Voltage zero-crossing detection circuit and electronic device

Abstract

The application is suitable for the technical field of voltage zero-crossing detection, and provides a voltage zero-crossing detection circuit and electronic equipment. The circuit comprises a voltage division module, an offset module, a capacitor module, a DC bias module and an operational amplifier module. The voltage division module is electrically connected with the offset module. The capacitor module is electrically connected with the offset module, the DC bias module and the operational amplifier module respectively. The voltage division module divides the input square wave voltage and outputs a divided voltage. The offset module performs potential offset processing on the divided voltage and outputs a first voltage smaller than the divided voltage. The capacitor module isolates the DC component in the first voltage and outputs an AC component. The DC bias module provides a DC bias for a first node, and the first node is a common terminal of the capacitor module and the DC bias module. The operational amplifier module compares the AC component superimposed with the DC bias with a reference voltage and outputs a zero-crossing detection comparison signal. The voltage zero-crossing detection circuit provided by the application can effectively reduce the cost of the operational amplifier module.

Description

Technical Field

[0001] This application belongs to the field of voltage zero-crossing detection technology, and particularly relates to a voltage zero-crossing detection circuit and electronic equipment. Background Technology

[0002] In systems such as switching power supplies, motor drives, and industrial wide-voltage electrical control, it is often necessary to detect the zero-crossing voltage of a wide-range square wave input signal with alternating positive and negative values ​​as the basis for the system control logic. Existing conventional zero-crossing detection schemes directly connect the high-voltage input signal to the input terminal of the operational amplifier module. To withstand wide-range high-voltage signals, the operational amplifier module needs to use high-voltage-resistant components, which significantly increases the cost of the operational amplifier module. Summary of the Invention

[0003] This application provides a voltage zero-crossing detection circuit and electronic device, which can solve the problem that existing conventional zero-crossing detection schemes significantly increase the cost of operational amplifier modules.

[0004] In a first aspect, embodiments of this application provide a voltage zero-crossing detection circuit, including a voltage divider module, an offset module, a capacitor module, a DC bias module, and an operational amplifier module. The voltage divider module is electrically connected to the offset module, and the capacitor module is electrically connected to the offset module, the DC bias module, and the operational amplifier module, respectively. The voltage divider module is used to divide the input square wave voltage and output the divided voltage; the offset module is used to perform potential offset processing on the divided voltage and output a first voltage less than the divided voltage; the capacitor module is used to isolate the DC component in the first voltage and output the AC component; the DC bias module is used to provide a DC bias for the first node, the first node being the common terminal of the capacitor module and the DC bias module; the operational amplifier module is used to compare the AC component after superimposing the DC bias with the reference voltage and output a zero-crossing detection comparison signal.

[0005] In one possible implementation of the first aspect, the voltage divider module includes a first resistor and a second resistor, a first end of the first resistor is used to receive the input square wave voltage, a second end of the first resistor is electrically connected to the first end of the second resistor and the offset module, and a second end of the second resistor is grounded.

[0006] In one possible implementation of the first aspect, the offset module includes a third resistor and a first constant current source, the first end of the third resistor is electrically connected to the voltage divider module, the second end of the third resistor is electrically connected to the first end of the first constant current source and the capacitor module, and the second end of the first constant current source is grounded.

[0007] In one possible implementation of the first aspect, the first constant current source is composed of a fourth resistor, a first transistor, and a second transistor. The first end of the fourth resistor is used to receive the supply voltage, and the second end of the fourth resistor is electrically connected to the base of the first transistor, the base of the second transistor, and the collector of the second transistor, respectively. The collector of the first transistor is electrically connected to the second end of the third resistor, and the emitters of the first transistor and the second transistor are both grounded.

[0008] In one possible implementation of the first aspect, the capacitor module includes a coupling capacitor, a first end of which is electrically connected to the offset module, and a second end of which is electrically connected to the DC bias module and the operational amplifier module, respectively.

[0009] In one possible implementation of the first aspect, the DC bias module includes a fifth resistor and a second constant current source. The first end of the fifth resistor is electrically connected to the first end of the second constant current source, the capacitor module, and the operational amplifier module, respectively. The second end of the fifth resistor is grounded, and the second end of the second constant current source is used to receive the supply voltage.

