The Kynix Blog

 There are a number of hot new technologies on the forefront of online and offline retail including machine learning, the Internet of Things (IoT) and Blockchain, the information-sharing technology behind Bitcoin.We have written a bit lately about machine learning because it perhaps has the highest “world-changing” potential. But the IoT – especially when it comes to radio frequency identification (RFID) – also has huge potential to transform any retail operation.RFID has been around for many years and has been adopted by a range of retailers including Walmart, Macy’s and Amazon. The way it works is simply that each product is given a radio frequency ID tag and that tag has its own unique magnetic signature. That signature is picked up by a receiver or “RFID reader” that not only records the unique ID, but also the location of the tagged product. RFID is also the same technology that you see on new tap-and-go credit cards.  Because the tags are read magnetically, it is a more efficient system than a typical visual scanning system because the tag and the reader do not need to be line-of-site to communicate.  Therefore, the immediate benefit for an RFID-based system is that a typical retailer can reduce the time required to take a typical physical inventory by something like 90 percent.  In other words, if it took 3 days to take an inventory using barcode scanning, that same inventory would take 45 minutes using RFID. RFID also increases accuracy substantially. Usually manual-scanned physical inventory has a 4 percent inaccuracy rate.  And that number is compounded throughout the year, so cycle counts done throughout the fiscal year can reach more than 60 percent inaccuracy by the holiday selling season. Conversely, RFID typically has less than a 0.5 percent inaccuracy rate, meaning that inventory is much more accurate throughout the year.Here are some more innovative uses for RFID: Adhering To The Master Merchandising Plan Most chain retail stores have their own planogram, designating where each product should go in the store. However, the more stores that a retail chain operates, the harder it is to get each store to execute the central buyer’s merchandise plan precisely. With enough readers placed in strategic locations throughout the store, most merchandise can be tracked within a very small area. This means that the central buyer can get a report of all of the misplaced merchandise in each store. This means that if a cellphone accessory is mistakenly placed in the video game section, it will show up on a report and can be immediately remedied in the field.  In addition, oftentimes products remain in the stockroom when in fact they should be out on the floor. A solid RFID system will be able to detect whether or not items are still in the backroom, where they probably won’t sell well. Inventory Accuracy – Improving Click & CollectMost retailers have an omnichannel strategy – meaning that customers can buy online and then pick up their orders in the store. Of course, this kind of click-and-collect strategy is predicated upon the accuracy of the inventory count in each store.  In other words, if the system says that there are two units of a certain SKU in a particular store, but actually there is an inaccuracy and there are zero, they will deliver a terrible customer experience when the customer shows up at the store only to find out that the product is not there. The far better accuracy of RFID will allow retailers to have a much greater confidence level that the product is actually in the place that the system says it is.  Understanding the Store’s Hot SpotsAnother benefit of RFID is that there is a record of where products are displayed in a store. And that record can be overlaid with sales data so that we understand what specific displays and traffic areas within the store deliver the most sales. Of course, different spots within a particular store may work better with some products than they do with others.  RFID technology can also help determine the best possible scenario when considering the SKU type, store type and display area. Fast & Accurate CheckoutOne of the most customer-facing use cases for RFID is being able to pay for the products much more quickly than ever before. With RFID, the cashier does not even need to take the products out of the customer’s basket in order ring them up in the system. The ability to skip the manual scanning process entirely makes a radical difference in wait times, especially during peak periods. In addition, RFID capability at checkout greatly reduces the cash reconciliation error at the register.  Detecting Fake Goods: A product’s legitimate manufacturer can embed an RFID tag into the product in a hidden place, allowing a reseller to scan for the signal to prove that the product is authentic. The trickier issue is whether or not the actual RFID tag can be forged, but that is fodder for another discussion. There are more and more companies that can deliver a range of RFID-related products and services, from hardware to full-blown systems.Kynix is one of them.  Ref. KY78-A4650KY78-B82450A2364A  

New Yorker Electronics has introduced a series ruggedised aluminium electrolytic capacitors with welded seals, the MLSG in both Flatpack and Slimpack. This series targets compact power supply applications in military and aerospace, as well as other critical systems.Design enhancements and an electrolyte push the MLSG to nearly double the operating life of its predecessor, the MLSH, at no added cost.Two principal package profiles are offered in this technology, the MLSG Flatpack which measures just 0.5" thick and 1.75" wide and the MLSG Slimpack measuring 0.5" thick by 1" wide, both offered in lengths of 1.5, 2, 2.5 or 3".MLSG Flatpack welded seals capacitors can be made to withstand up to 50g vibrations (10g standard) and altitudes greater than 80,000ft. With stainless steel cases and near hermetic welded seals, they are built for extended duty in very harsh conditions. Especially noteworthy is that a high level of performance is maintained over the full operating temperature range. Capacitance retention at -55°C is very strong, with excellent high temperature performance up to 125°C. The new electrolyte system is fully REACH compliant, allowing application of the components in a broad range of applications where space efficiency and extraordinarily long life are required.A wide range of standard capacitance values from 220 to 24,000µF are available, with voltage ratings up to 250VDC. The unique flat package design does more than save space. It is easily cooled, and can offer flexibility in ganging two or more devices in ways that conventional electrolytics can’t.Options include High Vibration (HVMLSG), for performance to 50g, and High Reliability (HRMLSG), with burn-in at rated voltage and 85°C. Where a true glass-to-metal hermetic seal is required, CDE offers the MLSH Slimpack, which is similarly constructed in a flat stainless steel package. It is available in nine values, from 120 to 3,200µF, with ratings up to 250VDC.With a profile of 1x0.5", the MLSG Slimpack welded seals capacitors fit into the tightest of spaces and meet a DC test of 5,000 hours at rated voltage, 125°C. MLSG Slimpack is a perfect fit for military and aerospace applications requiring a low profile, rugged design and long-life. The MSGL Slimpack is also available in an HRMLSG type for high reliability burn-in – and is rated to vibration levels of 80g.Features and benefits5,000 hours at rated voltage of 125°CStainless steel caseWithstands more than 80,000ft. altitudeType HR, high reliability burn-inType HV, high vibration levelsFlatpack to 50g; Slimpack to 80gApplicationsAerospaceMilitaryCritical systemsPower suppliesReference:F17724102900MKP1841410254BFC246816474 

