The Kynix Blog - General electronic semiconductor

SummaryAn innovative new method to engineer computer chips more easily and cheaper than conventioanl methods have been developed by researchers who from the University of Exeter.This new technique to produce cutting-edge,versatile microchips could revolutionize the speed,efficiency and capability of the next-gen of computers.About the researchThe discovery could revolutionise the production of optoelectronic materials – or devices that produce, detect and control light – which are vital to the next generation of renewable energy, security and defence technologies, the researchers said.Dr Anna Baldycheva, from Exeter's Centre for Graphene Science and author of the paper said:"This breakthrough will hopefully lead to a revolution in the development of vital new materials for computer electronics. The work provides a solid platform for the development of novel next-generation optoelectronic devices. Additionally, the materials and methods used are extremely promising for a wide range of further potential applications beyond the current devices." This innovative new research focused on developing a versatile,multi-functional technology to significantly enhance future computing capabilities. The team used microfluidics technology, which uses a series of minuscule channels in order to control the flow and direction of tiny amounts of fluid. For this research, the fluid contains graphene oxide flakes,that are mixed together in the channels, to construct the chips.While the graphene oxide flakes are two-dimensional- consisting of length and width only- the research team used a new sophisticated light-based system to drive the assembly of the three-dimensional chip structures.Crucially, the research team have analysed their methodology to not only confirm the technique is successful, but also to provide a blueprint for others to use to help manufacture the chips. "We are very excited about the potential of this breakthrough and look forward to seeing where it can take the optoelectronics industry in the future." added by professor Monica Craciun, co-author of the paper and Associate Professor of Nanoscience at Exeter.  This article provide by University of Exeter,and the research is  published in the respected journal Scientific Reports.Article edited by kynix. 

    This article shows how to use the buck converter for inverting or non-inverting voltage rails, and use it as an inverting buck-boost converter.     Catalog I. Brief Introduction II. Buck Converter III. Three DC/DC Converter Topologies 3.1 Isolated Buck Topology 3.2 Inverting Buck-boost (step-up and step-down)   Topology4 3.3 Isolated   Buck-boost Topology: +/- output5 FAQ   I. Brief Introduction   As we all known,power supply circuits come in the form of voltage step-up or step-down DC/DC converter. Nowadays,more and more applications require multiple voltage rails to drive ICs.The rails may be inverting,or non-inverting,with or without isolation.   While designers typically use multiple buck converters with single filter inductors, they add cost, footprint, and height. A simpler alternative is to use a single buck converter with coupled inductors or transformers configured in isolated converter topologies. Designers can use the buck converter for inverting or non-inverting voltage rails, and they can configure it for use as an inverting buck-boost converter.   Coupled inductors or transformers can also be used with a buck-boost converter to generate multiple inverting or non-inverting outputs with voltage step-up/down function. However, do you know what is isolated non-isolate DC/DC converter topologies? How they can be implemented using a single synchronous buck converter?   II. Buck Converter   A step-down transformer is a transformer that converts the higher voltage of the input end to the ideal voltage with relatively low output to achieve the purpose of reducing the pressure. A step-down transformer is a very important piece of equipment in the power transmission and transformation system.   Its normal operation is related to not only its own safety, but also the reliable power supply of users, and directly affects the stability of the power system. The protection configuration of the step-down transformer should satisfy in any case, the transformer can not be burned, the accident is enlarged, and the stability of the power system is affected. The principle of its work, the principle of relay protection, operation conditions, operation and requirements, and the abnormal operation and processing methods are introduced in detail. III. Three DC/DC Converter Topologies   The beauty of generating various converter topologies based on a single buck converter is that an optocoupler and its related circuitry are not required. This provides the benefit of a smaller footprint, lower component count, reduced complexity, and cost savings. Besides generating multiple outputs, the buck converter is configurable to operate as an inverting buck-boost converter, essentially providing a voltage step-up function. In addition, designers can create an isolated buck-boost converter using a similar concept.   