Illustrative IsoLoop Isolator Applications
Improve reliability with excellent transient immunity and magnetic immunity, and
unlimited life with no degradation. Up to 6 kVrms isolation and 1 kVrms
working voltage. Reduce board space with up to two channels per MSOP and up to
five channels in QSOPs. Popular IsoLoop Isolator applications include PLCs, RS-485,
PROFIBUS, CAN, I²C, SPI, high-fidelity audio, and power interfaces.
PLCs |
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RS-422/RS-485/PROFIBUS |
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RS-422 Network with Two IL610 Receivers
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RS-485 Repeater Using IL610 |
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Controller Area Network (CAN) Bus |
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Other Serial Interfaces |
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Isolated ADCs, DACs and Serial Peripheral Interface (SPI) |
IL600-Series Isolators for True Channel-to-Channel Isolation
In addition to 2,500 Vrms input-to-output withstand voltage,
the IL600 series of IsoLoop isolators provide outstanding isolation of 400 Vrms between adjacent channels. These unique devices allow very simple channel
separation in industrial process control applications, especially PLCs,
where the reference ground of each channel may be different. The data line
is powered by the signal, so no input power supply is required. With two
channels available in the tiny MSOP footprint, more functionality can be
crammed into a smaller space without sacrificing channel-to-channel or ground-to-ground
isolation.
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Single-Chip
RS-485 Isolated Transceivers 
NVE offers the industry's broadest line of single-chip isolated
RS-485 transceivers, including digital- and passive-input versions, fractional-load
versions, and PROFIBUS-compliant versions. Termination resistors can be
added to maximize speed and transmission length. Fail-safe resistors guarantee
a known state on a terminated bus with no active transceivers. NVE transceivers
are available with data rates are up to 40 Mbps. Parts are available
in 0.3" and 0.15" 16-pin SOIC packages.
IsoLoop logic isolators can also be used as part of multi-chip designs to
isolate signals using particular non-isolated transceivers (see examples
below).
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Single-Component RS-485 Receiver Using IL610
An IL610 can be used as a simple isolated RS-485/RS-422 receiver. No external
resistors are required, and cabling is greatly simplified by eliminating the
need to power the input side of the receiving board. The circuit is failsafe
because the IL610 is guaranteed to switch to the high state when the coil
input current is less than 500 µA. No current-limiting resistor
is needed for a single receiver because it will draw less current than the
driver maximum. There is also no need for line termination resistors in most
IL610 line receiver applications below a data rate of about 10 Mbps because
the IL610 coil resistance of approximately 70 Ohms is close to the characteristic
impedance of most cables.
The IL610 provides 2.5 kVrms isolation (one minute), and 20 kV/µs
transient immunity. The IL610-1 is a unique MSOP isolator for space-critical
boards.
For more information on using IL600-Series Isolators as differential receivers,
see Application Bulletin No. 10 (.pdf).
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Single-Chip
RS-422 Isolated Transceivers
NVEs single-chip isolated RS-422 transceivers include digital-
and passive-input versions, and fractional-load versions. Termination resistors can be added to maximize speed and transmission
length. Fail-safe resistors guarantee a known state on a terminated bus
with no active transceivers. NVE transceivers are available with data rates
are up to 40 Mbps. Parts are available in 0.3" and 0.15" 16-pin SOIC
packages.
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RS-422 Network with Two IL610 Receivers
This circuit shows a two-receiver RS-422 network using IL610s. Two 17 Ohm
current-limiting resistors prevent two IL610 coils from exceeding the maximum
load of the transceiver chip. Placement of the current-limiting resistors
on both lines provides better dynamic signal balance. Back to top
RS-485 Repeater Using IL610
Simple, low cost, isolated repeater systems can be made with an RS-422 transmitter/receiver
pair (or an RS-485 transceiver in drive mode) and an IL610. Repeaters can
extend the useful cable length and node count indefinitely, provided the network
controller can tolerate the additional propagation delays. Back to top
Isolated Fractional Load RS-485 Using IL614
NVE offers a broad line of single-chip isolated RS-485 transceivers, but
the unique IL614 three-channel isolator can also be used as part of a multi-chip
design with non-isolated transceivers. The IL614 provides 2.5 kVrms isolation
(1 minute) and 20 kV/µs transient immunity. The IL614-3 is
in a narrow-body (0.15"-wide) package when board space is critical. Back to top
Isolated PROFIBUS Using IL3685 Single-Chip Transceiver

The 220 ohm termination resistor, along with another 220 ohm resistor and the other end of the bus, matches the bus impedance to minimize reflections. The 390 ohm "fail-safe" resistors guarantee a known state with no active transceivers.
