Circuit structure suitable for analog optical coupling and electronic device

Abstract

The application provides a circuit structure suitable for analog optical coupling and an electronic device. The circuit structure comprises an input driving module, an optoelectronic coupling chip and an output matching module. The output matching module comprises a load resistor, which is electrically connected with an output-side photosensitive receiving unit and an output-side power supply. The resistance value determination of the load resistor comprises the following steps: obtaining a preset parameter range of the current transfer ratio of the optoelectronic coupling chip, extracting a preset minimum value of the current transfer ratio according to the preset parameter range, calculating a minimum allowable working current of the output-side photosensitive receiving unit of the optoelectronic coupling chip according to the preset minimum value, calculating a minimum allowable resistance value of the load resistor based on the minimum allowable working current, determining a nominal resistance value of the load resistor according to the minimum allowable resistance value, and the nominal resistance value of the load resistor is greater than or equal to the minimum allowable resistance value. The circuit structure can avoid the situation of waveform distortion or communication failure, and effectively improve the stability of signal transmission.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, and in particular to a circuit structure and electronic device suitable for analog optocouplers. Background Technology

[0002] In the analog signal transmission scenarios of electronic devices, electrical isolation is a core requirement to ensure equipment safety and avoid signal interference. Optical couplers, as the core device for realizing the isolation and conversion of electrical-optical-electrical signals, are widely used in various electronic devices such as industrial control, precision instruments, and new energy equipment.

[0003] Among the various performance parameters of an optocoupler, the Current Transfer Ratio (CTR) is the key parameter determining its signal transmission efficiency. It is defined as the percentage of the output collector current to the input forward current. The CTR value directly reflects the optocoupler's signal transmission and driving capabilities. However, the CTR value of an optocoupler is affected by various factors such as temperature drift and batch-to-batch material differences, which can easily lead to signal transmission abnormalities in practical applications. Summary of the Invention

[0004] In view of this, this application provides a circuit structure and electronic device suitable for analog optocouplers to solve the problem of unstable CTR values ​​caused by temperature drift and material batch differences in the prior art, avoid low signal amplitude, waveform distortion or communication failure, improve the stability of signal transmission and reduce the failure rate.

[0005] In a first aspect, this application provides a circuit structure suitable for analog optocouplers, the circuit structure comprising: An input driving module is electrically connected to the input-side light-emitting unit of the optocoupler chip and is used to provide the input-side light-emitting unit with a positive operating current within the rated operating range. An optocoupler chip, which integrates an input-side light-emitting unit and an output-side photosensitive receiving unit, is used to achieve electrical isolation and signal conversion between the input and output sides; and The output matching module includes a load resistor, which is electrically connected to the output-side photosensitive receiving unit and the output-side power supply, and forms an isolated signal output circuit with the output-side photosensitive receiving unit. The output terminal of the isolated signal output circuit is used to output the isolated target electrical signal. The step of determining the resistance value of the load resistor includes obtaining a preset parameter range of the current transfer ratio of the optocoupler chip, and extracting a preset minimum value of the current transfer ratio based on the preset parameter range. Based on the preset minimum value, the minimum allowable operating current of the photosensitive receiving unit on the output side of the optocoupler chip is calculated, and the minimum allowable resistance value of the load resistor is calculated based on the minimum allowable operating current. The nominal resistance of the load resistor is determined based on the minimum permissible resistance value, wherein the nominal resistance of the load resistor is greater than or equal to the minimum permissible resistance value.

[0006] Optionally, calculating the minimum allowable operating current of the photosensitive receiving unit on the output side of the optocoupler chip based on the preset minimum value includes: Obtain the positive operating current of the input driving module; Calculate the product of the preset minimum value and the forward operating current, and assign the product to the minimum allowable operating current.

[0007] Optionally, the calculation of the minimum allowable resistance value of the load resistor based on the minimum allowable operating current includes: Obtain the voltage value of the output-side power supply; Calculate the quotient of the voltage value and the minimum allowable operating current, and assign the quotient to the minimum allowable resistance value of the load resistor.

[0008] Optionally, the input driving module includes an input DC power supply, a series current-limiting resistor group, and a pulse signal source. The series current-limiting resistor group is composed of a first current-limiting resistor and a second current-limiting resistor connected in series. One end of the first current-limiting resistor is connected to the positive terminal of the input DC power supply, and the other end of the first current-limiting resistor is connected to the anode of the input-side light-emitting unit. The cathode of the input-side light-emitting unit is connected to one end of the second current-limiting resistor, and the other end of the second current-limiting resistor is connected to the positive terminal of the pulse signal source. The negative terminals of the pulse signal source and the input DC power supply are both grounded.

[0009] Optionally, obtaining the positive operating current of the input driving module includes: Obtain the voltage value of the input DC power supply and the forward saturation conduction voltage drop of the input side light-emitting unit, and calculate the difference between the voltage value and the forward saturation conduction voltage drop; Obtain the resistance values ​​of the first current-limiting resistor and the second current-limiting resistor, and calculate the sum of the values ​​of the first current-limiting resistor and the second current-limiting resistor; Calculate the quotient of the difference result and the sum result, and assign the quotient result to the positive working current; Verify and ensure that the forward operating current is within the allowable operating range of the forward current of the optocoupler chip.

[0010] Optionally, determining the nominal resistance value of the load resistor includes: The resistance value of the load resistor is less than the maximum allowable resistance value, wherein the maximum allowable resistance value is an upper limit of the resistance value determined in combination with the signal transmission rate and waveform falling edge characteristic requirements of the target circuit. The maximum allowable resistance value is used to ensure that the output waveform is not distorted and that the switching characteristics meet the preset requirements.

[0011] Optionally, the isolation signal output circuit is a common collector output topology, the output-side photosensitive receiving unit is a phototransistor, the collector of the phototransistor is connected to the positive terminal of the output-side power supply, the emitter is connected to one end of the load resistor, the other end of the load resistor is grounded, and the emitter of the phototransistor serves as the output terminal of the isolation signal output circuit, used to output an isolation electrical signal that is opposite to the input signal.

[0012] Optionally, the isolation signal output circuit is a common emitter output topology, the output-side photosensitive receiving unit is a phototransistor, the collector of the phototransistor is connected to one end of the load resistor, the other end of the load resistor is connected to the positive terminal of the output-side power supply, the emitter of the phototransistor is grounded, and the collector of the phototransistor serves as the output terminal of the isolation signal output circuit, used to output an isolation electrical signal in the same direction as the input signal.

[0013] Optionally, the output matching module further includes a push-pull output structure, the input of which is connected to the output of the isolation signal output circuit to improve the signal transmission rate.

[0014] Secondly, this application provides an electronic device, which includes the circuit structure provided in the embodiments of this application.

[0015] The circuit structure for analog optocouplers provided in this application can avoid fluctuations in the current transfer ratio caused by temperature drift or batch differences in materials, thereby avoiding problems such as insufficient signal amplitude, waveform distortion, and communication failure. Through precise module design and load resistor value calculation logic, the circuit structure achieves highly stable and high-fidelity transmission of the isolated signal from the analog optocoupler, reserving sufficient redundancy for the circuit design. Even under harsh operating conditions or batch differences in incoming materials, it ensures that the output signal amplitude meets the requirements and is distortion-free, improving the adaptability and reliability of the analog optocoupler circuit structure. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, 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 the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of a circuit structure suitable for analog optocouplers provided in an embodiment of this application; Figure 2 This is a circuit schematic diagram of a circuit structure suitable for analog optocouplers provided in the embodiments of this application; Figure 3 This is a schematic diagram of the steps for determining the load resistance provided in an embodiment of this application; Figure 4 This is a signal waveform test diagram of the circuit structure provided in the comparative embodiments of this application; Figure 5 This is a signal waveform test diagram of a circuit structure provided in another comparative embodiment of this application; Figure 6 This is a signal waveform test diagram of a circuit structure suitable for analog optocouplers provided in the embodiments of this application; Figure 7 This is a signal waveform test diagram of a circuit structure suitable for analog optocouplers provided in another embodiment of this application; Figure 8 This is a signal waveform test diagram of a circuit structure suitable for analog optocouplers provided in another embodiment of this application.

[0018] Explanation of reference numerals in the attached figures: 10 - Circuit structure suitable for analog optocouplers; 11 - Input driver module; 12 - Optocoupler chip; 13 - Output matching module. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0021] In this document, references to "embodiment" or "implementation" mean that a particular feature, structure, or characteristic described in connection with an embodiment or implementation may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0022] Before introducing the technical solution of this application, let's go over the technical issues in related technologies in detail.