[0010] In one possible implementation of the first aspect, the second constant current source is composed of a sixth resistor, a third transistor, and a fourth transistor. The first terminal of the sixth resistor and the collector of the third transistor are both used to receive the supply voltage. The second terminal of the sixth resistor is electrically connected to the base of the third transistor, the base of the fourth transistor, and the collector of the fourth transistor, respectively. The emitter of the third transistor is electrically connected to the first terminal of the fifth resistor, and the emitter of the fourth transistor is grounded.

[0011] In one possible implementation of the first aspect, the operational amplifier module includes a first operational amplifier, the first input terminal of the first operational amplifier being electrically connected to the capacitor module and the DC bias module respectively, the second input terminal of the first operational amplifier being used to receive the reference voltage, and the output terminal of the first operational amplifier being used to output the zero-crossing detection comparison signal.

[0012] In one possible implementation of the first aspect, the voltage zero-crossing detection circuit further includes a first diode and a second diode, the anodes of the first diode and the second diode are both grounded, the cathode of the first diode is electrically connected to the voltage divider module and the offset module respectively, and the cathode of the second diode is electrically connected to the capacitor module, the DC bias module and the operational amplifier module respectively.

[0013] Secondly, embodiments of this application provide an electronic device including the voltage zero-crossing detection circuit described in any one of the first aspects.

[0014] The beneficial effects of the embodiments of this application compared with the prior art are: This application provides a voltage zero-crossing detection circuit, including a voltage divider module, an offset module, a capacitor module, a DC bias module, and an operational amplifier module. First, the voltage divider module attenuates a wide-range input square wave voltage, converting the high-voltage square wave into a low-voltage divided voltage. Then, the offset module pulls down the divided voltage to obtain a first voltage with a lower amplitude. Subsequently, the capacitor module's DC-blocking and AC-passing characteristics isolate the DC component within the first voltage, transmitting only the AC component corresponding to the voltage jump to the first node. Simultaneously, the DC bias module provides a stable and adjustable DC bias to the first node, allowing the AC component to be superimposed with a fixed DC potential and input to the operational amplifier module for comparison with a reference voltage, outputting a zero-crossing detection comparison signal. Therefore, the voltage zero-crossing detection circuit provided in this application achieves electrical isolation between the high-voltage input signal and the operational amplifier module through a combination of voltage divider attenuation and capacitor isolation. High-voltage stress does not directly act on the input terminal of the operational amplifier module. Therefore, the operational amplifier module does not need to use high-voltage rated components; only conventional low-voltage operational amplifiers are needed to complete the zero-crossing comparison, effectively reducing the cost of the operational amplifier module.

[0015] It is understandable that the beneficial effects of the second aspect mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 It is an existing conventional zero-crossing detection solution; Figure 2 This is a block diagram of a voltage zero-crossing detection circuit provided in one embodiment of this application; Figure 3 This is a circuit connection diagram of a voltage zero-crossing detection circuit provided in an embodiment of this application; Figure 4 This is a circuit connection diagram of a voltage zero-crossing detection circuit provided in another embodiment of this application.

[0018] In the diagram: 101, voltage divider module; 102, offset module; 103, capacitor module; 104, DC bias module; 105, operational amplifier module. Detailed Implementation

[0019] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0020] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0021] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0022] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [the described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [the described condition or event] is detected," or "in response to detection of [the described condition or event]."

[0023] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0024] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0025] In systems such as switching power supplies, motor drives, and industrial wide-voltage electrical control, it is often necessary to detect the zero-crossing voltage of a wide-range square wave input signal with alternating positive and negative values, using this as a basis for the system's control logic. For example... Figure 1 As shown, existing conventional zero-crossing detection schemes directly connect the high-voltage input signal to the input terminal of the operational amplifier module (op-amp). In order to withstand wide-range high-voltage signals, the operational amplifier needs to have a sufficient voltage withstand value, which leads to a significant increase in the cost of the operational amplifier.