3.1 Isolated Buck Topology A. +/- Step-down output: circuit operation1 An inverting and non-inverting step-down output can be generated with an isolated buck topology. Fig1 shows how it delivers a +/- output rail to any application that requires a positive and a negative supply. Fig1 Synchronous buck regulator uses isolated buck topology to generate ± Vout rail1   With reference to Fig1, the primary and secondary outputs are given by the following equations, assuming the leakage inductance of the coupled inductor or transformer and the DC resistance of the windings is negligible: where VIN is the input voltage, VO1 and VO2 are the primary and secondary outputs, respectively, D is the duty cycle, N is the turns ratio of the transformer, and Vdiode is the forward voltage drop across the diode.   During the cycle when the high side switch is on (current flow indicated by the green arrow in Fig1), the primary current ramps up and stores the energy in the magnetizing inductance of the transformer and the primary output capacitor. The diode on the secondary side is reverse biased and the load current on the secondary side is supplied by the output capacitor.   During the cycle when the low side switch is on (current flow indicated by the red arrow in Fig1), the primary current ramps down and releases the stored energy in the magnetizing inductance of the transformer, and the load current on the primary side is supplied by the output capacitor.   The diode on the secondary side is forward biased and the current flows from the transformer to supply current to the load, and charges up the secondary output capacitor. At steady state, the voltage at the secondary output is proportionally inverted compared to the voltage at the primary output, assuming the diode voltage drop, transformer winding resistance, and leakage inductances are negligible. Fig2 shows the operating waveforms for this architecture.   Fig2 Operating waveforms for a +/- step-down design1   B. +/+ step-down output2 Employing the same concept of generating secondary outputs using a coupled inductor or transformer, the secondary side can be configured differently to generate positive or negative secondary voltages. To generate a positive secondary output, the polarities of the transformer/coupled inductor as well as the secondary side diode are reversed. Fig3 shows an isolated buck topology to generate a dual +VOUT rail. Fig3 Isolated buck topology to generate a dual + VOUT rail2 C. +/+/- step-down output3 Fig4 shows an isolated buck topology to generate three outputs (dual +VOUT and single –VOUT rail). For a multiple output configuration, the total current of the various outputs reflected to the primary side must accounted for to make sure the IC is able to handle the resultant current. Fig4 Isolated buck topology to generate three outputs, dual +VOUT and single –VOUT rail3 The equations for the above circuit are as given below: Where VO1 is the primary output and VO2 and VO3 are the positive and negative secondary outputs, respectively, D is the duty cycle, N1 and N2 are the turns ratio of the transformer for VO2 and VO3, respectively. Vdiode is the forward voltage drop across the diode. IOUT1, IOUT2, and IOUT3 are the output current drawn from VO1, VO2, and VO3, respectively, IDS_pk is the peak current through the top switch and Δi is the triangular portion of the primary inductor ripple current.   3.2 Inverting Buck-boost (step-up and step-down) Topology4 An inverting buck-boost converter can be derived from the synchronous buck converter by connecting its GND terminal as the negative output of the buck-boost converter and the VOUT terminal of the buck converter as the GND of the buck-boost converter. Fig5 shows the circuit diagram of configuring the ISL85415 buck switcher as an inverting buck-boost converter. FigConfiguring a buck converter into an inverting buck-boost converter4 The equation for output voltage and output current are as follows: where VIN is the input voltage, VO1 is the output voltage, D is the duty cycle, IOUT is the output current, and IL is the inductor current.   During the cycle when the high side switch is on (current flow indicated by the green arrow in Fig5), the inductor current ramps up and stores energy in the inductor, and the output capacitor provides current to the load.    