Datasheet

ADM2483 Data Sheet
Rev. F | Page 16 of 18
100.000
10.000
1.000
0.100
0.010
0.001
1k 10k 100k 1M 10M 100M
04736-027
MAGNETIC FIELD FREQUENCY (Hz)
MAXIMUM ALLOWABLE MAGNETIC
FLUX DENSITY (kGAUSS)
Figure 27. Maximum Allowable External Magnetic Flux Density
For example, at a magnetic field frequency of 1 MHz, the maxi-
mum 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 occurs during a transmitted pulse and is the worst-
case polarity, it reduces the received pulse from >1.0 V to 0.75 V.
This is well above the 0.5 V sensing threshold of the decoder.
These magnetic flux density values are shown in Figure 28,
using more familiar quantities such as maximum allowable
current flow, at given distances away from the ADM2483
transformers.
1000.00
100.00
0.10
1.00
10.00
0.01
1k 10k 100k 1M 10M 100M
04736-028
MAGNETIC FIELD FREQUENCY (Hz)
MAXIMUM ALLOWABLE CURRENT (kA)
DISTANCE = 1m
DISTANCE = 5mm
DISTANCE = 100mm
Figure 28. Maximum Allowable Current for Various
Current-to-ADM2483 Spacings
At combinations of strong magnetic field and high frequency,
any loops formed by printed circuit board traces could induce
large enough error voltages to trigger the thresholds of succeeding
circuitry. To avoid this possibility, care should be taken in the
layout of such traces.
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