Catalog Overview       Structure and Working Principle of Power   MOSFET Structure of Power MOSFET WorkingPrinciple of Power MOSFET   Basic Characteristics of Power MOSFET Static Properties Dynamic Characteristics Switching Speed of MOSFET Improvement of Dynamic Performance                   Principle and Performance Analysis of High Voltage MOSFET Principle and Method of Reducing on Resistance of High Voltage MOSFET On-Resistance Distribution of MOSFET with Different Voltage Resistance The Idea of Reducing the On-Resistance of High Voltage MOSFET     Main Characteristics of Built-In Transverse Electric Field MOSFET The Decrease of On-Resistance The Reduction of Package and the Reduction of Thermal Resistance Improvement of Switching Characteristics Anti-Avalanche Breakdown Ability and SCSOA Development Status of Built-in Transverse Electric Field High Voltage MOSFET Comparison Between COOLMOS and IGBT Power MOSFET Drive Circuit Introduction and Analysis of Several MOSFET Drive Circuits An Unisolated Complementary Drive Circuit Isolated Drive Circuit   1. Overview The original meaning of MOSFET is Metal-Oxide-Semiconductor Field-Effect-Transistor. MOS means that the gate of the metal layer (M) is separated by the oxide layer (O) to control the field effect transistor of the semiconductor (S) by the effect of electric field. Power field effect transistors are divided into junction type and insulated gate type, but it usually refers to the MOS type（Metal Oxide Semiconductor FET） in the insulation grid type, which is referred to as power MOSFET. Junction power field effect transistors are generally referred to as Static Induction Transistor (SIT). It is characterized in that the gate voltage is used to control the drain current, the drive circuit is simple, the drive power is small, the switching speed is fast, the working frequency is high, and the thermal stability is better than that of GTR. However, its current capacity is small and it can just withstand low voltage. Generally speaking, it is only suitable for power electronic devices whose power does not exceed 10kW.   2. Structure and working principle of Power MOSFET Types of Power MOSFET: According to the conductive channel, it can be divided into P channel and N channel.  According to the amplitude of gate voltage, it can be divided into: depletion type and enhancement type. Power MOSFET is mainly N-channel enhancement type.   2.1 Structure of Power MOSFET The internal structure and electrical symbols of the power MOSFET are shown in figure 1. When a monopole transistor is turned on, only one polar carrier (multiple carriers) is involved in the conduction. The conductive mechanism is the same as that of the low power MOSFET, but the structure is quite different. The low power MOSFET is a transverse conductive device. The power MOSFET mostly adopts the vertical conductive structure, also known as VMOSFET (Vertical MOSFET), which greatly improves the voltage and current resistance of MOSFET devices. Fig 1.   According to the difference of vertical conductive structure, it can be divided into two types. One is VVMOSFET, which use V-shaped slot to achieve vertical conduction. Another is VDMOSFET (Vertical Double-diffused MOSFET), which has vertical conductive double diffusion MOS structure. In this article, VDMOS devices are discussed as an example.  The power MOSFET is a multivariate integrated structure, such as the hexagonal unit adopted by the HEXFET of International Rectifier, the square unit adopted by the SIPMOSFET of Siemens and rectangular unit adopted by TMOS of Motorola.   2.2 Working principle of Power MOSFET Cut-off: Positive power supply is added between drain and source, and the voltage between gate and source is zero. The J1 of the PN junction formed between the P base region P and the drift region N is inversely biased, and there is no current flow between the drain and source.  Conduction: By adding a positive voltage UGS between the gate sources, the gate is insulated, so no gate current flows through it. However, the positive voltage of the gate pushes away the holes in the region P below it, and attracts the electrons, minority carrier in the region P to the surface of the region P below the gate.  When the UGS is greater than the UT (turn-on voltage or threshold voltage), the electron concentration on the surface of the region P under the gate will exceed the hole concentration, making the P-type semiconductor inverse into the N-type and become the inversion layer. The inversion layer forms the N channel and makes the PN junction J1 disappear. The drain and source conduct electricity.   2.3 Basic characteristics of Power MOSFET  2.3.1 Static properties: the transfer and output properties are shown in figure 2. Fig 2. The relationship between drain current ID and gate source voltage UGS is called the transfer characteristic of MOSFET. When the ID is large, the relationship between ID and UGS is approximately linear, and the slope of the curve is defined as transconductance Gfs.  The drain volt-ampere characteristics (output characteristics) of MOSFET are as follows: Cutoff region (corresponding to the cutoff region of GTR) Saturation region (corresponding to the magnification region of GTR) Unsaturated region (corresponding to the saturation region of GTR)  The power MOSFET works in the switching state, which means that it switches back and forth between the cut-off zone and the unsaturated zone. There is a parasitic diode between the drain and source of power MOSFET, and the device is turned on when the reverse voltage is applied between the drain and source. The on-state resistance of power MOSFET has a positive temperature coefficient, which is beneficial to the current sharing of the devices connected in parallel.   2.3.2 Dynamic characteristics; the test circuit and switching process waveforms are shown in figure 3 Fig 3. 2.3.3 Switching Speed of MOSFET The switching speed of MOSFET has a lot to do with the charge and discharge of Cin. The user can not reduce the Cin, but can reduce the internal resistance of the drive circuit Rs, reduce the time constant and speeds up the switching speed. MOSFET only depends on multiple carriers to conduct electricity, and there is no minority carrier storage effect, so the turn-off process is very fast. The switching time is between 10-100ns, and the working frequency can reach more than 100kHz, which is the highest among the main power electronic devices. When the field control device is static, there is little need for input current. However, during the process of switching, the input capacitor needs to be charged and discharged, and a certain amount of drive power is still needed. The higher the switching frequency, the greater the drive power required.   2.4 Improvement of dynamic performance In the application of the device, in addition to considering the voltage, current and frequency of the device, we must also grasp how to protect the device in the application so as not to damage the device in the transient change. Of course, the thyristor is a combination of two bipolar transistors, coupled with the large capacitance brought by large area, so its dv/dt capability is relatively fragile. For di/dt, it also has a conduction zone extension problem, so it also brings quite strict restrictions. The case of power MOSFET is very different. Its dv/dt and di/dt capabilities are often measured by its ability per nanosecond rather than per microsecond. But in spite of this, it also has the limitation of dynamic performance. These can be understood from the basic structure of power MOSFET.  