CM3202-00 Datasheet, PDF (10/11 Pages) ON Semiconductor – VTT Termination Voltage Regulator

CM3202−00
APPLICATION INFORMATION (Cont’d)
PCB Layout Considerations
TheCM3202−00 has a heat spreader attached to the bottom of the WDFN8 package in order for the heat to be transferred
more easily from the package to the PCB. The heat spreader is a copper pad of dimensions just smaller than the package itself.
By positioning the matching pad on the PCB top layer to connect to the spreader during the manufacturing, the heat will be
transferred between the two pads. See the Thermal Layout, the CM3202−00 shows the recommended PCB layout. Please be
noted that there are four vias on either side to allow the heat to dissipate into the ground and power planes on the inner layers
of the PCB. Vias can be placed underneath the chip, but this can be resulted in blocking of the solder. The ground and power
planes need to be at least 2 square inches of copper by the vias. It also helps dissipation if the chip is positioned away from
the edge of the PCB, and not near other heat−dissipating devices. A good thermal link from the PCB pad to the rest of the PCB
will assure the best heat transfer from the CM3202−00 to ambient, q_JA, of approximately 55°C/W.
Top View
Bottom Layer
Ground Plane
Top Layer Copper
Connects to Heat Spreader
Pin Solder Mask
Vias ( 0. 3 mm Diameter )
Thermal PAD
Solder Mask
Figure 2. Thermal Layout for WDFN8 Package
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