AP1186
1.5A Ultra Low Dropout Positive Adjustable or Fixed-mode Regulator
Functional Descriptions (Continued)
Thermal Design
Assuming, the following conditions:
The AP1186-XXX incorporates an internal thermal
shutdown that protects the device when the junction
temperature exceeds the allowable maximum
junction temperature. Although this device can
operate with junction temperatures in the range of
150oC, it is recommended that the selected heat
sink be chosen such that during maximum
continuous load operation the junction temperature
is kept below this number. The example below
shows the steps in selecting the proper surface
mount package.
Vout=2.5V
Vin=3.3V
Vctrl=5V
Iout=1.5A DC Avg.
Calculate the maximum power dissipation using
the following equation:
Pd=Iout*(Vin-Vout)+(Iout/60)*(Vctrl-Vout)
Pd=2*(3.3-2.5)+(2/60)*(5-2.5)=1.68W
Using table below select the proper package
and the amount of copper board needed.
Package
Copper Area
ΘJA (oC/W)
Max Pd (Ta=25oC) Max Pd (Ta=45oC)
TO263
Pad Size-1.4”X1.4”
25-45
2.4W-4.4W
2.0W-3.6W
Note: Above table is based on the maximum junction temperature of 135oC.
As shown in the above table, any of the two packages will do the job.
Marking Information
Blank : Adj, 15=1.5V,
18=1.8V, 25=2.5V,
33=3.3V, 50=5.0V
Blank : normal
1186-XX
YYWWX X
L : Lead Free Package
ID Code
Xth Week : 01~52
Year : "01"=2001
"02"=2002
TO263-5L,TO220-5L
Anachip Corp.
www.anachip.com.tw
Rev.1.1 Sep.7, 2004
6/8
ANACHIP [ ANACHIP CORP ]
