USB 2.0 - Mandatory 4 layers and impedance matching?

autodeskguest over 17 years ago

I have brougth this topic up again, because I have some doubts: people

usually say that it is mandatory to use a 4-layered boards with impedance

matching when you have a USB 2.0 circuit on board. But my question is: even

if I know that the circuit won´t reach 20Mbps tops (very far from 480Mbps of

USB 2.0) is it really mandatory to have a 4-layers board? And the impedance?

What if I make the trace as short as possible, from the connector to the IC?

Thanks

Thiago

Parents

esilviu over 17 years ago

"Thiago" <thiago_hr@yahoo.com.br> wrote in message
news:gf0i08$6k8$1@cheetah.cadsoft.de...
I have brougth this topic up again, because I have some doubts: people
usually say that it is mandatory to use a 4-layered boards with impedance
matching when you have a USB 2.0 circuit on board. But my question is: even
if I know that the circuit won´t reach 20Mbps tops (very far from 480Mbps
of USB 2.0) is it really mandatory to have a 4-layers board? And the
impedance? What if I make the trace as short as possible, from the
connector to the IC?

Thanks

Thiago

I've done-it without 4 layers, and without any "impedance matching". And it
worked.
if wires are as short as possible, it's ok.
Cancel
Vote Up 0 Vote Down

Sign in to reply

Cancel
Former Member over 17 years ago in reply to esilviu

Here is an excellent PDF for board layout of USB 2.0 devices. It shows how
to do it right...

http://www.bigcarrotdigital.com/high_speed_usb_pcb_layout_recommendations___an1168_12.pdf

"eSilviu" <Silviu.Epure@ugal.ro> wrote in message
news:gf0ses$hlh$1@cheetah.cadsoft.de...
"Thiago" <thiago_hr@yahoo.com.br> wrote in message
news:gf0i08$6k8$1@cheetah.cadsoft.de...
I have brougth this topic up again, because I have some doubts: people
usually say that it is mandatory to use a 4-layered boards with impedance
matching when you have a USB 2.0 circuit on board. But my question is:
even if I know that the circuit won´t reach 20Mbps tops (very far from
480Mbps of USB 2.0) is it really mandatory to have a 4-layers board? And
the impedance? What if I make the trace as short as possible, from the
connector to the IC?

Thanks

Thiago

I've done-it without 4 layers, and without any "impedance matching". And
it worked.
if wires are as short as possible, it's ok.
Cancel
Vote Up 0 Vote Down

Sign in to reply

Cancel

Reply

Former Member over 17 years ago in reply to esilviu

Here is an excellent PDF for board layout of USB 2.0 devices. It shows how
to do it right...

http://www.bigcarrotdigital.com/high_speed_usb_pcb_layout_recommendations___an1168_12.pdf

"eSilviu" <Silviu.Epure@ugal.ro> wrote in message
news:gf0ses$hlh$1@cheetah.cadsoft.de...
"Thiago" <thiago_hr@yahoo.com.br> wrote in message
news:gf0i08$6k8$1@cheetah.cadsoft.de...
I have brougth this topic up again, because I have some doubts: people
usually say that it is mandatory to use a 4-layered boards with impedance
matching when you have a USB 2.0 circuit on board. But my question is:
even if I know that the circuit won´t reach 20Mbps tops (very far from
480Mbps of USB 2.0) is it really mandatory to have a 4-layers board? And
the impedance? What if I make the trace as short as possible, from the
connector to the IC?

Thanks

Thiago

I've done-it without 4 layers, and without any "impedance matching". And
it worked.
if wires are as short as possible, it's ok.
Cancel
Vote Up 0 Vote Down

Sign in to reply

Cancel

Children

No Data