MIC5318 Datasheet, PDF (9/11 Pages) Micrel Semiconductor – High Performance 300mA uCap ULDO TM

Micrel, Inc.
⎛ ^TJ(MAX) ^{- T}A
⎝ ^{PD(MAX) =}
JA
T_J(max) = 125°C, the maximum junction temperature of
the die θ_JA thermal resistance = 100°C/W.
The table below shows junction-to-ambient thermal
resistance for the MIC5318 in the 6-pin 1.6mm x
1.6mm Thin MLF^® package.
Package
6-Pin 1.6x1.6 Thin MLF^®
θ_JA Recommended
Minimum Footprint
100°C/W
Thermal Resistance
Substituting P_D for P_D(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 100°C/W.
MIC5318
The maximum power dissipation must not be
exceeded for proper operation.
For example, when operating the MIC5318-2.8YMT at
an input voltage of 3.3V and 300mA load with a
minimum footprint layout, the maximum ambient
operating temperature T_A can be determined as
follows:
0.15W = (125°C – T_A)/(100°C/W)
T_A = 110°C
Therefore, a 2.8V application with 300mA of output
current can accept an ambient operating temperature
of 110°C in a 1.6mm x 1.6mm Thin MLF^® 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 informa-
tion can be found on Micrel's website at:
http://www.micrel.com/_PDF/other/LDOBk_ds.pdf
January 2007
9
M9999-011207