en5322 Enpirion, en5322 Datasheet - Page 14

• Manufacturer Part Number: en5322
• Description: 2 A Voltage Mode Synchronous Buck Pwm Dc-dc Converter With Integrated Inductor
• Manufacturer: Enpirion

EN5322QI
March 2008
Design Considerations for Lead-Frame Based Modules
Exposed Metal Pads on Package Bottom
QFN lead-frame based package technology utilizes exposed metal pads on the bottom of the
package that provide improved thermal dissipation and low package thermal resistance, smaller
package footprint and thickness, large lead size and pitch, and excellent lead co-planarity. As the
EN5322 package is a fully integrated module consisting of multiple internal devices, the lead-frame
provides circuit interconnection and mechanical support of these devices resulting in multiple
exposed metal pads on the package bottom.
Only the two large thermal pads and the perimeter leads are to be mechanically/electrically
connected to the PCB through a SMT soldering process. All other exposed metal is to remain free of
any interconnection to the PCB. Figure 6 shows the recommended PCB metal layout for the EN5322
package. A GND pad with a solder mask "bridge" to separate into two pads and 24 signal pads are to
be used to match the metal on the package. The PCB should be clear of any other metal, including
traces, vias, etc., under the package to avoid electrical shorting.
Figure 6. Recommended Footprint for PCB.
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