Dual-channel isolators provide data and power isolation in single package


ADI extends iCoupler(R) family of digital isolators with a
complete solution that dramatically reduces board space and cost for
industrial, instrumentation and power applications.

NORWOOD, Mass.— Analog Devices, Inc., a global leader
in high-performance semiconductors for signal processing applications,
is extending its industry-leading family of iCoupler(R) digital
isolators with the industry's first products that provide both data
and power isolation in a single package. Unlike existing solutions
that require the configuration of separate signal and power circuitry
involving multiple components, this advancement provides designers of
industrial, instrumentation, and power systems with a simple,
low-cost, space-saving alternative. The products incorporate ADI's new
proprietary isoPower(TM) technology that integrates a micro-power
supply with independent signal channels. This eliminates the need for
complex, sizeable, and costly combinations of optocouplers,
transformers and other components, thereby reducing cost by as much as
70 percent and board space by as much as 80 percent.

Announced today, the ADuM5240, ADuM5241 and ADuM5242 are
dual-channel isolators incorporating isoPower technology. These new
products, provided in 8-lead SOIC (small-outline integrated circuit)
packaging, integrate an isolated power supply with two digital signal
channels to create a complete isolation solution for low-power
applications found in factory automation equipment, instrumentation
and secondary control power supplies. In such applications, where
designers are under great pressure to reduce size, cost and
development time, the ADuM524x product family simplifies the challenge
of isolated designs with a single-component solution. As with all
iCoupler products, these new devices will carry regulatory safety
approvals from the major North American and European agencies upon
product release.

“ADI's iCoupler digital isolation products have a solid five-year
track record of safe, reliable operation in a wide variety of
applications. Since 2001 when we first introduced the breakthrough
iCoupler products, which proved far superior to optocouplers, iCoupler
usage has grown to more than 50 million isolation channels in the
field,” said Dick Meaney, vice president, precision signal processing
group, Analog Devices. “We are now leveraging our iCoupler technology
to solve a challenging problem: isolating power along with data in a
small space at a low cost. Our new iCoupler products with isoPower
capabilities enable customers to achieve these savings as well as
reduce development time.”

About the ADuM524x iCoupler Digital Isolators with isoPower Technology

The ADuM524x products incorporate the isoPower technology, which
integrates an isolated DC/DC converter with two channels of digital
signal isolation in an 8-lead SOIC. Intended for low-power
applications, the integrated DC/DC converter provides up to 50 mW of
isolated, regulated power at 5 V. The ADuM524x devices operate with a
supply voltage ranging from 2.7 V to 5.5 V with the internal DC/DC
converter enabled at supply voltages above 4.5 V. The signal channels
have excellent timing specifications with propagation delay less than
55 nanoseconds and channel-to-channel matching better than three
nanoseconds. All three ADuM24x products carry a 2.5 KV isolation

Each product varies by the directionality of each channel. The
ADuM5240 has two signal outputs on the same side as the power output.
The ADuM5241, with signal channels in each direction, is ideal for
bi-directional communications, such as an RS-232 transceiver, that
require isolated power for interface electronics. The ADuM5242, with
the two signal outputs on the same side as the power input, is ideal
for power supply applications that employ secondary side control and
require isolated power to initiate start-up.

About ADI's iCoupler Digital Isolators

Isolation devices are used in a wide range of applications to
protect people and equipment from unsafe voltage levels and disruptive
noise sources. Analog Devices' iCoupler isolation technology employs
chip-scale, micro-transformers in contrast to the LEDs and photodiodes
used in optocouplers. Compared to optocouplers, iCoupler products
consume less power, achieve higher data rates and provide more precise
timing, yet still provide isolation ratings of up to 5 kV. Because the
micro-transformer structures are integrated on semiconductor
substrates, iCoupler products can achieve high levels of integration
enabling greater functionality, smaller size and lower cost.
Underscoring the scalability and flexibility of the iCoupler
technology, isoPower is the latest development in ADI's digital
isolation product portfolio.

Pricing and Availability

The ADuM524x digital isolators are sampling to lead customers now
with samples to the open market scheduled for July 2006. Each of the
three devices is available in Pb-free 8-lead SOIC packaging and is
priced at $2.95 per unit in 1,000-piece quantities. For additional
information on the ADuM524x family, please visit

Analog Devices has been serving the electronics industry with isolation products for nearly five years. Its iCoupler chips integrate very small transformers, using magnetic technology rather than optical methods that are used in optocouplers.

