ADUM5400ARWZ-RL Analog Devices Inc, ADUM5400ARWZ-RL Datasheet - Page 13

• Manufacturer Part Number: ADUM5400ARWZ-RL
• Description: QUAD-CHANNEL DIGITAL ISOLATORS
• Manufacturer: Analog Devices Inc
• Series: IsoPower®, iCoupler®r

Specifications of ADUM5400ARWZ-RL

• Inputs - Side 1/side 2: 4/0
• Number Of Channels: 4
• Isolation Rating: 2500Vrms
• Voltage - Supply: 3.35V, 4.1V, 5V
• Data Rate: 1Mbps
• Propagation Delay: 55ns
• Output Type: Logic
• Package / Case: 16-SOIC (0.300", 7.5mm Width)
• Operating Temperature: -40°C ~ 105°C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: EVAL-ADUM540XEBZ - BOARD EVAL FOR ADUM540x
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PROPAGATION DELAY PARAMETERS
Propagation delay is a parameter that describes the time it takes a
logic signal to propagate through a component (see Figure 13).
The propagation delay to a logic low output may differ from the
propagation delay to a logic high output.
Pulse width distortion is the maximum difference between
these two propagation delay values and is an indication of how
accurately the timing of the input signal is preserved.
Channel-to-channel matching refers to the maximum amount
that the propagation delay differs between channels within a
single ADuM5400 component.
Propagation delay skew refers to the maximum amount that
the propagation delay differs between multiple ADuM540x
components operating under the same conditions.
DC CORRECTNESS AND MAGNETIC FIELD
IMMUNITY
Positive and negative logic transitions at the isolator input cause
narrow (~1 ns) pulses to be sent to the decoder via the trans-
former. The decoder is bistable and is, therefore, either set or
reset by the pulses, indicating input logic transitions. In the
absence of logic transitions at the input for more than 1 μs,
periodic sets of refresh pulses indicative of the correct input
state are sent to ensure dc correctness at the output. If the decoder
receives no internal pulses for more than approximately 5 μs,
the input side is assumed to be unpowered or nonfunctional, in
which case the isolator output is forced to a default state by the
watchdog timer circuit. This situation should occur in the
ADuM5400 only during power-up and power-down operations.
The limitation on the ADuM5400 magnetic field immunity is
set by the condition in which induced voltage in the receiving
coil of the transformer is sufficiently large to falsely set or reset
the decoder. The following analysis defines the conditions
under which this can occur.
The 3.3 V operating condition of the ADuM5400 is examined
because it represents the most susceptible mode of operation.
The pulses at the transformer output have an amplitude of >1.0 V.
The decoder has a sensing threshold of about 0.5 V, thus estab-
lishing a 0.5 V margin in which induced voltages can be tolerated.
The voltage induced across the receiving coil is given by
where:
β is the magnetic flux density (gauss).
N is the number of turns in the receiving coil.
r
INPUT (V
OUTPUT (V
n
is the radius of the n
V = (−dβ/dt)
Ix
)
Ox
)
Figure 13. Propagation Delay Parameters
∑π
r
n
t
2
PLH
th
; n = 1, 2, … , N
turn in the receiving coil (cm).
t
PHL
50%
50%
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Given the geometry of the receiving coil in the ADuM5400 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 14.
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 occurs during a transmitted pulse
(and is of the worst-case polarity), the received pulse is reduced
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 from the
ADuM5400 transformers. Figure 15 expresses these allowable
current magnitudes as a function of frequency for selected
distances. As shown in Figure 15, the ADuM5400 is extremely
immune and can be affected only by extremely large currents
operated at high frequency very close to the component. For
example, at a magnetic field frequency of 1 MHz, a 0.5 kA current
placed 5 mm away from the ADuM5400 is required to affect the
operation of the component.
0.001
1000
0.01
0.01
Figure 14. Maximum Allowable External Magnetic Flux Density
100
100
0.1
0.1
10
10
1
1
1k
1k
DISTANCE = 100mm
for Various Current-to-ADuM5400 Spacings
Figure 15. Maximum Allowable Current
10k
DISTANCE = 5mm
10k
MAGNETIC FIELD FREQUENCY (Hz)
MAGNETIC FIELD FREQUENCY (Hz)
100k
100k
1M
1M
DISTANCE = 1m
10M
10M
ADuM5400
100M
100M