IXYS Thyristor/Diode Module Types M##501-12io2 to M##501-18io2
Rating Report. Types M##501-12io2 and M##501-18io2 Issue 3 Page 4 of 10 September, 2014
8.0 Computer Modelling Parameters
8.1 Thyristor Dissipation Calculations
T
AVTTT
AV
rff
WrffVV
I
2
2
2
00
2
4
and:
Kj
th
AV
TTT
R
T
W
max
Where V
T0
= 0.85 V, r
T
= 0.30 m.
R
th
= Supplementary thermal impedance, see table below and
ff = Form factor, see table below.
Supplementary Thermal Impedance
8.2 Calculating thyristor V
T
using ABCD Coefficients
The on-state characteristic I
T
vs. V
T
, on page 6 is represented by a set of constants A, B, C, D, forming
the coefficients of the representative equation for V
T
in terms of I
T
given below:
TTTT
IDICIBAV ln
The constants, derived by curve fitting software, are given below for both hot and cold characteristics. The
resulting values for V
T
agree with the true device characteristic over a current range, which is limited to
that plotted.