During the cycle when the low side switch is on (current flow indicated by the red arrow in Fig5), the inductor current ramps down and provides current to the load as well as charges the output capacitor. Operating waveforms for the inverting buck-boost design are shown in Fig6.     Fig6 Operating waveforms for an inverting buck-boost design4   3.3 Isolated Buck-boost Topology: +/- output5 A ± step-up/down output voltage can be realized using the isolated buck-boost topology. The filter inductor can be replaced with a transformer (or coupled inductor) to obtain a positive secondary output. Fig7 shows an isolated buck-boost topology to generate a ± step-up/down VOUT rail. Fig8 shows the operating waveforms for the isolated buck-boost design.   Fig7 Isolated buck-boost topology to generate a ± VOUT rail5 The voltage and current equations for the above circuit are given below: where VIN is the input voltage, VO2 is the secondary output voltage, Vdiode is the forward voltage drop across the diode, D is the duty cycle, N is the turns ratio of the transformer, IDS_pk is the peak current through the top switch, Δi is the triangular portion of the primary inductor ripple current, and IOUT1 and IOUT2 are the output current drawn from VO1 and VO2, respectively. Fig8 Operating waveforms for an Isolated buck-boost Topology: +/- output5 FAQ   1. What does a buck converter do? The buck converter is a very simple type of DC-DC converter that produces an output voltage that is less than its input. The buck converter is so named because the inductor always “bucks” or acts against the input voltage. The output voltage of an ideal buck converter is equal to the product of the switching duty cycle and the supply voltage. Like many power supply topologies, the buck converter operates on the principal of storing energy in an inductor. The voltage drop across an inductor is proportional to changes in electric current flowing through the device. 2. What is principle of Buck-boost converter? A Buck-Boost converter transforms a positive DC voltage at the input to a negative DC voltage at the output. The circuit operation depends on the conduction state of the MOSFET: On-state: The current through the inductor increases and the diode is in blocking state. 3. Are buck converters safe? A buck converter is probably no less reliable than most other topologies. It usually comes down to the reliability of the solder joints. The thing to remember about buck regulators is; if the series switch transistor fails SC - it dumps the full unregulated voltage into the load. 4. Are buck converters efficient? Buck converters can be highly efficient (often higher than 90%), making them useful for tasks such as converting a computer's main (bulk) supply voltage (often 12 V) down to lower voltages needed by USB, DRAM and the CPU (5V, 3.3V or 1.8V, see PSU). 5. How do buck converters work? The buck Converter circuit consists of the switching transistor, together with the flywheel circuit (Dl, L1 and C1). While the transistor is on, current is flowing through the load via the inductor L1. The action of any inductor opposes changes in current flow and also acts as a store of energy. 6. Do buck converters waste power? In a buck or boost converter, some energy is transferred directly from the source to the load as well, but the same principle applies. You can also look at a buck converter as an L-C filter on a square wave from the source. Again, all components are lossless, so there's no waste. 7. Does a buck converter limit current? The buck converter must operate at a very small duty cycle to keep the inductor current below the peak current limit threshold. ... Valley Current Limiting: Provides an additional level of protection. You can implement valley current limiting by sensing the inductor current when the low-side switch is on. 8. How do you adjust the current in a buck converter? You don't "adjust" output current. Loads draw whatever amount of current they need, provided the power supply can deliver it. If your total load exceeds the buck converter's rating of 3A, then you will be overloading it. If your total load is less than 3A, then you need not adjust anything. 9. How do you control a buck converter? A Buck converter consists of a transistor and diode that applies the supply voltage on an inductor capacitor, LC, circuit. The output voltage is the voltage across the capacitor. The input voltage u on the LC circuit is controlled by pulse width modulation, PWM. 10. What is the difference between buck and boost converter? In PV applications, generally, a Buck converter is used to charge the battery (since the output from a Buck converter is supposed to be less than its input), while a Boost converter is used to "match the load voltage" from the (supposedly) low voltage PV input.  

