SI9185 Datasheet, PDF (12/12 Pages) Vishay Siliconix – Micropower 500-mA CMOS LDO Regulator

Si9185
Vishay Siliconix
PCB Footprint and Layout Considerations
The Si9185 comes in the MLP33 PowerPAK package with an
exposed pad on the bottom to provide a low thermal
impedance path into the PC board. When the PC board layout
is designed, a copper plane, referred to as spreading copper,
is recommended to be placed under the package to which the
exposed pad is soldered. This spreading copper is the path for
the heat to move away from the package into the PC board.
With the Si9185 mounted on a four layer board measuring 2”
2”, a spreading copper area of 0.25 square inches will yield an
Rq_ja of 50_C/W. This allows for power dissipation in excess of
1 watt in an 80_C ambient environment.
0.650
0.026
0.906
0.026
1.425
0.056
0.396
0.016
1.426
0.056
2.852
0.112
0.325
0.013
2.245
0.088
mm
inches
Figure 7. MLP33 PowerPAK Pad Pattern
www.vishay.com
12
Document Number: 71765
S-20641—Rev. B, 06-May-02