[0023] In analog signal transmission scenarios of electronic devices, electrical isolation is a core requirement for ensuring equipment safety and preventing signal interference. Optical couplers, as the core device for achieving electro-optical-electrical signal isolation conversion, are widely used in various electronic devices such as industrial control, precision instruments, and new energy equipment. The working principle of an optocoupler is as follows: the light-emitting diode on the input side emits light after receiving a driving current, and the photosensitive device on the output side receives the optical signal and converts it into an electrical signal. Using the optical signal as an intermediate medium, the electrical connection between the input and output circuits is completely severed, effectively isolating high-voltage and low-voltage circuits, blocking high-voltage crosstalk and electromagnetic interference, and ensuring the safety of internal components and the stability of signal transmission in electronic equipment.

[0024] Among the various performance parameters of an optocoupler, the Current Transfer Ratio (CTR) is the key parameter that determines its signal transmission efficiency. It is defined as the percentage of the output collector current to the input forward current. The CTR value directly reflects the optocoupler's signal transmission capability and driving capability. The higher the CTR value, the larger the output collector current under the same input forward current, the stronger the optocoupler's driving capability, and the higher the signal transmission efficiency.

[0025] However, the CTR value of an optocoupler is not fixed and fluctuates due to various factors, which can easily lead to signal transmission abnormalities in practical applications. Specific influencing factors and their manifestations are as follows: First, temperature drift affects the CTR value. Changes in ambient temperature can reduce the luminous efficiency of the LED, causing CTR drift. When the temperature rises, the LED's luminous intensity weakens, reducing the energy of the light signal received by the photosensitive device, thus lowering the CTR value. While the CTR value may slightly increase when the temperature decreases, the overall fluctuation range is large, making it impossible to guarantee signal transmission stability. Second, batch differences in materials affect the CTR value. Due to subtle differences in manufacturing processes and device materials, different production batches of optocouplers exhibit significant inconsistencies in their CTR values. Even for optocouplers of the same model and grade, the actual CTR values ​​of different batches may deviate considerably.

[0026] The combination of these two factors leads to two fatal problems frequently occurring in optocouplers during practical applications: first, the signal amplitude is too low, causing signal transmission performance failure and inability to drive subsequent circuits; second, the output waveform is severely distorted, causing the communication function of electronic devices to fail, seriously affecting the normal operation of the entire electronic device. Please refer to [link / reference]. Figure 4 and Figure 5 , Figure 4 This is a signal waveform test diagram of the circuit structure provided in the comparative embodiments of this application. Figure 5 This is a signal waveform test diagram of a circuit structure provided in another comparative embodiment of this application. Related waveform anomalies can be visually observed experimentally, fully demonstrating the adverse effects of CTR value fluctuations on optocoupler signal transmission. For example... Figure 4 As shown in the figure, the horizontal axis represents time in milliseconds, the left side of the vertical axis represents voltage in volts, and the right side represents current in milliamperes. The input-side waveform, i.e., the high-voltage square wave, can drive the input-side LED unit normally, and the operation is stable. However, the high-level amplitude of the output-side waveform, i.e., the low-voltage square wave, is significantly insufficient. Figure 5 As shown in the figure, the horizontal axis is the time axis in milliseconds, the left vertical axis is the voltage axis in volts, and the right vertical axis is the current axis in milliamperes. The input-side drive signal is a standard square wave, and the operating current of the input-side LED unit is synchronously stable, indicating that the input drive module is working normally. However, the output-side isolation signal exhibits obvious falling edge tailing and waveform distortion characteristics. The voltage decays slowly when transitioning from high to low level, rather than a steep step change, indicating deterioration in the switching response characteristics.

[0027] To address the issues caused by CTR value fluctuations, existing solutions include: (1) determining the actual operating temperature, voltage, current, and other parameters based on the application scenario of the electronic device, then consulting the normalized CTR curve in the optocoupler specification sheet to select a CTR level that meets the actual requirements. This method requires matching and selecting for different application scenarios one by one, which is cumbersome and cannot cope with CTR fluctuations caused by dynamic temperature changes and material batch differences, resulting in poor adaptability; (2) reserving a long-term aging margin. Considering that the optocoupler CTR value will decay over time, typically by about 20%, an additional 25% derating is applied during circuit design to ensure the long-term aging of the optocoupler. After the period of operation, the performance stability of the optocoupler will be sacrificed. The setting of the derating ratio lacks precise basis, which may lead to waste of resources or still cannot avoid signal abnormalities in the later stage. (3) Optimize the optocoupler manufacturing process. In the silicone dispensing process of optocoupler production, silicone and color paste that do not affect the light transmittance are used. The dispensing amount is adjusted by the dispensing machine to control the silicone height, thereby adjusting the CTR value. At the same time, it is ensured that the withstand voltage, switching time and other parameters of the optocoupler are not affected. This method can only optimize the CTR consistency in the optocoupler production process. It cannot solve the CTR fluctuation caused by temperature drift in actual application. Moreover, the manufacturing process is complicated, which leads to increased production cost and low efficiency of optocoupler.

[0028] Therefore, this application provides a circuit structure 10 suitable for analog optocouplers. Please refer to... Figure 1 , Figure 2 and Figure 3 , Figure 1 This is a schematic diagram of a circuit structure suitable for analog optocouplers provided in an embodiment of this application. Figure 2 This is a circuit schematic diagram of a circuit structure suitable for analog optocouplers provided in the embodiments of this application. Figure 3 This is a schematic diagram illustrating the steps for determining the load resistance provided in an embodiment of this application. This application provides a circuit structure 10 suitable for analog optocouplers, which includes an input driving module 11, an optocoupler chip 12, and an output matching module 13. The input driving module 11 is electrically connected to the input-side light-emitting unit of the optocoupler chip 12, providing a positive operating current within its rated operating range to the input-side light-emitting unit. The optocoupler chip 12 integrates an input-side light-emitting unit and an output-side photosensitive receiving unit, enabling electrical isolation and signal conversion between the input and output sides. The output matching module 13 includes a load resistor R3, which is electrically connected to the output-side photosensitive receiving unit and the output-side power supply, forming an isolated signal output circuit with the output-side photosensitive receiving unit. The output terminal of the isolated signal output circuit is used to output the isolated target electrical signal.

[0029] Optionally, the circuit structure 10 for analog optocouplers provided in this embodiment can be applied to analog signal isolation sampling transmission in industrial scenarios such as new energy vehicles, photovoltaic inverters, and charging piles. It is used to solve the problem of insufficient output signal amplitude and unstable transmission caused by the fluctuation of the current transmission ratio of the optocoupler chip 12 in the prior art, and to achieve high-fidelity and high-stability isolation transmission of analog signals.

[0030] Optionally, the circuit structure 10 suitable for analog optocouplers includes an input driving module 11, an optocoupler chip 12, and an output matching module 13. The input driving module 11, the optocoupler chip 12, and the output matching module 13 are electrically connected to each other to realize the reception of input signals, electrical isolation conversion, and stable output of output signals, thus forming a complete isolated signal transmission link.

[0031] Specifically, the input driving module 11 is electrically connected to the input-side light-emitting unit of the optocoupler chip 12, and is used to provide the input-side light-emitting unit with a positive working current within the rated working range, so as to ensure that the input-side light-emitting unit can emit light stably, thereby ensuring the signal conversion accuracy of the optocoupler chip 12 and avoiding signal transmission distortion caused by abnormal driving current.

[0032] Optionally, the input-side light-emitting unit can be understood as a light-emitting device integrated inside the optocoupler chip 12, which is usually a light-emitting diode. Its light-emitting intensity is positively correlated with the forward operating current and there is a rated operating current range. Exceeding this range will cause the light-emitting diode to age faster, the light-emitting intensity to be unstable, or even damage the device.

[0033] Optionally, the forward operating current can be understood as the current required for the input-side light-emitting unit to operate normally. Its value must be within the rated operating range specified in the optocoupler chip 12 device manual. This range is determined by the characteristics of the device itself and can be obtained from the official device manual of the optocoupler chip 12.

[0034] Optionally, the input driving module 11 may include an input DC power supply, a series current-limiting resistor group, and a pulse signal source. The series current-limiting resistor group is used to adjust the magnitude of the forward operating current to ensure that it is within the rated range. The pulse signal source is used to input the electrical signal to be transmitted. By controlling the on / off state of the forward operating current, the electrical signal is converted into an optical signal.

[0035] It should be noted that the specific circuit structure of the input driving module 11 is not limited to the above form. As long as it can achieve the core function of providing the input-side light-emitting unit with a positive working current within the rated working range, it can be used as the input driving module 11 of the present invention. For example, a constant current source driving circuit can be used to replace the series current limiting resistor group to achieve a stable positive working current output.