[0026] To address the aforementioned issues, this application provides a voltage zero-crossing detection circuit, comprising a voltage divider module, an offset module, a capacitor module, a DC bias module, and an operational amplifier module. First, the voltage divider module attenuates a wide-range input square wave voltage, converting the high-voltage square wave into a low-voltage divided voltage. Then, the offset module pulls down the divided voltage to obtain a first voltage with a lower amplitude. Subsequently, the capacitor module's DC-blocking and AC-passing characteristics isolate the DC component within the first voltage, transmitting only the AC component corresponding to the voltage jump to the first node. Simultaneously, the DC bias module provides a stable and adjustable DC bias to the first node, allowing the AC component to be superimposed with a fixed DC potential and input to the operational amplifier module for comparison with a reference voltage, outputting a zero-crossing detection comparison signal. Therefore, the voltage zero-crossing detection circuit provided in this application achieves electrical isolation between the high-voltage input signal and the operational amplifier module through a combination of voltage divider attenuation and capacitor isolation. High-voltage stress does not directly act on the input terminal of the operational amplifier module; therefore, the operational amplifier module does not need to use high-voltage rated components, and only conventional low-voltage operational amplifiers can be used to complete the zero-crossing comparison, effectively reducing the cost of the operational amplifier module.

[0027] To illustrate the technical solution described in this application, specific embodiments are provided below.

[0028] Figure 2 This diagram illustrates the application principle of a voltage zero-crossing detection circuit according to an embodiment of this application in a BUCK. See also... Figure 2 As shown, the voltage zero-crossing detection circuit includes a voltage divider module 101, an offset module 102, a capacitor module 103, a DC bias module 104, and an operational amplifier module 105. The voltage divider module 101 is electrically connected to the offset module 102, and the capacitor module 103 is electrically connected to the offset module 102, the DC bias module 104, and the operational amplifier module 105, respectively.

[0029] Specifically, the voltage zero-crossing detection circuit first uses a voltage divider module 101 to attenuate the wide-range input square wave voltage VDD, converting the high-voltage square wave into a low-voltage divided voltage. Then, the offset module 102 pulls down the divided voltage to obtain a first voltage with a lower amplitude. Subsequently, the capacitor module 103 isolates the DC component in the first voltage by blocking DC and passing AC, transmitting only the AC component corresponding to the voltage jump to the first node. At the same time, the DC bias module 104 provides a stable and adjustable DC bias for the first node, so that the AC component is superimposed with a fixed DC potential and input to the operational amplifier module 105 for comparison with the reference voltage Vref, outputting a zero-crossing detection comparison signal. Thus, the voltage zero-crossing detection circuit provided in this application achieves electrical isolation between the high-voltage input signal and the operational amplifier module 105 through a combination of voltage division attenuation and capacitor isolation. The high-voltage stress will not directly act on the input terminal of the operational amplifier module 105. Therefore, the operational amplifier module 105 does not need to use high-voltage rated components; only conventional low-voltage operational amplifiers are needed to complete the zero-crossing comparison, effectively reducing the cost of the operational amplifier module 105.

[0030] It should be noted that since the capacitor module 103 can only transmit the AC component of voltage transitions and cannot provide a fixed DC potential, without the DC bias module 104, the potential of the first node connected to the capacitor module 103 and the operational amplifier module 105 will be in a floating state. The AC waveform will easily exceed the common-mode voltage range of the operational amplifier module 105, making it impossible to stably complete the voltage comparison. This application adds a DC bias module 104 to introduce a controllable DC bias at the first node, which is equivalent to superimposing an adjustable static DC potential on the coupled AC waveform. This static potential directly determines the effective sampling level at the input of the operational amplifier module 105. Only the parameters of the DC bias module 104 need to be adjusted to shift the judgment reference on the operational amplifier module 105 side without modifying the front-end circuit, thereby enabling flexible setting of the voltage reference point for the operational amplifier module 105 to perform zero-crossing judgment.

[0031] The following is combined Figure 3 and Figure 4 The working principle of the voltage zero-crossing detection circuit is explained in detail.

[0032] In one embodiment of this application, such as Figure 3 and Figure 4 As shown, the voltage divider module 101 includes a first resistor R1 and a second resistor R2. The first end of the first resistor R1 is used to receive the input square wave voltage VDD. The second end of the first resistor R1 is electrically connected to the first end of the second resistor R2 and the offset module 102, respectively. The second end of the second resistor R2 is grounded.

