TUSB216: Fully functional USB-C to USB-C cable design by TUSB216

Hello,

Are you looking to implement a USB2 redriver into your cable for this design? Or are you looking to design a system that incorporates a 10 meter cable? For a 10 meter application, a redriver would likely be needed on both sides of the cable.

However, we typically recommend against implementing our USB2 redrivers into an active cable implementation. This is because our redriver must be powered and out of reset before the high speed connection takes place. If the redrivers are not powered before this connection takes place, our redrivers will not be able to detect the HS handshake and will not boost the HS signal.

For a 15 meter cable, our redrivers would likely not be able to fully support the loss caused by the cabling. Our redrivers support up to 5 meters of USB2 traces/cabling each, so for a 15 meter cable there would need to be at least 3 redrivers in the cable. And again, all these redrivers would need to be powered and out of reset before the HS handshake takes place.

Please let me know if you have any other questions.

Thanks,

Ryan

Hello Ryan,

What we want to design is a 10m length cable that supports USB 2.0 communication, regardless of direction.The product function diagram is as follows:

Is there any problem with this design?

The power supply timing can be implemented through hardware. We would like to confirm what you mean by 'Out of reset'. Can you help to explain it in detail?

Ryan Kitto said:

However, we typically recommend against implementing our USB2 redrivers into an active cable implementation. This is because our redriver must be powered and out of reset before the high speed connection takes place. If the redrivers are not powered before this connection takes place, our redrivers will not be able to detect the HS handshake and will not boost the HS signal.

Thanks,

Kind Regards

Hi Lumina,

Lumina Gui said:

Is there any problem with this design?

For the cable, this would be okay. My only concern is that if this cable is used with a host or device that also has a redriver, this may cause overcompensation for HS connection. Additionally, any noise in the signal from the cable or the host/device will be increased by the redriver, so you would also want to ensure as little noise in the signal as possible.

Lumina Gui said:

The power supply timing can be implemented through hardware. We would like to confirm what you mean by 'Out of reset'. Can you help to explain it in detail?

Please ensure that the RSTN pin is held low until VCC is 2.3V at minimum. Once the VCC is at least 2.3V, the RSTN pin can go high to take the redriver out of reset. Once VCC and RSTN are both high and stable, then the redriver should be ready to detect the HS handshake and begin boosting the signal.

Thanks,

Ryan

Hi Ryan,

Thanks for your suggestion. Also, if our product does not use DCP and CDP functions, would TUSB211A be a good choice? If yes, we have some question about the TUSB211A.

From the datasheet of TUSB211A we can learned that the high-speed EQ (combination of edge boost and DC boost) improves the eye width for USB2.0 high-speed signals. Does the EQ have the same effect on Low-Speed (LS) and Full-Speed (FS) Mode?

Thanks,

Kind Regards

Hi Lumina,

If CDP/DCP is not being used and you don't want to directly control RX_SEN, then the TUSB211A would be a good choice, yes.

Lumina Gui said:

Does the EQ have the same effect on Low-Speed (LS) and Full-Speed (FS) Mode?

Our USB2 redrivers are only active for HS signaling. Our redrivers have no effect on LS or FS signaling.

Thanks,

Ryan

Hi Ryan,

The EQ of TUSB211A only supports 4-speed adjustment through external resistors, while the EQ of TUSB216 supports adjustment by I2C. Does this means that TUSB216 can make more precise adjustments to the actual attenuation value of the cable?

Thanks,

Kind Regards

Hi Lumina,

Correct, however these I2C settings do not stick between device resets. You would need to reconfigure the TUSB216 each time it is reset to the desired I2C settings. Typically for customer applications for longer cables, the max setting via GPIO tends to be enough for up to 5 meters per redriver.

Thanks,

Ryan