[0036] Optionally, the optocoupler chip 12 integrates an input-side light-emitting unit and an output-side photosensitive receiving unit to achieve electrical isolation and signal conversion between the input and output sides. Electrical isolation can be understood as electrically separating the input-side circuit from the output-side circuit, preventing current flow between them, thereby achieving high-voltage isolation and anti-interference effects, and ensuring the safe and stable operation of the output-side circuit. Signal conversion can be understood as converting the input-side electrical signal into the output-side electrical signal, ensuring that the waveform, amplitude, and other characteristics of the signal are not significantly distorted, achieving high-fidelity signal transmission. Internally, the optocoupler chip 12 converts the input-side electrical signal into an optical signal through optical signal coupling, and then converts the optical signal into an output-side electrical signal, thereby cutting off the electrical connection between the input and output sides and preventing high-voltage signals from interfering with or damaging the low-voltage side circuit. Specifically, the input-side light-emitting unit emits light under the positive operating current provided by the input driving module 11, and the output-side photosensitive receiving unit receives the optical signal and generates a corresponding electrical signal, completing the signal conversion process.

[0037] Optionally, the optocoupler chip 12 is an analog optocoupler, whose output-side photosensitive receiving unit can be a phototransistor, and its input-side light-emitting unit can be a light-emitting diode. The two work together to achieve isolated transmission of analog signals. The nominal current transfer ratio (CTR) of the optocoupler chip 12 has a preset parameter range, which can be obtained from the chip's datasheet, providing a basic parameter for the subsequent calculation of the resistance value of the load resistor R3.

[0038] Optionally, the output-side power supply provides the operating voltage for the isolated signal output circuit. Its voltage value can be set according to the actual application scenario and the parameter requirements of the optocoupler chip 12. It is typically a DC power supply with a stable voltage value to ensure stable amplitude of the output signal. The output terminal of the isolated signal output circuit transmits the isolated target electrical signal to the subsequent circuit. The subsequent circuit can further process or utilize the target electrical signal according to actual needs, realizing the isolated sampling and transmission function of analog signals.

[0039] Optionally, the output matching module 13 includes a load resistor R3, which is electrically connected to the output-side photosensitive receiving unit and the output-side power supply, and forms an isolated signal output circuit with the output-side photosensitive receiving unit. The output terminal of the isolated signal output circuit is used to output the isolated target electrical signal. The output matching module 13, through proper matching of the load resistor R3, ensures that the electrical signal converted by the output-side photosensitive receiving unit can be output completely and without distortion, avoiding problems such as insufficient signal amplitude and waveform distortion caused by load mismatch.

[0040] Optionally, the operation of the circuit structure 10 suitable for analog optocouplers includes: the input driving module 11 provides a positive operating current within the rated operating range to the input-side light-emitting unit of the optocoupler chip 12, and the input-side light-emitting unit emits light under the action of the current, converting the input electrical signal into an optical signal; the output-side photosensitive receiving unit of the optocoupler chip 12 receives the optical signal and generates a corresponding electrical signal, completing signal conversion and electrical isolation; the load resistor R3 in the output matching module 13, together with the output-side photosensitive receiving unit and the output-side power supply, forms an isolated signal output circuit, stably outputting the converted electrical signal to form an isolated target electrical signal, which is then transmitted to the subsequent circuit.

[0041] In this embodiment, the resistance value of the load resistor R3 needs to be determined through specific steps to ensure that it can adapt to the working characteristics of the optocoupler chip 12 and ensure stable transmission of the output signal. Specifically, the determination steps are as follows.

[0042] Step S101: Obtain the preset parameter range of the current transfer ratio of the optocoupler chip, and extract the preset minimum value of the current transfer ratio based on the preset parameter range.

[0043] Specifically, the current transfer ratio is used to characterize the ratio between the forward operating current of the input-side light-emitting unit and the operating current of the output-side photosensitive receiving unit. The larger the value, the higher the optical signal conversion efficiency.

[0044] Optionally, the preset parameter range of the current transfer ratio can be understood as the CTR value range specified in the datasheet of the optocoupler chip 12. This range is determined by the manufacturing process and inherent characteristics of the device. Different models of optocoupler chips 12 have different preset CTR parameter ranges, which can be directly obtained from the corresponding datasheet. For example, the preset CTR parameter range of the optocoupler chip 12 is 50% to 600%.

[0045] Optionally, the preset minimum value of the current transfer ratio can be understood as the minimum value in the preset parameter range of CTR. The core purpose of extracting this preset minimum value is to ensure that the circuit can still achieve stable signal transmission under extreme operating conditions, such as temperature rise, device aging, or material batch differences that cause CTR to drop, and to avoid insufficient output signal amplitude due to excessively low CTR.

[0046] Step S102: Based on the preset minimum value, calculate the minimum allowable operating current of the photosensitive receiving unit on the output side of the optocoupler chip, and calculate the minimum allowable resistance value of the load resistor based on the minimum allowable operating current.

[0047] Optionally, the minimum allowable operating current can be understood as the minimum operating current required for the output-side photosensitive receiving unit to stably output the target electrical signal, and its value is determined by the forward operating current on the input side and the preset minimum value of CTR.

[0048] Specifically, the minimum allowable operating current can be expressed by formula Ic. min =I f ×CTR min The calculation yields, where I f The CTR provides the positive operating current for the input drive module 11. min This is the preset minimum value of the current transfer ratio extracted in step S101. The core logic of this formula is that the operating current of the output-side photosensitive receiving unit is proportional to the forward operating current of the input-side light-emitting unit, with a proportionality coefficient of CTR. When CTR reaches its minimum value, the corresponding output current is the minimum allowable operating current, which is the minimum threshold to ensure the amplitude of the output signal.

[0049] Optionally, the minimum allowable resistance value R of the load resistor R3 is... Lmin This can be understood as the load resistor R3 ensuring that the output-side photosensitive receiver unit reaches the minimum allowable operating current, and its value is determined by the voltage V of the output-side power supply. cc With minimum allowable operating current Ic min A joint decision can be made using formula R. Lmin =V cc / Ic min Calculated.

[0050] Among them, V cc The voltage value of the power supply to the output side can be set according to the actual circuit design requirements, for example, set to 5V. Lmin This is the minimum allowable resistance value of the load resistor R3, which is the lower limit of the value of the load resistor R3.

[0051] In one specific embodiment of this application, when the forward operating current I... f =19mA, CTR min When the current is 50%, the calculated minimum allowable operating current Ic min =19mA×50%=9.5mA, meaning that the output-side photosensitive receiving unit needs to provide at least 9.5mA of operating current to ensure that the amplitude of the output signal meets the standard and to avoid signal transmission failure.

[0052] Furthermore, when the output side power supply voltage V cc =5V, minimum allowable operating current Ic min When the current is 9.5mA, the calculated minimum allowable resistance value of the load resistor R3 is R. Lmin=5V / 9.5mA≈500Ω, meaning the resistance of the load resistor R3 must not be less than 500Ω, otherwise the output signal amplitude will be insufficient.

[0053] Step S103: Determine the nominal resistance value of the load resistor based on the minimum allowable resistance value, wherein the nominal resistance value of the load resistor is greater than or equal to the minimum allowable resistance value.

[0054] Optionally, the nominal resistance value can be understood as a resistance value that conforms to the nominal specification system of the resistor industry and is used for actual circuit soldering applications. Its value needs to be selected within a range not less than the minimum allowable resistance value according to the actual working requirements of the circuit, so as to ensure that the working current of the photosensitive receiving unit on the output side is not lower than the minimum allowable working current and to ensure the stable transmission of the output signal.

[0055] Optionally, the nominal resistance value of the load resistor R3 must conform to the general nominal specifications of the resistor industry. For example, when R... Lmin When the resistance is 500Ω, resistance values ​​that conform to industry specifications, such as 510Ω and 550Ω, can be selected as the nominal resistance value of the load resistor R3. These resistance values ​​are all greater than the minimum allowable resistance value and can meet the working requirements of the circuit.

[0056] Optionally, when determining the nominal resistance value of the load resistor R3, the signal transmission rate and waveform falling edge characteristics of the target circuit can be considered, and the value should not be less than R3. Lmin The nominal resistance value should be adjusted within the specified range to ensure that the output signal is distortion-free and the transmission rate meets the standard. For example, in an optional embodiment of this application, 550Ω can be selected as the nominal resistance value of the load resistor R3. This resistance value is greater than the minimum allowable resistance value of 500Ω, and at the same time, it can optimize the falling edge characteristics of the output waveform and improve the stability of signal transmission.

[0057] In this embodiment, the nominal resistance value of the load resistor R3 is selected through the above determination steps and is not less than the minimum allowable resistance value. This ensures that the operating current of the output-side photosensitive receiving unit is not lower than the minimum allowable operating current, avoiding problems such as insufficient output signal amplitude and unstable transmission caused by CTR fluctuations, thereby achieving high-fidelity and high-stability isolated transmission of analog signals.