Bypass capacitors should be placed as close as possible to the appropriate IC.
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Isolated
PROFIBUS Using IL710 and IL711
NVE offers the unique IL3685 single-chip isolated PROFIBUS transceiver, but
IL700 high-speed digital signal isolators can also be used as part of multi-chip
designs using non-isolated PROFIBUS transceivers. Circuits can be configured
with three IL710s (circuit above) or one IL710 and one IL711 (circuit below).
The IL710 and IL711 provide 2.5 kVrms isolation (1 minute) and 30 kV/µs
typical common-mode transient immunity. The IL710-1 and IL711-1
are unique MSOP one- and two-channel isolators to minimize board space.

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Single-Chip Isolated CAN Transceiver
 The L41050 single-chip isolated CAN transceiver provides an isolated CAN interface in a single chip. Designed for harsh CAN and DeviceNet environments, the transceivers have a -55 to +125°C operating range, transmit data dominant time-out, bus pin transient protection, thermal shutdown protection, short-circuit protection, 2,500 volt isolation, and typical transient immunity of 30 kilovolts per microsecond. Unique edge-triggered inputs improve noise performance.
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Isolating Standard CAN Transceivers
This simple circuit works with any CAN transceiver with a TxD dominant timeout, which includes all of the current-generation transceivers including the ubiquitous Philips/NXP TJA1050. Propagation delay is critical for CANbus, and the IL712 and IL721 bidirectional isolators have best-in-class propagation delay of 10 ns typical. This minimizes CAN loop delay and maximizes data rate over any given bus length,
making IsoLoop Isolators ideal for CAN isolation. NVE also offers the smallest two-channel isolator, the IL712-1, in a unique MSOP-8.
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Isolating Legacy CAN Transceivers
Power-on reset circuitry allows an IL712 to isolate legacy transceivers that lack TxD integrated TxD timeout, such as the Philips/NXP PCA82C250.
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Differential Signal Isolation Using an IL611
IL600-Series Isolators are ideal for isolating differential signals
because you have access to the input coils and do not need
input power to drive the signal across the barrier.
When the voltage at node Y is greater than the voltage at node Z there is a logic high at the OUT+ node and a low
on the OUT- node.
Outputs are reversed when the voltage at node Z is higher than the voltage
at node Y. Current-limiting resistors can be selected to ensure input coil
currents are at least ±5 mA and no more than ±10 mA.
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Isolated RS-232 Using IL712s
IL712s provide 2.5 kVrms isolation (1 minute) and 30 kV/µs typical
common-mode transient immunity. The IL712-1 is a unique MSOP dual-channel
isolator to minimize board space. Back to top
Isolated I²C Using IL612A
This circuit provides bidirectional isolation of I²C bus signals with no restrictions on data rate and none of the I²C bus latch-up problems common with other isolation circuits. The SCL section is similar as shown in the schematic using the other half of the P82B96.
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Isolated USB Using IL710s
In this illustrative circuit, power is supplied by USB bus power on one side
of the isolation barrier, and the USB nodes external supply on the other
side of the barrier. IL700-Series Isolators are specified at just 3 ns
worst-case pulse width distortion. The IL700s provide 2.5 kVrms isolation
(1 minute) and 30 kV/µs typical common-mode transient immunity.
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Isolated I²S Using IL710/IL711
Isolating a CD transport DAC with an isolated Inter-IC Sound (I²S)
bus eliminates ground loops. The IL700-Series isolators' precision edge placement
(just 100 ps jitter) all but eliminates noise-induced phase error
and hum in the analog side of the audio system.
