Data Sheet ADuM3300/ADuM3301
Rev. D | Page 19 of 20
INSULATION LIFETIME
All insulation structures eventually break down when subjected
to voltage stress over a sufficiently long period. The rate of
insulation degradation is dependent on the characteristics of the
voltage waveform applied across the insulation. In addition to
the testing performed by the regulatory agencies, Analog
Devices executes an extensive set of evaluations to determine
the lifetime of the insulation structure within the ADuM3300/
ADuM3301.
Analog Devices performs accelerated life testing using voltage
levels higher than the rated continuous working voltage.
Acceleration factors for several operating conditions are
determined. These factors allow calculation of the time to
failure at the actual working voltage.
The values shown in Table 10 summarize the peak voltage for
50 years of service life for a bipolar ac operating condition, and
the maximum CSA/VDE approved working voltages. In many
cases, the approved working voltage is higher than 50-year
service life voltage. Operation at these high working voltages
can lead to shortened insulation life.
The insulation lifetime of the ADuM3300/ADuM3301 depends
on the voltage waveform type imposed across the isolation
barrier. The iCoupler insulation structure degrades at different
rates depending on whether the waveform is bipolar ac,
unipolar ac, or dc. Figure 18, Figure 19, and Figure 20 illustrate
these different isolation voltage waveforms.
Bipolar ac voltage is the most stringent environment. The goal
of a 50-year operating lifetime under the ac bipolar condition
determines the Analog Devices recommended maximum
working voltage.
In the case of unipolar ac or dc voltage, the stress on the insula-
tion is significantly lower. This allows operation at higher working
voltages while still achieving a 50-year service life. The working
voltages listed in Table 10 can be applied while maintaining the
50-year minimum lifetime, provided that the voltage conforms
to either the unipolar ac or dc voltage cases. Any cross-insulation
voltage waveform that does not conform to Figure 19 or Figure 20
should be treated as a bipolar ac waveform, and its peak voltage
should be limited to the 50-year lifetime voltage value listed in
Table 10.
Note that the voltage presented in Figure 19 is shown as
sinusoidal for illustration purposes only. It is meant to represent
any voltage waveform varying between 0 V and some limiting
value. The limiting value can be positive or negative, but the
voltage cannot cross 0 V.
0V
RATED PEAK VOLTAGE
05984-020
Figure 18. Bipolar AC Waveform
0V
RATED PEAK VOLTAGE
05984-021
Figure 19. Unipolar AC Waveform
0V
RATED PEAK VOLTAGE
05984-022
Figure 20. DC Waveform
