Data Sheet ADuM6000
Rev. D | Page 15 of 16
INSULATION LIFETIME
All insulation structures eventually break down when subjected
to voltage stress over a sufficiently long period. The rate of insu-
lation 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
carries out an extensive set of evaluations to determine the life-
time of the insulation structure within the ADuM6000.
Analog Devices performs accelerated life testing using voltage
levels higher than the rated continuous working voltage. Accel-
eration 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 11 summarize the
peak voltage for 50 years of service life for a bipolar ac operating
condition and the maximum CSA/VDE approved working volt-
ages. In many cases, the approved working voltage is higher than
the 50-year service life voltage. Operation at these high working
voltages can lead to shortened insulation life in some cases.
The insulation lifetime of the ADuM6000 depends on the
voltage waveform imposed across the isolation barrier. The
iCoupler insulation structure degrades at different rates depend-
ing on whether the waveform is bipolar ac, unipolar ac, or dc.
Figure 15, Figure 16, and Figure 17 illustrate these different
isolation voltage waveforms.
Bipolar ac voltage is the most stringent environment. The goal
of a 50-year operating lifetime under the bipolar ac condition
determines the maximum working voltage recommended by
Analog Devices.
In the case of unipolar ac or dc voltage, the stress on the insu-
lation is significantly lower. This allows operation at higher
working voltages while still achieving a 50-year service life.
The working voltages listed in Table 11 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 16 or Figure 17 should be treated as a bipolar ac wave-
form and its peak voltage limited to the 50-year lifetime voltage
value listed in Table 11. The voltage presented in Figure 16 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
08624-021
Figure 15. Bipolar AC Waveform
0V
RATED PEAK VOLTAGE
08624-022
Figure 16. Unipolar AC Waveform
0V
RATED PEAK VOLTAGE
08624-023
Figure 17. DC Waveform
