<span style='color:red'>novosns</span>：Technical Sharing | The Introduction of Gate Drivers and the Applications
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novosns：Technical Sharing | The Introduction of Gate Drivers and the Applications

　　1) Introduction of the Gate Drivers　　Gate driver is a buffer circuit between the low-voltage controller and the high-power circuit, which is used to amplify the control signals of the controller for more effective turn-on and turn-off of power devices.　　1. The functions of gate driver are as follows　　- Gate driver can convert the low-voltage signal from the controller to higher-voltage drive signal, so as to achieve stable turn-on and turn-off of power devices.　　- Gate driver can provide transient source and sink peak currents, which can improve the switching speed of power devices and reduce the switching loss.　　- Gate driver can effectively isolate the noise of high-power circuits and protect sensitive circuits against interference.　　- Gate driver typically integrates protection functions to effectively prevent damages to power devices.　　It can be seen that gate driver is used to ensure better performance of power devices in the system.　　2. There are four types of common power devices　　- Si-MOSFET devices, which withstand voltage of 20V-650V and are suitable for low-power systems.　　- Si-IGBT devices, which withstand voltage of greater than 650V and provide a strong current endurance capability. This type is suitable for high-voltage and high-power systems.　　--- Both Si-MOSFET and Si-IGBT are Si-based power devices that have been widely used, and their manufacturing technologies are mature and stable.　　- SiC-MOSFET devices, which provide withstand voltage range comparable to IGBT, but feature fast switching speed and low switching loss. They are more suitable for high-voltage and high-power systems.　　- GaN devices, currently constrained by the manufacturing technology, typically have a withstand voltage of less than 650V, but provide obviously advantageous switching performance. This power device type is suitable for high-frequency and high-power systems.　　--- SiC-MOSFET and GaN devices are wide bandgap semiconductors that boast significant performance advantages over Si-based ones, and will have a broad range of applications in the future.　　3. NOVOSENSE gate drivers　　Different power devices have varied requirements for gate drivers. Currently, NOVOSENSE has developed driver products suitable for these four types of power devices.　　4. Switching process of power devices　　How does a gate driver control the turn-on and turn-off of power devices? Below is a detailed explanation of the switching process of power devices. In power devices, there are equivalent parasitic capacitances, such as CGS, CGD and CDS. The switching process of a power device can be equivalent to the charging and discharging process of its parasitic capacitances.　　4.1 Turn-on process　　In the turn-on process, the driver IC connects the output signal to the driver power supply through an internal source current MOS, and charges CGS and discharges CGD through a gate resistor.　　- (t0-t1) stage: The gate current charges CGS, and VGS gradually increases. At this point, the power device is still turned off.　　- (t1-t2) stage: When VGS increases to a value greater than the gate threshold voltage Vth, the power device begins to turn on, and IDS increases with VGS until it reaches the maximum value.　　- (t2-t3) stage: This is the Miller Plateau period, where the gate current mainly discharges CGD, and VDS begins to decrease. The device is fully turned on.　　- (t3-t4) stage: The gate current continues to charge CGS, and VGS gradually increases to the power supply voltage. When the gate current reduces to zero, the turn-on process ends. The turn-on loss of the power device mainly occurs at the t1-t3 stage.　　4.2 Turn-off process　　In the turn-off process, the driver IC connects the output signal to the GND through an internal sink current MOS, and discharges CGS and charges CGD through a gate resistor.　　- (t0-t1) stage: The gate current mainly discharges CGS, and VGS gradually decreases.　　- (t1-t2) stage: This is the Miller Plateau period, where the gate current mainly charges CGD, and VDS begins to increase. When the voltage reaches VDC, the Miller Plateau ends.　　- (t2-t3) stage: IDS begins to decrease. When VGS decreases to Vth, IDS drops to zero, and the power device is completely turned off.　　- (t3-t4) stage: The gate current continues to discharge CGS, and VGS eventually drops to zero. The turn-off process ends. The turn-off loss of the power device mainly occurs at the t1-t3 stage.　　It can be seen from the analysis above that shortening the t1-t3 stage can effectively reduce the switching loss of power devices.　　4.3 Three types of common driver IC　　At present, there are three types of commonly used driver ICs, namely non-isolated low-side drivers, non-isolated half-bridge drivers, and isolated drivers.　　- Non-isolated low-side drivers are only suitable for power devices with a reference to GND, and provide dual-channel or single-channel driving capability. Non-isolated drivers are relatively simple to implement, requiring only single power supply. They are mainly used in low-voltage systems, such as AC/DC converters, electric tools, and low-voltage DC/DC converters. Currently, NOVOSENSE offers non-isolated low-side driver ICs including NSD1026V and NSD1015.　　- Non-isolated half-bridge drivers are used in power systems with a half-bridge configuration. The withstand voltage of the high and low sides is usually achieved through level shifting or isolation, ranging from 200V to 600V. To prevent shoot-through, half-bridge drivers provide an interlock function. When a non-isolated half-bridge driver is used in a system, single power supply plus bootstrap power is typically adopted. This driver IC type is mainly used in low-voltage or high-voltage systems, such as AC/DC converters, motor drives, and on-board DC/DC converters. Currently, the half-bridge driver ICs from NOVOSENSE include NSD1624 and NSD1224.　　- Isolated drivers use an internal isolation barrier to physically isolate high and low voltages. Isolated drivers provide flexibility in application. Single-channel and dual-channel isolated drivers are available for low-side, high-side, or half-bridge applications. To achieve primary and secondary isolation in the system, the high-voltage side requires an isolated power supply, making the power supply system relatively complex. Isolated drivers are mainly used in high-voltage systems, such as electric drives, photovoltaic inverters, and OBCs. Currently, NOVOSENSE offers NSI6602 dual-channel isolated driver IC, NSI6601/NSI6601M single-channel isolated driver IC, NSI6801 opto-compatible isolated single-channel driver IC, and NSI6611/NSI68515 smart isolated driver IC.　　2) Introduction to Isolation Solutions　　In a high-voltage power system, there is usually isolation between high voltage and high voltage, as well as between high voltage and low voltage. Why is isolation driver needed? First, an isolated driver can avoid harm to human body caused by high-voltage electricity, and meet safety standards through isolation. Second, it can protect the control system from damages that can be caused by lightning strikes and high voltage transients. Third, an isolated driver can eliminate ground loops and reduce interference from the high voltage side to the low voltage side. Fourth, it can realize voltage or current change and energy transfer.　　There are three commonly used isolation schemes. The first is optocoupler isolation, which achieves signal transmission through light-emitting diodes and phototransistors. This isolation scheme is low-cost, but provides weak CMTI (Common Mode Transient Immunity), limited temperature range, and short service life. The second isolation scheme is magnetic isolation, where the chip integrates micro-transformer and electronic circuit to achieve signal transmission. The magnetic isolation chips deliver benefits such as long lifetime, wide temperature range, and strong CMTI, but involve complex technology, high cost, and prominent EMI issue. The third isolation scheme is capacitive isolation, which achieves signal transmission through isolation capacitors and electronic circuits. It usually uses silicon dioxide (SiO2) as the insulating material. The capacitive isolation scheme features low cost, long isolation life, wide temperature range, and strong CMTI. NOVOSENSE adopts the capacitive isolation scheme.　　