4W backup type switching power supply circuit

Published:2011/7/12 20:04:00 Author:TaoXi | Keyword: 4W, backup type, switching, power supply | From:SeekIC

The +5V and +12V dual-channel output 4W backup type switching power supply circuit which is composed of the TOP221P is as shown in the figure. This circuit uses one piece of TOP221P(ICl) and one piece of optocoupler PC817A (IC2). The circuit can continue to supply power if the main power is failure, so it can ensure that the data of the CPU and real time clock chip internal RAM will not loss. The input port is connected with the DC voltage Ui. The value of Vi is decided by the change range of the AC input voltage u (such as 85~245V). T is the high frequency transformer, N1 is the primary coil, N2 is the subprime coil, N3 is the feedback coil.



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