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AN5950 Datasheet, PDF (3/23 Pages) Dynex Semiconductor – TABLES OF CHARACTERISTICS
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AN 5950
transients are largely determined, usually in
the case of self commutated converters with
large energy storage elements. If the
transients on the mains supply are unknown
then a safety factor of 2 to 2.5 should be
used.
VDSM & VRSM are the peak non-repetitive
voltages in the forward and reverse directions
and are the voltages that can be applied
occasionally and non-repetitively and should
not be exceeded under any circumstances.
ORDERING INFORMATION
This specifies the correct part number for
ordering the device, for example:
DCR3030V42 (4200V part)
Other voltage grades can be selected as given
in the table of voltage ratings.
TABLES OF RATINGS
 CURRENT RATINGS
IT(AV) – Mean on-state current
IT(AV) is the average value of a half sine wave
current flowing in a thyristor such that the
peak junction temperature is limited to the
rated temperature of 125°C with the case
temperature specified. The average current
rating of the device is related to the thermal
rating of the device package and thus by
equating the power generated within the
device to the power dissipated in the package,
the average current rating can be calculated.
A more thorough analysis of the current rating
derivation is given in the Appendix 1.
There is no industry standard definition for
IT(AV), manufacturers quote IT(AV) with case
temperatures of 60°C, 65°C, 70°C and 85°C .
Others quote with respect to a heatsink
temperature of 55°C (see Fig.17 Appendix 1).
Thus direct comparison of headline ratings is
very difficult. Even if all manufacturers quoted
at the same case temperature this would still
not resolve the problem because, in reality,
what is really important in the application is
how the device performs on the heatsink.
Some manufacturers quote low values of
thermal resistance junction to case with
correspondingly higher values for thermal
resistance case to heatsink but with similar
thermals junction to heatsink. Therefore their
headline IT(AV) at a given case temperature may
be quoted as being higher than competitors’
devices but when rated on the same heatsink
there is no appreciable difference in
performance.
Dynex quotes a headline IT(AV) at 60°C case
temperature but gives full de-rating curves for
both half sine and rectangular waves to
enable the user to make direct and
meaningful comparisons.
IT(RMS) – RMS current rating
For today’s capsule devices IT(RMS) = π. IT(AV) /2.
Historically IT(RMS) could have been different
because, for single sided devices with a
flexible lead for the load current terminal, the
current carrying capability of the connections
could be less than the capability of the silicon.
For capsule (puk) devices, the cross sectional
area of the electrodes is the same as the
silicon so no allowance needs to be made. The
limitation is now the equipment busbars.
IT – Continuous (direct) on-state current
IT is the maximum continuous current that the
thyristor can conduct while maintaining the
junction temperature to its maximum rated
value of 125°C. Note that, like IT(AV) , this figure
depends upon the stated reference case
temperature.
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