Fig. 4 is the structure of the power MOSFET and its corresponding equivalent circuit. In addition to the fact that almost every part of the device has a capacitance, it must also be considered that the MOSFET is connected in parallel with a diode. At the same time, from a certain point of view, it also has a parasitic transistor, just as IGBT is parasitic on a thyristor. These aspects are very important factors to study the dynamic characteristics of MOSFET. Fig 4. First of all, the intrinsic diode attached to the MOSFET structure has certain avalanche ability. It is usually expressed as the ability of a single avalanche and the ability of repeated avalanche. When the reverse di/dt is very large, the diode will withstand a very fast pulse spike. It may enter the avalanche area, once its avalanche capacity is exceeded, the device may be damaged. As any kind of PN junction diode, it is very complex to study its dynamic characteristics carefully. They are very different from the simple concept that we generally understand that the PN junction is conducted when it is forward and blocked when it is backward. When the current drops rapidly, the diode loses its reverse blocking ability and this is the so-called backward recovery time. When the PN junction requires rapid conduction, there will be a period of time when the resistance is not very low. Once the diode has a positive injection in the power MOSFET, the injected minority carriers will also increase the complexity of the MOSFET as a multi-subdevice.  During the design process of power MOSFET, measures are taken to make the parasitic transistors as ineffective as possible. The measures are different in different generation of power MOSFET, but the general principle is to make the transverse resistance RB under the drain as small as possible. Because only when the transverse resistance under the region N of drain flows through enough current to establish the positive deviation condition for the region N, the parasitic bipolar thyristor begins to cause difficulties. However, under severe dynamic conditions, the transverse current caused by dv/dt through the corresponding capacitance may be large enough. At this point, the parasitic bipolar transistor will start, possibly causing damage to the MOSFET. Therefore, when considering the transient performance, attention must be paid to the internal capacitance of the power MOSFET device, which is the channel of the dv/dt.  The transient situation is closely related to the line condition, which should be paid enough attention in the application. In order to understand and analyze the corresponding problems, it is necessary to have an in-depth understanding of the device.   3. Principle and Performance Analysis of High Voltage MOSFET In power semiconductor devices, MOSFET plays an important role in all kinds of power conversion, especially in high frequency power conversion with high speed, low switching loss and low drive loss. In the low voltage field, MOSFET has no competitors, but with the increase of the voltage resistance of MOS, the on-resistance increases to the power of 2.4 to 2.6. The growth rate makes MOSFET manufacturers and users have to reduce the rated current by tens of times in order to compromise the contradiction between rated current, on resistance and cost. Even so, the on-voltage drop caused by the on-resistance of the high-voltage MOSFET at the rated junction temperature is still high. The rated junction temperature and current of the MOSFET withstanding voltage above 500V are very high, and the on-voltage above 800V is astonishingly high. The conduction loss accounts for two-thirds to four-fifths of the total loss of MOSFET, which greatly limits the application.   3.1 Principle and Method of Reducing on Resistance of High Voltage MOSFET  3.1.1 On-resistance distribution of MOSFET with different voltage resistance: The resistance proportional distribution of each part of the on-resistance of MOSFET with different voltage resistance is also different. For example, the epitaxial layer resistance of 30V MOSFET is only 29% of the total on resistance, and the epitaxial layer resistance of 600V MOSFET is 96.5% of the total on resistance. From this, it can be inferred that the on-resistance of 800V MOSFET will be almost occupied by the epitaxial layer resistance. In order to obtain high blocking voltage, the epitaxial layer with high resistivity must be used and thickened. This is the fundamental reason for the high on resistance caused by the conventional high voltage MOSFET structure.   3.1.2 The Idea of Reducing the On-Resistance of High Voltage MOSFET　　 Increasing the core area can reduce the on-resistance, but the cost is not allowed by commercial products. Although the introduction of minority carrier for conducting electricity can reduce the conduction voltage drop, but the price is the decrease of switching speed and the appearance of trailing current, the increase of switching loss and the loss of the high speed advantage of MOSFET. The above two methods can not reduce the on-resistance of high voltage MOSFET, the remaining idea is how to separately solve the low doping of high voltage, high resistivity region and the high doping, low resistivity of conductive channel. For example, it has no other use except that the high voltage epitaxial layer low doping can only increase the on resistance. In this way, whether we can realize the conductive channel with high doping and low resistivity, and try to clamp the channel in some way when the MOSFET is turned off, so that the voltage withstand of the whole device depends only on the low doping N-epitaxial layer. Based on this idea, INFINEON introduced a built-in transverse electric field voltage of 600V COOLMOS in 1988 to realize this idea. The profile structure of the high voltage MOSFET with built-in transverse electric field and the schematic diagram of high blocking voltage and low on resistance are shown in figure 5. Different from the conventional MOSFET structure, the MOSFET with the built-in transverse electric field embeds the vertical region P and clamps the region N of the vertical conductive region in the middle, so that when the MOSFET is turned off, the transverse electric field is established between the vertical P and N. The N doping concentration in the vertical conductive region is higher than that in the epitaxial region. When VGS is less than VTH, the N-type conductive channel caused by the inversion of electric field cannot be formed, and the positive voltage between D and S makes the PN junction inside MOSFET backward bias to form a depletion layer and the vertically conductive region N is exhausted. This depletion layer has a longitudinal high blocking voltage, as shown in figure 5 (b), where the voltage resistance of the device depends on the voltage resistance of P and N-. Therefore, low doping and high resistivity of N-are necessary. Fig 5. When CGS is greater than VTH, the N-type conductive channel is formed by the inversion of electric field. The electrons in the source region enter the exhausted vertical region N to neutralize positive charge through the conductive channel, thereby restoring the exhausted N-type characteristics, so the conductive channel is formed. Because of the low resistivity in the vertical region N, the on-resistance will be significantly lower than that of the conventional MOSFET. Through the above analysis, we can see that the blocking voltage and on-resistance are in different functional areas. The contradiction between the blocking voltage and the on-resistance is solved by separating the blocking voltage from the on-resistance function. At the same time, the surface PN junction is transformed into a buried PN junction, and the blocking voltage can be further increased at the same N-doping concentration.   3.2 Main Characteristics of Built-in Transverse Electric Field MOSFET 3.2.1 The decrease of on-resistance The MOSFET of the built-in transverse electric field of the INFINEON withstands 600V and 800V respectively. Compared with conventional MOSFET devices, the on-resistance with the same core area decreases to one fifth and one tenth of conventional MOSFET, and the on-resistance decreases to one second and one third respectively at the same rated current. Under the conditions of rated junction temperature and rated current, the conduction voltage is reduced from 12.6V, 19.1V to 6.07V, 7.5V, and the conduction loss is reduced to one second and one third of conventional MOSFET, respectively. Because of the decrease of conduction loss, the decrease of heat and the relative coolness of the device, it is called COOLMOS.   