Diodes AP1184 - Manual (Page 7)

AP1184
4A ULTRA LOW DROPOUT POSITIVE ADJUSTABLE OR
FIXED-MODE REGULATOR
AP1184 Rev. 5 7 of 12 SEPTEMBER 2008
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Functional Descriptions
(Continued)
Assuming, the following conditions:
V
out
= 2.5V
V in = 3.3V
V ctrl = 5V
I
out
= 2A DC Avg.
Calculate the maximum power dissipation using the following equation:
P
d
= I
out
* ( V
in
- V
out
) + ( I
out
/60) * ( V
ctrl
- V
out
)
P
d
= 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 θ
JA
(
o
C/W) Max Pd (T A = 25
o
C) Max Pd (T A = 45
o
C)
TO263-5L Pad Size-1.4”X1.4” 25-45 2.4W-4.4W 2.0W-3.6W
Notes: 6. Above table is based on the maximum junction temperature of 135 o C.
As shown in the above table, any of the two packages will do the job.