ADuM5000 Data Sheet
Rev. B | Page 14 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 ADuM5000.
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
voltages. In many cases, the approved working voltage is higher
than 50-year service life voltage. Operation at these high work-
ing voltages can lead to shortened insulation life in some cases.
The insulation lifetime of the ADuM5000 depends on the voltage
waveform 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 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 ac bipolar condition
determines the maximum working voltage that Analog Devices
recommends.
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 11 can be applied while maintaining the
50-year minimum lifetime, provided the voltage conforms to
either the unipolar ac or dc voltage cases. Treat any cross insu-
lation voltage waveform that does not conform to Figure 16 or
Figure 17 as a bipolar ac waveform and limit its peak voltage 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
07539-021
Figure 15. Bipolar AC Waveform
0V
RATED PEAK VOLTAGE
07539-022
Figure 16. Unipolar AC Waveform
0V
RATED PEAK VOLTAGE
07539-023
Figure 17. DC Waveform
