T
treez
Guest
Because of the size of the restring in the footprint of these Y2 capacitors, (even the 7.5mm pitch ones) , they cannot singly be placed across the isolation barrier of an offline SMPS, since they would violate the rule of 8mm for isolation barrier.
DE2E3SA222MJ3BT02F
https://www.mouser.co.uk/datasheet/2/281/DE2_SA_T0_F_E-1115418.pdf
So therefore, they end up getting put in two-in-series across the isolation barrier…however, that means you have more stray inductance…..and this isnt good because common mode noise is of high frequency (typically >>1MHz), and therefore, the capacitor will look more like an inductor.
Why don’t they more commonly make these kind of capacitors with a pitch of 10mm? Then they could be used singly.
In fact, why dont people make more surface mount y caps?...because they would have even less stray inductance and be better for the high frequency common mode noise
DE2E3SA222MJ3BT02F
https://www.mouser.co.uk/datasheet/2/281/DE2_SA_T0_F_E-1115418.pdf
So therefore, they end up getting put in two-in-series across the isolation barrier…however, that means you have more stray inductance…..and this isnt good because common mode noise is of high frequency (typically >>1MHz), and therefore, the capacitor will look more like an inductor.
Why don’t they more commonly make these kind of capacitors with a pitch of 10mm? Then they could be used singly.
In fact, why dont people make more surface mount y caps?...because they would have even less stray inductance and be better for the high frequency common mode noise