Y-CAP to (+) pin of Bridge Rectifer or (-) pin of Bridge Rectifier?
Hello.
1. Y-CAP Location
I want to know whether
Y-CAP should be connected to the (+) pin side of primary bridge rectifer or to (-) pin side of primary bridge rectifer.
PIexpert indicates Y-CAP should be connected between (+) pin side of primary bridge rectifer and secondary side GND.
But the datasheet of TOP264KG indicates Y-CAP should be connected
between (-) pin side of primary bridge rectifer and secondary side GND.
I attached the screen captures from PIExpert and datasheet.
2. Y-CAP risk
If Transient Voltage Surge is generated primary side,
can such Transient Voltage Surge pass though Y-CAP and affect to secondary GND volatge?
In a test, I found erroneous sparks on the primary side,
can seem to damage the whole part of low voltage circuit (3.3VDC),
passing the surge through Y-CAP path.
Please give me your idea.
Comments
Is there any posibility for the (+) Surge voltage in the DC (+) to pass thought Y-CAP,
and generating (-) Surge to secondary GND?
Specially in case great amount of switching noise from PWM motor control IGBT is present in DC (+),
can such noise and surge affect through Y-CAP to secondary GND?
It is possible for surge from primary pass through secondary side. But your 3.3V is a differential voltage, and to transfer the curreent to high voltage, sufficent resistance is must for secondary side ground. So i donot think you need to worry about the Y cap. Actually, TOP/TNY are used a lot as a bias for motor drive application. But you need try your best to optimize the layout.
regards
I would like to connect Y cap from DC plus to secondary return. If it is connected to DC minus, there maybe some curent througn the part, and thus the power supply can fail during surge test.
I donot think the 3.3V have any risk because of Y cap. Y cap are widely used for all kinds of power supply design. It is a proved and reliable solution for EMI.
Regards
Peter