CC pin Impedance

Jim CHEN

Expert 4795 points

Hi Sir,

I have a simple question.

Why USB spec define the impedance of CC pin is from 32 ohms to 93 ohms, not a fixed value.

Thank you

over 8 years ago

0 Diego Cortes over 8 years ago

TI__Mastermind 36085 points

Hello Jim,

The CC pins must be terminated to a Rp/Rd impedance depending whether the devie is DFP or UFP.

0 Jim CHEN over 8 years ago in reply to Diego Cortes

TI__Expert 4795 points

Hi Diego,

Thanks for your reply.
Please see my above update screenshot.
My question is about the characteristic impedance of cc pin wire.
How wide of cc pin layout you will recommend to customer.

Thank you

0 Rahul Sharma16 over 8 years ago in reply to Jim CHEN

TI__Expert 6430 points

Hi Jim,

The reason for such a wide characteristic impedance is to provide wide tolerances to keep the manufacturing costs low.

If the characteristic impedance is fixed to a particular value then you need technology to achieve that exact value and this precision will make things expensive.

Hope it answers.

Thanks,

Rahul

Interface

Interface forum

CC pin Impedance