Another EMC resource from EMC Standards...EMC design of Switching Power Converters Part 4 - Design...

Helping you solve your EMC problems

1 Brassey Road, Old Potts Way, Shrewsbury, SY3 7FA T:+44 (0) 1785 660 247 E:info@emcstandards.co.uk

Another EMC resourcefrom EMC Standards

EMC design of Switching Power Converters Part 4 -Design techniques for HF isolating transformers

Helping you solve your EMC problems

9 Bracken View, Brocton, Stafford ST17 0TF T:+44 (0) 1785 660247 E:info@emcstandards.co.uk

Another EMC resourcefrom EMC Standards

EMC design of Switching Power Converters Part 4 -Design techniques for HF isolating transformers

Contents

all

all three plus

4.1 Introduction to the example

something

herethere

from the start of the project

when if

4.2 How the interwinding capacitance causes emissions

allalways always

cannot

But it is not what actually happens!

antiphase

outout

much lower

mightcannot

dV/dt

dV/dt dI/dt

4.3 Reducing emissions with an interwinding shield (or two, or more)

dV/dt

4.4 Reducing emissions with primary-secondary capacitors

Important Safety Note:

some

some

dV/dt

4.5 Using “buried” PCB capacitance for frequencies above 100MHz

”

4.6 Safety issues for capacitors that cross galvanic isolation barriers

neverapproved

inside

surfaces

internal

4.7 Connecting to interwinding shields, cores, and primary-secondary capacitors

4.8 Everything resonates

4.9 Connecting interwinding shields, cores, and primary-secondary capacitors to earth/ground/chassis/frame/etc.

However

in itself

4.10 Construction of the isolating transformer

dI/dt

dV/dtdV/dt

outside