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Single-Channel
Isolated SPI Delta-Sigma A/D Converter Using IL717
This circuit illustrates a typical single-channel delta-sigma isolated ADC
SPI interface. The ADC is located on the bridge with no signal conditioning
electronics between the bridge sensor and the ADC. The IL717 isolates the
control bus from the microcontroller and the system clock is located on the
isolated side of the system. Back to top
Multi-Channel Isolated Sampling A/D Converter Using IL261
 The IL261 is ideal for isolating multi-channel sampling ADCs. Isolated channels
A0 and A1 control the analog channel being sampled, while the three remaining
I/O lines on the IL261 isolate the SPI interface.
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Multi-Channel
Isolated SPI Delta-Sigma A/D Converter Using IL261s
This circuit illustrates multiple ADCs configured in a channel-to-channel
isolation configuration. The problem for designers is how to control clock
jitter and edge placement accuracy of the system clock for each ADC. The best
solution is to use a single clock on the system side and distribute this to
each ADC. The IL261 adds a fifth channel to the IL717. This fifth channel
is used to distribute a single, isolated SPI clock to multiple ADCs. Back to top
Isolated Multi-Channel SPI A/D Sampling With IL262s 
A multi-channel sampling system with separate A/D cells. The
IL262 is used to control the SPI lines and send back ADC BUSY commands to
the host, allowing efficient interrupt-driven sampling. The BUSY line may
also be used as a frame synchronization signal in video applications. Back to top
Isolated 12-Bit
DAC Using Three IL515s
The IL515 four-channel isolator is ideally suited for parallel bus isolation. The circuit above uses three IL515s to isolate a 12-bit DAC. The unique SYNC function allows the internal clock to be shut off, eliminating the small amount of noise associated with this clock. A reset pulse is applied at power-on to ensure correct data on the isolator outputs. After the reset pulse goes high, data transfer from input to output is initiated by the leading edge of each changing data bit.
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Isolated Audio DAC Using Two IL260s
Isolation ensures the best DAC performance by
eliminating much of the digital noise that tends to find its way onto the
analog output. The unique five-channel IL260 isolator series allows ten channels
of isolation with just two narrow-body or wide-body ICs.
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Intelligent
DC-DC Converter With Synchronous Rectification
A typical primary-side controller uses a IL511, IL611, or IL711
isolator to drive the synchronous rectification signals from primary side to secondary
side. IsoLoop pulse-width distortion as low as 0.3 ns typical minimizes MOSFET
dead time and maximizes system efficiency. Ultra-small isolator packages (including
two-channel MSOP-8s), allow the designer to squeeze more into less board area.
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Switch-Mode Power Supply Gate Driver with an IL711 Isolator
An IL711 isolates the PWM Controller from the MOS gate driver
for synchronous rectification. IsoLoop pulse-width distortion as low as 0.3 ns
and 100 ps jitter improves precision, minimizes MOSFET dead time and maximizes
system efficiency. The IL711V-1E provides two-channels and full 2.5 kV isolation
in an ultraminiature MSOP-8 package, allow the designer to squeeze more into less
board area. The wide-body IL711VE provides 5 kV isolation and best-in-class
1 kV Working Voltage in a true 8 mm creepage package.
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Isolated Power Control Using
IL610s
The fail-safe output (logic high output for zero coil current)
of IL600 Isolators ensures the power FETs will be off on power-up. The IL600
inputs can be configured for inverting or non-inverting operation (see
IL600 Product Data Sheet). The IL600 Isolators provide 2.5 kVrms
isolation (1 minute), and 20 kV/µs transient immunity. Back to top
Isolated 120 V AC Line Monitor Using IL610A
The wide input voltage range of IL600 Isolators allow connection to line
voltage through current-limiting resistors. In this illustrative circuit,
"Monitor Out" goes low when line voltage exceeds approximately 100 V, and high when line voltage drops below approximately 10 V. This circuit
provides 2.5 kVrms isolation and 20 kV/µs transient immunity.
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Multi-Channel
Isolated Alarm Monitor Using IL610As
IL600A Isolators' open-drain outputs can be wire-OR connected. A very wide
input voltage range is possible, and inputs can be configured for inverting
or non-inverting operation (see IL600A Product
Data Sheet). This illustrative circuit provides fail-safe output (logic
high output for zero coil current), 2.5 kVrms isolation, and 20 kV/µs
transient immunity. Typical logic output sink current is 10 mA for each
isolator. Unlike optocouplers, IsoLoop Isolators do not degrade over time
and have unlimited life.
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