SummaryRecently the designers found a approach to improve speed,cost and linearity of A-D conversion--Using  ‘voltage-to-frequency converters’(VFCs) to perform A-D conversions in data acquisition systems that require strict monotonic response,high resolution and reuced noise and moderate speed.The VFC produces a pluse train with frequency proportional to the input voltage.Then a microcontroller or logic converts fre quency into a number by opening a gate for a fixed amount of time and counting how many.However,this approach is not perfect.the main drawback is that to increase speed, designers have to run the VFC at high frequency, which deteriorates linearity.   Design Ideathe design idea of this aproach reverses things.A circuit converts input voltage into a proportional time interval;then,the micro uses that interval to count pulses coming from its internal clock.The results are impressive:1.Good linearity as the voltage-to-period converter runs at low frequency2.Faster A-to-D conversion due to the high value of the clock frequency3.Potentially simpler program or logic, as it only has to count clock pulses, gated by the circuit4.Low priceCircuit and Voltage IssueThe key is that increasing the count frequency does not affect linearity of the A-to-D conversion, while increasing the frequency of the VFC always means worse linearity.Just see the following picture: This picture is a circuit about modified VFC,where the input voltage VIN and the reference voltage VREF swap their roles. The R1-R2 network shifts the input voltage so it is always more positive than the reference voltage and maintain proper operating conditions. The circuit uses all switches of the 4066 part: two in parallel build S1 to reduce the effect of imperfect switch flatness on linearity, one switch goes for S2, and the last switch is part of the start-up circuit, paralleling CINT, and controlled by the logic during initialization.As the input voltage changes from 0 to 5V, the output period changes from 78 to 578µs. Integration capacitor CINT and the threshold level of the one-shot’s Schmitt input do not participate in the period vs voltage relation.Filling the period with 10MHz clock pulses generates numbers from 780 to 5780 – one count per millivolt. Linearity is one count or ±0.02%, which is not a surprise when the maximum frequency is only 12.8kHz. The maximum time of the A-to-D conversion is 578µs. This is 8.65 times faster compared to the case of a 1MHz VFC, where it would take 5,000µs to count 5,000 pulses of 1µs. The interface program is short and simple.Calibration involves some back and forth due to the shift of the input voltage: adjust sensitivity to 100µs/V using the trim-pot of the one-shot. The nominal duration of the one-shot pulse is 26µs. Cancel the 780 count offset in the controller.The following table  shows that the V-to-P approach is significantly better than the V-to-F one (Refs 3, 4). Surprisingly, no chip-maker offers this type of converter.

SummaryAs the development of socialty,basically a family will own one car even in the development country. In the future over-the-air updates keep them constantly up to date,and thus also secure.  In the future, car owners will be able to enhance their car’s security, intelligence, and performance without getting up from the sofa. In the future, updating their car’s software will be as simple as updating apps on their smartphones today. A swipe of the smartphone will be enough to automatically update vehicle software or to download new functions directly from the cloud – without any need to visit the repair shop.    Situation AnalysisMore electronics, more functions, more software: the car is turning into a smartphone on wheels. Keeping vehicle software up to date is thus becoming increasingly important. New functions can provide extra convenience, even after the vehicle has been bought. Over-the-air software updates will therefore soon be a standard feature.Today’s vehicles feature as many as 100 control units. Even compact cars have between 30 and 50. Their software governs nearly every function in the vehicle. In addition, more and more vehicles are now connected – with the internet, other cars, and the infrastructure. This means a greater risk of weak links in vehicle software, as well as of manipulation. In this context, software updates over the cloud offer a solution that keeps cars constantly up to date, and thus also secure. In addition, the cloud updates mean that ever more functions can be added, with ever greater scope.If the necessary hardware is already installed, a new software function can be tried out and subsequently downloaded. In this way, lane-keeping or park-assist functions can be added, for example. And it is not just drivers that benefit from over-the-air software updates: in 2015, 15 percent of recalls in the automotive industry in the U.S. had to do with software errors. Four years previously, this figure was only 5 percent, according to a U.S. study based on data from the National Highway Traffic Safety Association (NHTSA). For automakers and their customers alike, such repair-shop visits are a huge waste of time and money, and online updates can significantly reduce this.  