Data Sheet ADuM4400/ADuM4401/ADuM4402
Rev. D | Page 17 of 20
To calculate the total I
DD1
and I
DD2
, the supply currents for
each input and output channel corresponding to I
DD1
and I
DD2
are calculated and totaled. Figure 8 and Figure 9 provide per
channel supply currents as a function of data rate for an
unloaded output condition. Figure 10 provides per channel
supply current as a function of data rate for a 15 pF output
condition. Figure 11 through Figure 15 provide total I
DD1
and
I
DD2
as a function of data rate for ADuM4400/ADuM4401/
ADuM4402 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 ADuM440x.
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 19 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 ADuM440x 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 Analog Devices recommended maximum working
voltage.
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 19 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 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 19.
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
08157-021
Figure 21. Bipolar AC Waveform
0V
RATED PEAK VOLTAGE
08157-022
Figure 22. Unipolar AC Waveform
0V
RATED PEAK VOLTAGE
08157-023
Figure 23. DC Waveform
