adum7510 Analog Devices, Inc., adum7510 Datasheet - Page 9

• Manufacturer Part Number: adum7510
• Description: 5-channel, 1 Kv Unidirectional Digital Isolator
• Manufacturer: Analog Devices, Inc.

The preceding magnetic flux density values correspond to specific
current magnitudes at given distances away from the ADuM7510
transformers. Figure 12 expresses these allowable current magni-
tudes as a function of frequency for selected distances. The
ADuM7510 is very insensitive to external fields. Only extremely
large, high frequency currents, very close to the component can
potentially be a concern. For the 1 MHz example noted, a 1.2 kA
current must be placed 5 mm away from the ADuM7510 to affect
component operation.
Note that at combinations of strong magnetic field and high
frequency, any loops formed by PCB traces can induce
sufficiently large error voltages to trigger the thresholds of
succeeding circuitry. Take care to avoid PCB structures that
form loops.
POWER CONSUMPTION
The supply current at a given channel of the ADuM7510
isolator is a function of the supply voltage, the channel
data rate, and the channel output load.
For each input channel, the supply current is given by
I
I
1000
DDI
DDI
0.01
100
0.1
10
1
1k
= I
= I
DDI (Q)
DDI (D)
Figure 12. Maximum Allowable Current for
Various Current to ADuM7510 Spacings
DISTANCE = 5mm
DISTANCE = 100mm
DISTANCE = 1m
× (2f − f
10k
MAGNETIC FIELD FREQUENCY (Hz)
r
) + I
100k
DDI (Q)
1M
10M
100M
f ≤ 0.5f
f > 0.5f
Rev. A | Page 9 of 12
r
r
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
supply 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 the data
rate for an unloaded output condition. Figure 6 provides per-
channel supply current as a function of the data rate for a 15 pF
output condition. Figure 7 and Figure 8 provide total I
I
products.
POWER-UP/POWER-DOWN CONSIDERATIONS
The ADuM7510 behaves as specified in Table 8 during power-
up and power-down operations. However, the part can transfer
incorrect data when the power supplies are below the minimum
operating voltage but the internal circuits are not completely off.
Power-up/power-down errors can occur at V
the operating threshold of 1.9 V. The encoder generates data
pulses at low amplitude. The detector can miss data pulses that
are near the detection threshold. If the transferring state is a
logic high, the encoder generates a pair of pulses; the decoder
can reject one of the pulses for low amplitude. A single pulse is
interpreted as a logic low, and the output can be placed in the
wrong logic state for that refresh cycle.
Glitch-free operation is possible by following these
recommendations.
•
•
r
DDI (D)
DDI (Q)
DD1
DD2
L
DDO
is the input stage refresh rate (Mbps).
is the output load capacitance (pF).
and I
supply current as a function of the data rate for ADuM7510
I
I
Slew the power on or off as quickly as possible.
Use the default low operating mode by holding the inputs
low until power is stable.
is the output supply voltage (V).
DDO
DDO
, I
, I
DDO (D)
DDO (Q)
= I
= (I
DD2
DDO (Q)
are calculated and totaled. Figure 4 and Figure 5
DDO (D)
are the input and output dynamic supply currents
are the specified input and output quiescent
+ (0.5 × 10
DD1
and I
−3
DD2
) × C
supply current, the supply
L
× V
DDO
) × (2f − f
DDx
ADuM7510
voltage near
r
DD1
) + I
f ≤ 0.5f
f ≤ 0.5f
and
DDO (Q)
r
r