[0058] Please see Figure 6 , Figure 6 This is a signal waveform test diagram of a circuit structure suitable for analog optocouplers provided in an embodiment of this application. In one possible embodiment of this application, when the positive operating current I provided by the input driving module 11... f =19mA, CTR min =50%, Output power supply voltage V cc When the voltage is 5V, R is calculated. Lmin=500Ω, combined with industry specifications and waveform characteristics, the nominal resistance of load resistor R3 is selected as 550Ω. This nominal resistance is greater than the minimum allowable resistance, ensuring that the operating current of the output-side photosensitive receiver unit is not less than 9.5mA, the output signal amplitude meets the standard, the waveform is distortion-free, and stable isolated signal transmission is achieved. Figure 8 As shown, the horizontal axis represents time (milliseconds), the left vertical axis represents voltage (volts), and the right vertical axis represents current (milliamperes). The input-side drive signal is a standard square wave with a high-level amplitude close to 5.0V. The operating current of the input-side LED unit is synchronously stable, indicating that the input drive module is working normally. The high-level amplitude of the output-side isolation signal is close to 5.0V, with steep signal edges, no insufficient amplitude or falling edge tail distortion, and excellent switching response characteristics, fully preserving the waveform characteristics and level amplitude of the input signal.

[0059] Optionally, depending on the signal phase requirements of the target circuit, two output topologies can be selected, both of which can achieve stable signal transmission. When the circuit structure 10 suitable for analog optocouplers adopts a common-collector output topology, the output signal is in the opposite direction to the input signal. Experiments show that the input is a 0~5V square wave, the output is a 0~4.8V square wave, the input LED current is a 0~19mA square wave, the output waveform is undistorted, the amplitude is stable, and there are no communication abnormalities. When the circuit structure 10 suitable for analog optocouplers adopts a common-emitter output topology, the output signal is in the same direction as the input signal. Experiments show that the input is a 0~5V square wave, the output is a 0.2~5V square wave, the input LED current is a 0~19mA square wave, the output waveform is undistorted, the amplitude is stable, and there are no communication abnormalities.

[0060] In this embodiment, the minimum CTR value guaranteed by the optocoupler manufacturer is used in the calculation to avoid the impact of CTR fluctuations caused by temperature drift and batch differences in materials. The forward operating current on the input side and the minimum allowable current at the output collector are accurately calculated, thereby determining the appropriate resistance value of the load resistor R3 to ensure stable signal transmission. The circuit structure 10 suitable for analog optocouplers outputs high and low level amplitudes that meet design requirements, with no significant attenuation, and can reliably drive subsequent circuits. Furthermore, the output waveform is either in phase or out of phase with the input waveform, without tailing or amplitude fluctuations, accurately reproducing the input signal and solving the communication failure problems caused by low signal amplitude and waveform distortion in existing technologies.

[0061] Please refer to it again. Figure 4 , Figure 4 This is a signal waveform test diagram of the circuit structure provided in the comparative embodiment of this application. In the comparative embodiment of this application, the load resistor R3 is set to 100Ω, which is much smaller than the minimum allowable resistance value calculated based on the minimum CTR value. This causes the output high level to be pulled low, failing to meet the signal recognition requirements of the subsequent circuit, ultimately leading to communication failure. Figure 4As shown, the horizontal axis represents time, the left vertical axis represents voltage, and the right vertical axis represents current. The input-side drive signal is a standard square wave with a high level close to 5.0V. The operating current of the input-side LED unit is synchronously stable, indicating that the input drive module is working normally. However, the high-level amplitude of the output-side isolation signal is only about 2.5V, far below the expected standard level of 5.0V, indicating a severely insufficient signal amplitude.

[0062] In summary, the circuit structure 10 for analog optocouplers provided in this embodiment can avoid fluctuations in the current transfer ratio caused by temperature drift or batch differences in materials, thereby avoiding problems such as insufficient signal amplitude, waveform distortion, and communication failure. The circuit structure 10 for analog optocouplers achieves high stability and high-fidelity transmission of the isolated signal through precise module design and load resistor R3 value calculation logic. By extracting the preset minimum value of CTR and participating in the load resistor R3 value calculation, sufficient redundancy is reserved for the circuit design. Even under harsh operating conditions or batch differences in incoming materials, it ensures that the output signal amplitude meets the standard and is distortion-free, improving the adaptability and reliability of the circuit structure 10 for analog optocouplers. Furthermore, the logic for determining the load resistor R3 value in the circuit structure 10 for analog optocouplers is highly operable, requiring no complex selection process or optimization of the optocoupler manufacturing process. Accurate selection of the load resistor R3 can be achieved simply through parameter extraction and calculation, improving circuit design efficiency and facilitating actual production and application.

[0063] Optionally, calculating the minimum allowable operating current of the photosensitive receiving unit on the output side of the optocoupler chip based on the preset minimum value includes the following steps: S1021. Obtain the positive operating current of the input driving module.

[0064] S1022. Calculate the product of the preset minimum value and the forward operating current, and assign the product to the minimum allowable operating current.

[0065] Optionally, via formula Ic min =I f ×CTR min The minimum allowable operating current of the photosensitive receiving unit on the output side of the optocoupler chip 12 is calculated, where Ic min For the minimum allowable operating current, I f For the positive operating current, CTR min This is the preset minimum value for the current transfer ratio.

[0066] Optionally, Ic minThis can be understood as the minimum allowable operating current of the photosensitive receiving unit on the output side of the optocoupler chip 12, usually in milliamperes. It is the minimum current threshold to ensure that the output signal amplitude meets the standard and to avoid signal transmission failure. If the actual operating current of the photosensitive receiving unit on the output side is lower than this value, the output signal amplitude will be insufficient and it will be unable to drive the subsequent circuit to work normally.

[0067] Optionally, I f This can be understood as the positive operating current provided by the input driving module 11 to the light-emitting unit on the input side of the optocoupler chip 12. The unit is usually milliampere. This current needs to be within the rated operating range specified in the optocoupler chip 12 device manual. Its value can be calculated from the circuit parameters of the input driving module 11 or obtained from the design parameters of the input driving module 11.

[0068] Optionally, CTR min This can be understood as the preset minimum value of the current transfer ratio of the optocoupler chip 12, that is, the minimum value extracted from the preset parameter range of the CTR specified in the optocoupler chip 12 device datasheet. It provides a safety net for signal conversion capability under extreme operating conditions, ensuring that even if the CTR is reduced to the minimum due to temperature rise, device aging, or batch differences, the output side can still obtain sufficient operating current.

[0069] Optionally, the current transfer ratio (CTR) of the optocoupler chip 12 can be understood as the ratio of the operating current of the output-side photosensitive receiving unit to the forward operating current of the input-side light-emitting unit. When CTR takes a preset minimum value... min When this occurs, the corresponding output-side operating current is the minimum allowable operating current Ic. min At this time, Ic min =I f ×CTR min It can accurately calculate the minimum operating current required on the output side under extreme operating conditions.

[0070] In one possible embodiment, the preset CTR parameter range of the optocoupler chip 12 is 50%~600%, and the extracted CTR... min =50%, the forward operating current If=19mA provided by the input drive module 11, substitute the above parameters into the formula Ic min =I f ×CTR min The calculation process is as follows: Ic min =19mA × 50% = 9.5mA. This calculation result shows that the minimum allowable operating current of the output-side photosensitive receiving unit is 9.5mA. That is, the output-side photosensitive receiving unit needs to provide at least 9.5mA of operating current to ensure that the output signal amplitude meets the standard and to avoid signal transmission failure.

[0071] Optionally, calculating the minimum allowable resistance value of the load resistor based on the minimum allowable operating current includes the following steps: S1031. Obtain the voltage value of the power supply on the output side.

[0072] Optionally, the output-side power supply provides a stable operating voltage for the isolated signal output circuit. Typically, a DC power supply is selected, and its voltage value needs to be kept stable to avoid deviations in the calculation of the minimum allowable resistance value of the load resistor R3 due to voltage fluctuations, thereby affecting the stability of the output signal.

[0073] Optionally, the voltage value of the output-side power supply is determined based on the actual design requirements of the circuit, the operating parameters of the optocoupler chip 12, and the voltage requirements of the subsequent circuits. Furthermore, the voltage value of the output-side power supply can be flexibly set according to the actual application scenario. For example, in high-voltage isolation scenarios such as new energy vehicles and photovoltaic inverters, a 5V DC power supply can be selected, which can both meet the operating requirements of the optocoupler chip 12 and ensure that the amplitude of the output signal meets the requirements.

[0074] S1032. Calculate the quotient of the voltage value and the minimum allowable operating current, and assign the quotient to the minimum allowable resistance value of the load resistor.

[0075] Optionally, through formula R L =V cc / Ic min The minimum allowable resistance value of the load resistor R3 is calculated, where R L For the minimum allowable resistance, V cc The voltage value of the power supply for the output side.

[0076] Optionally, R L This can be understood as the minimum allowable resistance value of the load resistor R3, usually in ohms, which is the lower limit of the value of the load resistor R3.

