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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)
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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/PROFIBUS 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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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.
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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.
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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.
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Isolated
PROFIBUS Using IL710 and IL711
NVE offers the unique IL3585 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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Simple Isolated
Controller Area Network (CAN) Bus Using IL612
Low pulse width distortion is critical for CAN bus, and IL600 Isolators are
specified for just 3 ns typical pulse width distortion. Their fail-safe
output (logic high output for zero coil current) ensures ensures recessive
bus state on power-up with no additional circuitry. The speed of IL600 Isolators
easily supports the maximum CAN bus transfer speed of 1 Mbps. The IL612
provides 2.5 kVrms isolation (1 minute) and 20 kV/µs
transient immunity.
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High-Temperature
Isolated CAN Bus Using IL712T
With a maximum operating temperature of 125°C and no derating, the IL712T
tolerates the harshest CAN bus environments. The IL712T also provides one-third
to one-fourth the propagation delay of the fastest optocouplers. In this circuit,
the SN74F02 provides fail-safe start-up.
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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.
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Isolation of I²C
Nodes Using IL612A
This circuit provides isolated bidirectional isolation of Inter-IC (I²C)
bus signals.
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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
(only 50 ps typical jitter) all but eliminates noise-induced phase error
and hum in the analog side of the audio system.
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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 node’s 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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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.
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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.
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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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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.
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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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