AN1703 - APPLICATION NOTE

10/22

dissipation results:

The next figure shows the maximum allowable power dissipation as function of a PCB drain pad area for

Figure 14: Maximum allowable power dissipation versus drain pad area

7. PowerSO-8™

To enlarge our product range and, in the meantime, improve the performance of our MOSFETs housed in

SMD packages, we are introducing new options to comply with the next generation of DC to DC

converters for the computer and telecom areas. In such applications high output current and good

thermal performances are required. This new package tailored to the above requirements is PowerSO-8.

Furthermore, power devices housed in this package can be used for automotive applications such as

body electronic applications (door looking, wipers, seat positioning systems and so on).

PowerSO-8 is the power version of the standard SO-8 package. It maintains the same footprint as SO-8,

but it also has a solderable drain contact on the back. Given that heat is dissipated through the drain and

source leads and also through the back of the package, the junction-case thermal resistance is

W

R

T

P

PCB

THj

D

25

.

1

100

125 =

=

∆

=

−

(T

W

R

T

P

PCB

THj

D

25

.

1

100

125 =

=

∆

=

−

(T

W

R

T

P

W

C

R

PCB

THJ

D

PCB

THJ

5

.

2

50

=

∆

=

⇒

°

=

−

−

0

1

2

3

0

500

1000

1500

Tj-Ta=125°C

Tj-Ta=100°C

Tj-Ta=75°C

Tj-Ta=50°C

Area