International benchmark digital isolators under the development trend of isolation
Digital isolator
A digital isolator is a device that realizes digital signal transmission in the state of an electrical isolator, and serves as the basic function of providing galvanically isolated digital signal paths. In the electronic system, when the digital signal and the analog signal are transmitted, the digital isolator makes it have a high resistance isolation characteristic to realize the isolation between the electronic system and the user.
The reason for introducing isolation is to meet safety regulations or reduce ground loop noise. Galvanic isolation ensures that data transmission is not through electrical connections or leakage paths, thereby avoiding safety risks. However, it is inevitable that isolation will bring about limitations in terms of delay, power consumption, cost, and size. The goal of digital isolators is to meet safety requirements while minimizing adverse effects. At present, digital isolators mainly include three types: optocoupler isolator, magnetic coupling isolator, and capacitive coupling isolator.
Although the most common optocoupler digital isolator can meet common isolation requirements, it has a short life and high power consumption, and it is gradually replaced. Capacitive coupling adopts the principle of on-chip capacitance to realize signal isolation transmission, with long life, low power consumption and high transmission rate. The magnetic coupling type can transfer additional energy on the basis of capacitive coupling, which can greatly expand the application field of the isolator.
TI digital isolator
TI's basic digital isolators and reinforced digital isolators have advantages in high operating voltage, low radiation, low power consumption and high efficiency. TI series generally use proprietary silicon dioxide (SiO2) insulating gates on isolation materials to achieve these properties. In addition to basic performance requirements, TI's digital isolators can also meet small size or cost-sensitive applications.

(ISO67xx series, TI)
The ISO67xx series are capacitively coupled digital isolators, which provide excellent signal isolation performance while focusing on low design cost applications. This series of digital isolators can provide a variety of channel options, helping to improve the protection of critical circuits in various application configurations (SPI, UART, CAN, RS-485, GPIO, and I2C signals).
From the perspective of ISO6741 specific products in this series, ISO6741 is a four-channel digital isolator, which improves design flexibility through low-power operation and level conversion, and supports a wide power supply voltage range from 1.71V to 5.5V. The 8kV (contact) ESD performance prevents damage to the isolator during maintenance. The data rate is up to 50 Mbps, while the operating voltage is up to 1500V and the typical common-mode transient immunity is 75kV/µs. From the above index level, it can be said that ISO6741 provides an unbreakable isolation barrier.
If the ISO67xx series provide an excellent choice for low-cost applications, the ISO70xx series provides the industry's top ultra-low power consumption.
The full range of ISO67xx products can run at ultra-low power, with current consumption per channel as low as 4.2μA, total current consumption at 10kbps, less than 20μA, and power can be expanded to 2Mbps. At the same time of low power consumption, ISO67xx supports an isolation voltage of 3kVrms and a typical value of 100kV/μs for common-mode transient immunity. This isolation strength is sufficiently reliable.

(ISO6741, TI)
ADI digital isolator
ADI's digital isolators are magnetically coupled digital isolators that use iCoupler technology to achieve unlimited design. Overall, ADI's digital isolators have great advantages in robustness and multi-channel flexibility (up to 6 channels).

(ADuM141ES, ADI)
ADuM141ES, a 150 MBPS four-channel digital isolator for aerospace applications, uses ADI's patented iCoupler® technology. These isolation components combine high-speed, complementary metal oxide semiconductor (CMOS) and monolithic air-core transformer technology to provide better performance characteristics.
From the specific numerical point of view, when the ADuM141ES is running at 5 V, the maximum propagation delay is 13.5 ns, the pulse width distortion is less than 3 ns, and the common mode transient immunity is very high, which can achieve greater than 100 kV/μs. At the same time, the ADuM141ES data channels are independent of each other and can withstand a rated voltage of 400 V rms. This device works at a power supply voltage between 1.8 V-5 V and is compatible with lower voltage systems, and supports voltage conversion across isolation barriers.
Low power consumption is also reflected in the current value. At 150 MBPS, the power supply current on side 1 is 17 mA, and the power supply current on side 2 is 17.5 mA, ensuring the data transmission rate and reducing power consumption.

(ADuM260N, ADI)
The performance of the four-channel ADuM141ES is strong enough, let’s take a look at the robust 5.0 kVrms six-channel digital isolator with integrated fail-safe and zero reverse channels.
Common mode transient immunity 100 kV/μs, 13 ns propagation delay at 5V, low latency of 15 ns at 1.8V, maximum data rate of 150 Mbps, VIORM peak 849 V safety certification, 1 minute 5000 V rms UL Certified, 125℃ high temperature working environment, 16-pin wide body SOIC_IC package. High operating voltage, low radiation, low power consumption, and high efficiency are fully reflected in the above data.
Toshiba Digital Isolator
Toshiba's digital isolators mainly use optocouplers, so their performance will be weaker than the high-performance digital isolators provided by TI and ADI mentioned above.
Toshiba TLP350 is a newer digital isolator product, used in various inverters (such as industrial inverters, UPS and power conditioners for photovoltaic power generation) power element gate drive IC. The device is mainly improved in reliability, and the cost is lower.

(TLP350, Toshiba)
TLP350 can prevent the breakdown of power devices by suppressing the surge voltage rise that occurs during abnormal turn-off. When the power supply voltage is abnormal and over-current is detected, a fault signal will be fed back. At the same time, the soft turn-off function of over-current detection makes the power device turn off more softly. These improvements are focused on reliability and stability.
Because starting from the technical parameters alone, optocouplers have natural disadvantages compared to other types. The rated current of this product is 2.5A, which is undoubtedly a large power consumption burden. The common mode transient suppression is 25 kV/µs, which is actually quite good in optocoupler products.
Broadcom Digital Isolator
Broadcom has always been a leading supplier of opto-isolators. Currently, we provide highly reliable military sealed optocouplers, galvanic isolation optocouplers for industrial applications, and optocouplers designed to meet the insulation and reliability requirements of automotive-grade applications.
Although it is an optocoupler expert, its ACML-74xx series CMPS digital isolators adopt magnetic coupling through thick insulation, which has high speed and high insulation performance, and low power consumption at high data rates. The HCPL-90xx/-09xx series of CMOS digital isolators integrate giant magnetoresistance (GMR) technology with high-speed performance and excellent transient immunity specifications.

(ACML-7400, Broadcom)
The ACML-74x0 series of CMOS digital isolators consume a small amount of power, even at high data rates, and can achieve transient suppression performance through compact surface mount. These CMOS digital isolators meet a maximum propagation delay of 36ns and a maximum pulse width distortion of 3ns. They can also run at a data rate of 100 MBd.
In the four-channel ACML-7400 CMOS digital isolator in the above figure, a unidirectional device is configured, and there are four channels in one direction, and each channel is usually within the low power consumption range of 15mA. And the working voltage withstand ability is extremely high, the maximum can withstand 800V rms. The common-mode transient suppression capability is also excellent, with a minimum of 25 kV/µs and generally 50kV/µs.
summary
Digital isolation technology is an inevitable trend of isolation development, and the domestic digital isolator industry is still an underdeveloped market. In the next issue, we will focus on domestic digital isolator manufacturers to see how they can help the domestic market shed import dependence.