IL711/IL712/IL721
7
NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 Fax: (952) 829-9189 www.IsoLoop.com ©NVE Corporation
80 ns
Application Information
Electrostatic Discharge Sensitivity
This product has been tested for electrostatic sensitivity to the
limits stated in the specifications. However, NVE recommends that
all integrated circuits be handled with appropriate care to avoid
damage. Damage caused by inappropriate handling or storage could
range from performance degradation to complete failure.
Electromagnetic Compatibility
IsoLoop Isolators have the lowest EMC footprint of any isolation
technology. IsoLoop Isolators’ Wheatstone bridge configuration
and differential magnetic field signaling ensure excellent EMC
performance against all relevant standards.
These isolators are fully compliant with generic EMC standards
EN50081, EN50082-1 and the umbrella line-voltage standard for
Information Technology Equipment (ITE) EN61000. NVE has
completed compliance tests in the categories below:
EN50081-1
Residential, Commercial & Light Industrial
Methods EN55022, EN55014
EN50082-2: Industrial Environment
Methods EN61000-4-2 (ESD), EN61000-4-3 (Electromagnetic
Field Immunity), EN61000-4-4 (Electrical Transient Immunity),
EN61000-4-6 (RFI Immunity), EN61000-4-8 (Power Frequency
Magnetic Field Immunity), EN61000-4-9 (Pulsed Magnetic
Field), EN61000-4-10 (Damped Oscillatory Magnetic Field)
ENV50204
Radiated Field from Digital Telephones (Immunity Test)
Immunity to external magnetic fields is even higher if the field
direction is “end-to-end” rather than to “pin-to-pin” as shown in the
diagram below:
Cross-axis Field Direction
Dynamic Power Consumption
IsoLoop Isolators achieve their low power consumption from the
way they transmit data across the isolation barrier. By detecting the
edge transitions of the input logic signal and converting these to
narrow current pulses, a magnetic field is created around the GMR
Wheatstone bridge. Depending on the direction of the magnetic
field, the bridge causes the output comparator to switch following
the input logic signal. Since the current pulses are narrow, about
2.5 ns, the power consumption is independent of mark-to-space
ratio and solely dependent on frequency. This has obvious
advantages over optocouplers, which have power consumption
heavily dependent on mark-to-space ratio.
Power Supply Decoupling
Both power supplies to these devices should be decoupled with
low-ESR 47 nF ceramic capacitors. Ground planes for both GND
1
and GND
2
are highly recommended for data rates above 10 Mbps.
Capacitors must be located as close as possible to the V
DD
pins.
Maintaining Creepage
Creepage distances are often critical in isolated circuits. In addition to
meeting JEDEC standards, NVE isolator packages have unique creepage
specifications. Standard pad libraries often extend under the package,
compromising creepage and clearance. Similarly, ground planes, if used,
should be spaced to avoid compromising clearance. Package drawings
and recommended pad layouts are included in this datasheet.
Signal Status on Start-up and Shut Down
To minimize power dissipation, input signals are differentiated and
then latched on the output side of the isolation barrier to reconstruct
the signal. This could result in an ambiguous output state depending
on power up, shutdown and power loss sequencing. Unless the circuit
connected to the isolator performs its own power- on reset (POR), a
start-up initialization circuit should be considered. Initialization
consists of toggling the input either high then low, or low then high.
In CAN applications, the IL712 or IL721 should be used with CAN
transceivers with Dominant Timeout
functions for seamless POR. Most
CAN transceivers have Dominant Timeout options. Examples include
NXP’s TJA 1050 and TJA 1040 transceivers.
Data Transmission Rates
The reliability of a transmission system is directly related to the
accuracy and quality of the transmitted digital information. For a digital
system, those parameters which determine the limits of the data
transmission are pulse width distortion and propagation delay skew.
Propagation delay is the time taken for the signal to travel through
the device. This is usually different when sending a low-to-high
than when sending a high-to-low signal. This difference, or error, is
called pulse width distortion (PWD) and is usually in nanoseconds.
It may also be expressed as a percentage:
PWD% =
Maximum Pulse Width Distortion (ns)
x 100%
Signal Pulse Width (ns)
For example, with data rates of 12.5 Mbps:
PWD% =
3 ns
x 100% = 3.75%
This figure is almost three times better than any available
optocoupler with the same temperature range, and two times better
than any optocoupler regardless of published temperature range.
IsoLoop isolators exceed the 10% maximum PWD recommended
by PROFIBUS, and will run to nearly 35 Mb within the 10% limit.
Propagation delay skew is the signal propagation difference between two
or more channels. This becomes significant in clocked systems because it
is undesirable for the clock pulse to arrive before the data has settled.
Propagation delay skew is especially critical in high data rate parallel
systems for establishing and maintaining accuracy and repeatability.
Worst-case channel-to-channel skew in an IL700 Isolator is just 3 ns—
ten times better than any optocoupler. IL700 Isolators have a maximum
propagation delay skew of 6 ns— five times better than any optocoupler.
