WESTCODE
WESTCODE An IXYS Company
Soft Recovery Diode Types M0310YH300 to M0310YH350
Data Sheet. Types M0310YH300 to M0310YH350 Issue 1
Page 4 of 11
June, 2004
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thJK
MAX
J
SINK
R
f
k
E
T
+
=
)
(
5.0 Reverse Recovery Loss
The following procedure is recommended for use where it is necessary to include reverse recovery
loss.
From waveforms of recovery current obtained from a high frequency shunt (see Note 1) and reverse
voltage present during recovery, an instantaneous reverse recovery loss waveform must be
constructed. Let the area under this waveform be E joules per pulse. A new sink temperature can then
be evaluated from:
Where k = 0.2314 (°C/W)/s
E = Area under reverse loss waveform per pulse in joules (W.s.)
f = Rated frequency in Hz at the original sink temperature.
RthJK = d.c. thermal resistance (°C/W)
The total dissipation is now given by:
f
E
W
original
tot
+
=
)
(
)
(
NOTE 1 - Reverse Recovery Loss by Measurement
This device has a low reverse recovered charge and peak reverse recovery current. When measuring
the charge, care must be taken to ensure that:
(a) AC coupled devices such as current transformers are not affected by prior passage of high
amplitude forward current.
(b) A suitable, polarised, clipping circuit must be connected to the input of the measuring
oscilloscope to avoid overloading the internal amplifiers by the relatively high amplitude forward current
signal.
(c) Measurement of reverse recovery waveform should be carried out with an appropriate critically
damped snubber, connected across diode anode to cathode. The formula used for the calculation of
this snubber is shown below:
dt
di
S
r
C
V
R
= 4
2
Where:
Vr = Commutating source voltage
CS = Snubber capacitance
R = Snubber resistance
6.0 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.