NOVOSENSE isolation solution　　Isolated driver ICs from NOVOSENSE usually have two dies – the primary die on the input side and the secondary die on the output side. There is a physical isolation between the dies. Two isolation capacitors are connected in series on the die to achieve double insulation capability. If one of the dies experiences an EOS failure, the driver IC can still maintain basic insulation capability. The top and bottom substrates of the two isolation capacitors are insulated using SiO2, which can ensure stable material properties, good chip consistency, and long isolation life. The top substrates of the two isolation capacitors are connected by metal wires for signal transmission. NOVOSENSE’s isolated driver ICs can withstand surge voltage up to 12kV and 8kV transient insulation voltage test, far exceeding the insulation requirements of high-voltage systems.　　The communication between the dies adopts the differential OOK modulation scheme, which ensures stable and reliable communication. The input signal is modulated at a high frequency and then transmitted from the primary die to the high-voltage die through the isolation capacitor, with the modulation frequency at a level of over 100 MHz. A proprietary CMTI modular circuit is added at the input side of the differential signal, allowing the IC to achieve a stronger CMTI capability up to 150V/ns. For power systems with a high dv/dt, the IC can still work stably without abnormal wave emission.
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Release time：2024-06-21 11:23 reading：655 Continue reading>>
<span style='color:red'>novosns</span>：Must-Know Basic Facts about Digital Isolators
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novosns：Must-Know Basic Facts about Digital Isolators

　　Electrical isolation is a crucial concept in the design of electrical systems. Through the isolation of the high and low voltage systems, the following important functions can be achieved:　　1.Make the high and low voltage systems independent of each other and improve the anti-interference capability of the low voltage system;　　2.Ensure safe interaction between the high and low voltage systems so that the systems can work safely;　　3.Protect users' personal safety by avoiding electric shock from the high voltage.　　In this Technical Sharing, the basics of electrical isolation will be introduced in detail, including: the definition and importance of electrical isolation, the classification and definition of isolation levels, and the standards and specifications for isolator certification.(Click here to watch the video　　Definition and Importance of Electrical Isolation　　Electrical isolation uses isolators to prevent destructive electrical signals from being transmitted between high/low voltage subsystems, while allowing safe electrical signals required for system operation to interact between high/low voltage systems. Three system interaction scenarios are discussed below:　　1.When two low voltage systems interact, electrical signals can be freely transmitted between the two systems. In this state, we usually consider the systems to be working safely.　　2.When high/low voltage systems interact directly without isolators, due to the high potential difference between the high voltage system and the low voltage system, the high voltage system may transmit destructive electrical signals to the low voltage system, which will cause the low voltage system to malfunction and even cause permanent damage to the low voltage system. This will not only affect the functional safety of the systems, but also endanger personal safety and lead to major safety accidents.　　3.After using an isolator for electrical isolation between the high and low voltage systems, destructive electrical signals are blocked by the isolator. Safe electrical signals required for normal system operation interact between the high and low voltage systems, ensuring the functional safety of the systems.　　Classification and Definition of Isolation Levels　　Based on different isolation performance, electrical isolation is divided into different isolation levels. Functional isolation, basic isolation, dual isolation, and reinforced isolation are among typical isolation levels:　　1. Functional isolation can only achieve the isolation necessary for normal device operation and does not have the function of electric shock protection, such as the PCB materials on the circuit boards.　　2. Basic isolation only provides single-stage isolation and can achieve isolation while the insulation layer is intact. But once the insulation layer fails, the system will be at risk of electric shock. Under normal circumstances, the isolation voltage that basic isolators can isolate is around 3kV, and there are a few basic isolators whose isolation voltage can reach 5kV.　　3. Dual isolation adds a layer of isolation on the basis of basic isolation to achieve system redundancy. It can ensure system security when single-stage isolation fails. In this way, the isolation voltage can reach 5kV and above.　　4. Reinforced isolation is also single-stage isolation, but it can achieve the same isolation strength as dual isolation.　　Standards and Specifications for Isolator Certification　　Currently, most common isolators adopt basic and reinforced isolation. In order to be certified for the two isolation levels, the performance of isolators needs to comply with regional codes and safety standards.　　In terms of isolator standards and certifications, the International Electrotechnical Commission (IEC) is the earliest non-governmental international electrotechnical standardization organization in the world. IEC works with organizations in multiple regions to develop international safety standards for electrical/electronic devices. In different regions, local standards are developed by different organizations. For example, the United States, Canada, Germany, and China all have local organizations.　　Isolators must meet local standards before they can be legally marketed commercially and the electrical/electronic products fitted with them can be sold to customers. Typically, the first page of an isolator datasheet will list standards that the isolator has passed. The reinforced isolation level of digital isolators is mainly proposed by VDE and promoted by IEC as a global standard. NOVOSENSE is a leader of digital isolators in China and also the first semiconductor company to obtain the VDE enhanced isolation certification.　　Under the current VDE standards, both basic and reinforced isolators have corresponding test standards and parameter specifications.　　In the maximum surge voltage test, both basic and reinforced isolators are required to pass 50 bipolar surge impulses, and the final measured voltage must not exceed 1.3 times the maximum surge voltage in the datasheet, on top of which reinforced isolators are required to pass a surge voltage test of at least 10kV.　　In applications, partial discharge phenomenon occurs when there are defects inside a device. which does not affect the insulation strength in short time. However, under the repeated impact of high voltage, the defect will eventually lead to the breakdown of the isolation barrier. Therefore, these defects need to be detected through non-destructive testing. Basic isolators need to pass the 1.5 times VIOSM surge test, while partial discharge testing of reinforced isolators needs to be conducted at 1.875 times VIOSM voltage.　　According to the working life of chips at different temperatures and voltages, the working voltage of chips under the minimum rated life and failure rate during the target life can be fitted by Weibull distribution, and then VIORM and VIOSM can be obtained according to the requirements of the VDE correlation coefficients. It can also be seen from the table that reinforced isolators have a longer working life and a lower failure rate during their life.　　After passing the above tests, isolators are deemed to have met the requirements for VDE certification.　　To sum up, electrical isolation involves the working safety of devices and the personal safety of users, and is an indispensable part of electrical system design.
