Direct current voltage reduction and isolation system

Abstract

The invention provides a direct current voltage reduction and isolation system, and relates to the technical field of power supply conversion, the system comprises a low-pass filtering voltage stabilization module, a first voltage reduction voltage stabilizer and a power supply isolation conversion module, the low-pass filtering voltage stabilization module comprises a first low-pass filtering voltage stabilization module and a second low-pass filtering voltage stabilization module, the first low-pass filtering voltage stabilization module is connected with the first voltage reduction voltage stabilizer, and the second low-pass filtering voltage stabilization module is connected with the second voltage reduction voltage stabilizer. The voltage stabilizing module is used for carrying out filtering and voltage stabilizing processing on an input direct-current electric signal to generate a stable initial direct-current electric signal; the first step-down voltage stabilizer is used for carrying out step-down on the initial direct-current electric signal to generate a direct-current electric signal to be processed; the second low-pass filtering and voltage-stabilizing module is used for performing filtering and voltage-stabilizing processing on the direct-current electric signal to be processed to generate a target direct-current electric signal; and the power supply isolation conversion module is used for converting the initial direct-current electric signal into an isolation electric signal. The power supply has the technical effect of meeting the use requirements of electric equipment with relatively high requirements on the quality of the power supply.

Description

Technical Field

[0001] The present application relates to the technical field of power conversion, and in particular to a direct current step-down and isolation system. Background Art

[0002] With the continuous development of electronic equipment, the requirements for power supply systems are getting higher and higher. In practical applications, in order to ensure the safety and stability of electrical equipment, it is often necessary to step down the input DC power and achieve power isolation.

[0003] At present, the commonly used DC step-down and isolation solution is to use a single step-down circuit with an isolation transformer. Although this solution can achieve the functions of step-down and isolation, due to the lack of effective filtering and voltage stabilization processing, the output DC signal ripple is large and the stability is poor, which is difficult to meet the use needs of electrical equipment with high requirements for power quality. Summary of the invention

[0004] The present application provides a direct current step-down and isolation system for meeting the use requirements of electrical equipment with high requirements on power quality.

[0005] In a first aspect, the present application provides a DC step-down and isolation system, which includes: a low-pass filter and voltage regulator module, a first step-down voltage regulator and a power supply isolation conversion module, wherein the low-pass filter and voltage regulator module includes a first low-pass filter and voltage regulator module and a second low-pass filter and voltage regulator module, wherein the output end of the first low-pass filter and voltage regulator module is electrically connected to the input end of the first step-down voltage regulator, and the output end of the first step-down voltage regulator is electrically connected to the input end of the second low-pass filter and voltage regulator module; wherein the first low-pass filter and voltage regulator module is used to filter and stabilize the input DC signal to generate a stable initial DC signal; the first step-down voltage regulator is used to step down the initial DC signal to generate a DC signal to be processed; the second low-pass filter and voltage regulator module is used to filter and stabilize the DC signal to be processed to generate a target DC signal; and the power supply isolation conversion module is used to convert the initial DC signal into an isolated signal.

[0006] By adopting the above technical solution, the first low-pass filter voltage regulator module performs preliminary processing on the input DC signal, effectively suppresses the interference and ripple in the input power supply, and provides a stable voltage basis for subsequent processing. The first buck regulator realizes efficient voltage conversion and ensures the energy conversion efficiency of the system through a reasonable buck scheme. The second low-pass filter voltage regulator module further filters and stabilizes the signal after voltage reduction, further improving the stability and purity of the output voltage. At the same time, the power isolation conversion module realizes the electrical isolation function, effectively preventing mutual interference between systems. This multi-stage series system structure not only improves the accuracy and reliability of power conversion, but also enhances the anti-interference ability and safety of the system through isolation design, meeting the use requirements of electrical equipment with high requirements for power quality.

[0007] Optionally, the first low-pass filtering and voltage stabilization module includes a DC input filtering circuit and a step-down output filtering circuit; wherein the DC input filtering circuit is used to filter the input DC signal; and the step-down output filtering circuit is used to perform voltage stabilization filtering on the filtered DC signal to generate a stable initial DC signal.

