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Design of single chip switching power supply
来源: | 作者:electronics-101 | 发布时间: 2017-08-01 | 495 次浏览 | 分享到:
Switching power supply with high efficiency, light weight, small volume, wide range of advantages, from the middle of twentieth Century since the advent of extremely rapid development, has been widely used in computer, communication, aerospace, office and household appliances, is to replace the linear regulated power supply potential.

        Switching power supply with high efficiency, light weight, small volume, wide range of advantages, from the middle of twentieth Century since the advent of extremely rapid development, has been widely used in computer, communication, aerospace, office and household appliances, is to replace the linear regulated power supply potential. To improve the integration of the circuit is one of the pursuit of switching power supply, for small and medium power switching power supply is to achieve monolithic integration. Switch integrated voltage regulator refers to the control circuit, power switch tube and protection circuit integrated in a chip, and switching power regulator composed of switching power supply is called a single chip switching power supply. The single chip switching power supply series of PI Inc. is a significant representative of the company.
The 250W switching power supply circuit designed by TOPSwitch - GX is shown in figure 1. DC voltage by transformer primary side to TOPSwitch - drain D GX; frequency selection end F and current limit set source end X and S connected to the ends of the function are of no use, not from the external current limit set, since the current protection of ILIMIT automatic internal setting switch frequency for 132K control; pole and Optocoupler LTV817 connected to accept in order to achieve the duty ratio control of high voltage power MOS integrated tube internal feedback signal; line resistance and DC high voltage input 2M by detecting the end L positive terminal line voltage detection connected to achieve voltage under the line voltage feed-forward measurement. For high frequency capacitor C1 filter capacitor; transient voltage suppressor P6KE200 and ultrafast recovery diode clamp circuit composed of BYV26C, and in which the string into the RC snubber circuit (by R2, R3 and C6), so that in addition to absorb part of the leakage inductance energy, can also be a voltage clamp at 200V, the switching power supply in case of overload or start TOPSwitch GX internal integrated MOS tube drain voltage does not exceed 700V; high frequency transformer T1 side output through MURl640CT rectifier and C9, C10 and C11 filter, after L1 and C12 beads filter switch noise, get the output voltage; VD4 and C14 constitute a soft start circuit.
Single chip switching power supply has the advantages of monolithic integration, the simplest peripheral circuit, the best performance indicators, and can achieve full isolation without the power frequency transformer, so it is the ideal choice for the design of switching power supply below 290W.