3.2.2 The reduction of package and the reduction of thermal resistance Compared with the conventional MOSFET, the core of the COOLMOS with the same rated current is reduced to one third and one fourth, which reduces the package by two shell specifications. Because the thickness of COOLMOS core is only one third of that of conventional MOSFET, the RTHJC of TO-220 package is reduced from 1 ℃ / W to 0.6 ℃ / W, and the rated power is increased from 125W to 208W, which improves the heat dissipation capacity of the core.   3.2.3 Improvement of switching characteristics　　 The gate charge and switching parameters of COOLMOS are obviously better than those of conventional MOSFET. Due to the decrease of QG, especially QGD, the switching time of COOLMOS is about one second of that of conventional MOSFET, and the switching loss is reduced by about 50%. The decrease of turn-off time is also related to the low gate resistance in COOLMOS.   3.2.4 Anti-avalanche breakdown ability and SCSOA At present, the new MOSFET has the ability to resist avalanche breakdown without exception. COOLMOS also has the ability to resist avalanche. At the same rated current, the IAS of COOLMOS is the same as ID25 ℃. However, because of the decrease of the core area, when the IAS is smaller than the conventional MOSFET, and has the same core area, the IAS and EAS are larger than the conventional MOSFET. One of the biggest features of COOLMOS is that it has a short circuit safe operation area (SCSOA), but the conventional MOS does not have this feature. The SCSOA of COOLMOS is mainly due to the change of transfer characteristics and the decrease of core thermal resistance. The transfer characteristics of COOLMOS are shown in figure 6. As we can see from figure 6, when VGS is greater than 8V, the drain current of COOLMOS no longer increases, showing a constant current state. Especially when the junction temperature increases, the constant current value decreases, and at the highest junction temperature, it is about twice as much as ID25 ℃, that is, 3 to 3.5 times of the normal working current. In the short circuit state, the drain current will not rise to an intolerable ID25 ℃ due to the 15V drive voltage of the gate, so that the power dissipated by the COOLMOS in the short circuit is limited to 350V × 2ID25 ℃, so as to reduce the core heat during the short circuit as much as possible. The decrease of the thermal resistance of the core can make the heat generated by the core radiate quickly to the shell and restrain the rising rate of the core temperature. Therefore, COOLMOS can be driven by normal gate voltage, withstand 10 MS short circuit shock under 0.6VDSS power supply voltage for 1000 times without damage and the time interval is greater than 1s. Therefore, COOLMOS can be protected effectively in short circuit like IGBT. Fig 6. 3.3 Development Status of Built-in Transverse Electric Field High Voltage MOSFET Following the introduction of COOLMOS in 1988, ST introduced 500V internal structure similar to COOLMOS in early 2000, so that 500V, 12A MOSFET can be packaged in TO-220 shell, the on-resistance is 0.35 Ω, which is lower than that of IRFP450, and the current rating is similar to that of IRFP450. IXYS also has MOSFET that uses COOLMOS technology. IR also introduced the super MOSFET, rated current of 35A and 59A in SUPPER220, SUPPER247 package, and the on-voltage drop of about 4.7V when the on-resistance is 0.082 Ω, 0.045 Ω and 150C, respectively. From the comprehensive index, these MOSFET are superior to the conventional MOSFET. The proportional decrease of on resistance is not due to the increase of core area. Therefore, it can be considered that the above MOSFET must have a special structure similar to the transverse electric field. It can be seen that trying to reduce the conduction pressure drop of high pressure MOSFET has become a reality, and will promote the application of high voltage MOSFET.   3.4 Comparison between COOLMOS and IGBT The high temperature conduction voltage drop of 600V and 800V COOLMOS is about 6V and 7.5V respectively, the turn-off loss is reduced by one second, and the total loss is reduced by more than one second, so that the total loss is 40% to 50% of that of conventional MOSFET. The conduction loss of the conventional 600V MOSFET accounts for about 75% of the total loss, and the equilibrium point corresponding to the same total loss and ultra-high speed IGBT is 160KHZ, of which the switching loss accounts for about 75%. Because the total loss of COOLMOS is reduced to 40% to 50% of that of conventional MOSFET, the corresponding IGBT loss balance frequency will be reduced from 160KHZ to about 40KHZ, which increases the application of MOSFET in high voltage. From the above discussion, it can be seen that the new high voltage MOSFET solves the problem of high conduction voltage drop, and can simplify the design of the whole machine, such as the volume of heat dissipation device can be reduced to about 40%, drive circuit and buffer circuit are simplified. It has the ability to resist avalanche breakdown and short circuit, simplify the protection circuit and improve the reliability of the whole machine.   4. Power MOSFET drive circuit Power MOSFET is a voltage type driver. Because there is no minority carrier storage effect, the input impedance is high, the switching speed can be very high, the drive power is small, and the circuit is simple. However, the interpolar capacitance of the power MOSFET is large, and the relationship between the input capacitance CISS, the output capacitance COSS, the feedback capacitance CRSS and the interpolar capacitance can be expressed as follows: The gate input of the power MOSFET is equivalent to a capacitive network, and its working speed is related to the internal impedance of the drive source. Due to the existence of CISS, the gate drive current is almost zero in static state, but a certain drive current is still needed in the dynamic process of turning on and off. It is assumed that the gate voltage required for saturation conduction of the switch tube is VGS, the turn-on time TON of the switch includes two parts: the turn-on delay time TD and the rise time TR.   During the turn-off process of the switch tube, CISS is discharged through ROFF, COSS is charged by RL, COSS is larger, VDS(T) rises slowly. With the increase of VDS(T), COSS decreases rapidly to close to zero, and VDS(T) increases rapidly. According to the above analysis of the characteristics of the power MOSFET, the drive requirements are as follows: The trigger pulse should have a fast enough rise and fall speed;   Charging with low resistance gate capacitance when turned on, and providing low resistance discharge circuit for gate when turned off in order to improve the switching speed of power MOSFET;  In order to enable the power MOSFET to turn on by trigger, the trigger pulse voltage should be higher than the opening voltage of the tube. In order to prevent misconduction, a negative gate source voltage should be provided at its cut-off time; When the power switch switches, the drive current is the charge and discharge current of the gate capacitance. The larger the interelectrode capacitance of the power tube is, the greater the required current is, that is, the greater the load capacity is.   4.1 Introduction and Analysis of Several MOSFET Drive Circuits   4.1.1 An unisolated complementary drive circuit Figure 7 (a) is a commonly used low power drive circuit, which is simple, reliable and low cost. It is suitable for low power switchgear that does not require isolation. The drive circuit shown in figure 7 (b) has fast switching speed and strong drive capability. In order to prevent the two MOSFET tubes from going straight through, a 0.5 × 1 Ω low resistance is usually connected in series for current limiting. The circuit is suitable for medium power switchgear that does not require isolation. These