[0077] Optionally, V cc It can be understood as the voltage value of the power supply on the output side, usually in volts.

[0078] Optionally, the load resistor R3, the output-side photosensitive receiver, and the output-side power supply form an isolated signal output circuit. In this circuit, the voltage of the output-side power supply is entirely applied to the load resistor R3 and the output-side photosensitive receiver. Since the forward voltage drop of the output-side photosensitive receiver is much smaller than V... cc Therefore, V can be approximated as V cc The entire resistance is applied to the load resistor R3, thus deriving the minimum allowable resistance value R of the load resistor R3. L =V cc / Ic minThis formula can accurately calculate the minimum load resistance R3 required to ensure the minimum allowable operating current on the output side.

[0079] Furthermore, substituting the above parameters into formula R L =V cc / Ic min The calculation process is as follows: R L =5V / 9.5mA=5V / (9.5×10 - ³A) ≈ 526Ω, and considering the nominal resistance specifications in engineering design, a value of 500Ω can be taken. This calculation result shows that the minimum allowable resistance of the load resistor R3 is approximately 500Ω, that is, the nominal resistance of the load resistor R3 must be greater than or equal to 500Ω to ensure that the output signal amplitude meets the standard and the transmission is stable.

[0080] In this embodiment, the circuit structure 10 suitable for analog optocouplers quantifies the calculation standards for the minimum allowable operating current and the minimum allowable resistance through calculation formulas, which further enhances the ability to avoid CTR fluctuations, ensures the stability of the output signal under harsh operating conditions or differences in incoming material batches, and further improves the reliability and versatility of the entire circuit structure 10 suitable for analog optocouplers.

[0081] Optionally, the input driving module 11 includes an input DC power supply, a series current-limiting resistor group, and a pulse signal source. The series current-limiting resistor group is composed of a first current-limiting resistor R1 and a second current-limiting resistor R2 connected in series. One end of the first current-limiting resistor R1 is connected to the positive terminal of the input DC power supply, and the other end of the first current-limiting resistor R1 is connected to the anode of the input-side light-emitting unit. The cathode of the input-side light-emitting unit is connected to one end of the second current-limiting resistor R2, and the other end of the second current-limiting resistor R2 is connected to the positive terminal of the pulse signal source. The negative terminals of the pulse signal source and the input DC power supply are both grounded.

[0082] Optionally, the series current-limiting resistor group is used to adjust the magnitude of the forward operating current to ensure that it is within the rated operating range of the optocoupler chip 12. The input DC power supply provides operating power for the entire input drive module 11. The pulse signal source is used to input the electrical signal to be transmitted. By controlling the on / off state of the forward operating current, the electrical signal is converted into an optical signal, providing the input basis for the subsequent signal isolation and conversion of the optocoupler chip 12.

[0083] Optionally, the series current-limiting resistor group is composed of a first current-limiting resistor R1 and a second current-limiting resistor R2 connected in series. It is used to adjust the forward operating current of the input-side light-emitting unit to avoid damage to the light-emitting unit due to excessive current, while ensuring that the forward operating current is within the rated operating range specified in the optocoupler chip 12 device manual.

[0084] Optionally, one end of the first current-limiting resistor R1 is connected to the positive terminal of the input DC power supply to receive the electrical energy output from the input DC power supply and simultaneously serve as a preliminary current limiter to prevent the input current from directly impacting the input-side light-emitting unit. The other end of the first current-limiting resistor R1 is connected to the anode of the input-side light-emitting unit, transmitting the current after preliminary current limiting to the anode of the input-side light-emitting unit, providing an entry point for the light-emitting unit to conduct current. The cathode of the input-side light-emitting unit is connected to one end of the second current-limiting resistor R2. After the input-side light-emitting unit is turned on, current flows in from the anode and out from the cathode, entering the second current-limiting resistor R2. The second current-limiting resistor R2 further adjusts the current magnitude to ensure that the current flowing into the pulse signal source is stable. The other end of the second current-limiting resistor R2 is connected to the positive terminal of the pulse signal source, transmitting the current after two stages of current limiting to the pulse signal source, completing the current transmission of the input drive circuit.

[0085] It should be noted that the resistance values ​​of the first current-limiting resistor R1 and the second current-limiting resistor R2 can be calculated and determined based on the voltage value of the input DC power supply, the forward saturation conduction voltage drop of the input-side light-emitting unit, and the required forward operating current. The total resistance value after the two resistors are connected in series must meet the calculation requirements of the forward operating current. Optionally, the resistance values ​​of the first current-limiting resistor R1 and the second current-limiting resistor R2 can both be 100Ω, and the total resistance value after series connection is 200Ω, which is suitable for the parameter requirements of the conventional input DC power supply and the optocoupler chip 12.

[0086] Optionally, the positive terminal of the input DC power supply is connected to one end of the first current-limiting resistor R1, outputting a stable DC voltage to provide operating power for the series current-limiting resistor group and the input-side light-emitting unit. The negative terminal of the input DC power supply is grounded, forming a complete current loop, while fixing the potential of the input DC power supply to avoid output voltage fluctuations due to potential fluctuations, thereby affecting the stability of the forward operating current.

[0087] In this embodiment, the input driving module 11 achieves dual current limiting of the forward operating current by setting a series current-limiting resistor group. This effectively prevents excessive current from damaging the input-side light-emitting unit, while precisely stabilizing the forward operating current required by the optocoupler chip 12, ensuring that the current transfer ratio remains within a stable range. The pulse signal source can provide a suitable pulse driving signal to meet the requirements of analog signal isolation transmission, and the reasonable grounding design can avoid electromagnetic interference, ensure circuit operation safety, and improve the reliability and adaptability of the circuit structure 10 suitable for analog optocouplers.

[0088] Optionally, obtaining the positive operating current of the input driving module includes the following steps: S102a. Obtain the voltage value of the input DC power supply and the forward saturation conduction voltage drop of the input side light-emitting unit, and calculate the difference between the voltage value and the forward saturation conduction voltage drop.

[0089] Optionally, the voltage value of the input DC power supply can be understood as the output voltage of the input DC power supply, which is also the total power supply voltage of the entire input drive circuit.

[0090] Optionally, the forward saturation conduction voltage drop can be understood as the voltage difference between the anode and cathode of the input-side light-emitting unit when it is in a saturated conduction state.

[0091] S102b: Obtain the resistance value of the first current-limiting resistor and the resistance value of the second current-limiting resistor, and calculate the sum of the first current-limiting resistor and the second current-limiting resistor.

[0092] S102c. Calculate the quotient of the difference result and the sum result, and assign the quotient result to the positive working current.

[0093] Optionally, through formula I f =(V d -V f The forward operating current is calculated using I / (R1+R2). The calculated forward operating current is verified and ensured to be within the allowable forward current operating range of the optocoupler chip 12. f Forward operating current, V d V represents the voltage value of the input DC power supply. f R1 is the forward saturation conduction voltage drop of the input-side light-emitting unit, R2 is the resistance value of the first current-limiting resistor R1, and R2 is the resistance value of the second current-limiting resistor R2.

[0094] Optionally, I f This is the positive operating current, measured in milliamperes (mA), which is the operating current provided by the input drive module 11 to the input-side light-emitting unit. V d This refers to the voltage value of the input DC power supply, measured in volts (V). f R1 is the forward saturation voltage drop of the input-side light-emitting unit, in volts. R2 is the resistance value of the first current-limiting resistor, in ohms. R3 is the resistance value of the second current-limiting resistor, in ohms.

[0095] In one possible embodiment, the parameter V is known. d =5V, V f =0.7V, R1=100Ω, R2=100Ω, substitute into formula I f =(V d -V f The calculation process is as follows: ) / (R1+R2)f =(5V-0.7V) / (100Ω+100Ω) =4.3V / 200Ω=0.0215A=21.5mA. This calculation shows that the forward operating current I provided by the current input drive module 11 is... f =21.5mA.

[0096] S102d, verify and ensure that the forward operating current is within the allowable operating range of the forward current of the optocoupler chip.

[0097] Optionally, if I f If the current is within the allowable operating range for forward current, it indicates that the current forward operating current is compliant and can be directly used as a parameter for subsequent calculations. If I f If the current exceeds the allowable operating range for forward current, the resistance value of the series current-limiting resistor group needs to be adjusted, and I needs to be recalculated. f Until it falls within the compliance range.

[0098] In this embodiment, the circuit structure 10 suitable for analog optocouplers ensures that the calculated parameters closely match the actual operating conditions by acquiring the input DC power supply voltage and the forward saturation conduction voltage drop of the input-side light-emitting unit, thus avoiding current calculation errors caused by parameter deviations. Precise current control is achieved through accurate quantification of the forward operating current, combined with a series current-limiting resistor group. Furthermore, the additional verification step ensures that the calculated forward operating current is within the allowable range of the optocoupler's forward current, preventing damage to the light-emitting unit from excessive current and a decrease in CTR from excessive current, further enhancing the ability to avoid CTR fluctuations.

