Microchip Releases Long-reaching USB 3.2 Reclocker/Redriver Devices
As USB distances increase in automotive applications, signal integrity becomes a pressing issue. Microchip has released reclocker/redriver devices to help solve this challenge.
As modern automobiles become more electrified, in-vehicle networking is increasingly important. For all of the disparate vehicle modules and functions to be centralized, communication protocols like CAN, USB, and Ethernet have become mainstays in the automobile.
However, a significant challenge exists in ensuring that this communication occurs reliably across the long distances and harsh environments of the modern vehicle. To address this issue, Microchip recently released a new automotive-facing USB reclocker/redriver device to boost automotive signal integrity.
Long-reaching, USB 3.2-compatible reclocker/redriver devices. Image courtesy of Microchip
In this piece, we’ll look at challenges facing USB at long distances and how Microchip’s new product hopes to address this issue in automobiles.
USB at Distances
One of the biggest challenges with implementing the USB communication protocol in an electrical system is ensuring signal quality. This challenge is compounded as cable distances increase.
A major driver of signal degradation for USB is signal attenuation. Since real-world conductors are not ideal, they exhibit some degree of parasitic impedance in the forms of resistance, inductance, and capacitance. Since USB is a relatively high-speed signal, the impacts of these parasitics are significant, and they can work together to attenuate the data signal. This results in a decreased signal-to-noise ratio (SNR), an increased bit-error rate (BER), and an eventual loss of data.
USB signal integrity decreases as cable length increases. Image courtesy of Texas Instruments
Signal integrity is also negatively impacted by the length of the transmission cable for a number of reasons. One reason is the increased parasitics associated with a longer conductor. Greater distances also create more opportunities for interference and crosstalk, clock jitter, and signal reflections due to transmission line effects.
Because of long cable lengths and the electrically noisy environment of vehicles, automotive environments are especially prone to signal degradation.
Microchip Releases Automotive Reclockers/Redrivers
To address the issue of USB signal integrity in automotive solutions, Microchip recently released a new series of USB reclocker/redriver devices.
These devices are designed to intercept a data signal during long-distance communications and clean the signal up. Microchip claims they will amplify the signal to mitigate the impacts of attenuation, reset the impacts of clock jitter, and drive a clean output signal further downstream.
Typical EQC0510 link set-up. Image courtesy of Microchip
Microchip released two new reclocker/redriver devices, the EQC0510 and EQC05X31, both of which are designed to improve signal quality and support the USB 3.2 Generation 1 SuperSpeed protocol. To do this, the devices feature bit-level clock-data recovery hardware, which restores signal timing, prevents clock jitter accumulation, and restores the shape and level of USB signals.
Both devices are said to restore the incoming data signals effectively enough to extend the maximum USB 3.2 cable length from 1 m to 15 m. The main difference between the two devices is that the EQC0510 is designed as an automotive-facing dual-channel USB 3.2 Gen-1 product, while the EQC05X31 is designed to be an industrial dual-channel product.