By Diego de Azcuénaga

Toshiba has introduced four new AEC-Q100-certified, high-speed, two-channel digital isolators. The DCM32xx00 series is designed to deliver robust performance and support data transmission speeds of up to 50 Mbps. Onboard chargers and battery management systems used in electric vehicles are improving safety and reliability thanks to the design of these devices.

In an exclusive interview with Electropages, Kazuhiro Natori, Manager, Semiconductor Product Marketing at Toshiba Electronics Europe GmbH, emphasized that the isolators have the capability to resist common-mode electrical noise across input and output terminals, supporting consistent control signal integrity.

Increased reliability of automotive systems

“Toshiba’s DCM32xx00 series digital isolators enhance reliability by delivering robust noise immunity and stable signal transmission even under harsh conditions,” Natori said. With a high typical common-mode transient immunity (CMTI) of 100 kV/µs, they help prevent signal disturbances caused by fast-switching transients, a common challenge in automotive environments such as onboard chargers (OBC) and battery management systems (BMS). “This ensures critical subsystems maintain reliable communication and operation throughout the vehicle’s lifespan,” Natori added.

Features to deliver robust performance

Key design attributes include Toshiba’s proprietary magnetic coupling technology, high CMTI performance, and low pulse-width distortion of 0.8 ns (typ.). Devices in this series support data rates up to 50 Mbps and operate across a supply voltage range of 3.0 V to 5.5 V. “The 8-pin SOIC package is optimised for compact automotive systems and ensures thermal stability up to 125°C. Additionally, configurations with one forward and one reverse channel support bidirectional communication,” Natori explained. The use of two isolated semiconductor dies in a dual-insulation structure enhances safety, even if one insulation layer degrades, the other maintains protection. This design is instrumental in meeting the insulation life and surge withstand requirements of standards such as VDE V 0884-11 and IEC 61000-4-5, contributing to the long-term functional safety of powertrain and energy storage systems in EVs.

Improve the safety and reliability in electric vehicles

In systems such as OBCs and BMSs, galvanic isolation is essential to prevent cross-domain faults and to protect low-voltage control units from high-voltage transients. “By isolating control signals with high CMTI and fast propagation times, DCM32xx00 devices safeguard signal integrity and prevent latch-up or erroneous switching,” Natori said. Beyond immediate circuit protection, this enhanced isolation capability is critical for maintaining overall vehicle stability under diverse operating conditions.

Advanced magnetic coupling technology

“These digital isolators adopt a proprietary magnetic coupling architecture based on on-chip transformer structures formed by integrated coils,” Natori explained. The input-side coil modulates the logic signal into a high-frequency carrier using an on-off keying method, which is then transmitted across an insulation barrier via magnetic induction. This enables complete galvanic isolation between input and output without a physical electrical connection. 

“A key benefit of this method is its robustness in high-voltage environments. The DCM32xx00 series achieves a typical common-mode transient immunity (CMTI) of 100 kV/µs, ensuring signal stability even in the presence of steep voltage transients commonly found in automotive power systems,” Natori noted. Overall, the magnetic coupling approach offers excellent noise immunity, a long insulation life, and a compact footprint

Support stable operation of connected systems

Digital isolators like the DCM32xx00 series play a critical role in maintaining precise and reliable signal timing between subsystems that operate at different voltage domains. “Their high CMTI performance ensures that even in the presence of fast voltage transients or ground potential shifts, the signal output remains unaffected,” Natori said. “This is crucial in environments where electric motors, power switches, and charging circuits generate frequent switching events and common-mode noise.”

The series also features low propagation delay and low pulse-width distortion (PWD), with a typical PWD of just 0.8 ns. This allows for near-synchronous signal transmission, which is especially important in high-speed control interfaces such as PWM gate drive signals or digital communication links. “By ensuring minimal timing skew and logic level distortion, the DCM32xx00 devices help preserve the accuracy of control loops and prevent data corruption, ultimately contributing to stable system operation and safety compliance,” Natori added.

Configuration options

The DCM32xx00 series offers two-channel configurations to support both unidirectional and bidirectional signal transmission:

• DCM320C00 / DCM320D00: Two forward-direction channels (IN→OUT), ideal for sending multiple control signals from a microcontroller to a power stage.

• DCM321C00 / DCM321D00: One forward-direction and one reverse-direction channel, enabling bidirectional communication, allowing critical error and sensor signals to pass back from the power stage to the controller, which is vital for effective and safe system management in complex automotive architectures.

“Our lineup of two-channel models features configurable default output logic, either low or high. This feature ensures a stable output status when the input signal is open or the input-side power supply is cut off,” Natori explained. “This provides a safety redundancy design to stabilise the system’s output in unexpected situations, thereby enhancing overall system reliability.”

These options provide designers with the flexibility to minimise board area and component count in systems where isolated input/output paths are required. This integration simplifies circuit layout and enhances robustness by reducing the number of isolation devices required.

Suitable for high-speed communication tasks

Integrating digital isolators into a controller area network (CAN) bus system is important for protecting devices from ground potential differences and electrical noise, especially in industrial and automotive environments.

“The DCM32xx00 series supports data rates up to 50 Mbps, with low pulse-width distortion and high noise immunity. The two-channel devices offer flexible configuration options: two forward-only channels, and one forward and one reverse channel,” Natori said.

These attributes make the devices well-suited for high-speed digital communications in automotive systems, particularly those relying on timing-sensitive protocols. The isolators are optimised to preserve signal fidelity even in the presence of high dv/dt transients, which are typical in systems with wide-bandgap power devices or long cable harnesses.

“Leveraging Toshiba’s proprietary magnetic coupling technology offers electrical protection for the microcontroller while maintaining the speed and integrity of communication, which is critical for synchronised, real-time control tasks in powertrain or battery systems,” Natori noted.

DCM32xx00 series package

All devices in the series are housed in a narrow-body 8-pin SOIC (SOIC8-N) package. “The pinout includes two channels (each with input and output), separate VDD and GND for primary and secondary sides, and ensures a compact layout for integration into space-constrained automotive modules,” Natori added. A simplified diagram highlights the isolation between channel inputs on one side and outputs on the other, with VDD1/GND1 and VDD2/GND2 supplying each side, respectively.

Meeting evolving requirements in applications

The devices meet the stringent criteria of AEC-Q100 through comprehensive reliability testing across automotive operating temperature ranges (-40°C to +125°C) and voltage supply levels.

“Qualification includes assessments of temperature cycling, high-temperature operating life, and electrical stress, all of which the DCM32xx00 series successfully passed. This certifies them for demanding automotive applications,” Natori explained. Digital isolators like the DCM321x00 are well-suited to isolate the logic interface of a CAN transceiver from the microcontroller. “By providing galvanic isolation and filtering out transient noise, they protect the controller from electrical disturbances and ground potential differences commonly present on vehicle networks,” Natori added. 

This improves system robustness and ensures that communication remains uninterrupted during load transients or ground faults. In line with these advances, Toshiba is actively developing additional digital isolators with higher channel counts and expanded packaging options to address broader application needs.

“This includes support for future automotive networking, motor control, and factory automation systems where compact, high-speed, and long-life isolation solutions are increasingly required,” Natori noted.

The company’s roadmap reflects its commitment to advancing galvanic isolation technology with robust, high-performance solutions tailored to evolving customer requirements.