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Release time：2024-04-09 11:58 reading：706 Continue reading>>
<span style='color:red'>novosns</span>：Sensors improve the energy efficiency and environmental performance of central air conditioners through precise temperature, humidity, pressure, and current measurement
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novosns：Sensors improve the energy efficiency and environmental performance of central air conditioners through precise temperature, humidity, pressure, and current measurement

　　With the improvement in people's living standards and the growing demand for a more comfortable living environment, China's central air conditioning market has maintained relatively stable growth. Temperature and humidity, pressure, and current sensors with high-precision detection capability are critical to the various functions of central air conditioning. As a manufacturer of high-performance, high-reliability analog and mixed-signal chips, NOVOSENSE offers a wide range of sensor and analog IC solutions for central air conditioning applications.　　Development trends and new requirements for central air conditioning　　According to statistics, in the first half of 2023, in China's central air conditioning sales, multi-connected systems accounted for approximately 51%, continuing to rank first in the market. The reason why multi-connected systems are favored by the market mainly lies in their low installation cost, flexible applications, and high energy efficiency. For this reason, some well-decorated homes have also begun to standardize on this type of air conditioning.　　Commercial central air conditioners adopt a one-to-many architecture, in which an outdoor unit drives multiple indoor units. Each indoor unit has a corresponding line controller, which can automatically adjust the air outlet, airflow, and cooling and heating power through the feedback of temperature and humidity to maintain a comfortable indoor temperature.　　The development trend of multi-connection technology is mainly reflected in two directions. One is energy saving and noise reduction: outdoor units and even indoor units have frequency conversion capabilities, which can reduce noise by increasing the frequency while achieving low standby power consumption. The other is better comfort and improved environmental performance: meeting specific requirements for airflow, temperature and humidity control while reducing the damage of refrigerant leakage to the natural environment to ensure effective air conditioning.　　· NOVOSENSE's sensor products can exactly meet the above trend requirements. These products include temperature and humidity sensors and pressure sensors that meet comfort and environmental performance requirements, magnetic current sensors that ensure normal operation of outdoor units, and various analog IC products.　　NOVOSENSE offers comprehensive sensor solutions for central air conditioning applications　　The temperature and humidity sensor is used to detect the ambient temperature and humidity to control the airflow from the air outlet and balance the ambient humidity for improved comfort.　　NSHT30 is a temperature and humidity sensor with very small size and very high accuracy. It adopts a 2.5mm×2.5mm small package (LGA and DFN options). The MCU reads the temperature and humidity data through the I²C interface of the sensor. Temperature and humidity measurements are from -40°C to 125°C and from 0 to 100%, which can basically cover all temperature and humidity ranges.　　The advantage of NSHT30 is, first of all, the response time. The acquisition time of temperature and humidity is only 2s and 6s, respectively. Its accuracy is also higher than other similar products in the market. The chip calibration before leaving the factory can ensure high accuracy requirements. Under the condition of 0~50°C, the error of NSHT30 can be controlled at ±0.3°C (typical value); and under the condition of 50% relative humidity, the error can be controlled at ±3% to meet the accuracy requirements of air conditioning.　　The pressure sensor is usually placed on the outdoor unit or refrigerant transmission pipe to detect refrigerant leakage and refrigerant pressure, ensuring effective air conditioning while achieving environmental performance.　　NSPAS3 is an integrated absolute pressure sensor for refrigerant leakage pressure detection in air conditioners. Its operating temperature is from -40°C to 130°C, and its internally integrated temperature compensation circuit can achieve ±1% control accuracy in the range of 0~85°C and ±1.5% control accuracy in the range of -40°C to full temperature.　　NSPAS3 is compatible with the pressure test range of 10kPa~400kPa and can detect refrigerant leakage pressure. The standby power consumption of this product is less than 3mA, and the response time is within 0.8ms. In addition, the chip package is coated with anti-corrosion jelly glue, which can prevent some corrosive gases from damaging the chip package.　　NSC2860x is a capacitive pressure transmitter signal processing ASIC solution. It can detect the refrigerant pressure (3~5MPa) in the air conditioning compressor. The chip integrates various digital components such as PGA, ADC, MCU and various interfaces. It has a very high degree of integration and can convert the monitored pressure into a digital signal for processing by the MCU. NSC2860x also integrates a 4-20mA loop power supply, which enables longer distance transmission to meet the communication distance requirements between the pressure sensor and the MCU main control board in the refrigerant system.　　The magnetic current sensor is generally placed in the outdoor unit and is mainly used to monitor the current of the outdoor unit, such as PFC current or phase current of the air conditioning compressor motor. It achieves tracking feedback by collecting system current signals to ensure normal operation of the system.　　NSM2019 is an integrated Hall current sensor, mainly used to detect the motor current or PFC current of the air conditioner. The MCU reads the current value through the VOUT pin. It integrates the reference voltage and OCP (overcurrent protection) internally, eliminating the need for some peripheral devices such as comparators or op amplifiers. This product covers a range of 20A~200A, which can meet the power requirements of commercial air conditioners from several kilowatts to one hundred kilowatts.　　NSM2019 has an accuracy of ±2% and can guarantee accuracy over the full temperature range. Its isolation withstand voltage is up to 5,000V, the creepage distance is up to 8.2mm, and it can withstand 20kA surge current. Its input bandwidth is as high as 320K, which can meet the bandwidth requirements of current detection. Due to the small internal resistance, the heat output of the chip is also small.　　Other analog IC solutions for central air conditioning applications　　In addition to sensors, NOVOSENSE offers many analog IC product solutions. Analog ICs are mostly used in outdoor units. The topology of the outdoor unit determines that the 220V mains power needs to be rectified by PFC to approximately 400VDC, which then feeds the bus voltage of the two motors. The motor is directly driven by IGBT or IPM. The MCU that drives the IGBT is usually placed at the low voltage end, so it is necessary to use an isolated driver to rotate the motor. As a result, many isolated driver products are required. At the same time, the current and voltage must be monitored. The PLC also needs to collect the voltage and current, so op amplifier products are also used.　　The outdoor unit and the indoor unit communicate through 485 or CAN bus. Since the two generally do not share a common ground, some isolated interfaces are also needed. NOVOSENSE provides digital isolator products that convert high voltage to low voltage to power MCUs. The power supply is usually converted from high voltage to low voltage by flyback power supply, then converted to 5V by DC-DC, and then converted to 3.3V by LDO to power other chips.