[0033] Specifically, the first resistor R1 and the second resistor R2 are connected in series to form a voltage divider network. The first resistor R1 receives the input square wave voltage VDD with a wide amplitude range, and the second resistor R2 is grounded to form a voltage divider circuit. The two work together to attenuate the amplitude of the high-voltage input square wave, converting the large-amplitude input high-voltage signal into a lower-amplitude low-voltage divided voltage, reducing the voltage stress on the subsequent modules, avoiding the high-voltage signal from directly impacting the subsequent circuit devices, and providing a basis for the use of low-voltage components in the back end to realize signal processing.

[0034] In one embodiment of this application, such as Figure 3 As shown, the offset module 102 includes a third resistor R3 and a first constant current source I1. The first end of the third resistor R3 is electrically connected to the voltage divider module 101, and the second end of the third resistor R3 is electrically connected to the first end of the first constant current source I1 and the capacitor module 103, respectively. The second end of the first constant current source I1 is grounded.

[0035] Specifically, the third resistor R3 and the first constant current source I1 work together to form a potential offset branch. A constant current flows from the third resistor R3 through the first constant current source I1 to ground, creating a stable voltage drop across the third resistor R3. This ensures that the first voltage output from the third resistor R3 is always lower than the voltage divider output from the voltage divider module 101. This establishes a stable static DC voltage difference across the capacitor module 103, ensuring that AC voltage change signals can be transmitted completely and without distortion to the back end of the capacitor module 103. At the same time, the third resistor R3 can buffer the instantaneous voltage spikes generated by the rapid transition of the input square wave, weakening the impact of the inrush current on the capacitor module 103 and improving the stability of the circuit operation.

[0036] In one embodiment of this application, such as Figure 4 As shown, the first constant current source I1 is composed of a fourth resistor R4, a first transistor Q1, and a second transistor Q2. The first end of the fourth resistor R4 is used to receive the supply voltage VDDA. The second end of the fourth resistor R4 is electrically connected to the base of the first transistor Q1, the base of the second transistor Q2, and the collector of the second transistor Q2, respectively. The collector of the first transistor Q1 is electrically connected to the second end of the third resistor R3. The emitters of the first transistor Q1 and the second transistor Q2 are both grounded.

[0037] Specifically, the fourth resistor R4 receives the supply voltage VDDA and, together with the second transistor Q2, establishes a stable reference bias branch, providing a constant base drive voltage for the bases of the first transistor Q1 and the second transistor Q2. The collector and base of the second transistor Q2 are shorted to form a diode connection, used to generate a fixed reference current. This forms a current mirror structure with the first transistor Q1, enabling the output of the first transistor Q1 to match the constant pull-down current of the second transistor Q2. The first transistor Q1, acting as the mirror output transistor, continuously draws a constant current from the second terminal of the third resistor R3 to ground, forming a stable potential offset with the third resistor R3. These three components work together to achieve a constant current output, thus forming the first constant current source I1 required by the offset module 102.

[0038] It should be noted that the first transistor Q1 and the second transistor Q2 use the same size to ensure the matching degree of the mirrored current; it should be understood that the two are only preferred devices for realizing the current mirroring function. In actual circuit design, devices with the same current replication function, such as MOSFETs, can also be used for equivalent replacement. This application does not make a unique limitation on the type of current mirroring device.

[0039] For example, in practical designs, equivalent replacements can be made using active devices such as NMOS transistors or PMOS transistors that have the same current replication function.

[0040] In one embodiment of this application, such as Figure 3 and Figure 4 As shown, the capacitor module 103 includes a coupling capacitor C1. The first end of the coupling capacitor C1 is electrically connected to the offset module 102, and the second end of the coupling capacitor C1 is electrically connected to the DC bias module 104 and the operational amplifier module 105, respectively.

[0041] Specifically, by utilizing the inherent characteristic of capacitors to block DC and pass AC, the stable DC component in the first voltage is blocked, and only the AC voltage change generated by the input square wave transition is transmitted to the input terminal of the operational amplifier module 105. This isolates the direct connection between the front-end high-voltage DC signal and the back-end operational amplifier module 105, significantly reducing the voltage stress on the operational amplifier module 105. This allows the operational amplifier module 105 to use low-voltage devices, while still fully transmitting the voltage transition signal used for zero-crossing detection, ensuring the normal operation of the zero-crossing detection function.

