Data Sheet
ADuM5401/ADuM5402/ADuM5403/ADuM5404
Given the geometry of the receiving coil in the ADuM5401/
ADuM5402/ADuM5403/ADuM5404, and an imposed
requirement that the induced voltage be, at most, 50% of the
0.5 V margin at the decoder, a maximum allowable magnetic
field is calculated as shown in Figure 27.
Note that, at combinations of strong magnetic field and high
frequency, any loops formed by PCB traces can induce error
voltages sufficiently large to trigger the thresholds of succeeding
circuitry. Exercise care in the layout of such traces to avoid this
possibility.
100
POWER CONSUMPTION
The VDD1 power supply input provides power to the iCoupler data
channels, as well as to the power converter. For this reason, the
quiescent currents drawn by the data converter and the primary
and secondary input/output channels cannot be determined sepa-
rately. All of these quiescent power demands have been combined
into the IDD1 (Q) current, as shown in Figure 29. The total IDD1 supply
current is the sum of the quiescent operating current; the dynamic
current, IDD1 (D), demanded by the I/O channels; and any external
10
1
0.1
0.01
0.001
I
ISO load.
I
I
ISO
DD1(Q)
CONVERTER
PRIMARY
CONVERTER
SECONDARY
1k
10k
100k
1M
10M
100M
I
DD1(D)
MAGNETIC FIELD FREQUENCY (Hz)
Figure 27. Maximum Allowable External Magnetic Flux Density
I
I
ISO(D)
DDP(D)
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 voltage is approximately 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 of the
worst-case polarity), it reduces the received pulse from >1.0 V to
0.75 V, still well above the 0.5 V sensing threshold of the decoder.
PRIMARY
DATA
INPUT/OUTPUT
4-CHANNEL
SECONDARY
DATA
INPUT/OUTPUT
4-CHANNEL
Figure 29. Power Consumption Within the
ADuM5401/ADuM5402/ADuM5403/ADuM5404
The preceding magnetic flux density values correspond to specific
current magnitudes at given distances from the ADuM5401/
ADuM5402/ADuM5403/ADuM5404 transformers. Figure 28
expresses these allowable current magnitudes as a function of
frequency for selected distances. As shown in Figure 28, the
ADuM5401/ADuM5402/ADuM5403/ADuM5404 are extremely
immune and can be affected only by extremely large currents
operated at high frequency very close to the component. For the
1 MHz example, a 0.5 kA current placed 5 mm away from the
ADuM5401/ADuM5402/ADuM5403/ADuM5404 is required
Both dynamic input and output current is consumed only
when operating at channel speeds higher than the refresh rate,
fr. Each channel has a dynamic current determined by its data
rate. Figure 21 shows the current for a channel in the forward
direction, which means that the input is on the primary side of
the part. Figure 22 shows the current for a channel in the reverse
direction, which means that the input is on the secondary side of
the part. Both figures assume a typical 15 pF load. The follow-
ing relationship allows the total IDD1 current to be calculated:
to affect the operation of the device.
IDD1 = (IISO × VISO)/(E × VDD1) + Σ ICHn; n = 1 to 4
(1)
1k
where:
DISTANCE = 1m
I
I
DD1 is the total supply input current.
CHn is the current drawn by a single channel determined from
100
Figure 21 or Figure 22, depending on channel direction.
IISO is the current drawn by the secondary side external load.
10
E is the power supply efficiency at 100 mA load from Figure 11
DISTANCE = 100mm
at the VISO and VDD1 condition of interest.
1
DISTANCE = 5mm
0.1
0.01
1k
10k
100k
1M
10M
100M
MAGNETIC FIELD FREQUENCY (Hz)
Figure 28. Maximum Allowable Current for Various Current-to-
ADuM5401/ADuM5402/ADuM5403/ADuM5404 Spacings
Rev. C | Page 23 of 28
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