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Release time：2024-03-18 16:53 reading：879 Continue reading>>
<span style='color:red'>novosns</span>：Digital isolator selection starts with a good understanding of datasheet
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novosns：Digital isolator selection starts with a good understanding of datasheet

　　Digital isolators now enjoy increasingly greater popularity than optocouplers. Will you really choose a digital isolator? Since digital isolators provide basically same functions with optocouplers, these two device categories have many similar parameters, but also different ones. This article will talk about how to select a digital isolator using its datasheet.　　Explore further after datasheet reading　　When it comes to device selection, it’s advisable to turn to the datasheet. Speaking of datasheet, here may a slight digression. Previously, Chinese chip makers didn’t give due attention to datasheet, and it’s not easy to access the datasheet of a device. Now the datasheet of many products are easily available on the official website of the corresponding manufacturer. This reflects that Chinese chip makers dare to “battle” with global manufacturers in device parameters.　　Datasheet can be seen as the instruction manual of a device. Generally, the instruction manual of a product is devised in a progressive way, from overview to detailed parameters and then to the do’s and don’ts. This is also true of a datasheet. However, datasheet has its specific format, which includes introduction, key parameters, safety approvals (isolators can affect safety, so safety approvals are mandatory), applications, basic device information (package and size), and block diagrams.　　Accordingly, we should gradually determine the requirements and narrow the scope of selection. When we have a datasheet, the first step is to read the overview on Page 1, which is a brief summary of the product typically including parameters and introduction. It allows us to have a fast understanding of the performance indicators of the chip in a short time. Product selection and prototype verification are often the most time-consuming part of system design. Therefore, a detailed reading and understanding of the overview section is very helpful for our early-stage screening of devices.　　Afterwards, we should have a clear picture of the application’s specific requirements and evolution trajectory. A datasheet typically lists suitable applications, such as automotive, photovoltaic, motor, and industrial automation, etc.　　We have got a general picture of the product from the above-mentioned section of the datasheet. To select an ideal device for an application, more details are required. Here comes what we will talk about next – What parameters of digital isolator should be focused on?　　Look into the whole story behind parameters　　For a digital isolator, what parameters are important enough to warrant attention? To avoid talking on paper level, we asked Ye Jian, Product Line Director, NOVOSENSE, to share his insights. Having worked in the isolator field for years, Ye has fully witnessed how digital isolators replace optocouplers. Taking NSI82xx-Q1SWWR high-reliability multi-channel ultra-wide-body digital isolators for example, he explained the datasheet of digital isolators in detail.　　Although a datasheet lists an array of parameters that may leave you at a loss, such as insulation voltage, CMTI, package, data rate, power consumption, and ESD, Ye identified the items that should be given great attention. Specifically, he listed the following seven key parameters (in no particular order) using NOVOSENSE products as an example.　　First, insulation voltage. Isolator is a device that is required to comply with safety regulations, so the isolator selection must be made around safety. Insulation voltage is the most important influencing factor of safety. For example, NOVOSENSE offers a range of basic and enhanced isolators that feature different withstand voltage ranges, so as to meet different system requirements of customers.　　Second, ESD. ESD protection is an important contributor to high reliability of isolator. For the vast majority of chips, ESD immunity is a must-have property, but the capability level requirement depends. Isolators are placed in high-voltage environment, usually the high-low voltage interface in the system, so ESD immunity is also extremely important. NOVOSENSE isolators provide HBM withstand voltage of up to 8kV, the highest chip-level HBM ESD.　　Third, CMTI. It is another key parameter of isolator, which measures a chip’s capability to resist transient interference, that is, the device’s robustness in system applications. CMTI refers to the maximum tolerable rate of short time voltage rise or fall to the value that can destroy the output state of driver. The transient interference is caused by the high DV/DT on the switching node. If the CMTI capability is insufficient, output error or even short circuit may occur, affecting the system safety. The CMTI of isolators from NOVOSENSE is mainly ±200kV/μs, and can even reach ±250kV/μs in some models.　　Fourth, package. Package here is more than body size, and is also related to such parameters as withstand voltage and safe creepage. Different chips will be provided depending on customer requirements or system requirements, but the ultimate objective must be meeting the safety requirements in a smaller and higher-integration package. For example, NOVOSENSE provides different package types including SOP, SOW and SOWW to answer different safety requirements, which will be elaborated later.　　Fifth, data rate and propagation delay. Data rate is an indicator of whether a digital isolator is high-performance, which can be up to hundreds of Mbps or even Gbps level. Different communication standards and interfaces have different requirements for data rate, which need to be carefully checked. However, Ye also underlined that data rate, be it 1Mbps or 150Mbps, has small impact on the device cost. That’s why NOVOSENSE does not provide more product categories by data rate. Instead, basically all digital isolators from NOVOSENSE provide a data rate of 150Mbps, which can meet the requirements of the majority of applications. In addition to data rate, there will also be detailed parameters related to timing in the datasheet, which should also be taken into consideration in the system design.　　