[0008] By adopting the above technical solution, the first low-pass filter voltage stabilization module realizes dual filtering processing through the series connection of the DC input filter circuit and the step-down output filter circuit, wherein the DC input filter circuit first performs preliminary filtering on the input DC signal, effectively suppressing the noise and interference introduced by the external power supply, and the step-down output filter circuit further stabilizes and filters the signal, not only providing a higher filtering depth, but also realizing stable voltage output. This dual filtering structure significantly improves the filtering effect, can more effectively eliminate various types of interference, and ensure that the output initial DC signal has higher stability and purity.

[0009] Optionally, the first buck regulator includes a buck regulator and an adjustable buck regulator; wherein the buck regulator is used to perform a first-stage buck processing on the initial DC signal; and the adjustable buck regulator is used to perform a secondary buck regulation on the DC signal after the first-stage buck processing according to a preset voltage value to generate a DC signal to be processed.

[0010] By adopting the above technical scheme, the first buck regulator adopts a two-stage buck structure of a buck regulator and an adjustable buck regulator. The first-stage buck processing of the initial DC signal is realized by the buck regulator, and then the adjustable buck regulator performs precise secondary buck regulation according to a preset voltage value. This cascade buck scheme not only disperses the pressure of single-stage bucking and improves the reliability of the system, but also realizes flexible adjustment of the output voltage through the introduction of the adjustable buck regulator, so that the system can more accurately meet the voltage requirements of different loads, while also improving the overall conversion efficiency and voltage regulation accuracy.

[0011] Optionally, the system also includes: a second buck regulator, the output end of the first buck regulator is electrically connected to the input end of the second buck regulator; wherein the second buck regulator is used to step down the target DC signal to generate a stepped-down first DC signal; and the second low-pass filtering and voltage stabilization module is used to filter and stabilize the first DC signal to generate a second DC signal.

[0012] By adopting the above technical solution, the system forms a multi-channel buck output structure by adding a second buck regulator, realizing the hierarchical buck processing of the initial DC signal, wherein the target DC signal output by the first buck regulator can be used directly, and the second buck regulator further bucks the signal to generate a first DC signal with a lower voltage, which is then filtered and stabilized by the second low-pass filter and voltage regulator module, and finally outputs a stable second DC signal. This design not only expands the output capacity of the system, providing stable outputs of multiple different voltage levels at the same time, but also reduces the burden of each level of buck by hierarchical bucking, improving the reliability and conversion efficiency of the system.

[0013] Optionally, the system also includes: a third buck regulator, the output end of the second buck regulator is electrically connected to the input end of the third buck regulator; wherein the third buck regulator is used to step down the second DC signal to generate a stepped-down third DC signal; and the second low-pass filtering and voltage stabilization module is used to filter and stabilize the third DC signal to generate a fourth DC signal.

[0014] By adopting the above technical solution, the system forms a three-stage buck structure by further adding a third buck regulator. On the basis of the second buck regulator outputting the second DC signal, the third buck regulator continues to perform a buck process to obtain a third DC signal, and then passes through the filtering and voltage stabilization process of the second low-pass filter voltage regulator module, and finally outputs a fourth DC signal of a lower voltage level. This three-stage buck structure not only expands the voltage output range of the system, and can provide outputs of three different voltage levels at the same time, but also enables each buck to operate within a reasonable working range by stepping down the voltage step by step, which not only ensures the stability of the output at each level, but also improves the reliability and efficiency of the overall system.

[0015] Optionally, the first low-pass filter and voltage regulator module includes: a protection circuit, a filter circuit and a step-down circuit; wherein the protection circuit includes a fuse and a TVS tube; the filter circuit includes an electrolytic capacitor, a ceramic capacitor and an inductor; and the step-down circuit includes a step-down regulator.

[0016] By adopting the above technical scheme, the first low-pass filter voltage regulator module adopts a triple processing structure of protection circuit, filter circuit and buck circuit. The protection circuit composed of fuse and TVS tube effectively prevents overvoltage and overcurrent from damaging the system. The filter circuit composed of electrolytic capacitors, ceramic capacitors and inductors realizes comprehensive suppression of interference of different frequencies. The electrolytic capacitor mainly filters out low-frequency ripple, the ceramic capacitor handles high-frequency interference, and the inductor provides additional filtering effect. Finally, the buck regulator in the buck circuit realizes stable voltage output. This multiple protection and processing mechanism not only improves the safety and reliability of the system, but also ensures the stability and purity of the output voltage.

[0017] Optionally, the power isolation conversion module includes a power isolation chip and a filter capacitor; wherein the power isolation chip is used to perform power isolation processing on the initial DC power signal; and the filter capacitor is used to filter the initial DC power signal after power isolation processing to generate an isolated electrical signal.

