AN2344

Datasheet avalanche ratings

21/27

Figure 17.

STP11NM60FP rectangular pulse switching approximation

By using the superimposition principle (see Figure 18.) the maximum temperature at

avalanche onset is expressed as:

Equation 26

then,

Equation 27

thus,

Equation 28

The result, in this case, confirms the application of the simplified equation (see Equation

18).

temperatures or some heat sinking faults or, even some variation of other components in the

absolute maximum ratings and consequently risk the Power MOSFET’s failure.

T

∆

P

4

Zth

()

•

P

Zth

t

2

t

3

t

4

t

D4

++

++

()

–

()

+

=

+

*

*

*

P

3

Zth

t

D3

t

D4

t

4

++

+

() Zth

t

D4

t

4

++

()

–

[]

•

+

*

*

*

*

+

P

2

Zth

t

3

t

D4

t

4

++

+

() Zth

t

D4

t

4

++

()

–

[]

•

+

*

*

*

*

+

P

1

Zth

t

D1

t

2

t

3

t

D4

t

4

++

+

+

+

() Zth

t

2

t

3

t

D4

t

4

++

+

+

()

–

[]

•

**

*

*

T

∆

P

4

Zth

()

•

P

Zth

()

–

() P

3

Zth

() Zth

()

–

[]

•

++

=

+

*

*

P

2

Zth

() Zth

()

–

[]

•

+

*

+

P

1

Zth

() Zth

()

–

[]

•

47.28

° C

=

*

+

T

j

47.28

° C70° C117° C

≈

+

=