Sixth, power consumption. According to Ye, the power consumption of digital isolators has been greatly reduced, relative to optocouplers. Therefore, the power consumption requirement is relatively small, but the datasheet will still describe the power consumption level under various conditions.　　Seventh, operating temperature. Operating temperature is strongly linked to applications. For example, there are four grades of automotive digital isolators, from Grade 0 to Grade 3, which pose different operating temperature requirements. A Grade 0 device is required to cover the temperature range of -40°C-150°C. Industrial digital isolators have different temperature requirements depending on applications, and the maximum requirement is typically -40°C-150°C. These are described in detail in the datasheet.　　How can package make a difference　　As stressed by Ye, package can make a very big difference for isolators. The main reason is that the package size can directly affect the withstand voltage capability of a device. Therefore, particular attention needs to be paid to package. All desire compact devices, but the realization of higher isolation voltage requires a wider-body package. NOVOSENSE has introduced regular package, wide-body package, and ultra-wide-body package. The advantages of ultra-wide-body package are mainly reflected in two parameters – creepage of 15mm, and isolated withstand voltage of 8 kVRMS. Enhanced isolators can provide an insulation level comparable to two basic isolators connected in series. This makes enhanced isolator a perfect choice for some special applications, for example, photovoltaic inverter.　　In short, a larger package will allow higher isolation voltage specifications. If you can choose a smaller package to meet the regulatory requirements for the system, the smaller package undoubtedly helps reduce the footprint on board and costs. In addition, you need to consider how many isolation channels the communication interface requires, because the higher the number of channels is, the more important the package type will be.　　Clearance and creepage are two different parameters. Clearance is the shortest spatial distance measured between two conductive parts or between a conductive part and the device interface. Creepage refers to the shortest distance between two conductive parts or between a conductive part and the device interface measured along the insulating surface.　　Clearance and creepage can be affected by environmental pollution level, altitude, and CTI. Particularly in solar and wind power and other continuously operating applications in harsh field conditions, altitude and pollution have a very high impact on clearance and creepage. How can the clearance and creepage requirements be met while reducing the overall size? The CTI of NOVOSENSE products reaches 600V, which can minimize the creepage requirements of the system, thus reducing the system size.　　Safety standards are crucial　　Meeting the parameter specifications alone does not mean the end of isolator selection, and due attention needs to be paid to safety approvals. Isolator is a safety related device, so safety approvals are often shown in the most visible position. For example, the first page of a NOVOSENSE datasheet gives the safety approvals of the device, including UL1577, CQC, CSA and VDE. The reason why certification standards matter greatly is that manufacturers can easily obtain the system safety approvals, provided that they select products that have won safety certification, so that their systems can be used and sold worldwide with great confidence.　　UL1577 standard is a key component level certification requirement for digital isolators, and is applicable to optocouplers, magnetic isolators and capacitive isolators. To obtain the UL1577 approval, a device must withstand the isolation voltage VISO (specified by the manufacturer, usually 2.5kVRMS or 5kVRMS) for 1 minute. The standard also provides that isolators are required to pass 100% production tests using 120% isolation voltage for 1 second.　　In addition, digital isolators also need to refer to regional safety certification standards, such as CQC, CSA, and VDE. Behind the safety approvals are strict test procedures. A device is required to pass aging test, high withstand voltage test, sampling test, extended temperature test, life test and others. It’s especially noted that a complete cycle of life test lasts more than half a year.　　Passing certification tests of agencies does not mean a once-and-for-all thing. When a device is put into mass production, each product needs to be tested. For example, each isolator from NOVOSENSE has passed high voltage test at the factory, and batch sampling tests are carried out on quarterly basis. The complete testing procedures help ensure the safety and reliability of isolators.　　Closing remarks　　The following sections of a datasheet basically include specific pin layout diagrams, property parameters, description of details, detailed measured results, application note, package size diagram, and certification guide, providing references for engineers in different stages of system design.　　Since isolators are not master chips, there are not many do’s and don’ts in their service. For products like main processor, their datasheet may have hundreds of pages. As isolator is safety critical, engineers need to read all the relevant information carefully and fully.　　In the analysis of the datasheet from NOVOSENSE, we have understood how important the key parameters of digital isolator are in product selection, and have got a basic knowledge of safety standards. We also have seen the obvious progresses of devices from NOVOSENSE and Chinese chip makers at large. This is attributable to NOVOSENSE’s ongoing R&D investment, and its product development approach of getting close to applications and market requirements.　　In a nutshell, if you want to use a product or technology well, the first step is to understand it, and the best way to do so is to read its datasheet.
