AN444 APPLICATION NOTE

2/5

CURRENT IN THE TRANSIL

We can express the current i through the Transil by the following formula:

sus time.

Figure 3. Current Waveform

t1 can be calculated by:

TRANSIL POWER DISSIPATION

We can consider two cases, single pulse operation and repetitive pulses operation.

Single pulse operation

In this case, in order to define a Transil we need peak power Pp and the pulse current standard duration tp.

If we assimilate the pulse current with a triangle the standard exponential pulse duration tp is calculated

by the formula:

The energy in the Transil can be expressed by:

When r tends to zero we find:

iI

p

V

V

CC

–

r

---------------------------------------

+





r

t

L

---

–





exp

V

V

CC

–

r

---------------------------------------

+

=

t

r

t1

t1

L

r

---

–

V

V

CC

–

V

V

CC

–

rI

p

–

----------------------------------------------------





ln

=

tp

1.4L

2r

------------





–

V

V

CC

–

V

V

CC

–

rI

p

+

----------------------------------------------------





ln

=

W

V

L

⋅

r

----------------------------- I

p

[

V

V

CC

–

r

---------------------------------------





+

V

V

CC

–

V

V

CC

–

rI

p

+

----------------------------------------------------





ln

=

W

1

2

---LI

p

2

V

V

V

CC

–

---------------------------------------





=