R1271NS12x Westcode Semiconductors, R1271NS12x Datasheet - Page 5

• Manufacturer Part Number: R1271NS12x
• Description: (R1271NS10x / R1271NS12x) Distributed Gate Thyristor
• Manufacturer: Westcode Semiconductors

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The total dissipation is now given by:
In circumstances where it is not possible to measure voltage and current conditions, or for design
purposes, the additional losses E in joules may be estimated as follows.
Let E be the value of energy per reverse cycle in joules (curves in Figure 9).
Let f be the operating frequency in Hz
A suitable R-C snubber network is connected across the thyristor to restrict the transient reverse voltage
to a peak value (V
67% of Grade, the reverse loss may be approximated by a pro rata adjustment of the maximum value
obtained from the curves.
NOTE 1- Reverse Recovery Loss by Measurement
This thyristor has a low reverse recovered charge and peak reverse recovery current. When measuring
the charge care must be taken to ensure that:
Where: V
13.0 Gate Drive
The recommended pulse gate drive is 30V, 15
0.5µs. This gate drive must be applied when using the full di/dt capability of the device.
The duration of pulse may need to be configured with respect to the application but should be no shorter
than 20µs, otherwise an increase in pulse current could be needed to supply the necessary charge to
trigger the device.
Data Sheet. Types R1271NS10x to R1271NS12x Issue 1
W
T
R
SINK
2
(a) a.c. coupled devices such as current transformers are not affected by prior passage of high
(b) A suitable, polarised, clipping circuit must be connected to the input of the measuring oscilloscope
(c) Measurement of reverse recovery waveform should be carried out with an appropriate critically
(TOT)
12.2 Determination without Measurement
amplitude forward current.
to avoid overloading the internal amplifiers by the relatively high amplitude forward current signal
damped snubber, connected across diode anode to cathode. The formula used for the calculation
of this snubber is shown below:
Where T
T
4
new
C
R
SINK (original)
r
S
Positive development in power electronics
C
= Commutating source voltage
= Snubber capacitance
= Snubber resistance
S
V
W
SINK (new)
r
T
rm
di
is the heat sink temperature given with the frequency ratings.
) of 67% of the maximum grade. If a different grade is being used or V
(original)
SINK
dt
is the required maximum heat sink temperature and
original
E
E
f
R
Page 5 of 12
th
with a short-circuit current rise time of not more than
f
R1271NS10x to R1271NS12x
rm
is other than
June, 2001