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Release time：2023-11-03 15:10 reading：1913 Continue reading>>
<span style='color:red'>novosns</span>：Ultra-wide-body digital isolators make high-voltage applications more efficient and reliable
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novosns：Ultra-wide-body digital isolators make high-voltage applications more efficient and reliable

　　In recent years, the number of photovoltaic systems, chargers, new energy vehicles, energy storage facilities and other emerging technologies is increasing, and the installed base of industrial control devices, power supply, electricity and other conventional applications is still climbing. In this setting, high-voltage digital control applications pose growing isolation requirements, and the market sees a strong demand for high-efficiency and high-reliability digital isolators accordingly.　　In high-voltage systems, a reliable isolation gate must be built using isolation means, which electrically isolates sensitive electronic components from fast transient high-voltage components to ensure power safety, better system performance and higher reliability. To this end, many factors need to be taken into account, including isolation rating, creepage distance and electric clearance, common-mode transient immunity (CMTI), and electromagnetic interference (EMI).　　Wide bandgap (WBG) devices like SiC and driver products pose higher requirements for isolators while continuously improving the power density. Digital isolator now has become one of the semiconductor devices that help unlock the huge potential of high-voltage applications. It is widely used in photovoltaic systems, new energy vehicles, industrial automation systems, isolated SPI, RS232, RS485, general-purpose multi-channel isolation unit, and motor control.　　Challenges facing high-voltage isolation　　The growing requirements for higher reliability, longer service life and higher signal integrity in industry and automotive fields present challenges for high-voltage applications.　　High voltage power conversion must enhance efficiency while minimizing the system power loss. High voltage isolation design requires a robust isolation barrier to ensure system security. Under harsh operating conditions, it is necessary to address the difficulty in accurately measuring temperature, current and voltage by high voltage sensors.　　In addition, the use of WBG power devices also makes low-delay real-time control of high voltage systems essential. As the electrification process advances and high-voltage power systems become more complex, designers need to consider how to improve product performance and service life while ensuring the right isolation level and system security.　　Digital isolator is a device that enables signal transmission in electrical isolation condition. Featuring high operating voltage, low radiation, low power consumption and high efficiency, it is extensively used in industrial control, electric energy, communication networks, instrumentation, consumer electronics, and other electronic systems and devices.　　At present, three mainstream isolation solutions are available in the market: optocouplers, capacitive isolators, and magnetic isolators.　　Optocoupler came as the earliest isolation technology. It uses optical characteristics to realize one-way transmission of signals. However, due to optical attenuation over time, optocouplers may experience the aging effect.　　Capacitive isolator uses the capacitance effect to eliminate cross interference between signals, and features low propagation delay. It can transmit data at a rate of more than 150 Mbps, and consumes less bias current. However, capacitive isolator requires separate bias supply voltages on both sides of the isolation boundary. The biggest advantage of capacitive isolator is that it is low cost and can adopt a multichannel design.　　Magnetic isolator isolates signals by shielding the magnetic field. This makes it advantageous in applications requiring high-frequency DC-DC power conversion, but it is relatively expensive.　　Ultra-wide-body package emerging at the right time　　In photovoltaic applications, monocrystalline silicon and polycrystalline silicon materials are required. To improve the power density of photovoltaic modules, the bus voltage has been increased to 1500 V. This requires an isolator that provides a longer creepage distance to meet the voltage withstand and creepage distance requirements specified in China’s national standard GB4943.1-2022. As a response, some wide-body (SOP) and even ultra-wide-body (DWW) packages emerged. Actually, different manufacturers designate different names for ultra-wide-body packages.　　Ultra-wide-body digital isolator is a highly reliable isolation product that features high electromagnetic immunity, low electromagnetic radiation and low power consumption, and can withstand higher isolation surge voltage. The creepage distance of the ultra-wide-body package is up to 15 mm, which can meet the safety requirements of customers’ high-voltage systems. In photovoltaic systems for example, the creepage distance of isolator under 1500 V enhanced insulation condition shall be more than 14 mm, as required in IEC 62109.　　NSI82xx digital isolators from NOVOSENSE are products in ultra-wide-body package. They provide a long creepage distance of 15 mm, and an outstanding EMC property. This makes this digital isolator series a perfect choice for photovoltaic facilities and other high-voltage systems having a high creepage distance requirement. Moreover, the NSI82xx series is compatible with high-precision, high-speed and two-way digital isolators from other manufacturers, such as ISO78xx, ISO774x-Q1, and ACNT-H6xL, etc.　　Depending on applications, NSI82xx series are divided into two sub-series – NSI82xx-DSWWR and NSI82xx-Q1SWWR high-reliability, multichannel ultra-wide-body digital isolators. NSI82xx-DSWWR sub-series is designed for industrial applications, including NSI822xWx-DSWWR (2-channel), NSI823xWx-DSWWR (3-channel), and NSI824xWx-DSWWR (quad-channel). NSI82xx-Q1SWWR sub-series is suitable for automotive applications, including NSI822xWx-Q1SWWR (2-channel), NSI823xWx-Q1SWWR (3-channel), and NSI824xWx-Q1SWWR (quad-channel).　　According to the available information, NSI82xx-DSWWR ultra-wide-body digital isolators started mass production in January 2022, and a total of more than one million devices have been sold currently. More specifically, customers from power supply, NEVs, electric power, industrial control, photovoltaic, energy storage and charging piles are using ultra-wide-body digital isolators from NOVOSENSE.　　Answering high efficiency, high reliability and multi-function requirements　　For example, the quad-channel NSI824x digital isolator has UL1577 safety approval, and can withstand several levels of insulation voltage (3 kVrms, 3.75 kVrms, 5 kVrms and 8 kVrms). It’s noted that the ultra-wide-body package provides insulation voltage withstand capability of up to 8 kVrms, data rate of up to 150 Mbps, and CMTI of up to 200 kV/μs (min.).　　The NSI824x device provides digital channel direction configuration and the default output level configuration when the input power is lost. Thanks to a wide supply voltage range, NSI824x can be directly connected with most digital interfaces, and allows easy level shift. Moreover, high system level EMC performance enhances its reliability and stability in service.　　The NSI824x series adopts the capacitive isolator technology, where the digital signal is modulated by the RF carrier generated by the internal oscillator on the transmitter side, then transmitted via capacitive isolator and demodulated on the receiver side. It’s especially noted that the proprietary Adaptive OOK® modulation technology from NOVOSENSE is used, which delivers many benefits including high noise resistance and low EMI.　　Key features　　NSI824x digital isolators have rich functional features as described below:　　• Insulation voltage: Up to 8kVrms (Ultra-wide-body package)　　• Data rate: DC to 150Mbps　　• Power supply voltage: 2.5V to 5.5V　　• High CMTI: 200kV/μs (min.)　　• Chip level ESD: ±8kV (human body model)　　• Robust electromagnetic compatibility (EMC)　　• System-Level ESD, EFT, and surge immunity　　• Low electromagnetic radiation　　• Default output high level or low level option　　• Low power consumption: 1.5mA/ch (1Mbps)　　• Low propagation delay: <15ns　　• Operating temperature: -55°C - 125°C　　• RoHS-compliant packages:　　• SOP16 (150mil), SSOP16, SOP16 (300mil) and SOP16 (600 mil)　　Part number, package and body size　　NSI824x digital isolators have the following safety regulatory approvals:　　• UL1577 recognition: Insulation voltage up to 8kVrms for 1 minute　　• CQC certification per GB4943.1-2011　　• CSA component notice 5A　　• DIN VDE V 0884-11:2017-01 enhanced isolator certification　　Tips for PCB layout　　In PCB layout, it should be noted that a 0.1μF bypass capacitor is required between VDD1 and GND1, and between VDD2 and GND2 of the NSI824x device, and that the capacitor should be placed as close to the package as possible. In the front of the recommended PCB layout, it should be ensured that there are no planes, traces, bonding pads and via holes in the space under the chip.　　In case of excessively high system noise, users can also place a resistor (50-300Ω) connected in series with the input and output for enhanced robustness of their design. A series resistor can also improve system reliability, for example, latch-up immunity. The typical output impedance of the isolator drive channel is about 50Ω (±40%). When the drive transmission line affects the load, the output pin should be appropriately terminated with a PCB trace having controlled impedance.
