adum1401 Analog Devices, Inc., adum1401 Datasheet - Page 20

• Manufacturer Part Number: adum1401
• Description: Quad-channel Digital Isolators
• Manufacturer: Analog Devices, Inc.

ADuM1400/ADuM1401/ADuM1402
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 was of the worst-case polarity), it would reduce the
received pulse from > 1.0 V to 0.75 V—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 from the ADuM140x trans-
formers.
a function of frequency for selected distances. As seen, the
ADuM140x is extremely immune and can be affected only by ex-
tremely large currents operated at high frequency, very close to the
component. For the 1 MHz example noted, one would have to place
a 0.5 kA current 5 mm away from the ADuM140x to affect the
component’s operation.
Note that at combinations of strong magnetic field and high
frequency, any loops formed by printed circuit board traces
could induce sufficiently large error voltages to trigger the
thresholds of succeeding circuitry. Care should be taken in the
layout of such traces to avoid this possibility.
1000.00
100.00
10.00
1.00
0.10
0.01
Figure 20
1k
DISTANCE = 100mm
for Various Current-to-ADuM140x Spacings
Figure 20. Maximum Allowable Current
expresses these allowable current magnitudes as
DISTANCE = 5mm
10k
MAGNETIC FIELD FREQUENCY (Hz)
100k
1M
DISTANCE = 1m
10M
100M
Rev. B | Page 20 of 24
POWER CONSUMPTION
The supply current at a given channel of the ADuM140x isola-
tor is a function of the supply voltage, the channel’s data rate,
and the channel’s 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
ply currents (mA).
To calculate the total I
currents for each input and output channel corresponding to
I
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 14 provide total
I
ADuM1400/ADuM1401/ADuM1402 channel configurations.
r
DDI (D)
DDI (Q)
DD1
DD1
L
DDO
is the input stage refresh rate (Mbps).
is output load capacitance (pF).
I
I
I
I
and I
and I
DDI
DDI
DDO
DDO
is the output supply voltage (V).
, I
, I
DDO (D)
DDO (Q)
= I
= I
= I
= (I
DD2
DD2
DDI (Q)
DDI (D)
DDO (Q)
DDO (D)
are calculated and totaled. Figure 8 and Figure 9
supply current as a function of data rate for
are the input and output dynamic supply currents
are the specified input and output quiescent sup-
× (2f – f
+ (0.5 × 10
DD1
r
) + I
and I
DDI (Q)
−3
) × C
DD2
supply current, the supply
L
V
DDO
) × (2f – f
r
) + I
f ≤ 0.5f
f > 0.5f
f ≤ 0.5f
f > 0.5f
DDO (Q)
r
r
r
r