[0042] In one embodiment of this application, such as Figure 3 As shown, the DC bias module 104 includes a fifth resistor R5 and a second constant current source I2. The first end of the fifth resistor R5 is electrically connected to the first end of the second constant current source I2, the capacitor module 103 and the operational amplifier module 105, respectively. The second end of the fifth resistor R5 is grounded. The second end of the second constant current source I2 is used to receive the supply voltage VDDA.

[0043] Specifically, the second constant current source I2 is connected to the supply voltage VDDA, continuously outputting a constant current to the first node shared by the coupling capacitor C1 and the operational amplifier module 105. One end of the fifth resistor R5 is connected to the first node, and the other end is grounded. The constant current flowing through the fifth resistor R5 forms a stable and controllable DC voltage drop, generating a fixed DC bias potential at the first node. This DC bias potential can be changed by adjusting the output current of the second constant current source I2 or the resistance value of the fifth resistor R5, providing a flexibly adjustable comparison reference point for the operational amplifier module 105. At the same time, the fifth resistor R5 acts as a current limiting buffer, suppressing the spikes caused by sudden changes in node voltage, stabilizing the common-mode level of the operational amplifier input, and ensuring that the operational amplifier module 105 can normally compare the AC component transmitted by the coupling capacitor C1, achieving accurate zero-crossing detection.

[0044] In one embodiment of this application, such as Figure 4 As shown, the second constant current source I2 is composed of a sixth resistor R6, a third transistor Q3, and a fourth transistor Q4. The first end of the sixth resistor R6 and the collector of the third transistor Q3 are used to receive the supply voltage VDDA. The second end of the sixth resistor R6 is electrically connected to the base of the third transistor Q3, the base of the fourth transistor Q4, and the collector of the fourth transistor Q4, respectively. The emitter of the third transistor Q3 is electrically connected to the first end of the fifth resistor R5, and the emitter of the fourth transistor Q4 is grounded.

[0045] Specifically, the sixth resistor R6 receives the supply voltage VDDA and, in conjunction with the fourth transistor Q4 (whose collector and base are shorted), generates a stable reference base voltage, providing a consistent base drive potential for the third transistor Q3 and the fourth transistor Q4. The fourth transistor Q4 uses a diode connection to construct a reference current branch, forming a current mirror structure with the third transistor Q3. Their dimensions are matched to achieve accurate current replication. The third transistor Q3, acting as the mirror output transistor, outputs a constant current from the supply voltage VDDA terminal to the first terminal of the fifth resistor R5, thus providing a stable and controllable constant current for the DC bias module 104. These three components work together to form the second constant current source I2 required by the circuit. Furthermore, the output current can be changed by adjusting the device parameters, thereby flexibly adjusting the DC comparison reference potential on the operational amplifier module 105 side.

[0046] It should be noted that the third transistor Q3 and the fourth transistor Q4 use the same size to ensure the matching degree of the mirror current; it should be understood that the two are only preferred devices for realizing the current mirror function. In actual circuit design, devices with the same current replication function, such as MOSFETs, can also be used for equivalent replacement. This application does not make a unique limitation on the type of current mirror device.

[0047] For example, in practical designs, equivalent replacements can be made using active devices such as NMOS transistors or PMOS transistors that have the same current replication function.

[0048] In one embodiment of this application, such as Figure 3 and Figure 4 As shown, the operational amplifier module 105 includes a first operational amplifier EA. The first input terminal of the first operational amplifier EA is electrically connected to the capacitor module 103 and the DC bias module 104, respectively. The second input terminal of the first operational amplifier EA is used to receive the reference voltage Vref. The output terminal of the first operational amplifier EA is used to output a zero-crossing detection comparison signal.

[0049] Specifically, the first input terminal (negative input terminal) of the first operational amplifier EA receives the sampling voltage V- after the superposition of the AC component transmitted by the coupling capacitor C1 and the fixed DC bias provided by the DC bias module 104. The second input terminal (positive input terminal) of the first operational amplifier EA is connected to a constant reference voltage Vref. The first operational amplifier EA performs a difference comparison on the two input levels in real time. When the sampling voltage jumps across the zero point with the input square wave, the output level of the first operational amplifier EA flips synchronously, and finally outputs a zero-crossing detection comparison signal that can characterize the zero-crossing moment of the input square wave, providing an accurate zero-crossing judgment basis for the subsequent control circuit.

