DS90UB954-Q1: Layout of useless output pin when using coax for transmission

Amelie Zheng

Genius 10865 points

Part Number: DS90UB954-Q1

Hi Team,

If using coax for transmission, why is another useless pin not grounded nearby?

over 7 years ago

0 Hamzeh Jaradat over 7 years ago

TI__Guru** 116990 points

Hello Amelie,

of course you can terminate the unused pin nearby the device, but it is recommended to route both traces as loosely coupled and terminate nearby the connector for better noise cancelling and EMI performance.

0 Amelie Zheng over 7 years ago in reply to Hamzeh Jaradat

TI__Genius 10865 points

hi Hamzeh,
Nice to see you again and thanks for your reply!
Why such recommended route (both traces as loosely coupled and terminate nearby the connector )can reduce noise and EMI?
Is it not the differential connect, right?

0 Hamzeh Jaradat over 7 years ago in reply to Amelie Zheng

TI__Guru** 116990 points

Yes, routing loosely coupled is a differential routing hence better for noise canceling!

0 Amelie Zheng over 7 years ago in reply to Hamzeh Jaradat

TI__Genius 10865 points

But the S2 in picture is >3w. Is it also differential connect?

0 Hamzeh Jaradat over 7 years ago in reply to Amelie Zheng

TI__Guru** 116990 points

Yes. This is the reason why it is caled loosely coupled.

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DS90UB954-Q1: Layout of useless output pin when using coax for transmission