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Release time：2023-10-31 14:05 reading：1507 Continue reading>>
<span style='color:red'>novosns</span> Digital isolators: Invisible guardians of system security and personal safety
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novosns Digital isolators: Invisible guardians of system security and personal safety

　　If there are anything requiring 100% attention in circuit design, they must include isolators.　　Isolators themselves do not have special computing, processing or conversion capabilities, but its evolution is inextricably linked to the development of industry, automotive, medical, and home electronics, etc. In view of the fact that their high reliability and performance soundly underpins system security, you should not brush aside isolators in your circuit design.　　Isolators as invisible guardians　　Some may see isolation a too-often-heard topic, but it actually plays an important role in protecting circuit and personal safety.　　In simple terms, the voltage of the execution system and the control system in electronic devices varies greatly – hundreds VAC vs. low VDC. In life, we isolate low-voltage and high-voltage systems, which also applies to circuit design. High-voltage systems often are more prone to electrostatic discharge, radio frequency, switching pulse and power disturbance, which can cause a voltage surge that is a thousand times higher than the voltage limit of many electronic components. Most importantly, these voltage surges are more likely to cause harm to human body, in addition to the noise and damages to electronic circuit.　　Here’s a simple example. The battery voltage in an electric vehicle (EV) can reach 400V, or even 800V, but the driver can calmly and safely operate all devices, instruments and knobs inside it. Behind this calmness and safety, various forms of isolation play a crucial role – they build a safe and reliable connection between high and low voltage systems.　　Considering such a profound effect, the selection of isolation type particularly matters.　　Since the day one of electricity use by human, people have longed for safe and reliable means of power control. In the 1830s, Joseph Henry, an American physicist, invented the electromagnetic relay using the theory of electromagnetic induction when he studied circuit control. Inspired by the phenomenon of magnetic force generation and disappearance in power-on and power-off conditions, he used a electromagnet to control the opening and closing of another circuit with high voltage and high current, enabling remote control and protection of the circuit.　　By controlling the electromagnet using a dry cell, a 220V AC electric circuit can be driven to enable safe control (or information transmission), which has a ring of “moving a thousand pounds with four ounces”. This simple procedure is the underlying principle of isolation, i.e. two unrelated circuits that are insulated from each other are connected in certain way.　　However, electromagnetic relay has obvious disadvantages, such as large footprint, high power consumption, and easy vulnerability.　　To overcome the aforesaid shortcomings, optocoupler came into being. It uses photovoltaic conversion to enable transmission and control, and implements a similar function at IC level. Opto-isolator, based on photoresistor, was launched in 1968. Compared with transformers, optocoupler that featured small footprint, light weight, low cost and high reliability, quickly became the mainstream in the market. The era of optocoupler development also saw the evolution of integrated circuit (IC) and information technology. With increasing interaction between low-voltage control and computing units and high-power motors and power supplies, optocouplers have been greatly improved.　　Undoubtedly, performance, power consumption and footprint are never-to-evade topics in the microelectronics world, and any strong technology cannot steer away from them. Optocouplers now meet the same challenges with electromagnetic relay – constrained by laser and photosensitive diode, optocouplers lose their edge in terms of footprint, power consumption, and reliability.　　Thanks to the advances of semiconductor technology, digital isolators have become rising stars.　　Merits and demerits of digital isolators　　It’s not difficult to understand digital isolators. They are similar to optocouplers, except that the photovoltaic conversion and modulation is changed to other technologies. However, it’s noted that optical attenuation will not occur in digital isolators. Unlike optocouplers, digital isolators provide many benefits, including good switching characteristic, low vulnerability to aging, high reliability, high voltage withstand ability, high speed, and energy transferability. All these are underpinned by semiconductor technology.　　By underlying principles, digital isolators can be divided into capacitive isolators and magnetic ones.　　Capacitive isolator, as its name suggests, uses the micro-capacitors inside the IC for high voltage isolation on the left and right sides, and adopts highly dielectric materials in the middle for voltage isolation. Capacitor is a device that can store charge, and comprises two conductor plates and medium. It allows high frequency to pass through, but blocks low frequency. The intermediate medium can isolate low frequency or DC high voltage signals.　　Using capacitor’s characteristic of allowing high frequency to pass through but blocking low frequency, modulation and transmission of signals can be performed. When a High-Low digital signal is input, the signal will be modulated inside the IC – the high frequency signal will be modulated into low frequency signal, allowing it to be transmitted to the other side of the IC. Typical OOK (On Off Key) modulation is as follows: “0, 1” signals will be modulated using different frequencies. For example, 1 represents high-frequency signal, and 0 represents unmodulated DC signal, and then two state switching signals are transmitted.　　Magnetic isolators are similar to capacitive ones, except that the former uses coils and electromagnetic conversion to implement data transmission.　　In a nutshell, digital isolators further address the disadvantages of optocouplers in terms of reliability, transmission rate, robustness, footprint, and service life.　　Perfection never exists in the realm of technology. Digital isolators boast visible advantages, but there are always trade-offs.　　First, digital isolators are relatively new, so their reliability is continuously being improved and demonstrated. With the successive introduction of related international and domestic standards, a complete range of approval processes and standards have been established, and customers from various industries have gradually given their recognition.　　