[0050] In one embodiment of this application, such as Figure 3 and Figure 4 As shown, the voltage zero-crossing detection circuit also includes a first diode D1 and a second diode D2. The anodes of the first diode D1 and the second diode D2 are both grounded. The cathode of the first diode D1 is electrically connected to the voltage divider module 101 and the offset module 102, respectively. The cathode of the second diode D2 is electrically connected to the capacitor module 103, the DC bias module 104 and the operational amplifier module 105, respectively.

[0051] Specifically, when the input square wave voltage VDD has a negative voltage and the corresponding node potential is lower than the ground potential, the two diodes conduct in the forward direction, clamping the negative voltage of the corresponding node (the cathode node of the first diode D1 and the cathode node of the second diode D2) to about -0.7V. This prevents the large negative voltage from directly impacting the subsequent resistors, constant current source and operational amplifier input devices, and prevents the components from being damaged by the negative voltage breakdown. This effectively widens the range of negative voltage input that the circuit can adapt to and improves the overall reliability of the circuit under wide voltage alternating signal conditions.

[0052] It should be noted that, as Figure 4As shown, the zero-crossing voltage detection circuit also includes a filter capacitor C2 connected in parallel with the first diode D1. This capacitor absorbs high-frequency voltage spikes and transient interference glitches generated by the square wave transition at the output node of the voltage divider module 101, smooths the node voltage waveform, and reduces the risk of false triggering caused by high-frequency noise being transmitted to the operational amplifier input through the offset module 102 and coupling capacitor C1. At the same time, it works with the first diode D1 to stabilize the clamping node potential, reduce voltage fluctuations caused by the diode's conduction and turn-off during negative voltage transitions, and further improve the stability and accuracy of the zero-crossing detection results.

[0053] In addition, the capacitance value of C2 can be flexibly selected according to the circuit's operating frequency. A small capacitance value is used for high-frequency operation, while a large capacitance value is used for low-frequency operation with large fluctuations. At the same time, C2 is an optional optimized structure and can be omitted in applications with extremely low noise without affecting the circuit's basic zero-crossing detection function.

[0054] Combination Figure 3 and Figure 4 As shown, the working principle of the voltage zero-crossing detection circuit is illustrated with an example. When an alternating square wave signal with a low level of -V1 and a high level of +V2 is input to VDD, the signal first undergoes amplitude attenuation through a voltage divider network composed of R1 and R2, generating a low-voltage square wave signal at the second terminal of R1. The high level VH of this low-voltage square wave is V2 / (R1+R2)*R2, and the low level VL is equal to the larger value between -V1 / (R1+R2)*R2 and -0.7V. Subsequently, R3 and I1 work together to pull down the potential, so that the voltage at the second terminal of R3 is always slightly lower than the voltage at the first terminal of R3. A stable voltage difference is formed across the coupling capacitor C1. The voltage change VT of the first node is equal to the static potential difference between the second terminal of R3 and the first node, completely following the voltage fluctuation at the second terminal of R3. When the voltage at the second terminal of R3 jumps from the high level VH to the low level VL, the voltage at the first node jumps down synchronously. Based on the working principle of this circuit, by simply adjusting the resistance values ​​of R1 and R2, the constant current output of Q3, and the parameters of R5, it can adapt to a wide range of input VDD signals. EA continuously compares the real-time sampled voltage of the first node of its negative input terminal with the reference voltage Vref, and outputs the level comparison result from the output terminal of EA, thereby realizing real-time zero-crossing detection of the input square wave signal.

[0055] This application also discloses an electronic device including the voltage zero-crossing detection circuit of any of the above embodiments. The electronic device using the voltage zero-crossing detection circuit provided in this application can achieve stable and accurate zero-crossing detection of a wide-range alternating square wave signal without using a high-voltage operational amplifier or adding external isolation devices. The circuit hardware cost is lower, the chip integration is higher, and the zero-crossing judgment benchmark can be flexibly adjusted to adapt to different power levels. At the same time, the noise reduction structure of the two-stage diode negative voltage clamping combined with the filter capacitor significantly reduces the probability of damage to the entire device and improves the long-term operational stability of the equipment.

