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WESTCODE An IXYS Company
Medium Voltage Thyristor Types K0443L#600 to K0443L#650
9.3 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:
VT = A + B ⋅ ln(IT ) + C ⋅ IT + D ⋅ IT
The constants, derived by curve fitting software, are given below for the 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
A 0.2103143
B 0.4754865
C 2.581886×10-3
D -0.09062255
115°C Coefficients
A -0.8731799
B 0.650089
C 3.072624×10-3
D -0.08511282
10.0 Snubber Components
When selecting snubber components, care must be taken not to use excessively large values of snubber
capacitor or excessively small values of snubber resistor. Such excessive component values may lead to
device damage due to the large resultant values of snubber discharge current. If required, please consult
the factory for assistance.
11.0 Reverse recovery ratings
(i) Qra is based on 50% Irm chord as shown in Fig. 1
(ii) Qrr is based on a 150µs integration time i.e.
150 µs
∫Qrr = irr .dt
0
(iii)
K
Factor
=
t1
t2
Fig. 1
12.0 Duty cycle lines
The 100% duty cycle is represented on the frequency ratings by a straight line. Other duties can be
included as parallel to the first.
Data Sheet. Types K0443L#600 to K0443L#650 Issue 1
Page 5 of 11
July, 2008

 5 Page



WESTCODE An IXYS Company
Figure 17 – Square Wave Frequency Ratings
1.00E+05
K0443L#600-650
Issue 1
THs=55°C
di/dt=50A/µs
200A
500A
1.00E+04
100% Duty Cycle
1000A
1.00E+03
1500A
2000A
Medium Voltage Thyristor Types K0443L#600 to K0443L#650
Figure 18 – Sine Wave Frequency Ratings
1.00E+05
200A
K0443L#600-650
Issue 1
THs=55°C
100% Duty Cycle
1.00E+04 500A
1000A
1.00E+03 1500A
2000A
1.00E+02
1.00E-05
1.00E-04
1.00E-03
Pulse width (s)
1.00E-02
Figure 19 – Maximum surge and I2t Ratings
100000
K0443L#600-650
Issue 1
Tj (initial) = 115°C
10000
1000
1.00E+02
1.00E-05
1.00E-04
1.00E-03
Pulse Width (s)
1.00E-02
1.00E+07
I2t: VRRM ≤10V
I2t: 60% VRRM
1.00E+06
ITSM: VRRM ≤10V
ITSM: 60% VRRM 1.00E+05
100
1
3 5 10
Duration of surge (ms)
1
5 10
50 100
Duration of surge (cycles @ 50Hz)
Data Sheet. Types K0443L#600 to K0443L#650 Issue 1
Page 10 of 11
1.00E+04
July, 2008

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