Meaning of floating/fixed secondary coil on transformer?

Hi there - I was just looking at a datasheet for some CCFL transformers

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and noticed that the secondary coils on some are labeled as floating, while others are labeled as fixed (see middle of page 2, schematic a and schematic b).

What exactly does this mean? Does it mean the secondary is shorted to the primary? Or something else?



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Dunno, if there were a connection I think it would be indicated. Maybe it refers to insulation value -- floating is higher pot?


Reply to
Tim Williams


** Email the company and ask them - as they seem to have invented their own term for the design.

The "floating" and "fixed" secondary versions vary only in pin out, as far as the specs indicate.

.... Phil

Reply to
Phil Allison

the connection is indicated. For the fixed type one end of the secondary has has same pin number as the center of primary


Reply to


The terminology appears to define how the back-light is wired. In the 'fixed' mode one end of the secondary and the light are connected to a current sense circuit that feeds back to the controlling IC. In the 'floating' mode however, it is connected only to the secondary winding (through a capacitor). It would seem from this that one end of the secondary is at a fixed potential in the first case but the whole of it floats in the other.

Cheers - Joe

Reply to
Joe McElvenney

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