MIC45116 datasheet(28/42 Pages) MICROCHIP

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MIC45116

DS20005571A-page 28

 2016 Microchip Technology Inc.

7.0

SIMPLIFIED PCB DESIGN

RECOMMENDATIONS

7.1

Periphery I/O Pad Layout and

Large Pad for Exposed Heatsink

The board design should begin with copper/metal pads

that sit beneath the periphery leads of a mounted QFN.

The board pads should extend outside the QFN

package edge a distance of approximately 0.20 mm

per side:

EQUATION 7-1:

After completion of the periphery pad design, the larger

exposed pads will be designed to create the mounting

surface of the QFN exposed heatsink. The primary

transfer of heat out of the QFN will be directly through

the bottom surface of the exposed heatsink. To aid in

the transfer of generated heat into the PCB, the use of

an array of plated through-hole vias beneath the

mounted part is recommended. The typical via hole

diameter is 0.30 mm to 0.35 mm, with center-to-center

pitch of 0.80 mm to 1.20 mm.

FIGURE 7-1:

Package Bottom View vs. PCB Recommended Exposed Metal Trace.

Please note the exposed metal trace is a “mirror image” of the package bottom view.

TotalPadLength

8mm

0.20mm 2sides





8.4mm

MIC45116 Datasheet(PDF) 28 Page - Microchip Technology