MURHB840CT Datasheet, PDF (3/6 Pages) Motorola, Inc – ULTRAFAST RECTIFIER 8.0 AMPERES 400 VOLTS

20
18
TJ = 175°C
16
14
12
SQUARE WAVE
DC
10
8
6
4
2
0
1 2 3 4 5 6 7 8 9 10
IF(AV), AVERAGE FORWARD CURRENT (AMPS)
Figure 5. Forward Power Dissipation, Per Leg
MURHB840CT
INFORMATION FOR USING THE D2PAK SURFACE MOUNT PACKAGE
MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS
Surface mount board layout is a critical portion of the total
design. The footprint for the semiconductor packages must be
the correct size to insure proper solder connection interface
between the board and the package. With the correct pad
geometry, the packages will self align when subjected to a
solder reflow process.
0.74
18.79
0.420
10.66
0.065
1.651
0.07
1.78
0.330
8.38
0.14
3.56
inches
mm
D2PAK POWER DISSIPATION
The power dissipation of the D2PAK is a function of the 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
TJ(max), the maximum rated junction temperature of the die,
R_θJA, the thermal resistance from the device junction to
ambient; and the operating temperature, TA. Using the values
provided on the data sheet for the D2PAK package, PD can be
calculated as follows:
PD =
TJ(max) – TA
R_θJA
The values for the equation are found in the maximum
ratings table on the data sheet. Substituting these values into
the equation for an ambient temperature TA of 25°C, one can
calculate the power dissipation of the device which in this case
is 3.0 watts.
PD = ^{175°C – 25°C} _{= 3.0 watts}
50°C/W
The 50°C/W for the D2PAK package assumes the
recommended drain pad area of 158K mil2 on FR–4 glass
epoxy printed circuit board to achieve a power dissipation of
3.0 watts using the footprint shown. Another alternative is to
use a ceramic substrate or an aluminum core board such as
Thermal Clad™. By using an aluminum core board material
such as Thermal Clad, the power dissipation can be doubled
using the same footprint.
Rectifier Device Data
3