Battery voltage detection circuit, vehicle-mounted power amplifier and vehicle-mounted audio-video system

Abstract

The utility model discloses a battery voltage detection circuit, a vehicle-mounted power amplifier and a vehicle-mounted audio-video system.The battery voltage detection circuit comprises an operational amplifier and a voltage stabilization chip level analog-to-digital converter ADC module, and a stable constant current source is provided for a voltage stabilization chip through the operational amplifier; and it is ensured that the voltage stabilizing chip can output stable reference voltage to the ADC module. And on the other hand, the ADC module samples the battery voltage, so that the actual value of the battery voltage can be obtained based on the sampled battery voltage and the reference voltage. A stable constant current source is provided for the voltage stabilizing chip through the operational amplifier, the voltage stabilizing chip is supported to output stable reference voltage, compared with reference voltage in an MCU, the voltage stabilizing chip is not prone to being affected by factors such as temperature, power noise and aging in a vehicle-mounted environment, drifting of the reference voltage is reduced, and therefore the precision of a battery voltage detection result is improved.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, and more specifically, to a battery voltage detection circuit, an in-vehicle power amplifier, and an in-vehicle audio-visual system. Background Technology

[0002] With the widespread adoption of intelligent electric vehicles and high-end in-vehicle audio-visual systems, the power density and dynamic response requirements of in-vehicle power amplifiers (referred to as "in-vehicle amplifiers") have significantly increased. Their supply voltage range typically covers 9-16V, and voltage fluctuations directly affect the output efficiency, THD (Total Harmonic Distortion), and thermal stability of the in-vehicle amplifier. Since in-vehicle amplifiers are generally powered by batteries, accurate monitoring of battery voltage to guide battery management is essential.

[0003] Traditional solutions use the built-in analog-to-digital converter (ADC) of the microcontroller unit (MCU) for voltage detection. This method relies on the stability of the MCU's internal reference voltage (such as AVDD). However, in the automotive environment, the reference voltage is easily affected by temperature, power supply noise, and aging, leading to reference voltage drift and ultimately amplifying the battery voltage detection error. Utility Model Content

[0004] In view of the above problems, this application is made to provide a battery voltage detection circuit, an in-vehicle power amplifier, and an in-vehicle audio-visual system to improve the accuracy of battery voltage detection results. The specific solution is as follows:

[0005] In a first aspect, a battery voltage detection circuit is provided, comprising:

[0006] Operational amplifiers, voltage regulator chips, and analog-to-digital converter (ADC) modules;

[0007] The operational amplifier provides a constant current source to the voltage regulator chip, so that the voltage regulator chip outputs a reference voltage to the ADC module under the action of the constant current source;

[0008] The ADC module samples the battery voltage and obtains the actual value of the battery voltage based on the sampled battery voltage and the reference voltage.

[0009] In one possible design, in another implementation of the first aspect of the embodiments of this application, the output terminal of the operational amplifier is grounded in sequence through a fourth resistor R4, the cathode and anode of the voltage regulator chip, and the reference terminal of the voltage regulator chip is connected to the cathode and the positive input terminal of the operational amplifier, respectively.

[0010] In one possible design, in another implementation of the first aspect of the embodiments of this application, the cathode of the voltage regulator chip is connected to the ADC module for outputting the reference voltage to the ADC module.

[0011] In one possible design, in another implementation of the first aspect of the embodiments of this application, the positive input terminal of the operational amplifier is connected to the power supply VCC+ through a sixth resistor R6, and the negative input terminal of the operational amplifier is grounded through a fifth resistor R5.

[0012] In one possible design, in another implementation of the first aspect of the embodiments of this application, the output terminal of the operational amplifier is connected to the negative input terminal through a third resistor R3.

[0013] In one possible design, another implementation of the first aspect of the embodiments of this application further includes: a resistor voltage divider network, the resistor voltage divider network including a first resistor R1 and a second resistor R2 connected in series, one end of the resistor voltage divider network being connected to the battery and the other end being grounded;

[0014] The ADC module samples the battery voltage through the resistor divider network.