[0018] By adopting the above technical solution, the power isolation conversion module realizes effective power isolation and signal processing functions through the combined design of power isolation chip and filter capacitor. The power isolation chip performs power isolation processing on the initial DC signal, effectively blocks the electrical connection between the input and output ends, and reduces the influence of common-mode interference and ground loop. The filter capacitor further filters the isolated signal, eliminating high-frequency interference and ripple that may be introduced during the isolation process, and finally outputs a stable and pure isolated electrical signal. This design significantly improves the system's anti-interference ability and electrical safety.

[0019] In a second aspect, the present application provides a DC step-down and isolation method, which includes: filtering and stabilizing an input DC signal to generate a stable initial DC signal; stepping down the initial DC signal to generate a DC signal to be processed; filtering and stabilizing the DC signal to be processed to generate a target DC signal; and converting the initial DC signal into an isolated signal.

[0020] In summary, the present application includes at least one of the following beneficial technical effects: The first low-pass filter voltage regulator module performs preliminary processing on the input DC signal, effectively suppresses the interference and ripple in the input power supply, and provides a stable voltage basis for subsequent processing. The first buck regulator realizes efficient voltage conversion and ensures the energy conversion efficiency of the system through a reasonable buck scheme. The second low-pass filter voltage regulator module further filters and stabilizes the signal after voltage reduction, further improving the stability and purity of the output voltage. At the same time, the power isolation conversion module realizes the electrical isolation function, effectively preventing mutual interference between systems. This multi-stage series system structure not only improves the accuracy and reliability of power conversion, but also enhances the anti-interference ability and safety of the system through isolation design, meeting the use needs of electrical equipment with high requirements for power quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of a DC step-down and isolation system provided in an embodiment of the present application; Figure 2 This is a first-stage buck principle block diagram provided by an embodiment of the present application; Figure 3 is a schematic diagram of a first-stage buck circuit provided in an embodiment of the present application; Figure 4 This is a second-stage buck principle block diagram provided in an embodiment of the present application; Figure 5 is a schematic diagram of a second-stage buck circuit provided in an embodiment of the present application; Figure 6 This is a third-stage buck principle block diagram provided in an embodiment of the present application; Figure 7 is a schematic diagram of a third-stage buck circuit provided in an embodiment of the present application; Figure 8 It is a flow chart of a DC step-down and isolation method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below in conjunction with the drawings in the embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments.

[0023] In the description of the embodiments of the present application, words such as "illustrative", "for example" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "illustrative", "for example" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "illustrative", "for example" or "for example" is intended to present related concepts in a concrete way.

[0024] Figure 1 It is a structural schematic diagram of a DC step-down and isolation system provided in an embodiment of the present application.

[0025] like Figure 1 As shown, the DC voltage reduction and isolation system provided by the present invention mainly solves the technical problem that multiple functional modules in existing integrated circuits require different power supply voltages. The system realizes the step-by-step voltage reduction and signal isolation functions by setting a combination of a low-pass filter voltage regulator module, a multi-stage voltage reduction regulator and a power isolation conversion module.

[0026] Specifically, a DC signal (such as 24V voltage) is first input into the first low-pass filter voltage stabilization module. The first low-pass filter voltage stabilization module includes a DC input filter circuit and a step-down output filter circuit, wherein the DC input filter circuit uses an LC filter structure composed of an electrolytic capacitor, a ceramic capacitor and an inductor to filter out the ripple component in the input voltage; the step-down output filter circuit further stabilizes the filtered voltage and outputs a stable initial DC signal. This dual filtering structure can not only effectively suppress the fluctuation of the input voltage, but also improve the anti-interference ability of the system.

[0027] The first low-pass filter voltage regulator module adopts multiple protection and filtering structures, and ensures the stability and safety of the output signal through the organic combination of protection circuit, filtering circuit and step-down circuit. First, configure the protection circuit at the input end, use a self-recovery fuse with a rated current of 2A as an overcurrent protection element, and cooperate with a bidirectional TVS tube with a working voltage of 15V (such as SMBJ15CA) for transient voltage suppression. This combination can effectively prevent overvoltage and overcurrent from causing damage to the subsequent circuit.

