MC34710 Datasheet, PDF (13/18 Pages) Motorola, Inc – Adjustable Dual Output Switching Power Supply

TYPICAL APPLICATIONS
This layout provides the lowest possible impedance as
well as lowest possible dc resistance for the power routing.
Note that the power path and its return should be placed, if
possible, on top of each other on different layers or opposite
sides of the pcb.
Small ceramic capacitors are placed in parallel with the
Aluminum electrolytics so that the overall bulk filtering
presents a low ESL to the high di/dt switching currents.
Alternatively, special low ESL/ESR switching-grade
electrolytics may be used.
An additional feature of the MC34710 is the 32 SOICW-EP
exposed pad package. The package allows heat to be
conducted from the die down through the exposed metal pad
underneath the package and into the copper of the pcb. In
order to best take advantage of this feature, a grid array of
thru-hole vias should be placed in the area corresponding to
the exposed pad, and these vias then should then connect to
a large ground plane of copper to dissipate the heat into the
ambient environment. An example of these vias can be seen
in the previous figures of a typical pcb layout.
Analog Integrated Circuit Device Data
Freescale Semiconductor
34710
13