MMFT1N10E ON Semiconductor, MMFT1N10E Datasheet - Page 7

• Manufacturer Part Number: MMFT1N10E
• Description: Medium Power Field Effect Transistor
• Manufacturer: ON Semiconductor

design. The footprint for the semiconductor packages must
be the correct size to insure proper solder connection
drain pad size. This can vary from the minimum pad size for
soldering to a pad size given for maximum power dissipation.
Power dissipation for a surface mount device is determined
by T
die, R
ambient, and the operating temperature, T
values provided on the data sheet for the SOT−223 package,
P
ratings table on the data sheet. Substituting these values into
the equation for an ambient temperature T
calculate the power dissipation of the device which in this
case is 800 milliwatts.
of the recommended footprint on a glass epoxy printed circuit
board to achieve a power dissipation of 800 milliwatts. There
are other alternatives to achieving higher power dissipation
from the SOT−223 package. One is to increase the area of
the drain pad. By increasing the area of the drain pad, the
power dissipation can be increased. Although one can
D
Surface mount board layout is a critical portion of the total
The power dissipation of the SOT−223 is a function of the
The values for the equation are found in the maximum
The 156°C/W for the SOT−223 package assumes the use
can be calculated as follows:
J(max)
θJA
, the thermal resistance from the device junction to
, the maximum rated junction temperature of the
INFORMATION FOR USING THE SOT−223 SURFACE MOUNT PACKAGE
MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS
P
D
P
=
D
=
150°C − 25°C
156°C/W
T
J(max)
R
θJA
− T
= 800 milliwatts
A
0.079
A
2.0
of 25°C, one can
SOT−223 POWER DISSIPATION
0.079
A
2.0
. Using the
0.059
1.5
http://onsemi.com
0.091
2.3
SOT−223
0.059
0.15
1.5
3.8
7
0.091
interface between the board and the package. With the
correct pad geometry, the packages will self align when
subjected to a solder reflow process.
almost double the power dissipation with this method, one
will be giving up area on the printed circuit board which can
defeat the purpose of using surface mount technology. A
graph of R
an aluminum core board such as Thermal Clad™. Using a
board material such as Thermal Clad, an aluminum core
board, the power dissipation can be doubled using the same
footprint.
2.3
Another alternative would be to use a ceramic substrate or
°
160
140
120
100
0.059
80
1.5
0.0
Figure 17. Thermal Resistance versus Drain Pad
*Mounted on the DPAK footprint
θJA
Board Material = 0.0625″
G−10/FR−4, 2 oz Copper
Area for the SOT−223 Package (Typical)
0.248
versus drain pad area is shown in Figure 17.
6.3
inches
mm
0.2
0.8 Watts
A, Area (square inches)
1.25 Watts*
0.4
0.6
T
0.8
A
1.5 Watts
= 25°C
1.0