Datasheet

-
=
q
J(max) A(max)
PKG
JA
T T
P
= ´
DISS(snk) VTT VTT(snk)
P V I
( )
= - ´
DISS(src) VLDOIN VTT VTT(src)
P V V I
TPS51206
www.ti.com SLUSAH1A –MAY 2011–REVISED OCTOBER 2013
THERMAL DESIGN
Because the TPS51206 is a linear regulator, the VTT current flows in both source and sink directions, thereby
dissipating power from the device. When the device is sourcing current, the voltage difference between VLDOIN
and VTT times I
VTT
(VTT current) current becomes the power dissipation as shown in Equation 1.
(1)
In this case, if the VLDOIN pin is connected to an alternative power supply lower than the VDDQ voltage, overall
power loss can be reduced. For the sink phase, VTT voltage is applied across the internal LDO regulator, and
the power dissipation can be calculated by Equation 2.
(2)
Maximum power dissipation allowed by the package is calculated by Equation 3.
where
• T
J(max)
is +125°C
• T
A(max)
is the maximum ambient temperature in the system
• θ
JA
is the thermal resistance from junction to ambient (3)
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