Datasheet

(a) Example DRC (SON) Package Measurement
T on PCB
B
T on of Itop
T
C
1mm
(b) Example RGW (QFN) Package Measurement
1mm
T on top
of IC
T
T on PCB
surface
B
12
10
8
6
4
2
0
Y Yand ( C/W)
JT JB
°
0 2
4
6 8 10
Board Copper Area (in )
2
51 3 7 9
Y
JT
Y
JB
DRC
RGW
TPS74801-Q1
www.ti.com SLVSAI4B –OCTOBER 2010–REVISED JULY 2013
Figure 30. Ψ
JT
and Ψ
JB
vs Board Size
For a more detailed discussion of why TI does not recommend using θ
JC(top)
to determine thermal characteristics,
refer to application report SBVA025, Using New Thermal Metrics, available for download at www.ti.com. For
further information, refer to application report SPRA953, IC Package Thermal Metrics, also available on the TI
website.
(1) T
T
is measured at the center of both the X- and Y-dimensional axes.
(2) T
B
is measured below the package lead on the PCB surface.
Figure 31. Measuring Points for T
T
and T
B
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