IRU1502-33CH IRF [International Rectifier], IRU1502-33CH Datasheet - Page 9

• Manufacturer Part Number: IRU1502-33CH
• Description: MICROPOWER 1A LOW DROPOUT PMOS VOLTAGE REGULATOR
• Manufacturer: IRF [International Rectifier]

The thermal pad of MLPM is connected to a 1 inch square
copper through vias for a four layer PCB board design.
From the datasheet, this thermal junction-to-ambient re-
sistance is given as:
For IRU1502-33, the thermal design needs to be con-
sider so that the resultant junction temperature is lower
than the maximum operating temperature, which is 1258C.
Therefore:
Assuming, the following conditions:
Calculate the maximum power dissipation using the fol-
lowing equation:
For MLPM package, we have:
Rev. 1.0
07/17/03
Where:
T
u
T
DT = P
T
V
V
I
P
P
OUT
JA
J
A
J
JA
JC
CH
HA
OUT
IN
D
D
=
= T
= 458C
=428C/W
= 428C/W
= I
= 13(5 - 3.3) = 1.7W
= 5V
= 1A (DC Avg)
= 3.3V
JA
A
2.38C
OUT
38.78C
18C
+DT = 116.48C
D
3P
3u
3(V
D
JA
+T
IR WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, USA Tel: [phone]
IN
= 1.7342 = 71.4
A
- V
[ 1258C
OUT
)
www.irf.com
Data and specifications subject to change without notice. 02/01
Layout Consideration
The IRU1502-33, like many other high-speed regulators,
requires that the output capacitors be close to the de-
vice for stability. For power consideration, a ground plane
pad of approximately one-inch square on the compo-
nent side must be dedicated to the device where all
ground pins are connected to dissipate the power. If a
multilayer board is used, it is recommended that the
inner layers of the board are also dedicated to the size
of the pad for better thermal characteristics.
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TAC Fax: [phone]
IRU1502-33
9