MIC2870 Datasheet, PDF (21/25 Pages) Micrel Semiconductor – 1.5A Synchronous Boost Flash LED Driver with I2C Interface

Micrel, Inc.
Figure 5. Graph to Determine PC Board Area for a Given
PCB Thermal Resistance
Figure 5 shows the total area of a round or square pad,
centered on the device. The solid trace represents the
area of a square, single sided, horizontal, solder masked,
copper PC board trace heat sink, measured in square
millimeters. No airflow is assumed. The dashed line
shows PC boards trace heat sink covered in black oil-
based paint and with 1.3m/sec (250 feet per minute)
airflow. This approaches a “best case” pad heat sink.
Conservative design dictates using the solid trace data,
which indicates that a maximum pad size of 5000 mm² is
needed. This is a pad 71mm × 71mm (2.8 inches per
side).
MIC2870
September 5, 2013
21
Revision 1.0