Over-the-air Software UpdateThe over-the-air software updates work priciple is secure,fast and simple. On the driver's smartphone or the car’s infotainment system, the online security updates are started and any new functions that need to be downloaded are selected. This information is sent to the cloud, which acts like a kind of app store, holding the updates in readiness and starting the process of downloading software to the vehicle. The data can either be downloaded in the background while the car is moving, or overnight when it is parked in its garage. As soon as the vehicle is in a secure condition (once it has parked, for example), the software updates are installed on the appropriate control units, where they are immediately activated. Security and the smooth interaction of automotive electronics, cloud, and software are decisive for an over-the-air update. Data security is ensured by the latest encryption technologies. A complex security architecture with end-to-end encryption protects the data transmission against unauthorized access. At the car-cloud interfaces, secure protocols and filters act like a firewall to ward off any hacking attempts. To ensure that an over-the-air update is not just secure, but also fast and reliable, fast update technologies such as delta and compression mechanisms are used. These accelerate the update process and reduce cost, since the data volume for the transmission remains low. One further security measure is to transmit the updates in sequences. If problems occur, the update process can be stopped and adjusted. Article resources: BoschArticle edited by kynix 

SummaryPublished in the Joural Nature Materials in Nov.13,2017,reaearchers from Princeton University,the Georgia Institute of Technology and Humboldt Uniersity in Berlin is pointing the way to possibly more widespread use of organic electronics. Their research focuses on organic semiconductors,a class of materials prized for their applications in emerging technologies such as flexible electronics, solar energy conversion, and high-quality color displays for smartphones and televisions. In the short term, the advance should particularly help with organic light-emitting diodes that operate at high energy to emit colors such as green and blue.  Body“Organic semiconductors are ideal materials for the fabrication of mechanically flexible devices with energy-saving low-temperature processes,” said Xin Lin, a doctoral student in electrical engineering at Princeton and the lead author. “One of their major disadvantages has been their relatively poor electrical conductivity. In some applications, this can lead to difficulties and inefficient devices. We are working on new ways to improve the electrical properties of these organic semiconductors.” Semiconductors, typically made of silicon, are the foundation of modern electronics because engineers can take advantage of their unique properties to control electrical currents. Among many applications, semiconductor devices are used for computing, signal amplification and switching( signal switches ). They are used in energy-saving devices such as light-emitting diodes and devices that convert energy such as solar cells. In the doping process used to make semiconductors their chemical makeup is modified by adding a small amount of chemicals or impurities. By carefully choosing the type and amount of dopant, researchers are able to alter the electronic structure and electrical behaviour of the semiconductor in a number of ways. As the article shows,researchers have developed an approach for greatly increasing the conductivity of organic semiconductors,which are formed of carbon-based molecules rather than silicon atoms. The dopant, a ruthenium-containing compound, is a reducing agent, which means it adds electrons to the organic semiconductor as part of the doping process. The addition of the electrons is the key to increasing the semiconductor’s conductivity. The compound belongs to a newly introduced class of dopants called dimeric organometallic dopants. Unlike many other powerful reducing agents, these dopants are stable when exposed to air but still work as strong electron donors both in solution and solid state. Seth Marder and Stephen Barlow from the Georgia Institute of Technology, who led the development of the new dopant, called the ruthenium compound a “hyper-reducing dopant.” They said it is unusual, not only in its combination of electron donation strength and air stability, but in its ability to work with a class of organic semiconductors that have previously been very difficult to dope. In studies conducted at Princeton, the researchers found that the new dopant increased the conductivity of these semiconductors about a million times. The ruthenium compound is a dimer, which means it consists of two identical molecules, or monomers, connected by a chemical bond. As is, the compound is relatively stable and, when added to these difficult-to-dope semiconductors, it does not react and remains in its equilibrium state. That posed a problem because to increase the conductivity of the organic semiconductor, the ruthenium dimer needs to react with the semiconductor it and then split apart. The