[0015] In one possible design, in another implementation of the first aspect of the embodiments of this application, the ADC module is built into the microcontroller unit (MCU), and the output terminal of the voltage regulator chip is connected to the MCU to transmit the reference voltage to the ADC module through the MCU.

[0016] In one possible design, in another implementation of the first aspect of the embodiments of this application, the voltage regulator chip adopts a three-terminal adjustable voltage reference chip AZ431.

[0017] In a second aspect, an on-board power amplifier is provided, including a power module and a battery voltage detection circuit as described in any of the first aspects above, wherein the battery voltage detection circuit is used to detect the voltage of the power module.

[0018] Thirdly, an in-vehicle audio-visual system is provided, including the in-vehicle power amplifier described in the second aspect above.

[0019] Using the above technical solution, the battery voltage detection circuit of this application includes an operational amplifier and a voltage regulator chip-level analog-to-digital converter (ADC) module. The operational amplifier provides a stable constant current source to the voltage regulator chip, ensuring that the voltage regulator chip can output a stable reference voltage to the ADC module. On the other hand, the ADC module samples the battery voltage, and then obtains the actual value of the battery voltage based on the sampled battery voltage and the reference voltage. This application provides a stable constant current source to the voltage regulator chip through the operational amplifier, supporting the voltage regulator chip to output a stable reference voltage. Compared with the reference voltage inside the MCU, it is less affected by factors such as temperature, power supply noise, and aging in the vehicle environment, reducing reference voltage drift and thus improving the accuracy of the battery voltage detection results. Experimental comparison shows that using the solution of this application can improve the battery voltage detection accuracy from 1% in the prior art to about 0.2%. Attached Figure Description

[0020] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0021] Figure 1 This is a schematic diagram of a battery voltage detection circuit structure provided in an embodiment of this application;

[0022] Figure 2 This is a schematic diagram of another battery voltage detection circuit structure provided in an embodiment of this application;

[0023] Figure 3 This is a schematic diagram of a simulation waveform provided for an embodiment of this application. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] Traditional methods use the built-in analog-to-digital converter (ADC) of the microcontroller unit (MCU) for voltage detection. This approach relies on the stability of the MCU's internal reference voltage (such as AVDD) and is prone to the following drawbacks:

[0026] 1. Temperature dependence: The internal reference temperature of the MCU drifts by 50~100ppm / °C, introducing an error of more than ±1% in a wide temperature range of -40°C to 125°C;

[0027] 2. Power supply noise coupling: Operating conditions such as vehicle ignition and motor drive cause ±100mV ripple in the MCU power supply rail (such as 3.3V DVDD), which directly pollutes the reference voltage;

[0028] 3. Insufficient long-term stability: The MCU reference voltage ages over time (annual drift rate > 0.1%), affecting the long-term reliability of the detection system.

[0029] To address the shortcomings of existing solutions, this application provides a battery voltage detection circuit, combined with... Figure 1 As shown, the battery voltage detection circuit of this application includes:

[0030] Operational amplifiers, voltage regulator chips, and analog-to-digital converter (ADC) modules.

[0031] The operational amplifier provides a constant current source to the voltage regulator chip, enabling the voltage regulator chip to output a reference voltage to the ADC module under the action of the constant current source.

[0032] The ADC module samples the battery voltage and, based on the sampled battery voltage and a reference voltage, obtains the actual value of the battery voltage.

[0033] Specifically, the ADC module samples the battery voltage (such as the voltage after voltage division) to obtain the sampled battery voltage. Further, the sampled battery voltage is compared with a reference voltage and converted into a digital value proportionally (e.g., a 12-bit ADC outputs 0~4095).

[0034] Conversion formula: Digital value = Input voltage / Reference voltage × ADC full-scale value

[0035] For example:

[0036] If the reference voltage is 3.3V and the sampled battery voltage is 1.65V, the 12-bit ADC output is: 1.65 / 3.3×4095=2047.5≈2048.