[0099] Optionally, determining the nominal resistance value of the load resistor includes: The resistance value of the load resistor R3 is less than the maximum allowable resistance value. The maximum allowable resistance value is the upper limit of the resistance value determined in combination with the signal transmission rate and waveform falling edge characteristic requirements of the target circuit. The maximum allowable resistance value is used to ensure that the output waveform is not distorted and that the switching characteristics meet the preset requirements.

[0100] Optionally, the maximum allowable resistance value can be understood as the upper limit of the load resistor R3, which is determined in combination with the signal transmission rate and waveform falling edge characteristics requirements of the target circuit, and is the maximum load resistor value that can ensure that the output waveform is not distorted and the switching characteristics meet the preset requirements.

[0101] Understandably, in the analog optocoupler isolation circuit, the load resistor R3 and the junction capacitance inside the optocoupler chip 12 form a time constant. The magnitude of the time constant is positively correlated with the resistance value of the load resistor R3; that is, the larger the resistance value of the load resistor R3, the larger the time constant, and the longer the signal turn-off time, resulting in a slower falling edge and waveform distortion in the output waveform. Setting the maximum allowable resistance value controls the magnitude of the time constant by limiting the maximum resistance value of the load resistor R3, preventing it from becoming too large and causing output waveform distortion, ensuring that the output signal can accurately reproduce the waveform characteristics of the input signal, and achieving high-fidelity signal transmission. For example, when the resistance value of the load resistor R3 exceeds the maximum allowable resistance value, the falling edge of the output waveform will be severely trailed, and the original pulse signal will become a smooth ramp signal, causing the subsequent circuit to be unable to accurately identify the signal, resulting in communication failure.

[0102] Optionally, the core basis for determining the maximum allowable resistance value is the signal transmission rate and waveform falling edge characteristics requirements of the target circuit. The two work together to determine the specific value of the maximum allowable resistance value, ensuring that the maximum allowable resistance value can adapt to the circuit requirements of different scenarios.

[0103] Specifically, the higher the signal transmission rate of the target circuit, the higher the requirement for the switching response speed of the photosensitive receiving unit, and the smaller the corresponding maximum allowable resistance value. For example, when the signal transmission rate of the target circuit is 10kHz, the off-time Toff of the photosensitive receiving unit is required to be ≤10μs. In this case, the time constant needs to be small enough by limiting the maximum allowable resistance value to meet this requirement. If the transmission rate of the target circuit is reduced to 1kHz, the requirement for the off-time can be appropriately relaxed, and the maximum allowable resistance value can be increased accordingly, improving the flexibility of the circuit design.

[0104] Furthermore, the output signal waveform typically requires a steep falling edge without trailing, ensuring that subsequent circuits can accurately identify high-low level transitions. A larger load resistor R3 results in a smoother falling edge and a longer trailing edge in the output waveform, making it more difficult to meet the falling edge characteristic requirements. Conversely, when the load resistor R3 is controlled within the maximum allowable resistance value, the output waveform has a steep falling edge without significant trailing, satisfying the waveform requirements of the target circuit. Therefore, when determining the maximum allowable resistance value, it is necessary to consider the specific requirements of the target circuit regarding the falling edge of the waveform and reasonably set the upper limit of the maximum allowable resistance value.

[0105] Please refer to it again. Figure 5 , Figure 5This is a signal waveform test diagram of a circuit structure provided in another comparative embodiment of this application. In this comparative embodiment, the load resistor R3 is set to 10KΩ, which is much larger than the minimum allowable resistance calculated based on the minimum CTR value, and exceeds the upper limit of the maximum allowable resistance value. This results in an excessively small collector current on the output side, far below the minimum allowable operating current, causing severe distortion of the output waveform. The input signal cannot be accurately reproduced, ultimately leading to communication failure. Figure 5 As shown, the horizontal axis represents time, the left vertical axis represents voltage, and the right vertical axis represents current. The input-side drive signal is a standard square wave with a high level close to 5.0V. The operating current of the input-side LED unit is synchronously stable, indicating that the input drive module is working normally. However, the output-side isolation signal exhibits obvious falling edge tailing and waveform distortion characteristics. The voltage decays slowly from high to low level instead of a steep step change, indicating a significant deterioration in the switching response characteristics.

[0106] In this embodiment, the circuit structure 10 suitable for analog optocouplers limits the load resistor R3 to a value less than the maximum allowable resistance value. This maximum allowable resistance value is determined in conjunction with the signal transmission rate and waveform falling edge characteristics of the target circuit, allowing for precise adaptation to signal transmission requirements in different scenarios. This effectively avoids problems such as output waveform distortion and slow switching response caused by an excessively large load resistor R3, ensuring a complete output waveform without trailing and that the switching characteristics meet preset requirements.

[0107] Please see Figure 7 , Figure 7 This is a signal waveform test diagram of a circuit structure suitable for analog optocouplers provided in another embodiment of this application, and the circuit structure adopts a common collector output topology. The isolation signal output circuit is a common collector output topology, the output-side photosensitive receiving unit is a phototransistor, the collector of the phototransistor is connected to the positive terminal of the output-side power supply, the emitter is connected to one end of the load resistor R3, the other end of the load resistor R3 is grounded, and the emitter of the phototransistor serves as the output terminal of the isolation signal output circuit, used to output an isolation electrical signal that is opposite to the input signal.

[0108] Optionally, the isolation signal output circuit is a common collector output topology, which has an input signal and an output signal with opposite phase, low output impedance and strong load-carrying capacity, and can stably output the isolated electrical signal, adapting to most analog signal isolation transmission scenarios, such as signal sampling transmission in new energy vehicles and photovoltaic inverters.

[0109] In this embodiment, the common-collector output topology uses a phototransistor as the core device. The load resistor R3, the output power supply, and the phototransistor work together to form a complete output circuit, which can effectively suppress interference in the output signal and improve the stability of the output signal. At the same time, by properly matching the load resistor R3, the amplitude and waveform of the output signal can be flexibly adjusted to meet the signal transmission requirements of the target circuit.

[0110] Optionally, the output-side photosensitive receiving unit is a phototransistor, used to receive the optical signal emitted by the input-side light-emitting unit of the optocoupler chip 12, convert the optical signal into an electrical signal, and then output it through an isolated signal output circuit to complete the signal conversion. Its on / off state is controlled by the intensity of the input optical signal. When the input-side light-emitting unit emits light, the phototransistor receives the optical signal and conducts, forming a current loop. When the input-side light-emitting unit stops emitting light, the phototransistor loses its optical signal excitation and is in the off state, interrupting the current loop.

[0111] Optionally, the collector of the phototransistor is connected to the positive terminal of the output power supply. The output power supply provides operating power to the phototransistor and is the energy source for the isolated signal output circuit. When the phototransistor is turned on, the current from the output power supply flows into the phototransistor through the collector, providing the current basis for signal output; when the phototransistor is turned off, the current is interrupted, and there is no signal output.

[0112] Optionally, the emitter of the phototransistor is connected to one end of the load resistor R3, and the other end of the load resistor R3 is grounded. When the phototransistor is turned on, the load resistor R3 and the phototransistor cooperate to form a complete current loop. At the same time, through its own voltage division effect, it adjusts the amplitude of the output signal to ensure that the output signal meets the requirements of the target circuit. When the phototransistor is turned off, no current flows through the load resistor R3, and the output signal is high.

[0113] Optionally, the emitter of the phototransistor serves as the output terminal of the isolation signal output circuit, used to output an isolated electrical signal that is inversely proportional to the input signal. This output terminal is directly connected to the subsequent circuit, transmitting the isolated electrical signal to the subsequent circuit for further processing or utilization.

[0114] Optionally, when the input driving module 11 provides a positive operating current to the input-side light-emitting unit of the optocoupler chip 12, the input-side light-emitting unit emits light, the corresponding input signal is high level, and the phototransistor conducts after receiving the light signal; when the input driving module 11 stops providing a positive operating current, the input-side light-emitting unit stops emitting light, the corresponding input signal is low level, and the phototransistor is cut off.

[0115] Optionally, when the phototransistor is turned on, current flows from the positive terminal of the output power supply into the collector of the phototransistor, through the emitter to the load resistor R3, and then back to the negative terminal of the output power supply through the ground terminal, forming a complete current loop. At this time, a voltage drop occurs across the load resistor R3, and the potential of the phototransistor's emitter is close to ground potential, resulting in a low-level output signal. When the phototransistor is turned off, no current flows through the isolation signal output loop, there is no voltage drop across the load resistor R3, and the potential of the phototransistor's emitter is close to the voltage value of the output power supply, resulting in a high-level output signal.