researchers looked for different ways to break up the ruthenium dimer and activate the doping, eventually they added energy by irradiating with ultraviolet light, which effectively excited the molecules in the semiconductor and initiated the reaction. Under exposure to the light, the dimers split into monomers, and the conductivity rose. "Once the light is turned off, one might expect the reverse reaction to occur" and the increased conductivity to disappear, Marder said. "However, this is not the case." The researchers found that the ruthenium monomers remained isolated in the semiconductor even though thermodynamics should return the molecules to their original configuration as dimers. The team's hypothesis is that the monomers are scattered in the semiconductor in such a way that it is very difficult for them to return to their original configuration and re-form the ruthenium dimer. They are, according to the team “kinetically trapped." The researchers also discovered that doping was continuously re-activated by the light produced by the device. The light activates the system more, which leads to more light production and more activation until the system is fully activated, Marder said. "This alone is a novel and surprising observation." The work was supported in part by the National Science Foundation and the U.S. Department of Energy. Article edited by kynix   

DescriptionFor everyone,electrical energy is essential. We always trying to get unlimited electrical energy without spending money. Now kynix share a simple design proposed as small wind turbine for home use or low power usage,it requires low initial cost and gives best return in terms of electrical energy. Use the following small wind turbine circuit and setup to charge laptop,to charge electronic gadgets or to electronic appliances in home and outstations.  NoteBefore we start,we should emphasis that we should note:* High voltage caution! This Circuit Involves in operating High voltage handle with extreme care.* Handle the Wind Turbine Generator and Rotor blade as per the Instructions given by manufacturer.  Windmill Generator DesignSmall 12V wind turbine generator is capable of producing alternate energy through wind, the Bridge rectifier and controller rectifies the energy came from wind turbine generator and regulator-battery charger circuit helps 12V/4.5Ah SLA battery to get charging, then Step-up inverter circuit produce high voltage AC enough to operate home appliances.  Schematic of Wind Turbine Generator is as following.  WorkingThere are five stages:  1. 12V Wind turbine generator/Bridge Rectifier Circuit  2. Regulator / Battery charger circuit  3. Inverter circuit using CD4047  4. mosFET Drivers  5. Output Stage 12V Wind Turbine Generator12 Volt wind turbine or windmill available with different watts range, choose depends on your requirement. Bridge RectifierWe know the bridge rectifier converts AC supply into DC and here we used 1N4007 diode as a bridge rectifier element, it converts the energy from wind turbine into Direct Current (DC) supply. Regulator / Battery ChargerThe LM317 adjustable three terminal Positive voltage Regulator used here and it can give output voltage range from 1.25 V to 37 V with more than 1.5A current rating. final output from the regulator is given to 12/4.5Ah SLA Battery, this Battery provides DC bias to the inverter circuit. Regulator LM317 output voltage Vout can be obtained asVout = 1.25V *(R2/R1+1) R2 => R2+VR1 for given inverter circuit.Inverter Circuit using IC CD4047 (Switching Pulse Oscillator) Monostable / Astable multivibrator  CD4047 used here to produce switching pulse, This IC works in low power and available in 14 pin Dual in line package. It provides full Oscillation output F at Pin 13, 1/2 of oscillation at Pin 10 as Q and Pin 11 as Q’. each output pin gives 50% duty cycle.f = 1/8.8RCHere R => R4+VR2 and C=> C3. by using this formula we can obtain frequency output at pin 13. For pin 10 and 11 the formula changes as f=1/4.4RC. MosFET driversIRF540 N Channel power mosfet from vishay siliconix used as a switching drivers for this inverter circuit. It gives fast switching, and have high operating temperature characteristics (175ºC). Output StageMain part of wind turbine generator is output stage, here transformer X1 is used in reverse with specifications as 230V primary, 9V-0-9V / 1.5A secondary winding center tapped transformer. MOV (Metal oxide Varistor) protects electronic device connected at output. Wind turbine generator output voltage is directly fed into LM317 positive Regulator circuit and it is adjusted to give 12 volt output and Battery connected to this bias through (3A, 50V) Schottky diode. The CD4047 IC is connected and configured as Astable multivibrator, When we turn ON SPST switch this circuit starts oscillation. Output Q and Q’ are directly fed into switching power mosfet IRF540 & drives X1 transformer secondary winding, here the current flow occurs particular duration and not for particular duration. So varying electromagnet induced and primary winding coil produce EMF, hence we get Alternating current output. Depends on the count of winding and switching frequency output Voltage/Frequency get varied.