[0028] The filter circuit that follows uses a π-type filter network composed of 100μF / 25V aluminum electrolytic capacitors, 0.1μF / 50V ceramic capacitors and 100μH power inductors. The electrolytic capacitors are mainly used to filter out low-frequency ripples, while the ceramic capacitors can effectively suppress high-frequency noise due to their excellent high-frequency characteristics. Together with the inductor, an LC filter circuit is formed, which can achieve an attenuation characteristic of 20dB / decade and significantly reduce power supply ripple.

[0029] The final step-down circuit uses a low-dropout linear regulator such as the AMS1117-3.3 as a step-down regulator. This device has a low voltage drop (typical value 1.1V) and a good load regulation rate (better than 0.2%), which can stably convert the input voltage to the required level. This multi-level protection and processing design ensures the reliability of the system through the protection circuit (can withstand 15V / 600W transient impact), reduces the ripple to less than 50mV through the filtering circuit, and finally outputs a stable DC voltage through the step-down circuit with a regulation rate better than 1%. The overall solution not only ensures system safety, but also achieves excellent filtering and voltage regulation performance, which is particularly suitable for precision electronic equipment that requires high reliability and low ripple characteristics of the power supply.

[0030] The initial DC signal processed by the first low-pass filter voltage regulator module is input to the first buck regulator and the power isolation conversion module at the same time. The first buck regulator uses the LM2575S chip to achieve the first level of voltage reduction (such as down to 5V) and outputs the DC signal to be processed; while the power isolation conversion module uses the LD2-05S05S power isolation chip with a filter capacitor to convert the initial DC signal into an isolated electrical signal, realize the electrical isolation function, and effectively prevent mutual interference between different circuit modules.

[0031] The buck regulator adopts a dual-stage buck design, and realizes accurate voltage conversion through the series connection of the buck regulator and the adjustable buck regulator. The initial DC signal first enters the buck regulator for the first stage of buck processing. Fixed output switching buck chips such as LM2596 can be selected. Such chips have high conversion efficiency and good load capacity, and can reduce higher voltages (such as 12V or 5V) to a relatively low level that is still higher than the target voltage (such as 3.3V).

[0032] The reason why the fixed output solution is used in the first-stage buck is that it has strong anti-interference ability and stability, and can provide a stable voltage basis for subsequent fine adjustment. Subsequently, the DC signal after the first-stage buck enters the adjustable buck regulator for secondary buck regulation. This stage can use adjustable linear regulators such as LM317 or TPS7A47. By adjusting the external resistor divider network, the output voltage can be accurately adjusted according to the preset voltage value (such as 1.5V, 1.8V, etc.). The advantage of using an adjustable solution is that it has higher adjustment accuracy and lower output noise, and the output voltage value can be flexibly adjusted according to actual application requirements.

[0033] This dual-stage buck structure design, on the one hand, achieves efficient energy conversion through the first-stage switch buck, and on the other hand, ensures the accuracy and purity of the output voltage through the second-stage linear regulation, and ultimately achieves performance indicators of output voltage accuracy better than ±0.5% and ripple less than 5mV. The overall solution not only ensures system efficiency, but also meets the strict requirements for power quality, and is particularly suitable for precision instruments and communication equipment that have high requirements for power supply quality.

[0034] The power isolation conversion module realizes electrical isolation and signal purification through the cooperation of power isolation chip and filter capacitor. The module uses digital isolation power chips such as ADuM5000 as core components. This type of chip adopts advanced iCoupler magnetic coupling isolation technology, with an isolation withstand voltage of more than 2.5kV and a high power conversion efficiency (typical value is 80%).

[0035] The power isolation chip converts the initial DC signal into a high-frequency AC signal through an internal high-frequency transformer, and then re-rectifies it into a DC signal inside the chip, achieving electrical isolation while completing energy transfer. A 47μF / 16V low-impedance electrolytic capacitor and a 0.1μF / 50V multilayer ceramic capacitor are configured in parallel at the output end of the power isolation chip as a filter capacitor. This configuration can effectively filter out the switching noise and ripple generated during the isolation conversion process. The electrolytic capacitor mainly handles low-frequency ripple, while the ceramic capacitor is responsible for suppressing high-frequency noise. The combination of the two can control the output ripple below 20mV.

[0036] This design not only achieves a high degree of electrical isolation between input and output (common mode transient suppression capability of 25kV / μs), but also ensures the purity of the isolated electrical signal through reasonable filtering design, effectively preventing ground loop interference and the conduction of common mode noise. The overall solution can achieve a signal delay of less than 100ps and an output accuracy better than ±1% while ensuring 2.5kV isolation withstand voltage, which is particularly suitable for medical equipment, industrial control and other application scenarios that require high isolation and low noise.

