Transformerless power supply from 220V with LM2575

Published:2013/3/22 3:26:00 Author:Ecco | Keyword: Transformerless, power supply, 220V | From:SeekIC

Is often requiredtosupply electricityto theconsumerlowvoltage 220V. Youcanusean externaladapter- butit’s bad,andtoreduce the size ofthe devicerequires apower supplylocatedin the device. This 5v power supply used LM2995 to the convertercircuitwhichcan be connected directly to220V. Todo this, ACconvertedto DCvoltageacross the diodebridgeVD1, andthenloweredto40V. Above 40Vwe should notuse it, due to the factthat theLM2995maximum input voltagemustnotexceed45V. Transistors T1 and T2 form a pulsating stress amplitude up to 40V, which depends on the zener diode D1. This pulsating voltage is applied to the capacitor C1, which is slightly smoothed. Next on the chip down-converter output voltage is stabilized, defined applied chips : so for LM2575-5 5V it will be equal. Schottky diode D2, L1, C2 and C3 are the standard strapping of the chip.



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