[0056] Electronic devices can be power and industrial control products that require AC / AC voltage sampling, such as AC-DC switching power supplies, fast charging adapters, brushless DC motor drivers, photovoltaic inverter controllers, industrial frequency conversion control boards, and vehicle-mounted DC-DC power supply devices.

[0057] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0058] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A voltage zero-crossing detection circuit, characterized in that, It includes a voltage divider module, an offset module, a capacitor module, a DC bias module, and an operational amplifier module. The voltage divider module is electrically connected to the offset module, and the capacitor module is electrically connected to the offset module, the DC bias module, and the operational amplifier module, respectively. The voltage divider module is used to divide the input square wave voltage and output the divided voltage; the offset module is used to perform potential offset processing on the divided voltage and output a first voltage less than the divided voltage; the capacitor module is used to isolate the DC component in the first voltage and output the AC component; the DC bias module is used to provide a DC bias for the first node, the first node being the common terminal of the capacitor module and the DC bias module; the operational amplifier module is used to compare the AC component after superimposing the DC bias with the reference voltage and output a zero-crossing detection comparison signal. The capacitor module includes a coupling capacitor. The first end of the coupling capacitor is electrically connected to the offset module, and the second end of the coupling capacitor is electrically connected to the DC bias module and the operational amplifier module, respectively.

2. The voltage zero-crossing detection circuit according to claim 1, characterized in that, The voltage divider module includes a first resistor and a second resistor. The first end of the first resistor is used to receive the input square wave voltage. The second end of the first resistor is electrically connected to the first end of the second resistor and the offset module, respectively. The second end of the second resistor is grounded.

3. The voltage zero-crossing detection circuit according to claim 1, characterized in that, The offset module includes a third resistor and a first constant current source. The first end of the third resistor is electrically connected to the voltage divider module, and the second end of the third resistor is electrically connected to the first end of the first constant current source and the capacitor module, respectively. The second end of the first constant current source is grounded.

4. The voltage zero-crossing detection circuit according to claim 3, characterized in that, The first constant current source is composed of a fourth resistor, a first transistor, and a second transistor. The first end of the fourth resistor is used to receive the supply voltage. The second end of the fourth resistor is electrically connected to the base of the first transistor, the base of the second transistor, and the collector of the second transistor, respectively. The collector of the first transistor is electrically connected to the second end of the third resistor. The emitters of the first transistor and the second transistor are both grounded.

5. The voltage zero-crossing detection circuit according to claim 1, characterized in that, The DC bias module includes a fifth resistor and a second constant current source. The first end of the fifth resistor is electrically connected to the first end of the second constant current source, the capacitor module, and the operational amplifier module, respectively. The second end of the fifth resistor is grounded, and the second end of the second constant current source is used to receive the supply voltage.

6. The voltage zero-crossing detection circuit according to claim 5, characterized in that, The second constant current source is composed of a sixth resistor, a third transistor, and a fourth transistor. The first end of the sixth resistor and the collector of the third transistor are both used to receive the supply voltage. The second end of the sixth resistor is electrically connected to the base of the third transistor, the base of the fourth transistor, and the collector of the fourth transistor, respectively. The emitter of the third transistor is electrically connected to the first end of the fifth resistor, and the emitter of the fourth transistor is grounded.

7. The voltage zero-crossing detection circuit according to claim 1, characterized in that, The operational amplifier module includes a first operational amplifier, the first input terminal of which is electrically connected to the capacitor module and the DC bias module, the second input terminal of which is used to receive the reference voltage, and the output terminal of which is used to output the zero-crossing detection comparison signal.

8. The voltage zero-crossing detection circuit according to any one of claims 1-7, characterized in that, The voltage zero-crossing detection circuit further includes a first diode and a second diode. The anodes of the first diode and the second diode are both grounded. The cathode of the first diode is electrically connected to the voltage divider module and the offset module, respectively. The cathode of the second diode is electrically connected to the capacitor module, the DC bias module and the operational amplifier module, respectively.

9. An electronic device, characterized in that, Includes the voltage zero-crossing detection circuit as described in any one of claims 1-8.

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