Its latest iCoupler family of digital isolators employs ADI's proprietary technology called isoPower, which enables the transformers not only to isolate data or signals, but also power in a single package. The extension of isoPower has been done in response to customers needs to reduce cost and size, mainly in the industrial sector.

'This is an industry first,” said Ronn Kliger, product line manager, iCoupler products. “Up to now, designers are really forced to configure signal isolation and power isolation solutions independently with different components and different technology.”

There are three devices that incorporate isoPower technology—the ADuM5240, ADuM5241 and ADuM5242. The only difference between the products is the direction of the signal flow. The products output 10-milliamps of 5-volts of isolated power that the designers can use to power anything they desire on as isolated portion of the system.

The dual-channel products have two channels of signal isolation, which transmit data at a rate of 1-Mbits/s to 100-Mbits/s. Although the products are capable of data rates as high as 400-Mbits/s, the company chose to cap it at 100-Mbits/s because it hasn't seen demand for anything above that level.

Systems have typically used optocouplers to act as the isolation barrier, supporting the flow of signals between two points in a system. The problem with optocouplers, as well as other conventional devices, is not only sending signals but power across an isolation barrier. Power can't be taken from point A and run through a wire to point B—it must be sent over in an isolated fashion, Kliger explained.

Using traditional methods, designers have typically built an isolated power supply that is based on discrete transformers that takes input power and sends it magnetically across that transformer. That's a mature and costly way of handling isolation. There are also vendors that sell power supplies in an integrated fashion. It is a smaller, design-your-own method way of sending power across the isolation barrier. In both cases, the designer still needs two devices— one product, such as an optocoupler, to send signals across the isolation barrier and another device to send power. ADI has found a way to integrate both functions in one component.

Compared with existing products, such as a two-channel optocoupler and an isolated DC-DC converter, using ADI's dual-channel saves designers 80% in board space and 70% in cost, he said.

“Our first isoPower product is really optimized for low-power applications. The output of this product is 50-milliwatts, which is a relatively small amount of power compared with an isolated DC-to-DC converter, which are typically 1 or 2 watts,” Kliger said. “That was a conscious decision that we made on these first products. We're targeting certain applications where the amount of power is sufficient and our focus here is to minimize cost and size.”

The company plans to develop iCoupler products that operate in the sub-watt area, he said.

isoPower technology
The parts have three transformers inside—two are used for signals and one for power. Using transformers to provide isolation instead of LEDs like optocouplers is a more flexible method since they support both signals and power. With CMOS technology, ADI has been able to surround the power transformer with the right amount of circuitry to integrate the functions in one device. The transformers are very small and rated for 2.5-kV insulation strength.

The transformers are two coils stacked above each other separated by some insulation. When there's a signal or power present in one coil, it couples magnetically to the second coil and the spacing between the two is only 20-microns.

“The coupling is strong enough to allow us to make usable product to get signals and power across,” he said.

Pricing between the devices doesn't vary. With the stacked configuration, signals can communicate in either direction. As a result, the products can go into a variety of applications.

Kliger cited several applications, including data acquisition and RS-232 interface, but power supplies is one of the major areas where it saw a pull for this kind of technology, he said.

One of the trends is to put the control function on the secondary side of the power supply so that's it is closer to the load and can respond more quickly and accurately to changes in the load. One of the problems with this architecture is during system start-up, Kliger explained.

The controller requires power to start operating; however, there's no power available until the power supply is up and running. The power supply can't start operating until the controller is operating. Power supply companies resolved this by adding an auxiliary supply, which adds cost, board space and complexity.

The ADuM5242 eliminates that problem by sending power directly from the input to the output, triggering the controller. When the controller gets going, it sends two digital signals back to the primary side to start the power-supply loop operating. The ADuM5242 supports the two PWM signals coming back from right to left, allowing the power supply to start running. The isoPower portion of the product can be disabled, if the user desires. And the power supply functions on its own.

The company has started to sample its isoPower-based iCoupler products to power supply companies. It expects to ship in full production starting in July 2006.

Analog Devices Inc., 1-800-262-5643,

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