TUSB320LAI: TUSB320LAIRWBR Schematic review

320LAI review.pdf

Hi Kavin,

I attached the review as a pdf.

One thing I noticed is that you have common mode chokes on the CC1/2 lines. These are ok, but may be unnecessary for the low speed signals on these lines.

I am not sure what the FL11 device is between your VBUS_TYPEC and VBUS_MAIN. It says 70Ohms but does not appear to be a resistor. Could you confirm what that is?

Best,

Shane 

Hi Shane,

Thank you for your prompt response.

FL11 is a Chip Ferrite Bead (BLM18SG700TN1D) with 70 OHM impedance and a rated current of 4A @ 85℃.

Thank you.

Regards,

Kavin

Hi Kavin,

I see. In that case you should connect VDD and VBUS_DET on the 320LAI directly to VBUS_TYPEC, instead of VBUS_MAIN. I am concerned a 70ohm impedance could lower the VBUS voltage below the voltage our device expects. Do you know what voltage drop the ferrite bead would cause?

Generally bypass capacitors are enough to stabilize noise on the VBUS.

Best,

Shane