adum3210 Analog Devices, Inc., adum3210 Datasheet - Page 17

• Manufacturer Part Number: adum3210
• Description: Dual-channel Digital Isolator, Enhanced System-level Esd Reliability
• Manufacturer: Analog Devices, Inc.

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 lifetime of the insulation structure within the ADuM3210.
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 12 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 in some cases.
The insulation lifetime of the ADuM3210 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 12, Figure 13, and Figure 14 illustrate these
different isolation voltage waveforms.
A bipolar ac voltage environment is the most stringent. The
goal of a 50-year operating lifetime under the ac bipolar
condition determines the Analog Devices recommended
maximum working voltage.
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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 12 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 13 or Figure 14 should be treated as a bipolar ac wave-
form, and its peak voltage should be limited to the 50-year
lifetime voltage value listed in Table 12.
Note that the voltage presented in Figure 13 is shown as sinu-
soidal 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.
RATED PEAK VOLTAGE
RATED PEAK VOLTAGE
RATED PEAK VOLTAGE
0V
0V
0V
Figure 13. Unipolar AC Waveform
Figure 12. Bipolar AC Waveform
Figure 14. DC Waveform
ADuM3210