Renesas Claims Another Debut in I3C—The First I3C Intelligent Switch

June 06, 2022 by Jake Hertz

Moving beyond I2C, Renesas is introducing a new I3C intelligent switch family to boost performance and speed in the data center.

Few fields are as dynamic and fast-evolving as the data center. With new software, use-cases, and applications popping up every year, the underlying hardware has become increasingly difficult to keep up with.

One relatively new technology designed to improve upon legacy hardware is I3C, the successor to conventional I2C. Boasting improvements on I2C, I3C has still yet to become widespread in the data center, a place where its value could be significant. 


An example I2C overview with STMicroelectronics' STM32. Image used courtesy of STMicroelectronics


Recently, Renesas announced the release of a new I3C intelligent switch, a product that they hope can accelerate I3C adoption in the data center.

In this article, we’ll look at I3C, its challenges toward data center adoption, and how Renesas’ newest product hopes to be the answer. 


What is I3C?

I2C, which was created in 1982, has since become one of the most standard communication protocols used in electronics. However, the field has changed significantly over the past 40 years, and, today, I2C may no longer be well suited for all IC-IC communication applications.

To address this issue and build off the already popular I2C, I3C was released by the MIPI Alliance in 2016. The I3C protocol operates similarly to I2C, consisting of only two lines: serial data (SDA) and shared clock (SCL). 

Like I2C, I3C is a protocol for synchronized serial data transfer between master and slave devices and is intended for communication between integrated circuits or sensors. However, one significant change from I2C to I3C is the change from an open-drain output to a push-pull output.


An overview diagram of an I3C system.

An overview diagram of an I3C system. Image used courtesy of MIPI Alliance


By making this change, I3C benefits from removing the need for pull-up resistors in the SDA line, a feature that plagued I2C. This attribute can be seen as a direct result of I3C requiring less space and components than I2C. Moreover, removing the pull-up resistors is also vital in allowing I3C to operate at faster data rates and lower power consumption than I2C.

Overall, I3C offers a standard data rate of 12.5 MHz and a maximum of 100 Mbps, while I2C maxes out at roughly 5 MHz. Beyond this, I3C claims advantages such as lower power consumption, support for dynamic addressing, in-band interrupts, and backward compatibility with I2C.


I3C Intelligent Switch

According to Renesas, the faster speeds that I3C brings to the table are now causing challenges in data centers. Historically, system designs have relied on the I2C protocol and simple field-effect transistor (FET) switches to connect initiator and target devices on a motherboard—a technique Renesas believes will struggle to scale I3C speeds.

Renesas released the industry’s first I3C intelligent switch devices to address this challenge. The new family of devices, called the RG3Mxx, is designed to keep up with the faster speeds of I3C while allowing for scalability and high-performance systems. 

The design claims to allow the expansion of two upstream ports into multiple ports that can operate at max speed with full protocol awareness and compliance. The first two devices in the family will be one with two upstream ports and four downstream ports and another with two upstream ports and eight downstream ports. 


Block diagram of the RG3Mxx family.

Block diagram of the RG3Mxx family. Image used courtesy of Renesas


While there is not much publically available technical information on these devices, according to the available short-form datasheet, the switches should support transfer speeds up to 12.5 MHz and have backward compatibility with I2C. 

With these switches, Renesas claims that designers can enable I3C control plane networks with multiple initiator controllers, such as CPU and baseboard management controllers (BMC). 

All in all, as technology advances, we need to develop new protocols and hardware to keep up with demands. I3C is one of these technologies, and the new products, like this one from Renesas, are hopefully poised to accelerate the adoption of I3C in data center and server infrastructure.


Featured image used courtesy of Renesas