Anti-EMI Circuit

Published:2011/9/13 5:45:00 Author:Michel | Keyword: Anti-EMI | From:SeekIC

Theanti-EMI circuit is shown as above. MAX1703 is dc/dc boost converter, the input is 3.6 V, output is 5 V / 0.5 A.External random noise (PN) generating circuit provides the clock signal for 9 feet of the converter. In the wide frequency range, the PN generating circuit reduces EMI power density by extending interference frequency.PN generating circuit consists of 74HC164 and74HC74.74HC164 is eight shift register and it feedbacks through the different or a gate G1 and G2.PN signal is output by G2 and its rating frequency is 650kHZ and it is composed of repeatting 0 and 1 . The experimental measurement shows that frequency power density peak reduces to 15dB when it's around 300 kHZ and the efficiency of the converter remains unchanged except PN generating circuit adpots 9mA current from the converter.



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