two kinds of circuits are characterized by simple structure. Fig 7. Power MOSFET is a voltage type control device. As long as the voltage applied between the gate and the source exceeds its threshold voltage, it will be turned on. Because of the junction capacitance of MOSFET, the sudden rise of the voltage at both ends of the drain source will produce interference voltage at both ends of the gate source through the junction capacitance when it is turned off. The turn-off circuit of the commonly used complementary drive circuit has small impedance and fast turn-off speed, but it cannot provide negative pressure, so its anti-interference is poor. In order to improve the anti-interference of the circuit, a circuit composed of V1, V2 and R can be added to the drive circuit to produce a negative pressure. The circuit schematic diagram is shown in Fig. 8. Fig 8. When V1 is turned on, V 2 is turned off, the gate and source of the upper tube in the two MOSFET are discharged, and the gate and source of the lower tube are charged, that is, the upper tube is turned off and the lower tube is turned on, which is turned off by the driven power tube. On the contrary, when V1 is turned off, V 2 is turned on, the upper tube is turned on, and the lower tube is turned off thus to turn on the driven pipe. Because the gate and source of the upper and lower tubes are charged and discharged through different circuits, including the circuit of V 2 and because V2 will continue to exit saturation until it is turned off, it is slower for S1 to turn on than to turn off, and faster to turn on than to turn off for S2. Therefore, the degree of fever of the two tubes is not exactly the same; S1 is more serious than S2. The disadvantage of the drive circuit is that it needs double power supply, and because the value of R cannot be too large, otherwise it will make V1 deeply saturated and affect the turn-off speed. So, there will be a certain loss on R.   4.1.2 Isolated drive circuit Forward drive circuit The circuit principle is shown in figure 9 (a). N3 is demagnetizing winding and S2 is the driven power tube. R2 is a damping resistance to prevent voltage oscillation at the gate and source end of the power tube. Because the leakage sense is not required to be small, and in terms of speed, R2 is generally small, so it is ignored in the analysis. Fig 9. Its equivalent circuit diagram, as shown in figure 9 (b), is a secondary side parallel resistor R1, which is not required for pulse and used as a false load of the forward converter to eliminate the misconduction caused by output voltage oscillations during the turn-off period. At the same time, it can also be used as an energy release circuit when the power MOSFET is turned off. The conduction speed of the drive circuit is mainly related to the driven S2 gate, the equivalent input capacitance of the source, the speed of the drive signal of S1 and the current provided by S1. From the simulation and analysis, we know that the smaller the duty ratio D, the larger R1, the larger L, the smaller the magnetization current, the smaller the U1 value, the slower the turn-off speed. The circuit has the following advantages: The structure of the circuit is simple and reliable, and the isolated drive is realized;   Only a single power supply can provide positive pressure when on and negative pressure when off;   When the duty ratio is fixed, the drive circuit can have a fast switching speed through the reasonable parameter design.   The disadvantages of the circuit are as follows:　 First, because the secondary side of the isolation transformer needs a false load to prevent oscillation, so the circuit loss is large; second, when the duty ratio changes, the turn-off speed changes greatly. When the pulse width is narrow, the turn-off speed of MOSFET gate becomes slower due to the decrease of stored energy.   A complementary drive circuit with an isolation transformer As shown in figure 10, V1 and V2 are complementary, capacitance C acts as an isolated DC, and T1 is a magnetic ring or tank with high frequency and high magnetic flux. Fig 10. The voltage on the isolation transformer is (1 / D) Ui when it is on and D Ui when it is turned off. If the voltage of the main power tube S by conduction is 12 V and the original side-to-turn ratio N1/N2 of the isolation transformer is 12 / [(1 / (1) Ui], the C value can be slightly larger in order to ensure the voltage stability of GS during the conduction period. The circuit has the following advantages: The circuit structure is simple and reliable, and has the function of electrical isolation. The turn-off ability of the drive does not change when the pulse width changes;   The circuit only needs one power supply, that is, it works as a single power supply. The function of isolated capacitance C can provide a negative pressure when the driven tube is turned off, which accelerates the turn-off of the power tube and has high anti-interference ability;   However, one of the major disadvantages of the circuit is that the amplitude of the output voltage will change with the change of duty ratio. When D is small, the negative voltage is small, the anti-interference of the circuit becomes worse, and the positive voltage is higher, so we should pay attention to make its amplitude not exceed the allowable voltage of MOSFET gate. When D is greater than 0.5, the positive voltage of drive voltage is less than its negative voltage, so it should be noted that the negative voltage does not exceed the allowable voltage of MOAFET gate. Therefore, the circuit is more suitable for situations where the duty ratio is fixed or the duty ratio variation range is small or the duty ratio is less than 0.5.   Drive Circuit composed of Integrated Chip UC3724/3725 The circuit composition is shown in fig. 11. UC3724 is used to generate high frequency carrier signal, and the carrier frequency is determined by capacitance CT and resistance RT. In general, the carrier frequency is less than 600kHz, and high frequency modulation waves are generated at both ends of feet 4 and 6. After being isolated by high frequency small magnetic ring transformer, it is sent to feet 7 and 8 of UC3725 chip and modulated by UC3725 and the Drive signal is obtained. A Schottky rectifier bridge in UC3725 simultaneously rectifies the high frequency modulation waves of feet 7 and 8 into a DC voltage for drive power.Generally speaking, the higher the carrier frequency is, the shorter the drive delay time will be, but the anti-interference will become worse if it is too high. The larger the magnetization inductance of the isolation transformer is, the smaller the magnetization current, the less the UC3724 heat will be. However, with the increase of the number of turns, the influence of parasitic parameters becomes greater, and the anti-interference ability will also be weakened.According to the experimental data, it is concluded that for the signal whose switching frequency is less than 100kHz, it is better to choose (400 to 500) kHz carrier frequency, the transformer uses high magnetic conductivity such as 5K, 7K and other high frequency ring magnetic core, the original magnetization inductance is less than about 1 milligram. This kind of drive circuit is only suitable for the situation where the signal frequency is less than 100kHz. If the signal frequency relative carrier frequency is too high, the relative delay is too much, and the drive power is increased, and the heating temperature of UC3724 and UC3725 chips is higher. Therefore, the switching frequency above 100kHz can only be applied to the MOSFET with smaller pole capacitance. When switching frequency of 1kVA is less than 100kHz, it is a good drive circuit. The circuit has the following characteristics: single power supply, the control signal is isolated from the drive, and the structure is simple and small, especially suitable for the situation where the duty ratio is uncertain or the signal frequency is also changed.   Fig 11.

