IL3422-3E NVE, IL3422-3E Datasheet - Page 8

• Manufacturer Part Number: IL3422-3E
• Description: TXRX ISO BUS 20MBPS RS422 16SOIC
• Manufacturer: NVE
• Series: IsoLoop®r

Specifications of IL3422-3E

• Inputs - Side 1/side 2: RS-422
• Number Of Channels: 2
• Isolation Rating: 2500Vrms
• Voltage - Supply: 4.25V, 5V
• Data Rate: 20Mbps
• Propagation Delay: 55ns
• Output Type: Logic
• Package / Case: 16-SOIC (3.9mm Width)
• Operating Temperature: -40°C ~ 85°C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 390-1129-5

Magnetic Field Immunity
IsoLoop devices operate by imposing a magnetic field on a GMR sensor, which translates the change in field into a change in logic
state. The devices are manufactured with a magnetic shield above the sensor. The shield acts as a flux concentrator to boost the
magnetic signal from the internal coil, and as a shield against external magnetic fields. The shield absorbs surrounding stray flux
until it becomes saturated. At saturation the shield is transparent to external applied fields, and the GMR sensor may react to the
field. To compensate for this effect, IsoLoop Isolators use Wheatstone Bridge structures that are only sensitive to differential
magnetic fields. There are several ways to further enhanced the magnetic field immunity of IL3000 Transceivers. Providing a
larger internal field will reduce the effect of an external field on the GMR sensor. Immunity to external magnetic fields can also be
enhanced by proper orientation of the device with respect to the field direction and field boosting capacitors.
Orientation of the device with respect to the field direction
An applied field in the “H1” direction is the worst case for magnetic immunity. In this case the external field is in the same
Data Rate and Magnetic Field Immunity
It is easier to disrupt an isolated DC signal with an external magnetic field than it is to disrupt an isolated AC signal. Similarly, a
DC magnetic field will have a greater effect on the device than an AC magnetic field of the same effective magnitude. For
example, signals with pulses greater than 100 μs long are more susceptible to magnetic fields than shorter pulse widths. For input
signals faster than 1 MHz, rising in less than 3 ns, a 470 pF field-boost capacitor provides as much as 400 Gauss immunity, while
the same input capacitor might provide just 70 Gauss of immunity at 50 kHz.
Figure 3. Orientation of External Magnetic Field
Method
Field applied in direction H1
Field applied in direction H2
Field applied in any direction but with field
booster capacitor (470 pF) in circuit
Table 1. Magnetic Immunity
NVE Corporation
GND
V
GND
V
COIL1
RE
DE
DD1
R
D
1
1
H2
11409 Valley View Road, Eden Prairie, MN 55344-3617
V
GND
NC
B
A
V
NC
GND
COIL2
DD2
2
2
H1
Approximate Immunity
±20 Gauss
±70 Gauss
±250 Gauss
direction as the applied internal field. In one direction it will tend to
help switching; in the other it will hinder switching. This can cause
unpredictable operation.
An applied field in the direction of “H2” has considerably less effect on
the sensor and will result in significantly higher immunity levels as
shown in Table 1.
The greatest magnetic immunity is achieved by adding the current boost
capacitor across the input resistor. Very high immunity can be achieved
with this method.
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Immunity Description
A DC current of 16 A flowing in a conductor
1 cm from the device could cause disturbance
A DC current of 56 A flowing in a conductor
1 cm from the device could cause disturbance
A DC current of 200 A flowing in a conductor
1 cm from the device could cause disturbance
IL3485/IL3422
www.IsoLoop.com
©NVE Corporation