YB1696
150KHz, 3A PWM Buck Switching Regulator
used for a quick check for the approximate
junction temperature for various conditions,
but be aware that there are many factors
that can affect the junction temperature.
When load currents higher than 3A are
used, double sided or multilayer PC boards
with large copper areas and/or airflow
might be needed, especially for high
ambient temperatures and high output
voltages.
For the best thermal performance, wide
copper traces and generous amounts of
printed circuit board copper should be used
in the board layout. (Once exception to
this is the output (switch) pin, which should
not have large areas of copper.) Large
areas of copper provide the best transfer of
heat (lower thermal resistance) to the
surrounding air, and moving air lowers the
thermal resistance even further.
Package thermal resistance and junction
temperature rise numbers are all
approximate, and there are many factors
that will affect these numbers. Some of
these factors include board size, shape,
thickness, position, location, and even
board temperature. Other factors are,
trace width, total printed circuit copper area,
copper thickness, single or double-sided,
multilayer board and the amount of solder
on the board. The effectiveness of the PC
board to dissipate heat also depends on
the size, quantity and spacing of other
components on the board, as well as
whether the surrounding air is still or
YB1696 MRev.1.1
moving. Furthermore, some of these
components such as the catch diode will
add heat to the PC board and the heat can
vary as the input voltage changes. For the
inductor, depending on the physical size,
type of core material and the DC resistance,
it could either act as a heat sink taking heat
away from the board, or it could add heat to
the board.
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