Datasheet avalanche ratings

AN2344

22/27

Figure 18.

STP11NM60FP rectangular pulse superimposition principle graph

The temperature increase due to a finite number of repetitive avalanche phenomena may be

duration

τ :

Equation 29

Other methods may be used. For example, using ‘ti’ as the rise and fall times for each

principle for each pulse contribution. This method can be used for trains of few pulses. At the

end of the Nth pulse,

Equation 30

However, for a considerably high number of pulses, this equivalent method should be used

Equation 31

This result is to be added (by the superimposition principle) to the temperature increase

due to the conduction and switching losses.

Figure 19.

Equally spaced, same amplitude pulse train timing diagram

T

JC max

()

P

0

t

AV

T

--------Zth

()

1

t

AV

T

--------

–



 Zth

()

+





=

∆

T

() P

0

Zth

JC

ni

–

()Tt

AV

+

() Zth

–

()T

–

() )

i1

=

n

∑

=

∆

T

()

∆

P

0

t

AV

T

--------Zth n

2

–

()Tt

AV

+

()

1

t

AV

T

--------

–



 Zth

+

() Zth

()

–

Zth

()

++









=