adum3211 Analog Devices, Inc., adum3211 Datasheet - Page 17

• Manufacturer Part Number: adum3211
• Description: Dual-channel Digital Isolator, Enhanced System-level Esd Reliability
• Manufacturer: Analog Devices, Inc.

For example, at a magnetic field frequency of 1 MHz, the
maximum allowable magnetic field of 0.2 kgauss induces a
voltage of 0.25 V at the receiving coil. This is about 50% of the
sensing threshold and does not cause a faulty output transition.
Similarly, if such an event were to occur during a transmitted
pulse (and had the worst-case polarity), it would reduce the
received pulse from >1.0 V to 0.75 V, which is still well above
the 0.5 V sensing threshold of the decoder.
The preceding magnetic flux density values correspond to
specific current magnitudes at given distances away from the
ADuM321x transformers. Figure 14 expresses these allowable
current magnitudes as a function of frequency for selected
distances. As shown, the ADuM321x is immune and can be
affected only by extremely large currents operated at a high
frequency and very close to the component. For the 1 MHz
example, one would have to place a 0.5 kA current 5 mm away
from the ADuM321x to affect the operation of the component.
Note that at combinations of strong magnetic fields and high
frequencies, any loops formed by PCB traces may induce
sufficiently large error voltages to trigger the threshold of
succeeding circuitry. Care should be taken in the layout of
such traces to avoid this possibility.
1000
0.01
100
0.1
10
1
1k
Figure 14. Maximum Allowable Current for Various
DISTANCE = 100mm
Current-to-ADuM3210/ADuM3211 Spacings
DISTANCE = 5mm
10k
MAGNETIC FIELD FREQUENCY (Hz)
100k
1M
DISTANCE = 1m
10M
100M
Rev. C | Page 17 of 20
POWER CONSUMPTION
The supply current at a given channel of the ADuM321x
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).
I
supply currents (mA).
C
V
f is the input logic signal frequency (MHz, half of the input data
rate, NRZ signaling).
f
To calculate the total I
currents for each input and output channel corresponding to
I
Figure 6 provides per-channel input supply currents as a function
of data rate. Figure 7 and Figure 8 provide per-channel output
supply currents as a function of data rate for an unloaded
output condition and for a 15 pF output condition, respectively.
Figure 9 through Figure 11 provide total I
current as a function of data rate for the ADuM3210 and
ADuM3211 channel configurations.
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
is the output supply voltage (V).
DDI
DDI
DDO
DDO
, I
, I
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
× (2f – f
+ (0.5 × 10
DD1
r
) + I
and I
ADuM3210/ADuM3211
DDI (Q)
−3
DD2
) × C
supply current, the supply
L
V
DDO
DD1
) × (2f – f
and I
DD2
r
) + I
f ≤ 0.5f
f ≤ 0.5f
f > 0.5f
f > 0.5f
supply
DDO (Q)
r
r
r
r