T. Yanada et O. Ichinokura, HIGH-PERFORMANCE STEP-DOWN NOISE-REDUCTION TRANSFORMER CONSTRUCTED WITH C-CORE, IEEE transactions on magnetics, 33(5), 1997, pp. 3331-3333
Noise-reduction transformers have a filter function against conductive
noise transmission. Several types of noise-reduction transformers hav
e been presented. Few papers, however, have reported a noise-reduction
transformer for direct power supply to electronics equipments. In thi
s paper, we propose a prototype step-down noise-reduction transformer
suitable for digital circuit. The input voltage of the transformer is
100 V and the output voltage is 5 V. Frequency characteristics of nois
e attenuation are discussed and prevention of pulse noise transmission
is demonstrated. The results of the experiments can be summarized as
follows: (1) Normal mode noise attenuation is -70 dB, and common mode
exceeds -80 dB; (2) Prototype step-down noise-reduction transformer el
iminates pulse noise efficiently. Our noise-reduction transformer has
a good noise attenuation characteristic and is an efficient noise atte
nuator.