STMicroelectronics A 200 W ripple-free input current PFC pre-regulator with the L6563S EVL6563S-200ZRC EVL6563S-200ZRC Data Sheet

   

   

   

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 Doc ID 17273 Rev 1

The zoomed image of 

 

shows a residual ripple current in the DC winding of 114 

mA pk-pk, against a 2.962 A pk-pk of the AC winding current, and so resulting in 
0.114/2.962 = 38.5*10-3 (-28.3 dB) attenuation.

The EMI filter used for reducing the line conducted interferences is a single cell filter made 
up of two X capacitors and a common mode inductor (see the electrical schematic in 

: CX1, CX2, L1) and two further Y capacitors (CY1, CY2). In standard transition 

mode PFC converters (without the cancellation winding) a double cell filter is usually 
necessary to reduce the EMI emission to levels within the maximum allowed by current 
regulations. The effect of ripple steering is particularly conspicuous up to about 2 MHz, with 
more than 20 dB attenuation provided. For higher frequencies, where common mode noise 
is dominant, its effect becomes negligible and emissions must be controlled resorting to the 
usual noise control techniques. The EMI measurement results are shown in 

 and 

: the emission level with peak detection is well below the quasi-peak and average limits 

envisaged by EN50022 class B.