[0037] The DC signal to be processed is filtered by the second low-pass filter voltage regulator module and then outputs the target DC signal. The target DC signal can be directly output as a power supply signal for the digital circuit on the one hand, and sent to the second buck regulator for further step-down processing on the other hand. The second buck regulator uses the LM1117SX adjustable voltage regulator chip, and its input end is connected with an anti-reverse diode and an LC filter circuit, which can effectively prevent the reverse voltage from damaging the chip and ensure the stability of the input voltage. The chip uses an external precision resistor voltage divider network for feedback regulation, and performs a secondary voltage reduction, such as reducing it to 3.3V, and outputs the first DC signal. The first DC signal is processed by the LC low-pass filter circuit composed of a 10μH inductor and a 100μF electrolytic capacitor to form a second DC signal with a ripple less than 50mV. The signal can be output as a 3.3V digital circuit power supply signal on the one hand, and input to the third buck regulator on the other hand. The third step-down regulator also uses the LM1117SX chip, and achieves the final step of voltage reduction by adjusting the feedback resistor, such as reducing it to 1.5V, and finally forms a fourth DC signal with a ripple less than 30mV through similar LC filtering, which is used to power the low-voltage digital circuit module.

[0038] This multi-channel output design not only meets the power supply requirements of devices with different voltage levels, but also ensures the stability and reliability of each output voltage through reasonable filtering design.

[0039] Figure 2 This is a first-stage buck principle block diagram provided by an embodiment of the present application. Specifically, the externally input 24V DC signal is first protected against overvoltage and overcurrent by a protection circuit. The protection circuit uses a combination of a fuse and a TVS tube to effectively prevent abnormal voltage from causing damage to subsequent circuits. The protected voltage signal enters the first low-pass filter voltage regulator module, and the input voltage is filtered by a combination of LC filter circuits. Here, a 24V DC voltage can be directly drawn out for use by other circuits. The filtered voltage then enters the first buck regulator, which uses the LM2575S switch-type buck chip to efficiently reduce the 24V voltage to 5V. The stepped-down voltage is further filtered out by the second low-pass filter voltage regulator module to output a stable 5V DC digital signal after the switching noise is further filtered out. At the same time, this 5V voltage will also be sent to the power isolation conversion module (which can be a power isolator, using the LD2-05S05S chip), and the isolated +5V DC analog signal is output through electromagnetic isolation, which effectively avoids mutual interference between digital circuits and analog circuits. This design not only ensures the stability and reliability of power supply through multi-stage filtering and protection circuits, but also meets the power supply requirements of different types of circuits through isolation design and multi-channel output, making the entire system highly practical and adaptable.

[0040] Figure 3This is a schematic diagram of a first-stage buck circuit provided by an embodiment of the present application. As shown in the figure, a protection circuit is formed by a fuse F1 and TVS tubes Z1 and Z2. A first-stage filter circuit is formed by capacitors C1, C2, C3 and inductor L1. A buck regulator U1 is used to form a buck circuit. An inductor L2 and capacitors C4 and C5 are used to form a second-stage filter circuit. A power isolator U2 and capacitors C6, C7, and C8 are used to form an isolation circuit.

[0041] F1 is connected in series to the signal line, with one pin connected to the 24V input electrical signal, Z1 and C1 are connected in parallel between the signal lines, the connection point between Z1 and C1 is connected to DGND, L1 is connected in series to the signal line, C2 and C3 are connected in parallel between the signal lines, the connection point between C2 and C3 is connected to DGND, and the other end is connected to pin 1 of the buck regulator U1. Pins 3, 5, and 6 of U1 are connected to DGND, Z2 is connected in parallel between pin 2 and DGND of U1, pin 2 is connected in series with L2 and then connected to pin 4, and connected to +5VD pull-up. The other pin of L2 is connected to C4, and the other pin of C4 is connected to DGND. C5 is connected in parallel between the signal lines, with one pin connected to DGND and the other pin connected to pin 2 of U2, pin 1 of U2 is connected to DGND, and pin 6 is connected to +5VA pull-up. After C6 and C7 are connected in parallel, one pin is connected to pin 6 of U2, and the other pin is connected to 0VA pull-down. One pin of C8 is connected to PGND, and the other pin is connected to pin 7 of U2. One pin of C8 connected to pin 7 of U2 is also connected to the 0VA pull-down pin of C6 and C7.

