ADuM3400/ADuM3401/ADuM3402 Data Sheet
Rev. E | Page 22 of 24
To calculate the total I
DD1
and I
DD2
supply current, the supply
currents for each input and output channel corresponding to
V
DD1
and V
DD2
are calculated and totaled. Figure 8 provides the
per-channel input supply current as a function of the data rate.
Figure 9 and Figure 10 provide the per-channel supply output
current as a function of the data rate for an unloaded output
condition and for a 15 pF output condition, respectively. Figure 11
through Figure 15 provide the total V
DD1
and V
DD2
supply current
as a function of the data rate for the ADuM3400/ADuM3401/
ADuM3402 channel configurations.
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 carries out an extensive set of evaluations to determine
the lifetime of the insulation structure within the ADuM3400/
ADuM3401/ADuM3402.
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 Figure 21 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 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 ADuM3400/ADuM3401/
ADuM3402 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 21, Figure 22, and Figure 23
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 recommended maximum working voltage of
Analog Devices.
In the case of unipolar ac or dc voltage, the stress on the insulation
is significantly lower, which 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 the voltage conforms to either
the unipolar ac or dc voltage cases. Any cross insulation voltage
waveform that does not conform to Figure 22 or Figure 23 must
be treated as a bipolar ac waveform and the peak voltage must
be limited to the 50-year lifetime voltage value listed in Table 10.
Note that the voltage presented in Figure 22 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
05985-021
Figure 21. Bipolar AC Waveform
0V
RATED PEAK VOLTAGE
05985-022
Figure 22. Unipolar AC Waveform
0V
RATED PEAK VOLTAGE
05985-023
Figure 23. DC Waveform