[0116] like Figure 7 As shown, the horizontal axis represents time (milliseconds), the left vertical axis represents voltage (volts), and the right vertical axis represents current (milliamperes). The input side uses a standard square wave drive signal with an amplitude range of 0V to 5.0V; the operating current signal of the input-side LED unit ranges from 0mA to 19mA, changing synchronously with the input drive signal, indicating stable operation of the input drive module. The output side uses an isolated square wave signal with an amplitude range of 0V to approximately 4.8V, and is out of phase with the input drive signal; simultaneously, the output signal edges are extremely steep, with almost no trailing on the falling edge, significantly improving switching response speed, and achieving excellent waveform integrity and transmission rate.

[0117] In this embodiment, the circuit structure 10 suitable for analog optocouplers adopts a common-collector output topology, paired with a phototransistor as the output-side photosensitive receiver unit. This topology is mature and reliable, with low output impedance and strong load-carrying capacity, effectively driving subsequent circuits. By clearly defining the specific connection relationships between the phototransistor, the output-side power supply, and the load resistor R3, the integrity of the current loop and smooth signal transmission are ensured, avoiding waveform distortion caused by improper connections. Simultaneously, by limiting the phototransistor's emitter to the output terminal, a stable isolated electrical signal opposite to the input signal can be output, suitable for applications requiring signal phase reversal without the need for additional inverting circuitry. This further enhances the circuit's reliability and practicality, expanding the applicability of the circuit structure 10 suitable for analog optocouplers.

[0118] Please see Figure 8 , Figure 8 This is a signal waveform test diagram of a circuit structure suitable for analog optocouplers provided in another embodiment of this application, and the circuit structure adopts a common-emitter output topology. The isolation signal output circuit is a common-emitter output topology, the output-side photosensitive receiving unit is a phototransistor, the collector of the phototransistor is connected to one end of the load resistor R3, the other end of the load resistor R3 is connected to the positive terminal of the output-side power supply, the emitter of the phototransistor is grounded, and the collector of the phototransistor serves as the output terminal of the isolation signal output circuit, used to output an isolation electrical signal in the same direction as the input signal.

[0119] Optionally, the isolated signal output circuit is a common-emitter output topology, which has the same phase between the input signal and the output signal, high output impedance, and strong signal amplification capability. It can accurately restore the phase characteristics of the input signal and is suitable for analog signal isolation transmission scenarios that require phase consistency of the paired signal, such as signal sampling of precision instruments and signal transmission in industrial control.

[0120] In this embodiment of the invention, the common-emitter output topology also uses a phototransistor as the core device. The load resistor R3, the output power supply, and the phototransistor work together to form a complete output circuit. Its signal phase is not reversed, and it can directly output an isolated electrical signal in the same direction as the input signal without the need for an additional inverting circuit, which simplifies the circuit design. At the same time, it has a certain signal amplification capability, which can improve the amplitude stability of the output signal.

[0121] Optionally, the output-side photosensitive receiving unit is a phototransistor, used to receive the light signal emitted by the input-side light-emitting unit of the optocoupler chip 12, and convert the light signal into an electrical signal to complete the signal conversion.

[0122] Optionally, the collector of the phototransistor is connected to one end of the load resistor R3, and the other end of the load resistor R3 is connected to the positive terminal of the output power supply. Unlike the common-collector topology, in the common-emitter topology, the load resistor R3 is connected in series between the output power supply and the collector of the phototransistor. When the phototransistor is turned on, it works with the phototransistor to form a complete current loop, and simultaneously adjusts the amplitude of the output signal through its own voltage division effect, ensuring that the output signal meets the requirements of the target circuit. When the phototransistor is turned off, the voltage across the load resistor R3 is equal to the voltage of the output power supply, and the output signal is high.

[0123] Optionally, the emitter of the phototransistor is grounded. Grounding the emitter can fix the emitter potential of the phototransistor, ensure the stability of the phototransistor's conduction and cutoff states, avoid output signal distortion due to potential fluctuations, and form a complete current loop to ensure signal output.

[0124] Optionally, the collector of the phototransistor serves as the output terminal of the isolation signal output circuit, used to output an isolated electrical signal in the same direction as the input signal. This output terminal is directly connected to the subsequent circuit, transmitting the isolated electrical signal to the subsequent circuit for further processing or utilization.

[0125] like Figure 8As shown, the horizontal axis represents time (milliseconds), the left vertical axis represents voltage (volts), and the right vertical axis represents current (milliamperes). The amplitude range of the input-side square wave drive signal is 0V to 5.0V, serving as the original drive signal for the circuit. The amplitude range of the operating current signal of the input-side LED unit is 0mA to 19mA, changing synchronously with the input drive signal, fully demonstrating the stable and reliable operation of the input drive module. The amplitude range of the output-side isolation signal is 0.2V to 5.0V. This output signal maintains the same phase as the original input drive signal. Furthermore, the output signal has steep and crisp edges without significant tailing or distortion, exhibiting excellent switching response speed and fully preserving the waveform characteristics and amplitude of the input signal.

[0126] In this embodiment, the circuit structure 10 suitable for analog optocouplers adopts a common-emitter output topology, paired with a phototransistor as the output-side photosensitive receiver unit. This topology is mature and reliable, with strong signal amplification capability and high output impedance, enabling high-fidelity signal transmission. By clearly defining the specific connection relationships between the phototransistor, the load resistor R3, and the output-side power supply, the integrity of the current loop and smooth signal transmission are ensured, avoiding waveform distortion caused by improper connections. Simultaneously, by limiting the phototransistor's collector to the output terminal, a stable isolated electrical signal in the same direction as the input signal can be output, suitable for applications requiring signal phase consistency. This eliminates the need for additional phase adjustment circuitry, further enhancing the circuit's reliability and practicality.

[0127] Optionally, the step of determining the resistance value of the load resistor R3 further includes determining the nominal resistance value of the load resistor R3 by fine-tuning it according to the signal transmission rate or waveform falling edge characteristics of the target circuit, and the deviation between the resistance value of the load resistor R3 and the minimum allowable resistance value does not exceed 20% of the minimum allowable resistance value.

[0128] Optionally, the nominal resistance value of the load resistor R3 can be determined by fine-tuning based on the signal transmission rate or waveform falling edge characteristics of the target circuit. This fine-tuning requirement is a further optimization based on the fundamental constraint that the nominal resistance value is greater than or equal to the minimum allowable resistance, so that the resistance value of the load resistor R3 is adapted to the signal transmission requirements of the target circuit, ensuring the waveform quality and transmission stability of the output signal, and avoiding problems such as signal distortion and transmission delay caused by improper resistance value adaptation.

[0129] It should be noted that the core basis for fine-tuning is the signal transmission rate and waveform falling edge characteristics of the target circuit. Either can be chosen as the basis for fine-tuning, or both can be combined. The specific method depends on the actual needs of the target circuit and does not deviate from the technical limitations of this embodiment. Furthermore, the nominal resistance value after fine-tuning must still meet all the constraints mentioned above to ensure basic compliance.

[0130] Optionally, when the signal transmission rate of the target circuit is high, the nominal resistance value of the load resistor R3 needs to be appropriately reduced. The higher the transmission rate, the higher the requirement for the switching response speed of the output-side photosensitive receiving unit. Reducing the resistance value of the load resistor R3 can reduce the time constant, shorten the turn-off time of the photosensitive receiving unit, avoid signal tailing and misalignment, and ensure stable transmission of high-speed signals.

[0131] Optionally, when the signal transmission rate of the target circuit is low, the nominal resistance value of the load resistor R3 can be appropriately increased. In this case, the requirement for switching response speed is lower, and appropriately increasing the resistance value can improve the amplitude stability of the output signal, while reducing the power loss of the circuit and optimizing the circuit's operating efficiency.

[0132] Optionally, when the target circuit requires a steep falling edge and no trailing in the output waveform, the nominal resistance of the load resistor R3 should be appropriately reduced. Reducing the resistance reduces the time constant, making the falling edge of the output waveform steeper and the trailing edge shorter, thus meeting the waveform characteristic requirements. When the target circuit has relatively relaxed requirements for the falling edge characteristics of the waveform, the nominal resistance of the load resistor R3 can be appropriately increased to optimize circuit power loss while ensuring that the waveform is not significantly distorted.

[0133] Optionally, the nominal resistance value of the load resistor R3 after fine-tuning should not deviate from the minimum allowable resistance value by more than 20% of the minimum allowable resistance value. This is to avoid the load resistor R3 deviating too much from the minimum allowable resistance value due to excessive fine-tuning, which could affect the operating current of the photosensitive receiving unit on the output side, resulting in problems such as insufficient output signal amplitude and waveform distortion, and to ensure the basic working stability of the circuit.

[0134] Optionally, the deviation is the absolute difference between the nominal resistance value of the load resistor R3 and the minimum allowable resistance value, and the ratio of the deviation to the minimum allowable resistance value does not exceed 20%.