If you want the fastest and most reliable wired connection, cat 7 ethernet stands out as a strong choice for 2025. Many homeowners worry about speed, cable quality, and network performance. You should also think about how cat 7 ethernet can be good for smart home technology. Common concerns include:Managing cable lengths for best performanceAvoiding electrical interferencePicking the right cable type for your needsConsider what matters most for your home—streaming, gaming, or building a connected smart space.Cat 7 Ethernet OverviewImage Source: unsplashWhat Is Cat7?You may wonder what makes cat7 different from other network cables. Cat7 is a type of Ethernet cable designed for high-speed and high-performance networks. Cat 7 ethernet supports speeds up to 10 Gbps over 100 meters and can even reach 40 Gbps at shorter distances. The cable operates at a bandwidth of up to 600 MHz, which means it can handle more data at once compared to older cables. Each twisted pair inside cat7 has its own shield, and there is an extra shield around the whole cable. This strong shielding protects your network from electromagnetic interference, making cat 7 cables very reliable in busy or noisy environments.Here is a quick look at the technical details:Specification AspectCat7 Ethernet Cable DetailsSpeedUp to 10 Gbps at 100 meters; up to 40 Gbps at 50 metersBandwidthTypically 600 MHz (Cat7), up to 1 GHz (Cat7a)ShieldingFull shielding required: each twisted pair individually shielded plus an overall shield (STP)Standard RatificationRatified by ISO/IEC, not by TIAConnectorsSpecialized connectors like TERA or GG45 to support higher frequenciesNotesCat7 cables are heavier, more expensive, and require specialized termination hardware and toolsCat 7 ethernet is not as common in North American homes, but you might see it in places where interference is a big problem or where future-proofing is important.Cat 7 vs Cat 6 and Cat 8When you compare cat7 to cat6 and cat8, you see some clear differences. Cat6 is the most popular choice for home networks. It supports up to 10 Gbps, but only for distances up to 55 meters, and its bandwidth is up to 250 MHz. Cat7 keeps the same 10 Gbps speed but can do it over 100 meters and offers much better shielding. Cat 7 cables also have a higher bandwidth of 600 MHz, which helps with data-heavy tasks.Cat8 is even faster, supporting up to 40 Gbps, but only for short runs up to 30 meters. Its bandwidth can reach 2000 MHz, making it best for special uses like data centers.Here is a table to help you compare:Cable CategoryBandwidthMaximum SpeedMaximum DistanceCat6250 MHz10 Gbps55 metersCat7600 MHz10 Gbps100 metersCat82000 MHz40 Gbps30 metersImage Source: statics.mylandingpages.coYou will find cat6 in most homes because it is affordable and easy to install. Cat7 is growing in popularity for smart homes and places with lots of devices. Cat8 is usually for special jobs like high-speed servers or scientific labs.Tip: For most home users, cat6 gives you enough speed and bandwidth for streaming, gaming, and smart devices. Cat7 is a good choice if you want extra protection from interference or plan to upgrade your network in the future. Cat8 is often more than you need unless you run a server room at home.Performance and ReliabilitySpeed and BandwidthWhen you set up your home network, you want high speeds and stable connections. Cat7 cables deliver up to 10 Gbps for distances up to 100 meters. This means you can enjoy high-speed data transmission for gaming, streaming, or working from home. Cat7 also gives you more bandwidth than cat6 or cat6a. More bandwidth allows your network to handle more devices and more data at once.Here is a table that shows how cat7 compares to other Ethernet cables:Ethernet CableMax SpeedMax BandwidthMax Length for Max SpeedTypical Use CasesCat5e1 Gbps100 MHzUp to 100 metersResidential, basic office useCat610 Gbps250 MHzUp to 55 meters (for 10 Gbps)General office, some data centersCat6a10 Gbps500 MHzUp to 100 metersAdvanced office, data centers, industrialCat710 Gbps600 MHzUp to 100 metersHigh-speed networks, data centers, server roomsCat825-40 Gbps2000 MHzUp to 30 metersHigh-performance data centers, server-to-serverImage Source: statics.mylandingpages.coCat7 cables improve on cat6 by offering more bandwidth (600 MHz vs. 250 MHz) and better insulation. This means you get reduced noise and crosstalk, which helps keep your connection strong. Cat7 does not boost your speed above 10 Gbps unless you use advanced equipment, but it gives you more headroom for future upgrades. For most homes, cat6 or cat6a will meet your needs, but cat7 offers extra stability and more bandwidth if you want to future-proof your setup.Shielding and InterferenceInsulation plays a big role in network reliability. Cat6 cables usually have basic insulation and rely on twisted pairs to fight interference. Cat7 cables use advanced insulation with foil or braided mesh shields around each pair and the whole cable. This extra insulation blocks electromagnetic interference from other electronics in your home.Cat6 cables use simple insulation and tight twists to lower interference.Cat7 cables add more insulation with shields on each twisted pair and the whole cable, giving you better protection.Cat7 insulation means you get more stable connections in rooms with lots of electrical devices.Cat8 cables use even more complex insulation, but they work best for short distances in data centers.With cat7, you get more bandwidth and better insulation, so your network stays strong even in busy environments. You will notice fewer drops in connection and less lag during high-speed data transmission. Cat7 insulation helps keep your network reliable, especially if you have many smart devices or live in an area with lots of electrical noise.Tip: If you want the most reliable connection and more bandwidth for your home, cat7 insulation and shielding give you a clear advantage over cat6.Cat 7 Cables CompatibilityDevice SupportYou want your network cables to work with all your devices at home. Most cat 7 cables you find for home use come with RJ45 connectors. These connectors fit into the same ports as older cables, so you can use them with your router, modem, computer, gaming console, or smart TV. Many popular routers, like the TP-Link Archer C7 and Linksys EA7500, support these cables and can deliver speeds up to 10 Gbps.Cat 7 cables with RJ45 connectors are backwards compatible with Cat 5, Cat 5e, and Cat 6 devices.You can use them with Power over Ethernet (PoE) devices, such as smart cameras or Wi-Fi access points.The extra shielding in cat 7 cables helps reduce interference, which is useful if you have many electronics in one room.Note: The official cat 7 standard uses GG45 or TERA connectors, but most home devices use RJ45. This makes cat 7 cables with RJ45 connectors a practical choice for your home network.Home Network IssuesYou may face some challenges when using cat 7 cables in your home. While these cables are backwards compatible, the speed and performance depend on your equipment. If you plug a cat 7 cable into a Cat 5e port, your network will only run at Cat 5e speeds, up to 1 Gbps. The cable cannot make your devices faster than their own limits.Cat 7 cables are thicker and less flexible, which can make installation harder, especially in tight spaces.Proper termination is important. The shielding in cat 7 cables needs good grounding to avoid problems like ground loop interference.Using backwards compatible cables with older routers or switches will not give you the full benefits of cat 7. Your network will work, but it will not reach the highest speeds unless all parts support them.Tip: If you want to future-proof your home, cat 7 cables offer strong shielding and high speeds. Just remember that your network will only be as fast as your slowest device.Installation and CostImage Source: pexelsInstallation ChallengesYou might find that installing Cat 7 Ethernet cables in your home is not as simple as running older cables. Cat 7 cables have extra shielding and are thicker than Cat 5e or Cat 6. This makes them less flexible and harder to pull through walls or tight spaces. You may need to plan your cable routes carefully.Here are some common challenges you could face:Cat 7 cables are bulkier and more rigid, which makes them tough to bend around corners or fit behind baseboards.The extra shielding adds weight and stiffness, so you need more effort to install them in existing walls.You must handle the shielding with care. If you damage it, you could lose the benefit of reduced interference.Proper cable termination is important. You may need to upgrade your wall jacks or connectors to match Cat 7 standards.Cat 7 cables cost more than Cat 6, so you should consider your budget before starting a big project.You might need special tools or help from a professional