[0037] The battery voltage detection circuit of this application includes an operational amplifier and a voltage regulator chip-level analog-to-digital converter (ADC) module. The operational amplifier provides a stable constant current source to the voltage regulator chip, ensuring that the voltage regulator chip can output a stable reference voltage to the ADC module. On the other hand, the ADC module samples the battery voltage and then obtains the actual battery voltage value based on the sampled battery voltage and the reference voltage. This application provides a stable constant current source to the voltage regulator chip through the operational amplifier, supporting the voltage regulator chip to output a stable reference voltage. Compared to the reference voltage inside the MCU, it is less affected by factors such as temperature, power supply noise, and aging in the automotive environment, reducing reference voltage drift and thus improving the accuracy of the battery voltage detection results. Experimental comparisons show that using the solution of this application can improve the battery voltage detection accuracy from 1% in the prior art to approximately 0.2%.

[0038] Combination Figure 2 As shown, the ADC module can be integrated into a microcontroller unit (MCU). The output of the voltage regulator chip is connected to the MCU to transmit the reference voltage to the ADC module via the MCU.

[0039] Combination Figure 2 As shown, the battery voltage detection circuit of this application may further include a resistor divider network. This resistor divider network includes a first resistor R1 and a second resistor R2 connected in series. One end of the resistor divider network is connected to the battery voltage VBATT+, and the other end is grounded. The ADC module samples the battery voltage through the resistor divider network.

[0040] The ADC module is connected to the common terminal of R1 and R2. A voltage acquisition value can be obtained by voltage division through resistors R1 and R2. The ADC module converts the voltage acquisition value based on the input reference voltage to obtain the actual measured battery voltage.

[0041] like Figure 2 As shown, the resistor divider network may also include a Zener diode D1, which is connected in parallel between the battery and ground to prevent excessive abnormal fluctuations in battery power from damaging the MCU device.

[0042] In some possible implementations, the voltage regulator chip can be a three-terminal adjustable voltage reference chip, such as the AZ431 voltage regulator chip.

[0043] The AZ431 voltage regulator chip has a reference voltage Vref of 2.5V (±0.5% accuracy). Its operating voltage range is 1.24V~18V, offering a wide input voltage range and compatibility with low-voltage systems. The minimum cathode current can reach 0.4mA, meaning lower current is required to maintain regulation, making it more suitable for battery-powered applications. With a temperature drift coefficient of 50ppm / ℃, it boasts high temperature stability, making it suitable for precision circuits.

[0044] The AZ431 voltage regulator chip has three pins: C, R, and A. Pin C represents the cathode, pin R represents the reference electrode (REF), and pin A represents the anode.

[0045] In some possible implementations, combined Figure 2 As shown, the output terminal of operational amplifier U1 is grounded through the fourth resistor R4, the cathode C and anode A of voltage regulator chip D2 in sequence, and the reference terminal R of voltage regulator chip D2 is connected to the cathode C and the positive input terminal of operational amplifier U1 respectively.

[0046] The cathode C of the voltage regulator chip D2 is connected to the ADC module to output a reference voltage to the ADC module.

[0047] In some possible implementations, operational amplifier U1 can be a positive closed-loop amplifier. The positive input terminal of operational amplifier U1 is connected to the power supply VCC+ through the sixth resistor R6, and the negative input terminal of operational amplifier U1 is grounded through the fifth resistor R5.

[0048] The output of operational amplifier U1 can be connected to the negative input via the third resistor R3.

[0049] Operational amplifier U1 can be any type of amplifier, such as the OPA2377. Operational amplifier U1 is powered by power supply Vs+.

[0050] like Figure 2 As shown, in this embodiment, by directly connecting the reference terminal R of the voltage regulator chip to the cathode C, the voltage regulator chip can clamp the output reference voltage to its reference voltage. Taking the AZ431 voltage regulator chip as an example, its reference voltage is 2.5V, therefore the voltage at the cathode of the voltage regulator chip is stable at 2.5V.

