Demand for automotive ADAS sensors from Rohm's new products

Advanced driver assistance system (ADAS) technology is evolving from high-end cars to mid-range and even low-end models. The growing market space also means that technology must evolve rapidly. In addition to the core SoC, it also includes vehicle-mounted camera systems, radars, lidars, and systems that integrate multiple sensors. Among them, cameras are still the most mainstream sensor technology.

These cameras require higher transmission rates to ensure that cars can obtain more useful information, while maintaining low power consumption and noise levels. In addition, functional safety requirements are also being further improved.

Recently, Chen Xingle, technical center manager of Rohm Semiconductor (Shanghai) Co., Ltd., gave a detailed introduction to Rohm's newly launched SerDes and power management chips for ADAS. Compared with last year's products, there have been many improvements, which shows that Rohm is accelerating the development of new products to meet the emerging challenges of ADAS.

SerDes interfaces for different applications

There are two main applications of automotive SerDes ICs: one is data transmission from camera to SoC, and the other is data transmission from SoC to screen.

Chen Xingle said that Rohm's SerDes has two technical features: one is that the transmission rate can be optimized, and the other is that it supports the spread spectrum function. The rate optimization means that different transmission rates can be accurately set according to the pixels and applications of the camera. Compared with a fixed transmission rate, lower power consumption and less EMI can be achieved. The spread spectrum function can also optimize EMI, especially in multi-channel transmission, where noise will overlap each other, and the spread spectrum function can disperse the peak energy, thereby reducing EMI.

In 2021, ROHM mass-produced the camera SerDes BU18xMxx-C series, demonstrating the reliability of the "transmission rate optimization" and "spread spectrum" functions.

In 2022, Rohm launched the display SerDes BU18xx82-M series, including the serializer BU18TL82-M and the deserializer BU18RL82-M. The SerDes supports daisy chain connection to simplify the transmission path and save costs. Chen Xingle said that with more and more display screens in cars, including instruments, central control, co-pilot, rear display and even electronic rearview mirrors, SerDes connections are required. Compared with the previous one-to-one SerDes method, daisy chains can save serializers and some cables, thereby saving costs and simplifying layout.

Chen Xingle also mentioned the role of Rohm SerDes in data security and stability. The CRC parity check ensures data integrity. In addition, the BU92 series LVDS bridge chip supports SoC or SerDes abnormal interrupt detection and can display warning information directly on the screen, thus ensuring system reliability.

Simplify the use of Ser (serializer) through daisy chain connection

New PMIC products——safer and more integrated

BD868xxMUF-C is a PMIC developed specifically for automotive camera modules. It contains three switching regulators and one LDO. Compared with the BD86852MUF-C launched last year, it has one more channel, thus achieving higher integration. In addition, BD86852MUF-C also has an abnormal state detection function, with overvoltage, overcurrent or temperature detection, which can detect CMOS or SerDes failures, thereby ensuring the reliable operation of the ADAS system. BD868xxMUF-C incorporates the functional safety production process system, that is, it complies with ISO 26262 and ASIL-B standards. In the ComfySIL series of products under ROHM's functional safety brand, it is a product that meets its highest level requirements.

The product uses a one-time programmable (OTP) memory to change the output voltage value and boot sequence at the factory, which makes it flexible to support almost all image sensors.

Rohm also gave the development plan for camera PMIC in the next few years, including more power channels, more secure non-volatile memory, etc., which will be introduced into the product series, thereby continuously strengthening the advantages in integration and reliability.

Chen Xingle said that in order to lower the development threshold for customers, Rohm provided a detailed reference design. Currently, Rohm has cooperated with Xinchi and selected Rohm's SerDes and PMIC in its four-screen display smart cockpit evaluation board system, in addition to Rohm's LED backlight driver IC.

Summarize

More advanced ADAS and autonomous driving technologies cannot be separated from more image sensors. Therefore, more integrated, lower power consumption, and higher reliability PMIC and SerDes will become one of the keys. As one of the major automotive IC suppliers, Rohm is continuing to make efforts in this field.