Beginner's power supply, then drawn to its, but there are so many knowledge, easy to forget, to learning content, records,
MOSFET switching power supply is an extremely important components, now integrated more and more high, many will FET switch power supply controller and the controller integrated one, makes the design more simple, greatly improve reliability, highly integrated controller, make a design more limited, small volume, make the device cannot be used in high-power power supply,
As the controller external devices will FET, makes the design with more flexibility and realize the maximum heat dissipation, power range is more widely applied,
Choose FET, should consider its rated voltage, working environment temperature, the switching frequency, the controller drive ability, heat dissipation component area, due to the loss of switch power supply, the junction temperature of FET will be affected, including the power consumption of the FET, and factors influencing the junction temperature cooling component area and the environmental temperature,
Compared with the linear power supply, switch power supply is the biggest advantage of high efficiency, its power loss is mainly manifested in the magnetic device and the switch device, magnetic device loss including loss of dc and ac loss, will be more clear in the study, and the wastage of the switching device also includes dc and ac loss, loss of dc mainly embodied in the device conduction time, FET resistance losses, generated by the current through the FET with, switch conduction time; Ac loss is caused by the switch conduction and shut off excessive, voltage current exist at the same time, in order to lead to loss of communication, so the ac loss and the leakage source, the voltage between the current related, with the rise along with the fall of the switch along the time, the number of related, therefore, the effective method to reduce the loss of dc is reduce the internal resistance, reduce the switching loss can reduce the switching frequency, reduced implementation, input voltage, etc.