[0042] The input electrical signal passes through a fuse and an LC low-pass filter and is then input into the first step-down regulator U1. U1 processes the DC signal from the LC low-pass filter voltage regulator circuit to obtain a stepped-down DC signal, which is then stabilized at a +5V output after LC low-pass filtering. The signal is then sent to the power isolation module U2, which outputs an isolated +5V analog electrical signal.

[0043] Figure 4 This is a second-stage buck principle block diagram provided by an embodiment of the present application; as shown in the figure, the input 5V DC power supply is first converted to 3.3V by the second buck regulator, which can ensure the output of a stable 3.3V voltage and eliminate the influence of input voltage fluctuations. The 3.3V DC signal after voltage reduction passes through the second low-pass filter voltage regulator module. This filtering link can effectively filter out high-frequency interference and noise, and only allow low-frequency signals to pass, thereby providing a purer signal source. After filtering, one path is directly output as a 3.3V DC digital signal, and the other path is processed by an isolation circuit and output as a 3.3V analog signal. The function of the isolation circuit is to prevent the switching noise of the digital circuit from coupling into the analog circuit through the power supply or ground line, ensuring the quality of the analog signal. Such a design can meet the power supply requirements of both digital and analog circuits, and ensure signal quality through reasonable filtering and isolation measures. It is a common and practical power supply processing solution in mixed signal systems.

[0044] Figure 5 is a schematic diagram of a second-stage buck circuit provided in an embodiment of the present application; Figure 5 As shown, one foot of C9 is connected to +5V and U3's 3rd foot, and the other foot is connected to DGND. U3's 2nd foot is connected to 4th foot, and 1st foot is connected to DGND. C10 and C11 are connected in parallel between U3's 4th foot and DGND, and then L3 is connected in series with U3's 4th foot. C12 is connected in parallel between the other foot of L3 and DGND, and the foot connected to L3 by C12 is connected to +3.3VD pull-up. L5 and L6 are connected in series with two signal lines, L5 is connected in series with the foot connected to L3 by C12, and L6 is connected in series with the foot connected to DGND by C12. C18, C19, and C20 are connected in parallel between two signal lines, and the foot connected to L5 is connected to +3.3VA pull-up, and the foot connected to L6 is connected to AGND.

[0045] The +5V DC digital signal output by the first buck regulator U1 is input to the second buck regulator U3, and then outputs a +3.3V DC digital signal after LC low-pass filtering. This DC signal is subjected to another LC low-pass filtering to obtain an isolated +3.3V analog signal with smaller ripple.

[0046] Figure 6 This is a third-level buck principle block diagram provided by an embodiment of the present application; as shown in the figure, the input 3.3V DC power supply is first converted to 1.5V by the third buck regulator, and the third buck regulator can ensure the output of a stable 1.5V voltage and eliminate the influence of input voltage fluctuations. The 1.5V signal after voltage reduction passes through the second low-pass filter voltage regulator module. This filtering link can effectively filter out high-frequency interference and noise, and only allow low-frequency signals to pass, thereby providing a purer signal source. After filtering, one path is directly output as a 1.5V DC digital signal, and the other path is processed by the isolation circuit and output as a 1.5V DC analog signal.

[0047] Figure 7 is a schematic diagram of a third-stage step-down circuit provided in an embodiment of the present application; Figure 7 As shown, one leg of C13 is connected to +3.3VD pull-up and connected to U4's 3rd leg, and the other leg is connected to DGND. U4's 2nd and 4th legs are connected to +1.5VD pull-up, C14 and C15 are connected in parallel between U4's 4th leg and DGND, U4's 4th leg is connected in series with L4, C16 and C17 are connected in parallel between L4's other leg and DGND, and the leg of C17 connected to L4 is connected to +1.5VA pull-up.

[0048] The +3.3V DC signal output by the second buck regulator U3 is input to the third buck regulator U4, which then outputs a +1.5V DC signal, which is then filtered through a first-stage LC low-pass filter and outputs a +1.5V analog signal isolated from the above electrical signal.