installer, especially if you want to keep the shielding intact.Tip: If you want the best performance from Cat 7, plan your installation ahead of time and make sure your connectors and jacks are compatible.Price ComparisonWhen you look at the cost of Cat 7 Ethernet cables, you will notice a big difference compared to Cat 6. Cat 7 cables cost about two to three times more per meter than Cat 6. Cat 8 cables are even more expensive.Here is a quick comparison:Cable TypePrice Range per Meter (USD)Relative Cost Compared to Cat6Cat6$5 - $10BaselineCat7$10 - $302 to 3 times Cat6Cat8$25 - $1005 to 10 times Cat6The total installation cost for Cat 7 in a typical home is higher than Cat 6 but less than Cat 8. For example, Cat 6 installation averages about $3,800 for a home. Cat 7 installation costs more because of the cable price and the extra work needed. Cat 8 is the most expensive and is usually not needed for home use.Note: Cat 6 remains the standard for most homes because it balances speed, cost, and ease of installation. Cat 7 and Cat 8 offer better performance but come with higher prices and more complex installation.Pros and Cons of Cat7AdvantagesYou will find several strong reasons to choose cat7 for your home network. Here is a table that shows the main advantages and what they mean for you:AdvantageWhat It Means for YouHigher Bandwidth CapacityCat7 supports up to 600 MHz, so your network can handle more data than cat6 or cat5e.Faster Data Transfer SpeedsYou get up to 10 Gbps over 100 meters, which is faster than cat6 at longer distances.Superior ShieldingCat7 uses extra shielding to block interference from other electronics, giving you a more stable connection.Backward CompatibilityYou can use cat7 cables with older devices that support cat5e or cat6, making upgrades easier.Stronger ConstructionCat7 cables last longer because they use tough materials and extra layers.Ideal for High-Interference EnvironmentsCat7 works well in homes with lots of electronics or electrical noise.Future-ProofingCat7 supports new technology, so you will not need to upgrade your cables soon.Tip: If you want a network that can handle heavy streaming, gaming, or many smart devices, cat7 gives you extra speed and reliability.DrawbacksCat7 also comes with some downsides that you should consider before you buy.Cat7 cables cost much more than cat6, making them a bigger investment for most homes.You may find cat7 cables stiff and hard to install, especially in tight spaces.Cat7 uses special connectors like GG45 or TERA, which do not always fit standard home equipment that uses RJ45.Most home networks do not need the extra speed or shielding that cat7 offers. Cat6 usually meets your needs for streaming, gaming, and smart devices.Cat7 is not widely recognized in North America, so you might have trouble finding support or compatible hardware.You need special tools and skills to install cat7 properly, which can add to your costs.Cat7 cables are heavier and take up more space than cat6, which can make cable management harder.Note: For most homes, cat6 provides enough speed and is easier to install. Cat7 may be more than you need unless you have a very busy network or lots of interference.Is Cat 7 Ethernet Right for Your Home?Best Use CasesYou want your home network to be fast, stable, and ready for new technology. Cat 7 Ethernet cables work best in homes where you need top performance and strong protection from interference. If you have a smart home with many connected devices, Cat 7 can help keep everything running smoothly. Homes with lots of smart gadgets—like security cameras, smart lights, voice assistants, and smart fridges—benefit from Cat 7’s high bandwidth and strong shielding. This cable keeps your network stable, even when many devices use the internet at the same time.Gamers also see big advantages with Cat 7. The cable supports speeds up to 10 Gbps and a bandwidth of 600 MHz. Its advanced shielding reduces interference and crosstalk. You get lower latency, less lag, and fewer dropped connections. Many gamers notice smoother gameplay and lower ping rates, sometimes by 5-10 milliseconds. If you play online games or use VR, Cat 7 gives you a more reliable connection.Cat 7 is also great for homes with high-bandwidth needs, such as 4K streaming or advanced home theaters. The cable’s shielding keeps your video streams clear and free from buffering. You may prepare for future growth by choosing Cat 7, especially if you plan to add more smart devices or upgrade your internet speed later.Tip: Cat 7 cables shine in homes with lots of electronics, smart devices, or gaming setups. If you want a network that stays strong even in busy, noisy environments, Cat 7 is a smart pick.Here is a quick look at how Cat 7 compares to other cables for high-bandwidth activities:FeatureCat5Cat6Cat7Max SpeedUp to 100 MbpsUp to 1 GbpsUp to 10 GbpsBandwidth100 MHz250 MHz600 MHzShieldingMinimalImprovedSuperior (reduces interference)Max DistanceUp to 100 metersUp to 100 metersUp to 50 metersCat 7’s shielding and speed make it ideal for homes with many devices or high-tech setups.Image Source: statics.mylandingpages.coAlternativesYou have several good alternatives to Cat 7 for your home network. Cat 6 and Cat 6a cables are the most popular choices in 2025. Cat 6 supports up to 10 Gbps for short distances and works well for most homes. Cat 6a offers 10 Gbps speeds at up to 100 meters and uses standard RJ45 connectors, making it easy to install and compatible with most devices. Cat 6a is also cost-effective and provides enough speed for streaming, gaming, and smart home devices.Cat 8 cables deliver the highest speeds—up to 40 Gbps—and the most bandwidth. However, Cat 8 is usually overkill for home use. It costs much more and only works at top speed for short distances (up to 30 meters). Most homes do not need this level of performance unless you run a server room or need the fastest possible speeds for special projects.Here is a table to help you compare the main alternatives:Cable CategoryMax Speed & DistanceFrequency (MHz)Recommended Use CasePopularity in 2025Cat6Up to 10 Gbps (55m), 1 Gbps (100m)250Baseline for new home and office installations, cost-effective future-proofingMost popular alternative to Cat7, de facto standardCat6A10 Gbps (100m)500High-performance, future-proof installations, multi-gigabit networksIncreasingly standard for high-density and enterprise environmentsCat8Up to 40 Gbps (30m)2000Specialized data center and short-run applications, generally overkill for home useNiche, not common for home networkingCat5eUp to 1 Gbps (100m)100Legacy or budget installations, temporary setupsRarely recommended for new installationsImage Source: statics.mylandingpages.coCat 6a stands out as the best balance of cost, performance, and future-proofing for most homes. It supports 10 Gbps speeds, works with standard connectors, and is easy to install. Cat 7 is more expensive and harder to install, with little extra benefit for most users. Cat 8 is best for special cases where you need the fastest speeds over short distances.Note: When you choose a cable, think about your current devices, your internet speed, and whether you plan future upgrades. Cat 6a usually gives you the best mix of speed, price, and ease of use for home networks.Choosing cat 7 ethernet gives you strong speed, excellent shielding, and future-proofing for your home network. You get reliable performance for gaming, streaming, and smart devices, but you pay more and face tougher installation. Think about your needs—if you want the best for a busy, tech-filled home, cat 7 ethernet is a smart investment. For basic setups, Cat 6 may be enough. Weigh your budget, network demands, and plans for future upgrades before you decide.FAQCan you use Cat 7 cables with older devices?Yes, you can use Cat 7 cables with most older devices. The RJ45 connectors fit standard Ethernet ports. Your network speed will match the slowest device in your setup.Is Cat 7 Ethernet overkill for most homes?For many homes, Cat 6 or Cat 6a cables provide enough speed and reliability. Cat 7 works best if you have many smart devices, lots of interference, or want to future-proof your network.Do Cat 7 cables improve Wi-Fi speed?Cat 7 cables do not make your Wi-Fi faster. They improve wired connections between devices. You get better speed and stability for computers, gaming consoles, or smart TVs that use Ethernet.How long do Cat 7 cables last?Cat 7 cables last many years. The strong shielding and tough materials protect them from damage. You can expect reliable performance for at least 10 years if you install them properly.Can you install Cat 7 cables yourself?You can install Cat 7 cables yourself if you have basic tools and patience. The cables are thick and stiff, so plan your routes carefully. For best results, consider hiring a professional installer.