[0051] Combination Figure 2 The circuit's working principle is explained as shown below:

[0052] Before VCC+ is powered on, operational amplifier U1 has no current output, and voltage regulator D2 is not activated. When VCC+ is powered on, resistor R6 provides an initial voltage to the non-inverting input of operational amplifier U1. This voltage is higher than the inverting input, causing operational amplifier U1 to output current, and the voltage across voltage regulator D2 to rise until D2 starts normally. The voltage between the resistors R and C of voltage regulator D2 remains constant at a 2.5V reference voltage. Due to the characteristics of operational amplifiers, the voltage at the inverting input will be close to the voltage at the non-inverting input. Because of the voltage divider formed by resistors R3 and R5, the output voltage of operational amplifier U1 is: 2.5 / R5*(R5+R3). At this point, the circuit reaches a stable state. From the perspective of the ADC module in the MCU, there will be a 2.5V reference voltage and a sampled battery voltage input. The MCU will use the ADC module to calculate the actual battery voltage.

[0053] In practical applications, power supplies Vs+ and VCC+ can be powered by the motherboard of the microcontroller unit (MCU). That is, the battery power supply on the MCU motherboard is used to generate power supplies Vs+ and VCC+ through a step-down network. Alternatively, power supplies Vs+ and VCC+ can also be powered by other methods, such as independent batteries or external power sources.

[0054] In one possible implementation, in order to reduce the impact of power supply VCC+ fluctuations on the operation of the voltage regulator chip, the resistance value of the sixth resistor R6 in the circuit can be set to a large value. For example, the resistance value of R6 is not less than 2000KΩ, such as 2000KΩ or 3000KΩ.

[0055] In one possible implementation, the value of resistor R4 is related to the operating current of the voltage regulator chip D2, ensuring that the operating current of the voltage regulator chip D2 is within the normal range.

[0056] In one possible implementation, the values ​​of resistors R3 and R5 can range from 1KΩ to 1MΩ.

[0057] Combination Figure 2 As shown, taking the voltage V1=14.4V of battery VBATT+, the voltage V2=5V of power supply Vs+, and the voltage V3=3.3V of power supply VCC+ as an example, a possible resistance value setting scheme for resistors R1-R6 is given.

[0058] R1=240KΩ, R2=47KΩ, R3=120KΩ, R4=680Ω, R5=220KΩ, R6=2000KΩ.

[0059] With the above resistor values, the output voltage of operational amplifier U1 is: 2.5 / R5*(R5+R3)=3.86V.

[0060] The operating current of voltage regulator chip D2 is: (3.3—2.5) / R6 + (3.86—2.5) / R4. Since the resistance of R6 is very large, the operating current of voltage regulator chip D2 is approximately (3.86—2.5) / R4 = 2mA. When the VCC+ voltage fluctuates, for every 1V change in VCC+, the operating current of voltage regulator chip D2 changes by 1 / R6 = 0.5uA, which has a negligible impact on the operating current of voltage regulator chip D2. Therefore, voltage regulator chip D2 can continuously output a stable reference voltage.

[0061] In one possible implementation, the resistor used in the battery voltage detection circuit of this application can be a high-precision low-temperature drift resistor, with a resistance change of ±0.1% over a wide temperature range of -40°C to 125°C.

[0062] In one possible implementation, the reference temperature drift of the voltage regulator chip D2 can be no more than 10 ppm / °C, and the error over a wide temperature range of -40°C to 125°C can be no more than 0.2%.

[0063] against Figure 2 The circuit structure shown, with the resistance values ​​of each resistor as illustrated in the above embodiments, was simulated and tested in this application. The simulation waveforms are referenced. Figure 3 . Figure 3 It describes how the reference voltage changes with the VCC+ voltage.

