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Isolator FAQs

Why is isolation need?
Isolators transfer data without a direct electrical connection. Isolation reduces noise, eliminates ground loops, and improves safety.

What are the advantages of IsoLoop Isolators?
The advantages of IsoLoop spintronic GMR isolators are summarized with the five Bs: Boxes (small packages including MSOPs); Bits (up to 5 channels per device); Baud (up to 150 Mbps and 100 ps jitter); Batteries (1.5 mA/channel quiescent); and Bullet-proof (up to 125°C; unlimited life). This video has more.

What is “GMR”?
Giant magnetoresistors, where resistance changes due to conduction electrons scattering at interfaces. The technology is faster, lower power, and more reliable than conventional semiconductors. In awarding the 2007 Nobel Prize in Physics for GMR, the Nobel Committee said, “GMR can be considered one of the first real applications of the promising field of nanotechnology.” This video has illustrative animations.

What are isolators used for?
Popular applications include RS-485, PROFIBUS, serial interfaces, isolated I˛C, isolated Controller Area Network (CAN Bus), isolated Serial Peripheral Interface (SPI), isolated A/D converters, isolated PLCs, isolated audio, and isolated power interfaces.

Why do folks hate optos?
Optocouplers are big, slow, and unreliable. One of the biggest problems is that LEDs degrade over time. Every photon depletes the LED, so the output decreases and eventually it will fail. IsoLoop isolators use magnetics and spintronics rather than optics. Nothing is depleted.

What types of IsoLoop Isolators are available?
Product lines include the industry-standard IL700 / IL200-Series, the IL4- / IL3-Series single-chip isolated RS-485/RS-422/PROFIBUS/CAN transceivers, the cost-effective IL500-Series, and IL600-Series Passive-Input Isolators.

What packages are available?
IsoLoop Isolators are available in MSOP, SOIC, PDIP, 0.15" SOIC-16, 0.3" SOIC-16 and QSOP packages.

What channel configurations are available?
A wide range of channel configurations are available, including one, two, three, four, five, as well as RS-422, RS-485, PROFIBUS, and CAN.

How long is the isolation barrier life?
Other isolators have barriers that degrade over time, but IsoLoop Isolators have a “line in the sand” barrier—a patented glass-polymer composite structure that doesn’t degrade. Compared to conventional semiconductors, it’s like indestructible fiberglass versus rusting sheet metal. Reliability data shows failures-in-time of 2.6 per billion hours at 100°C, for an MTBF of 44,000 years. This video explains.

What safety approvals do IsoLoop Isolators have?
NVE Isolators are certified for 600 V Working Voltage under IEC 60747-5-5 (VDE 0884) and are recognized under UL1577. They also comply with IEC 61010-1 Edition 2 and meet the 8 mm creepage requirements of IEC 60601.

What is the MTBF of NVE isolators?
A remarkable 44,000 years at 100°C. A detailed reliability report is available on request.

What voltage can isolators stand indefinitely?
The maximum voltage indefinitely between the inputs and outputs of an isolator is called endurance voltage. For most isolators it’s not specified, but for NVE isolators, endurance voltage is 800 Vrms, or 1,130 Vpeak or DC. This video has details.

What’s the difference between “baud” and “hertz”?
Two bits of data are transmitted each cycle, so the maximum data rate (baud) is twice the maximum frequency (hertz).

What does “useable baud rate” mean?
Speed is worthless if it’s garbled. Some isolators specify high baud rates but have propagation delays too long to use that baud rate. Others have unrealistic pulse width specifications. NVE’s speed specifications support practical use at high speeds, including propagation delay, jitter, and channel-to-channel skew.

What are “passive input” isolators?
NVE offers both digital-input and passive-input isolators. Passive input isolators have current-mode input coils for flexibility similar to LED-input optocouplers. There is no need for an input-side power supply. Also, NVE passive input isolators are available with either CMOS or open-drain outputs for drop-in optocoupler replacement. Watch this video for specifics.

How much input current do I need to drive a passive input isolator?
Worst-case is 8 mA, which is for single-ended operation with a 3 V supply. In differential mode, where the input current reverses, the logic low threshold current is 5 mA for the range of supplies. A “boost capacitor” in parallel with the current-limiting resistor creates current reversals at edge transitions, reducing the input logic low threshold current to the differential level of 5 mA.

Can unused inputs be left unconnected?
Some can, but some can’t. Inputs with pull-down resistors are noted on the datasheet. Otherwise, unused inputs should be connected to Vdd or GND.

Can power supply decoupling capacitors be larger than recommended?
Yes. NVE recommends 47 nF minimum decoupling capacitors, and many customers use 0.1 µF or larger. The important thing is to use low-ESR ceramic capacitors. A parallel 10 µF tantalum capacitor is also recommended on Vdd2 for bus transceivers.

Are optocouplers good for anything?
Maybe you could use them for “geek chic” jewelry. Of course, if anyone notices they’re optocouplers, they won’t be considered very chic.

How can I try NVE isolators?
It’s easy to try its isolators. Distributors such as Digi-Key stock a wide variety. The NVE Online Store has no minimum order and $9.95 flat-rate shipping to North America, and Isolator Evaluation Boards are available to try out a variety of parts.

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