the pull-up resistor and the pull-down resistor are used for forming a voltage division network together with the internal resistance of the loudspeaker.
8. The control circuit of claim 1,
the fourth switch comprises a fifth NMOS transistor (VT 6).
9. A control method, comprising:
when the state of the loudspeaker needs to be detected, judging whether the loudspeaker is in an overvoltage state;
when the loudspeaker is not in an overvoltage state, sending an enabling signal to a detection circuit and reading the voltage on a positive line of the loudspeaker through the detection circuit so as to judge the state of the loudspeaker;
wherein, before sending the enable signal to the detection circuit, the method further comprises:
outputting a control signal to the overvoltage protection circuit to disconnect a switch in the overvoltage protection circuit;
wherein the detection circuit comprises a voltage divider circuit and a fourth switch (VT 6);
the voltage division circuit is coupled between a power supply voltage and the anode and the cathode of the loudspeaker, and the voltage division circuit switches on the power supply voltage and the anode of the loudspeaker and grounds the cathode of the loudspeaker when receiving the enabling signal; one end of the fourth switch is coupled to the positive electrode circuit of the loudspeaker, and the other end of the fourth switch is coupled to the power supply voltage; the fourth switch outputs the voltage on the positive line of the loudspeaker when the voltage division circuit receives the enabling signal;
the voltage division circuit further comprises two PMOS tubes (VT3, VT5) which are coupled between the supply voltage and the positive electrode of the loudspeaker and are respectively positioned at each side of the pull-up resistor, and a third NMOS tube (VT4) which is coupled between the negative electrode of the loudspeaker and the pull-down resistor, wherein the two PMOS tubes are connected in parallel and then are connected in series with a fourth NMOS tube, and the fourth NMOS tube is used for receiving an enabling signal and conducting the two PMOS tubes based on the enabling signal to switch on the supply voltage and the positive electrode of the loudspeaker; the third NMOS tube (VT4) is used for receiving an enabling signal to enable the negative pole of the loudspeaker to be grounded.
10. The method of claim 9,
judging whether the loudspeaker is in an overvoltage state or not comprises the following steps:
judging whether an overvoltage identification signal is received or not, if so, judging that the loudspeaker is in an overvoltage state, and if not, judging that the loudspeaker is not in the overvoltage state;
or actively reading the overvoltage protection signal, if the overvoltage protection signal is read, judging that the loudspeaker is in an overvoltage state, and if the overvoltage protection signal is not read, judging that the loudspeaker is not in the overvoltage state.
11. The method of claim 10, wherein when the voltage on the speaker positive line is read by the detection circuit, the method further comprises:
judging the state of the loudspeaker according to the voltage on the positive line, comprising the following steps:
when the voltage on the positive line is zero, the state of the loudspeaker is that the positive line SPK _ P of the loudspeaker is short-circuited to the ground;
when the voltage on the positive electrode line is VCC _ DEC × Rspk/(Rspk + R6), the state of the loudspeaker is that the negative electrode line SPK _ N of the loudspeaker is short-circuited to the ground;
when the voltage on the positive electrode circuit is VCC _ DEC R5/(R5+ R6), the state of the loudspeaker is that SPK _ P and SPK _ N are mutually short;
when the voltage on the positive line is the supply voltage VCC _ DEC of the loudspeaker, the state of the loudspeaker is open circuit, namely SPK _ P or SPK _ N is not short-circuited to the power supply and the ground and the loudspeaker SPK is not normally connected to the line of SPK _ P and SPK _ N;
wherein Rspk is the internal resistance of the loudspeaker, R6 is the pull-up resistance connected to the positive pole of the loudspeaker and forming a voltage dividing network together with the internal resistance of the loudspeaker, and R5 is the pull-down resistance connected to the negative pole of the loudspeaker and forming a voltage dividing network together with the internal resistance of the loudspeaker.
12. A control device, characterized in that the device comprises: memory, processor and program stored on the memory and executable on the processor, which when executed by the processor implements the method of any one of claims 9 to 11.
13. An electronic device comprising the control circuit of any of claims 1-8, and further comprising a controller configured to perform the method of any of claims 9-11.
14. A computer-readable storage medium having stored thereon computer-executable instructions that, when executed, implement the method of any of claims 9 to 11.
CN201810290854.6A 2018-04-03 2018-04-03 Control circuit, method and device Active CN110350473B (en)

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