The simplest semiconductor component, the diode, has an astonishing number of applications that are enabled by a number of practical and unique types of diodes that are vital in modern electronics.Now let's get start to learn about diodes.   Applications of Diodes While only two pin semiconductor devices, there are a number of applications of diodes that are vital in modern electronics. Diodes are known for only allowing current to move in one direction through the component.   This lets a diode acts as a one-way valve, keeping signals where they need to be or routing them around components. While diodes only let current move in one direction, each type of diode acts differently, making a number of useful applications for diodes.   Some of the typical applications of diodes include:   ·  Rectifying a voltage, such as turning AC into DC voltages ·  Isolating signals from a supply ·  Voltage Reference ·  Controlling the size of a signal ·  Mixing signals ·  Detection signals ·  Lighting ·Lasers diodes   Power Conversion One significant application of diodes is to convert AC power to DC power. A single diode or four diodes can be used to transform 110V household power to DC by forming a half-way (single diodes) or a full-wave (four diodes) rectifier. A diode does this by allowing only half of the AC waveform to travel through it. When this voltage pulse is used to charge a capacitor, the output voltage appears to be a steady DC voltage with a small voltage ripple.   Using a full wave rectifier makes this process even more efficient by routing the AC pulses so both the positive and negative halves of the input sine wave are seen as only positive pulses, effectively doubling the frequency of the input pulses to the capacitor which helps keep it charged and deliver a more stable voltage. Diodes and capacitors can also be used to create a number of types of voltage multipliers to take a small AC voltage and multiply it to create very high voltage outputs. Both AC and DC outputs are possible using the right configuration of capacitors and diodes.   Demodulation of Signals The most common use for diodes is to remove the negative component of an AC signal so it can be worked with easier with electronics. Since the negative portion of an AC waveform is usually identical to the positive half, very little information is effectively lost in this process. Signal demodulation is commonly used in radios as part of the filtering system to help extract the radio signal from the carrier wave.   Over-Voltage Protections Diodes also function well as protection devices for sensitive electronic components. When used as voltage protection devices, the diodes are non-conducting under normal operating conditions but immediately short any high voltage spike to ground where it cannot harm an integrated circuit. Specialized diodes called transient voltage suppressors are designed specifically for over-voltage protection and can handle very large power spikes for short time periods, typical characteristics of a voltage spike or electric shock, which would normally damage components and shorten the life of an electronic product.   Current Steering The basic application of diodes is to steer current and make sure it only flows in the proper direction. One area where the current steering capability of diodes is used to good effect is in switching from power from a power supply to running from a battery. When a device is plugged in and charging, for example, a cell phone or uninterruptible power supply, the device should be drawing power only from the external power supply and not the battery and while the device is plugged in the battery should be drawing power and recharging. As soon as the power source is removed, the battery should power the device so no interruption in noticed by the user.   Ref. MN3306 MURB1520 SBG1030L-T-F

SummaryThere is an article named "Working principle and Development of Solar Cell" in the Kynix Semiconductor Electronic Blog, it detailed shows that the development of new energy sources mainly concentrates on renewable energies such as solar energy,hydrogen energy, wind energy and geothermal energy, among which solar energy resources are abundant and widely distributed, and are the most promising renewable energy sources. In 1839,French scientist E.Becquerel discovered the photovoltaic effect of the liquid,the solar cell has undergone a long development history of more than 160 years. In terms of the overall development, both basic research and technological advancement have played a positive role in promoting them. Now,researchers at Osaka University, in an international collaboration with Max Planck Institute for Polymer Research, have redesigned one of their previously reported polymers to make a new kind of solar cell that needs no extra special treatments. They also managed to keep excellent power conversion efficiency of solar power to electricity, as recently reported in Advanced Energy Materials.  DiscussionIt's truely that energy industry  is not only the basic industry of national economy, but also a technology-intensive industry.Due to the continuous demand of mankind for renewable energy, people are devoted to developing new sources. The energy that the sun shines on the Earth's surface in 40 minutes can be used for one year at a speed of the current global energy consumption. Reasonable utilization of solar energy will be a long-term development strategy for mankind to solve energy problems and it is also one of the most studied research hot spots.Humankind is in the midst of a massive drive to harness solar energy to power our homes, gadgets, and industry. Plastic solar cells, based on blends of conducting organic polymers, are of interest for making lightweight and cheap solar cells. The problem with these kinds of solar cells is that their solar power efficiencies are very closely related to the way the different types of materials mix and crystalize in thin films. This means complex and careful processing is usually needed to make efficient polymer solar cells. According to lead author Yutaka le,Conventional organic solar cells have now achieved good efficiencies but the polymer films in these devices typically require special processing to ensure correct crystallization.(Organic solar cells, as its name implies, are solar cells that form of organic materials. We are not familiar with organic solar cells, which is a reasonable thing. More than 95% of today's solar cells are silicon-based, while less than 5% of the remaining solar cells are made from other inorganic materials.) Instead, we have been focusing on amorphous polymer blends to avoid these issues. Organic solar cells work based on light energy exciting electrons in a polymer. The excited electrons can then transfer to a soccer ball-shaped fullerene and move to the positive side of the solar cell. The space left by an electron is known as a hole. It too must move through the polymer to the other side of the device to complete the circuit. The Osaka researchers knew that one of their polymers could not transport holes so effectively. They redesigned the structure by adding an extra component, which improved its hole conductivity, and in turn enhanced the solar power conversion performance. Coauthor Yoshio Aso says, "Being able to make these cells without having to pay such close attention to the crystal structure of the polymer films could allow us to mass produce these devices by simple printing methods, which should considerably lower costs of the devices and lead to much wider uptake."