Second, optocouplers still account for a dominant share in the industry, especially in some conventional applications. Therefore, the shift from optocoupler to digital isolator cannot be done overnight, because the pins and input type of digital isolators are not fully compatible. This requires changes of design. Sometimes customers are not willing to switch to digital isolator because of risk considerations. To this end, there is an Pin to Pin replacement alternative in the industry. In this solution, the optocoupler can be directly replaced and pins are compatible, and the built-in circuit is implemented in the input characteristics to simulate the diode characteristics. In this way, digital isolator can function exactly same with a optocoupler device in same application settings, and direct design replacement can be achieved.　　At last, common mode interference may occur in capacitive isolators, which needs to be suppressed.　　A typical OOK technology is simple and clear, i.e. the input signal is directly and correspondingly modulated and then demodulated on the other side. After high-frequency modulation, the signal and high-frequency common mode circuit are transmitted through one same path, so there will be common mode interference. This is also a shortcoming of ordinary capacitive isolators.　　Considering the above-mentioned problems, particular attention should be paid to the selection of devices. There are several methods to significantly enhance the immunity to common-mode interference. Taking the Chinese isolator manufacturer NOVOSENSE as an example, it has developed the Adaptive OOK® proprietary modulation technology on the basis of OOK, which improves the capability of digital isolators to resist common-mode interference.　　The so-called Adaptive OOK® technology uses the common mode detection circuit inside the IC to detect the state of common mode signals, and then depending on the signals detected, dynamically and adaptively modulates the internal key circuit characteristics or gains. When the common mode noise is large, it can better suppress the noise, so as to provide higher robustness and enhanced immunity to common mode interference.　　Another benefit of adaptive modulation is that high common-mode interference resistance does not need to be guaranteed at full operation state. Only when the instantaneous interference is relatively high, the circuit needs to perform more functions to suppress interference. In most cases where there is no harsh conditions and a low requirement for common-mode interference resistance, Adaptive OOK® technology can strike a good balance between system properties and power consumption to optimize the overall performance.　　Bring isolators further　　In the digital isolator market segment, only a few companies provide magnetic isolators, and capacitive isolators are the preferred choice of more manufacturers. What’s more, the number of capacitive isolators sold is growing very fast. In addition to patent related reasons, the overall manufacturing process of capacitive isolators is relatively simple, and does not differ greatly from general non-isolated devices in terms of wafer production. This allows capacitive isolators to deliver a big cost advantage.　　Furthermore, the process capability and performance of capacitive isolators are constantly improved. Particularly, their voltage withstand and surge resistance capabilities have been basically comparable to magnetic isolators, allowing capacitive isolators to meet the requirements of a wide range of applications.　　The products from NOVOSENSE can prove the above-mentioned trend. For example, the first-generation NSI81xx series meets the basic isolation requirements. The second-generation NSI82xx series answers the requirements of enhanced isolation, and provides enhanced resistance to common-mode interference, EMC performance and other electrical properties. According to NOVOSENSE, its third-generation products will further improve the voltage withstand capability and robustness.　　When it comes to the design of a capacitive isolator, the theory is simple, but the optimization and innovation of some processes and microarchitectures will have highly great effects on the overall performance. A case in point, from OOK to Adaptive OOK®, NOVOSENSE has done a lot to realize this “one-step-further” effort.　　Performance. Process capability and microarchitecture optimization contribute to continuous improvement of voltage withstand capability. For example, assuming that highly dielectric SiO2 is filled, different elements are also needed to further improve the voltage withstand capability. In addition, the electric field strength distribution of the capacitor can greatly affect the voltage withstand capability of isolator. Therefore, the design of capacitor structure, shape and other micro-architectures of each manufacturer, will affect the performance.　　Robustness. Isolator products are more widely used in industry, automotive and other high-voltage applications. Isolators are required to meet safety specifications. In applications involving safety, the selection of isolators having safety approvals is mandatory.　　To match specific requirements of analog, interfaces and signal chains, manufacturers need to introduce different product families for more applications. Isolator makes no exception. By combining the basic isolation function with other interfaces, drives or sampling knowledge, isolator technology can have wider applications.　　Backward derivation of product definition from applications is the main idea of product development, and also the greatest challenge. The definition of “isolation+” product around applications is not exactly same with that of pure digital isolators.　　Take isolated driver for example, in addition to the digital signal processing capability, manufacturers are required to be familiar with the power knowledge related to the driver in specific applications and ensure compatibility with power tubes from different manufacturers. Furthermore, SiC and other third generation wide band gap semiconductor applications pose more security and data transmission requirements for isolated drivers.　　For isolated interface products, the ESD and anti-interference capabilities need to be considered. Isolated sampling also requires a good expertise in high-precision signal chain.　　In addition, isolators sometimes need to be used together with power supply. In this setting, isolators that integrate the isolated power supply were launched.　　According to our knowledge, NOVOSENSE and other Chinese and global manufacturers coincidentally plan more isolation product categories – shifting from single category to “isolation+” expansion strategy, so as to provide isolation capability for more products.　　An increasing number of new applications and new markets push digital isolators to the same starting line with optocouplers. More and more niche applications, including EV, photovoltaics, and energy storage, are emerging, and the demand for digital isolators is rocketing. Customers are more willing to select digital isolators in the design of these new applications.
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Release time：2023-10-09 13:42 reading：2198 Continue reading>>

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