Ideal for replacing PHOTOCOUPLERS! Features of digital isolators

iCoupler Advantages Over PHOTOCOUPLERS

low power consumption
PHOTOCOUPLERS consume a relatively large amount of power because they use light for isolation, but iCouplers use magnetic coupling, which can significantly reduce power consumption.

High-speed data transmission
Even the highest-speed PHOTOCOUPLERS products have a transmission speed limit of around 50 Mbps, but iCoupler standard products have speeds of up to 150 Mbps, and the lineup includes products for LVDS communication that reach extremely high speeds of 2.5 Gbps.

Less deterioration over time
With PHOTOCOUPLERS, degradation of the primary-side LED can cause a drop in current, potentially resulting in communication failure. However, because iCoupler uses magnetic isolation, it has high long-term reliability and suffers almost no performance degradation.

High CMTI (Common Mode Transient Immunity)
It has high noise resistance and can operate stably even in harsh noise environments such as industrial equipment and medical devices. It has been improved with each generation, and as of 2025, the latest generation has achieved extremely high performance with a CMTI of 180kV/µs.

Small size and high integration possible
iCoupler's ability to integrate multiple channels into a single package simplifies board design and reduces component count.

Excellent temperature characteristics, pressure resistance, and surge resistance
Because of their high reliability, they are increasingly being adopted in fields where quality is critical, such as automotive, industrial, and medical applications.

iCoupler Structure

Instead of using light like PHOTOCOUPLERS, iCoupler achieves isolation through magnetic coupling using a chip-TRANSFORMERS transformer.

Main components

Planar TRANSFORMERS structure
Planar TRANSFORMERS, consisting of CMOS metal layers and gold layers, are formed directly on the chip using wafer surface processing.

Insulation layer
A polyimide layer with high breakdown voltage provides insulation between the top and bottom coils of TRANSFORMERS.

CMOS circuit
It is connected to the upper coil and controls the transmission and reception of signals.

External Interface
The lower coil is connected to an external signal and transmits the signal through TRANSFORMERS.

Insulating materials

There are two main types of insulation methods for digital isolators: polyimide and SiO2. This section explains the characteristics of the polyimide insulation used by iCoupler.

High dielectric strength
Polyimide has a very high breakdown voltage and can withstand voltages of several thousand volts. In iCoupler, a layer of polyimide is sandwiched between the upper and lower coils of TRANSFORMERS to safely separate them.

Excellent thermal stability
Polyimide has stable physical properties even in high-temperature environments (over 200°C), making it ideal for industrial equipment and automotive applications.
It has high long-term reliability because it is less susceptible to deterioration due to heat.

Thin film formation possible
Using microfabrication techniques, polyimide can be formed into an extremely thin and uniform insulating layer.
This makes it easier to reduce chip size and integrate multiple channels.

Mechanical flexibility and impact resistance
Polyimide is flexible and resistant to mechanical stress and vibration, allowing it to maintain stable performance even in harsh environments.

Less deterioration over time
Unlike PHOTOCOUPLERS, there is no light source degradation, and stable signal transmission can be maintained for a long period of time.

For a detailed explanation of the insulating properties of polyimide, please refer to the following document from Analog Devices:

• https://www.analog.com/jp/resources/technical-articles/polyimide-film-uses-for-digital-isolators.html

Fail-safe polarity selection

It has a built-in fail-safe that freezes the output in the event of loss of input POWER SUPPLIES or input signal, and is available in two polarity options.

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  ADuM34xE 0 Fail-safe: Output fixed low​

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  ADuM34xE 1 Fail-safe: Output fixed high​

Package Selection

There are two types of packages with the same number of TERMINALS and layout, but different sizes.

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  SOIC Wide Body 16-pin package

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  QSOP 16-pin package

Generally, the type of package is selected taking into consideration factors such as board size, mounting constraints, and heat dissipation, but in the case of digital isolators, care must be taken as the type of package affects the insulation voltage.

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  SOIC Wide Body Dielectric Strength (Partial excerpt)

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  QSOP package insulation voltage (partial excerpt)

The SOIC Wide Body is larger and takes up more board space, but the primary side (PINs #1 to #8) and secondary side (PINs #9 to #16) are farther apart, resulting in longer clearance and creepage distances, and as a result a higher dielectric strength voltage.