[0135] In this embodiment, the circuit structure 10 suitable for analog optocouplers limits the nominal resistance value of the load resistor R3 to be fine-tuned in conjunction with the signal transmission rate or waveform falling edge characteristics of the target circuit. This allows for precise adaptation to the signal requirements of different scenarios, avoiding problems such as signal tailing and transmission delay caused by fixed resistance values, and ensuring complete output waveform and compliant transmission rate. Simultaneously, specifying that the deviation between the resistance value and the minimum allowable resistance value does not exceed 20% avoids excessive fine-tuning that could cause the output current to deviate from a reasonable range, further enhancing the ability to avoid CTR fluctuations and ensuring signal stability under harsh operating conditions.

[0136] Optionally, the output matching module 13 further includes a push-pull output structure, the input end of which is connected to the output end of the isolation signal output circuit to improve the signal transmission rate.

[0137] Optionally, the output matching module 13 is used to optimize the waveform and match the impedance of the electrical signal output by the isolation signal output circuit, reduce attenuation and distortion during signal transmission, and improve the stability and integrity of signal transmission.

[0138] Optionally, the isolation signal output circuit can adopt a common collector or common emitter output topology.

[0139] Optionally, the push-pull output structure consists of two complementary power transistors to achieve rapid signal turn-on and turn-off. For example, the push-pull output structure mainly includes an NPN type driver transistor and a PNP type driver transistor, with their emitters connected and serving as the output terminal of the push-pull output structure. Their collectors are connected to different power supplies, and their bases are connected and serve as the input terminal of the push-pull output structure, forming a symmetrical push-pull drive structure.

[0140] Optionally, the input terminal of the push-pull output structure is connected to the output terminal of the isolation signal output circuit. Specifically, the bases of the two complementary transistors of the push-pull output structure are connected to the output terminal of the isolation signal output circuit to receive the isolation electrical signal output by the isolation signal output circuit.

[0141] Optionally, the output terminal of the push-pull output structure is directly connected to the subsequent circuit, transmitting the signal optimized by the push-pull drive to the subsequent circuit. The collector of the NPN transistor is connected to the positive power supply, and the collector of the PNP transistor is connected to ground potential, forming a complete drive current loop to ensure stable operation of the push-pull output structure.

[0142] In this embodiment, the circuit structure 10 suitable for analog optocouplers effectively solves the problems of insufficient transmission rate and slow waveform response in the isolated signal output circuit by adding a push-pull output structure, further improving the efficiency and stability of circuit signal transmission. The input terminal of the push-pull output structure is connected to the output terminal of the isolated signal output circuit, without changing the original circuit's working principle and isolation effect, and without requiring an additional independent power supply module. The push-pull output structure can effectively improve the signal transmission rate. Through the alternating conduction and cutoff of complementary transistors, it reduces output impedance, accelerates the signal rise and fall edge response speed, avoids signal tailing and distortion, and is suitable for application scenarios with high requirements for transmission rate.

[0143] This application also provides an electronic device, which includes the circuit structure 10 suitable for analog optocouplers provided in the embodiments of this application.

[0144] Optionally, the electronic device includes, but is not limited to, industrial control equipment, precision measuring instruments, new energy equipment, medical equipment, etc.

[0145] The electronic device provided in this embodiment, by integrating the circuit structure suitable for analog optocouplers described in the embodiments of this application, effectively solves the problems of unstable analog signal isolation transmission, easy communication failure, and poor adaptability in existing electronic devices, thereby improving the reliability, stability, and practicality of the electronic device. The electronic device can effectively avoid problems such as insufficient signal amplitude and waveform distortion caused by CTR fluctuations in the optocoupler, achieving highly stable and high-fidelity isolated transmission of analog signals.

[0146] In this application, the terms "embodiment" and "implementation" mean that a specific feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of this application. The appearance of these phrases in various locations throughout the specification does not necessarily refer to the same embodiment, nor are they independent or alternative embodiments mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this application can be combined with other embodiments. Furthermore, it should be understood that the features, structures, or characteristics described in the various embodiments of this application can be arbitrarily combined to form another embodiment that does not depart from the spirit and scope of the technical solution of this application, provided there is no contradiction between them.

[0147] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application should not depart from the spirit and scope of the technical solutions of this application.

Claims

1. A circuit structure suitable for analog optocouplers, characterized in that, The circuit structure includes: An input driving module is electrically connected to the input-side light-emitting unit of the optocoupler chip and is used to provide the input-side light-emitting unit with a positive operating current within the rated operating range. An optocoupler chip, wherein the optocoupler chip is an analog optocoupler, the optocoupler chip integrates an input-side light-emitting unit and an output-side photosensitive receiving unit, the output-side photosensitive receiving unit being a phototransistor, used to achieve electrical isolation and signal conversion between the input and output sides; and The output matching module includes a load resistor with a nominal resistance value. The load resistor is electrically connected to the output-side photosensitive receiving unit and the output-side power supply, and forms an isolated signal output circuit with the output-side photosensitive receiving unit. The output terminal of the isolated signal output circuit is used to output the isolated target electrical signal. The step of determining the resistance value of the load resistor includes obtaining a preset parameter range of the current transfer ratio of the optocoupler chip, and extracting a preset minimum value of the current transfer ratio based on the preset parameter range. Based on the preset minimum value, the minimum allowable operating current of the photosensitive receiving unit on the output side of the optocoupler chip is calculated. Based on the minimum allowable operating current, the minimum allowable resistance value of the load resistor is calculated. The forward operating current of the input driving module is obtained. The product of the preset minimum value and the forward operating current is calculated, and the product result is assigned to the minimum allowable operating current. The voltage value of the output power supply is obtained. The quotient of the voltage value and the minimum allowable operating current is calculated, and the quotient result is assigned to the minimum allowable resistance value of the load resistor. The nominal resistance of the load resistor is determined based on the minimum permissible resistance value, wherein the nominal resistance of the load resistor is greater than or equal to the minimum permissible resistance value.

2. The circuit structure as described in claim 1, characterized in that, The input driving module includes an input DC power supply, a series current-limiting resistor group, and a pulse signal source. The series current-limiting resistor group is composed of a first current-limiting resistor and a second current-limiting resistor connected in series. One end of the first current-limiting resistor is connected to the positive terminal of the input DC power supply, and the other end of the first current-limiting resistor is connected to the anode of the input-side light-emitting unit. The cathode of the input-side light-emitting unit is connected to one end of the second current-limiting resistor, and the other end of the second current-limiting resistor is connected to the positive terminal of the pulse signal source. The negative terminals of the pulse signal source and the input DC power supply are both grounded.

3. The circuit structure as described in claim 2, characterized in that, The step of obtaining the positive operating current of the input driving module includes: Obtain the voltage value of the input DC power supply and the forward saturation conduction voltage drop of the input side light-emitting unit, and calculate the difference between the voltage value and the forward saturation conduction voltage drop; Obtain the resistance values ​​of the first current-limiting resistor and the second current-limiting resistor, and calculate the sum of the values ​​of the first current-limiting resistor and the second current-limiting resistor; Calculate the quotient of the difference result and the sum result, and assign the quotient result to the positive working current; Verify and ensure that the forward operating current is within the allowable operating range of the forward current of the optocoupler chip.

4. The circuit structure as described in claim 1, characterized in that, Determining the nominal resistance value of the load resistor includes: The resistance value of the load resistor is less than the maximum allowable resistance value, wherein the maximum allowable resistance value is an upper limit of the resistance value determined in combination with the signal transmission rate and waveform falling edge characteristic requirements of the target circuit. The maximum allowable resistance value is used to ensure that the output waveform is not distorted and that the switching characteristics meet the preset requirements.

5. The circuit structure as described in claim 1, characterized in that, The isolation signal output circuit is a common collector output topology. The output-side photosensitive receiving unit is a phototransistor. The collector of the phototransistor is connected to the positive terminal of the output-side power supply, and the emitter is connected to one end of the load resistor. The other end of the load resistor is grounded. The emitter of the phototransistor serves as the output terminal of the isolation signal output circuit, used to output an isolation electrical signal that is opposite to the input signal.

6. The circuit structure as described in claim 1, characterized in that, The isolation signal output circuit is a common emitter output topology. The output-side photosensitive receiving unit is a phototransistor. The collector of the phototransistor is connected to one end of the load resistor, and the other end of the load resistor is connected to the positive terminal of the output-side power supply. The emitter of the phototransistor is grounded. The collector of the phototransistor serves as the output terminal of the isolation signal output circuit, used to output an isolation electrical signal in the same direction as the input signal.

7. The circuit structure as described in claim 1, characterized in that, The output matching module also includes a push-pull output structure, the input of which is connected to the output of the isolation signal output circuit to improve the signal transmission rate.

8. An electronic device, characterized in that, The electronic device includes the circuit structure as described in any one of claims 1-7.

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