
WESTCODE
WESTCODE An IXYS Company
Wespack Phase Control Thyristor Types N2367MK200 to N2367MK220
Provisional Data Sheet. Types N2367MK200 to N2367MK220 Issue 1
Page 4 of 11
July, 2005
8.0 Computer Modelling Parameters
8.1 Device Dissipation Calculations
T
AV
T
AV
r
ff
W
r
ff
V
I
+
=
2
0
2
4
and:
K
j
th
AV
T
R
T
W
=
=
max
Where VT0=0.883V, rT=0.210m
,
Rth = Supplementary thermal impedance, see table below and
ff = Form factor, see table below.
Supplementary Thermal Impedance
Conduction Angle
30°
60°
90°
120°
180°
270°
d.c.
Square wave Double Side Cooled
0.0175
0.0168
0.0162
0.0157
0.0150
0.0143
0.0140
Square wave Cathode Side Cooled
0.0357
0.0344
0.0335
0.0329
0.0322
0.0316
0.0314
Sine wave Double Side Cooled
0.0169
0.0163
0.0158
0.0151
0.0140
Sine wave Cathode Side Cooled
0.0349
0.0340
0.0334
0.0324
0.0318
Form Factors
Conduction Angle
30°
60°
90°
120°
180°
270°
d.c.
Square wave
3.46
2.45
2
1.73
1.41
1.15
1
Sine wave
3.98
2.78
2.22
1.88
1.57
8.2 Calculating VT using ABCD Coefficients
The on-state characteristic IT vs. VT, on page 6 is represented in two ways;
(i)
the well established VT0 and rT tangent used for rating purposes and
(ii)
a set of constants A, B, C, D, forming the coefficients of the representative equation for VT in
terms of IT given below:
()
T
I
D
I
C
I
B
A
V
+
+
+
=
ln
The constants, derived by curve fitting software, are given below for both hot and cold characteristics. The
resulting values for VT agree with the true device characteristic over a current range, which is limited to
that plotted.
25°C Coefficients
125°C Coefficients
A
0.8230476
A
-0.1878519
B
0.07410681
B
0.2685822
C
1.691121×10
-4
C
3.595580×10
-4
D
-7.725044×10
-3
D
-0.02813815