[0049] It should be noted that 1.5VD pull-up refers to the 1.5V pull-up voltage in digital circuits (Digital). It is usually used in digital signal processing circuits, such as the I / O interface level of digital chips such as FPGA and CPLD. When using 1.5V pull-up, the signal line is connected to a 1.5V power supply through a pull-up resistor to ensure that the signal remains at 1.5V when in a high-level state. This low-voltage digital logic is mainly used in low-power designs to reduce chip power consumption and heat generation.

[0050] +1.5VA pull-up refers to the 1.5V pull-up voltage in analog circuits. This voltage is often used in analog signal processing circuits, such as the power supply or reference voltage of analog chips such as operational amplifiers, ADC / DAC, etc. Analog circuits have higher requirements for power quality and usually require better filtering and isolation measures. Therefore, +1.5VA often requires an independent power management circuit and a separate grounding system to prevent the switching noise of the digital circuit from interfering with the accuracy of the analog signal.

[0051] The main purpose of designing the pull-up voltages of digital and analog circuits separately is to prevent the switching noise of digital circuits from being coupled to analog circuits through the power supply, to improve the accuracy and stability of analog signals, to facilitate electromagnetic compatibility design, and to make the system have better anti-interference capabilities.

[0052] The present application also discloses a DC voltage reduction and isolation method, such as Figure 8 As shown, Figure 8 1 is a flow chart of a DC step-down and isolation method provided in an embodiment of the present application, specifically including S101-S104: S101, filtering and voltage stabilizing the input DC signal to generate a stable initial DC signal.

[0053] In one example, the DC voltage reduction and isolation method first performs filtering and voltage stabilization on the input DC signal, using an LC filter circuit composed of capacitors and inductors to eliminate high-frequency interference and fluctuations in the input signal, and using a voltage stabilization device to maintain voltage stability, thereby generating a stable initial DC signal. The purpose of this step is to ensure that the signal source for subsequent processing has good quality and to prevent unstable factors at the input end from affecting the entire system.

[0054] S102, stepping down the initial DC signal to generate a DC signal to be processed.

[0055] Subsequently, the initial DC signal is stepped down by a step-down module, which uses a switching power supply or a linear regulator to reduce the voltage to the required level and generate a DC signal to be processed. The step-down process is to meet the operating voltage requirements of subsequent circuits and improve the energy efficiency of the system.

[0056] S103, filtering and voltage stabilizing the DC signal to be processed to generate a target DC signal.

[0057] Next, the DC signal to be processed after voltage reduction is filtered and stabilized again. This step uses a low-pass filter and a voltage regulator circuit to eliminate the switching noise and ripple generated during the voltage reduction process to ensure that the output target DC signal has a higher purity.

[0058] S104, converting the initial direct current signal into an isolated electrical signal.

[0059] Finally, the initial DC signal is converted into an isolated electrical signal through isolation devices such as optocouplers or transformers to achieve electrical isolation. The purpose of isolation processing is to prevent interference in the system from affecting each other through the power supply or ground line, protect sensitive circuits from interference, and improve the reliability and stability of the system. This multi-level processing solution can effectively achieve accurate voltage conversion, and ensure signal quality through filtering and isolation measures, and finally output a stable, pure and mutually isolated power signal to meet the strict requirements of various electronic devices for power quality.

[0060] Take the common 5V to 3.3V and then to 1.5V power supply system in practical applications as an example: First, when the 5V DC signal is input into the system, it is initially filtered by the LC filter circuit composed of inductor L (typical value 100μH) and capacitor C (typical value 47μF), and then stabilized with voltage stabilization chips such as AMS1117 to generate a stable 5V initial DC signal. Such processing can effectively suppress the 50Hz power frequency interference and high-frequency switching noise that may exist in the input power supply, ensuring that the output voltage ripple is less than 50mV.

[0061] Subsequently, a switching buck chip such as LM2596 is used to reduce the 5V initial DC signal to 3.3V to form a DC signal to be processed. The reason for choosing a switching power supply solution instead of a linear buck is that it has a higher energy conversion efficiency (usually more than 85%) and can effectively reduce heat generation.

[0062] The 3.3V DC signal to be processed is refined using a TPS7A series low-dropout linear regulator in conjunction with an LC filter circuit (L=47μH, C=22μF) to generate a 1.5V target DC signal with a ripple less than 10mV.

