Monday, May 20, 2024

Power Tree Reference Design For ADAS

The power tree board for automotive infotainment/ADAS integrates functional safety features, ensuring EMC compliance with supervisor ICs for reliability and space-saving.

power tree

CISPR 25 Class 5 compliance is crucial in automotive electronics due to the growing complexity of vehicle systems and the need to ensure they do not interfere with each other or external devices. Compliance ensures Electromagnetic Compatibility (EMC), preventing excessive electromagnetic interference (EMI) that could disrupt other systems or pose safety risks. Meeting EMC standards improves system reliability and safety, as EMI can lead to malfunctions or failures in critical systems. Regulatory compliance is another key driver, as adherence to standards like CISPR 25 is often required for certifications and approvals. In the challenging automotive environment, with various sources of EMI, compliance helps systems operate reliably. Non-compliance can lead to legal issues, making adherence to standards essential for automotive manufacturers.

The reference design from ROHM Semiconductor is a power tree solution board tailored for infotainment devices like automotive clusters, center information displays, and ECUs for ADAS applications. It integrates a power system capable of supporting functional safety onto a single board, optimizing the configuration as a power tree. The design ensures excellent EMC performance, meeting CISPR25 Class 5 standards across all power supply rails, while also reducing heat generation through the distribution of high-efficiency DCDCs. Additionally, two supervisor ICs with self-diagnosis functions can monitor the output of all power rails, enhancing functional safety.

The Automotive Infotainment/ADAS 8-channels power tree reference design has been verified to meet the EMC CISPR 25 class 5 standard, even without a common mode filter. To prevent interference with AM radio frequency bands, all DC/DC converters operate at a switching frequency of 2.2 MHz or higher. The thermal characteristics have been thoroughly tested, and voltage monitoring for the 8-channel power tree has been implemented to enhance functional safety to ASIL level standards. Additionally, space-saving features have been incorporated by integrating multiple power trees into the design.

The REFRPT001-EVK-001 features two power supply monitoring ICs, each dedicated to monitoring the DCDC_P5V and DCDC_P3V system power trees. These ICs provide Power Good signals, XRSTOUT signals, and Watchdog Timer outputs, which can be monitored using Monitor-terminal-1 / -2. The output signals of the power monitoring ICs can be verified using LED.
ROHM Semiconductorhas tested this reference design. It comes with a Bill of Material (BOM), schematics, Printed Circuit Board (PCB) layout, etc. You can find additional data about the reference design on the company’s website. To read more about this reference design, click here.

Nidhi Agarwal
Nidhi Agarwal
Nidhi Agarwal is a journalist at EFY. She is an Electronics and Communication Engineer with over five years of academic experience. Her expertise lies in working with development boards and IoT cloud. She enjoys writing as it enables her to share her knowledge and insights related to electronics, with like-minded techies.

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