MIC5265_07 Datasheet, PDF (10/11 Pages) Micrel Semiconductor – 150mA μCap LDO Regulator

Micrel, Inc.
MIC5265 Junction-To-Ambient Thermal Resistance
Package
SOT-23-5
(M5 or D5)
θ_JA Recommended
Minimum Footprint
235°C/W
θ_JA 1” Sq.
Copper Clad
125°C
θ_JC
145°C/W
Thermal Resistance
Substituting PD for PD(max) and solving for the ambient
operating temperature will give the maximum operating
conditions for the regulator circuit. The junction-to-
ambient thermal resistance for the minimum footprint is
235 C/W. The maximum power dissipation must not be
exceeded for proper operation.
For example, when operating the MIC5265-2.8YD5 at an
input voltage of 5.0V at 150mA with a minimum footprint
layout, the maximum ambient operating temperature TA
can be determined as follows:
MIC5265
0.33W = ^{125°C − TA}
235°C / W
TA = 47.45°C
Therefore, a 2.8V application at 150mA of output current
can accept an ambient operating temperature of 47°C in
a SOT-23-5 package. For a full discussion of heat
sinking and thermal effects on voltage regulators, refer
to the “Regulator Thermals” section of Micrel’s Designing
with Low-Dropout Voltage Regulators handbook. This
information can be found on Micrel's website at:
http://www.micrel.com/_PDF/other/LDOBk_ds.pdf
February 2007
10
M9999-022307