[0063] Finally, digital isolators such as ADUM1201 or optocoupler isolators such as TLP2768 are used to achieve signal isolation. These devices have a withstand voltage of more than 2.5kV, can effectively block common-mode interference, and have a fast response speed (transmission delay <100ns). Through this multi-level processing solution, the entire system can ultimately achieve output voltage accuracy better than ±1%, ripple less than 10mV, and isolation withstand voltage> 2.5kV performance indicators, meeting the power supply requirements of most high-precision electronic equipment.

[0064] The above is only an exemplary embodiment of the present disclosure, and the scope of the present disclosure cannot be limited thereto. That is, any equivalent changes and modifications made according to the teachings of the present disclosure are still within the scope of the present disclosure. After considering the specification and practicing the disclosure here, those skilled in the art will easily think of other embodiments of the present disclosure. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary technical means in the technical field not recorded in the present disclosure. The description and examples are only regarded as exemplary, and the scope and spirit of the present disclosure are defined by the claims.

Claims

1. A DC step-down and isolation system, characterized in that: The system comprises: a low-pass filter voltage regulator module, a first buck regulator and a power supply isolation conversion module, wherein the low-pass filter voltage regulator module comprises a first low-pass filter voltage regulator module and a second low-pass filter voltage regulator module, wherein the output end of the first low-pass filter voltage regulator module is electrically connected to the input end of the first buck regulator, and the output end of the first buck regulator is electrically connected to the input end of the second low-pass filter voltage regulator module; wherein, The first low-pass filtering and voltage stabilizing module is used to perform filtering and voltage stabilizing processing on the input DC signal to generate a stable initial DC signal; The first step-down regulator is used to step down the initial DC power signal to generate a DC power signal to be processed; The second low-pass filtering and voltage stabilizing module is used to perform filtering and voltage stabilization processing on the DC signal to be processed to generate a target DC signal; The power isolation conversion module is used to convert the initial direct current signal into an isolated electrical signal.

2. The DC step-down and isolation system according to claim 1, characterized in that: The first low-pass filter voltage stabilization module includes a DC input filter circuit and a step-down output filter circuit; wherein, The DC input filter circuit is used to filter the input DC signal; The step-down output filter circuit is used to perform voltage stabilization filtering on the filtered DC signal to generate a stable initial DC signal.

3. The DC step-down and isolation system according to claim 1, characterized in that: The first buck regulator includes a buck regulator and an adjustable buck regulator; wherein, The step-down regulator is used to perform a first-stage step-down process on the initial DC signal; The adjustable step-down regulator is used to perform secondary step-down regulation on the DC signal after the first-stage step-down processing according to a preset voltage value to generate a DC signal to be processed.

4. The DC step-down and isolation system according to claim 1, characterized in that: The system further includes: a second buck regulator, wherein the output terminal of the first buck regulator is electrically connected to the input terminal of the second buck regulator; wherein, The second step-down regulator is used to step down the target DC power signal to generate a stepped-down first DC power signal; The second low-pass filtering and voltage stabilizing module is used to perform filtering and voltage stabilization processing on the first direct current signal to generate a second direct current signal.

5. The DC step-down and isolation system according to claim 4, characterized in that: The system further includes: a third buck regulator, wherein the output terminal of the second buck regulator is electrically connected to the input terminal of the third buck regulator; wherein, The third step-down regulator is used to step down the second DC power signal to generate a stepped-down third DC power signal; The second low-pass filtering and voltage stabilizing module is used to perform filtering and voltage stabilization processing on the third DC signal to generate a fourth DC signal.

6. The DC step-down and isolation system according to claim 1, characterized in that: The first low-pass filter voltage stabilization module includes: a protection circuit, a filter circuit and a step-down circuit; wherein, The protection circuit includes a fuse and a TVS tube; the filter circuit includes an electrolytic capacitor, a ceramic capacitor and an inductor; and the step-down circuit includes a step-down regulator.

7. The DC step-down and isolation system according to claim 1, characterized in that: The power isolation conversion module includes a power isolation chip and a filter capacitor; wherein, The power isolation chip is used to perform power isolation processing on the initial DC power signal; The filter capacitor is used to filter the initial DC signal after power isolation processing to generate an isolated electrical signal.

8. A DC step-down and isolation method, characterized in that: The method comprises: Perform filtering and voltage stabilization on the input DC signal to generate a stable initial DC signal; Stepping down the voltage of the initial DC signal to generate a DC signal to be processed; Performing filtering and voltage stabilization processing on the DC signal to be processed to generate a target DC signal; The initial direct current electric signal is converted into an isolated electric signal.

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