[0064] Depend on Figure 3 It is known that a voltage change of ±2V in the power supply VCC+ results in a change of no more than 0.1% in the reference voltage. Therefore, the battery voltage detection circuit provided in this application can reduce the impact of power supply VCC+ changes on the voltage regulator chip D2, enabling the voltage regulator chip D2 to continuously output a stable reference voltage to the ADC module, thereby improving the accuracy of the ADC module's battery voltage detection results.

[0065] In some embodiments of this application, an on-board power amplifier is also provided, which includes a power module and a battery voltage detection circuit as described in any of the foregoing embodiments. The battery voltage detection circuit is used to detect the voltage of the power module.

[0066] In this embodiment, by applying the battery voltage detection circuit described in the previous embodiment to the vehicle power amplifier, the voltage of the power module in the vehicle power amplifier can be accurately detected, which facilitates the management of the power module and reduces the impact of power voltage fluctuations on the output efficiency, THD (total harmonic distortion) and thermal stability of the vehicle power amplifier, thereby improving the working stability of the vehicle power amplifier.

[0067] In some embodiments of this application, an in-vehicle audio-visual system is also provided, which includes the in-vehicle power amplifier described in the above embodiments.

[0068] The vehicle imaging system of this embodiment, by employing an on-board power amplifier that includes the battery voltage detection circuit of the aforementioned embodiment, can improve the working stability of the entire imaging system and reduce the impact of on-board power supply voltage fluctuations on the entire system.

[0069] In addition, the battery voltage detection circuit described in the foregoing embodiments of this application can also be applied to other scenarios where battery voltage needs to be detected, which will not be elaborated here.

[0070] In the description of the embodiments of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of the embodiments of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0071] In the embodiments of this application, unless otherwise explicitly specified and limited, terms such as "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0072] In the embodiments of this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0073] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A battery voltage detection circuit, characterized in that, include: Operational amplifiers, voltage regulator chips, and analog-to-digital converter (ADC) modules; The operational amplifier provides a constant current source to the voltage regulator chip, so that the voltage regulator chip outputs a reference voltage to the ADC module under the action of the constant current source; The ADC module samples the battery voltage and obtains the actual value of the battery voltage based on the sampled battery voltage and the reference voltage.

2. The battery voltage detection circuit according to claim 1, characterized in that, The output terminal of the operational amplifier is grounded in sequence through the fourth resistor R4, the cathode and anode of the voltage regulator chip, and the reference terminal of the voltage regulator chip is connected to the cathode and the positive input terminal of the operational amplifier, respectively.

3. The battery voltage detection circuit according to claim 2, characterized in that, The cathode of the voltage regulator chip is connected to the ADC module and is used to output the reference voltage to the ADC module.

4. The battery voltage detection circuit according to claim 2, characterized in that, The positive input terminal of the operational amplifier is connected to the power supply VCC+ through the sixth resistor R6, and the negative input terminal of the operational amplifier is grounded through the fifth resistor R5.

5. The battery voltage detection circuit according to claim 4, characterized in that, The output of the operational amplifier is connected to the negative input terminal via a third resistor R3.

6. The battery voltage detection circuit according to claim 1, characterized in that, Also includes: A resistor voltage divider network, comprising a first resistor R1 and a second resistor R2 connected in series, with one end of the resistor voltage divider network connected to the battery and the other end grounded. The ADC module samples the battery voltage through the resistor divider network.

7. The battery voltage detection circuit according to claim 1, characterized in that, The ADC module is built into the microcontroller unit (MCU), and the output terminal of the voltage regulator chip is connected to the MCU to transmit the reference voltage to the ADC module through the MCU.

8. The battery voltage detection circuit according to any one of claims 1-7, characterized in that, The voltage regulator chip is a three-terminal adjustable voltage reference chip AZ431.

9. A vehicle-mounted power amplifier, characterized in that, The device includes a power module and a battery voltage detection circuit as described in any one of claims 1-8, wherein the battery voltage detection circuit is used to detect the voltage of the power module.

10. A vehicle-mounted audio-visual system, characterized in that, Includes the vehicle power amplifier as described in claim 9.

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