adum3220 Analog Devices, Inc., adum3220 Datasheet - Page 13

• Manufacturer Part Number: adum3220
• Description: 4 A Dual-channel Gate Driver Adum3220
• Manufacturer: Analog Devices, Inc.

POWER CONSUMPTION
The supply current at a given channel of the ADuM3220
isolator is a function of the supply voltage, channel data rate,
and channel output load.
For each input channel, the supply current is given by
For each output channel, the supply current is given by
where:
I
per channel (mA/Mbps).
C
V
f is the input logic signal frequency (MHz, half of the input data
rate, NRZ signaling).
f
I
currents (mA).
To calculate the total I
currents for each input and output channel corresponding to
I
Figure 8 provides total input I
of data rate for both input channels. Figure 9 provides total I
supply current as a function of data rate for both outputs loaded
with 2 nF capacitance.
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 ADuM3220.
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.
r
DDI(D)
DDI(Q)
DD1
L
DDO
is the input stage refresh rate (Mbps).
is the output load capacitance (pF).
and I
I
I
I
I
, I
is the output supply voltage (V).
, I
DDI
DDI
DDO
DDO
DDO(D)
DDO(Q)
= I
= I
= I
= (I
DD2
DDI(Q)
DDI(D)
DDO(Q)
are calculated and totaled.
DDO(D)
are the input and output dynamic supply currents
are the specified input and output quiescent supply
× (2f – f
+ (0.5) × C
DD1
r
) + I
and I
DDI(Q)
DD1
L
V
DD2
DDO
supply current as a function
supply current, the supply
) × (2f – f
r
) + I
DDO(Q)
f ≤ 0.5f
f > 0.5f
f ≤ 0.5f
f > 0.5f
DD2
r
r
r
r
Rev. 0 | Page 13 of 16
The values shown in Table 9 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 ADuM3220 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.
A bipolar ac voltage environment is the worst case for the
iCoupler products and is also the 50-year operating lifetime
that Analog Devices recommends for maximum working
voltage. In the case of unipolar ac or dc voltage, the stress on the
insulation is significantly lower. This allows operation at higher
working voltages while still achieving a 50-year service life.
Any cross-insulation voltage waveform that does not conform
to Figure 22 or Figure 23 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 9.
Note that the voltage presented in Figure 22 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 22. Unipolar AC Waveform
Figure 21. Bipolar AC Waveform
Figure 23. DC Waveform
ADuM3220