ADUM5202CRWZ Analog Devices Inc, ADUM5202CRWZ Datasheet - Page 19

• Manufacturer Part Number: ADUM5202CRWZ
• Description: DUAL-CHANNEL ISOLATOR W/INTEGRATED DC/DC
• Manufacturer: Analog Devices Inc
• Series: IsoPower®, iCoupler®r

Specifications of ADUM5202CRWZ

• Inputs - Side 1/side 2: 0/2
• Number Of Channels: 2
• Isolation Rating: 2500Vrms
• Voltage - Supply: 3.3V, 5V
• Data Rate: 25Mbps
• Propagation Delay: 45ns
• 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

PROPAGATION DELAY PARAMETERS
Propagation delay is a parameter that describes the time it takes a
logic signal to propagate through a component. The propagation
delay to a logic low output may differ from the propagation delay
to a logic high.
Pulse width distortion is the maximum difference between these
two propagation delay values and is an indication of how
accurately timing of the input signal is preserved.
Channel-to-channel matching refers to the maximum amount
the propagation delay differs between channels within a single
ADuM520x component.
Propagation delay skew refers to the maximum amount the
propagation delay differs between multiple ADuM520x
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
transformer. 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, a
periodic set 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 of more than about 5 μs, the input
side is assumed to be unpowered or nonfunctional, in which case
the isolator output is forced to a default state (see Table 13) by
the watchdog timer circuit.
The limitation on the magnetic field immunity of the ADuM520x
is set by the condition in which induced voltage in the receiving
coil of the transformer is sufficiently large to either falsely set or
reset the decoder. The following analysis defines the conditions
under which this may occur. The 3 V operating condition of the
ADuM520x is examined because it represents the most suscept-
ible mode of operation.
The pulses at the transformer output have an amplitude greater
than 1.0 V. The decoder has a sensing threshold at about 0.5 V, thus
establishing 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
Given the geometry of the receiving coil in the ADuM520x and
an imposed requirement that the induced voltage be, at most,
n
INPUT (V
OUTPUT (V
is the radius of the n
V = (−dβ/dt)
IX
)
OX
)
Figure 22. Propagation Delay Parameters
∑
πr
n
2
t
th
; n = 1, 2, … , N
PLH
turn in the receiving coil (cm).
t
PHL
50%
50%
Rev. 0 | Page 19 of 24
50% of the 0.5 V margin at the decoder, a maximum allowable
magnetic field is calculated as shown in Figure 23.
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), 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.
The preceding magnetic flux density values correspond to
specific current magnitudes at given distances from the
ADuM520x transformers. Figure 24 expresses these allowable
current magnitudes as a function of frequency for selected
distances. As shown, the ADuM520x is 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 noted, a 0.5 kA current placed 5 mm away from the
ADuM520x is required to affect the operation of the
component.
Note that at combinations of strong magnetic field and high
frequency, any loops formed by PCB traces can induce error
0.001
1000
0.01
0.01
Figure 23. Maximum Allowable External Magnetic Flux Density
100
100
0.1
0.1
10
10
1
1
1k
1k
ADuM5200/ADuM5201/ADuM5202
DISTANCE = 100mm
for Various Current-to-ADuM520x Spacings
Figure 24. Maximum Allowable Current
10k
DISTANCE = 5mm
10k
MAGNETIC FIELD FREQUENCY (Hz)
MAGNETIC FIELD FREQUENCY (Hz)
100k
100k
1M
1M
DISTANCE = 1m
10M
10M
100M
100M