1, the driver chip wireless charging mos selection selection criteria When selecting the driver chip wireless charging mos selection , the technical parameters are decisive. The driving current should be greater than the minimum requirements shown in formula (7), and the power consumption should be coveredCap calculation power, transmission delay consistency to ensure the consistency of dead time, insulation voltage is higher than twice the rated voltage of the MOS tube, common mode transient suppression must be able to effectively withstand the dV/dt shock in the circuit.
2, the choice of the appropriate MOSFET tube is crucial to the design of the drive circuit. MOSFET tubes with low on-resistance, low reverse recovery charge, and high switching speed should be selected. In addition, the appropriate voltage and current capacity should be selected to meet the needs of practical applications. The driver circuit IC is responsible for controlling the switching state of the MOSFET tube. Selective combinationSuitable driver IC can improve the stability and efficiency of the system.
3, many motor drivers are integrated wireless charge mos selection charge pump, it should be noted that the appropriate external capacitor should be selected to get enough short circuit current to drive the MOS tube. The 4V or 10V mentioned above is the on-voltage of the commonly used MOS tube, and of course, there is a certain margin when designing. And the higher the voltage, the faster the switching speed, the smaller the switching resistance.
4, determine the rated current of the MOS tube. The rated current should be loaded at all timesThe maximum current that can be withstood under the condition. Similar to the case of voltage, ensure that the selected MOS tube can withstand this current rating, even when the system produces a spike current. The two current cases considered are continuous mode and pulse spikes. In continuous on-mode, the MOS tube is in steady state, at which time the current continuously passes through the device.
5, drive circuit strategy and protection In order to optimize MOSFET performance, the driver circuit design should pay attention to the following key points: grid resistance: moderate selection of balance switching speed and surge suppression, to avoid too small to cause damage or too much impact on speed. Rise time Tg: by regulating electricityid=' What is the specific design idea of high-power wireless charging road? '> What is the specific design idea of high-power wireless charging road?
1, wireless charging methods include electromagnetic induction, magnetic resonance, electric field coupling and radio wave transmission, wireless charging of mobile phones mostly uses the principle of electromagnetic induction. Electromagnetic induction wireless charging, when the current of the power supply through the coil (wireless charger's power supply coil) will generate a magnetic field, other unenergized coil (mobile phone side of the electric coil) close to the magnetic field will generate current, charging the mobile phone.
2, wireless charging transmitter outputIncoming DC Voltage (DC Voltage). The DC Voltage passes through the power bridge, producing an AC Voltage at SW1 and SW2, which is actually a square wave. Square wave loading generates an AC Current at both ends of the LC Tank. An alternating current passes through the coil to generate a magnetic field. The receiving coil senses this magnetic field and generates an AC Current in the receiving LC Tank. 3. A total of 60 such wireless chargers have been installed along Wuhan's Jianghan Road, according to officials with the Wuhan Construction BureauElectric street lights, each street lamp has two locations that can be wireless charging, and it is still high-power wireless charging, many people who have experienced it said that it is not bad, it is very useful, and it is also very convenient to charge on the roadside, of course, be careful that the phone is stolen.
4, simply put, the mobile phone can be charged through the wireless charger, and then through the wireless reverse charging, the mobile phone as a power source, to another device that can support wireless charging technology for wireless charging, but the disadvantage is that the charging power is small. Wireless charging technology originated from radio energy transmission technology, which is divided into high-power wireless charging and low-power wireless charging.
5, wireless charging is mainly based on the Faraday electromagnetic induction principle, which means that the charger and the electrical device are directly connected without wires, but transfer energy through the magnetic field. Wireless charging can be divided into low-power wireless charging and high-power wireless charging two ways, low-power wireless charging often uses electromagnetic induction, such as mobile phone charging.
In short, when choosing a MOSFET, it is necessary to comprehensively consider various indicators that affect efficiency, such as voltageClass, on-resistance, gate charge, coefficient of excellence, rated current and power dissipation, etc. Only on the basis of a full understanding of these indicators can we ensure the best performance of the MOSFET in applications such as slow start and anti-reverse connection.
Current parameters: ID, IDM, focus on pulse current capability. Temperature limit: such as TJ, TSTG, to ensure device performance and life. Energy-related: such as PD and EAS, reflect the overload capability of the device. Static electrical characteristics and dynamic electrical characteristics, such as V (BR) DSS, VGS (th), RDS (on), etc., are understood MThe key to OS management performance.
Voltage: The on-voltage of MOSFET is VGS, that is, the gate plus positive voltage (VD), because the MOS tube is a field-effect transistor, its input resistance is very small, as long as VGS is greater than VD can make the MOSFET on-.
Select the appropriate input voltage specification; Choose the right power. In order to increase the life of the power supply, it is recommended to choose a model with more than 30% output power rating. For example, if the system needs a 100W power supply, it is recommended to select a model with an output power rating greater than 130W, and so on can effectively improve the life of the power supply.Consider the load characteristics.
And the MOS tube has reached the speed of NS level, so the switching power supply below 150KHz frequency does not have to worry too much in this respect. Voltage tolerance Single-ended circuits should consider twice or more of the maximum input voltage value, and half or full Bridges should be twice or more. Current (Icm) single-ended circuits should be selected in accordance with the average conduction current of 5 times or more, while half Bridges need 10 times or more.
The two current cases considered are continuous mode and pulse spikes. In continuous on-mode, the MOS tube is in steady state, at which time the current continuously passes through the device. Pulse spikes areA large electrical surge (or spike current) flowing through a device. Once the maximum current under these conditions is determined, it is simply necessary to directly select a device that can withstand this maximum current.