DS280MB810: ARINC 818 over 100 Ohm STP Cabling

Michael Moon1

Part Number: DS280MB810

an this device be used to operate A818 over an existing interface that is 100 ohm STP cabling (thru a twinax connector). I know the standard specifies 150 ohm.

over 4 years ago

0 Rodrigo Natal over 4 years ago

TI__Mastermind 19235 points

Can you clarify the data rate, data encoding type and max run length (i.e.. max number of consecutive 1 bits) for this application?

Thanks,

Rodrigo Natal

HSSC Applications Engineer

0 Michael Moon1 over 4 years ago in reply to Rodrigo Natal

Prodigy 30 points

Hi Rodrigo

The data rate is 2.125 Gbps. It is 8b/10b encoding which guarantees no more than 5 consecutive 1"s or 0's in the data stream.

--Mike

0 Rodrigo Natal over 4 years ago in reply to Michael Moon1

TI__Mastermind 19235 points

Hi Michael,

The DS280MB810 is designed for 100ohm differential input and output terminations. If data is 2.125Gbps 8B/10B and impedance criteria are met then I believe this ARINC cable link case should work, assuming that your cable insertion loss for 2.125Gbps is within level that the DS280MB810 repeater equalization can compensate for.

Do note that the DS280MB810 is intended to be primarily a 28Gbps device. To that end its peak CTLE boost occurs at the Nyquist frequency for 28Gbps. Thus the DS280MB810 CTLE boost for 2.125Gbps is lower than for 28gbps. TI does have mux buffers and repeaters that are primarily intended for 10G and below rate and as such, have higher CTLE boost at lower frequencies. You may consider those part numbers as well. A couple of then are listed below:

http://www.ti.com/product/DS125BR820

http://www.ti.com/product/DS125MB203

http://www.ti.com/product/DS125BR401

0 Michael Moon1 over 4 years ago in reply to Rodrigo Natal

Prodigy 30 points

Thanks for the information and links.

Are there any issues running ARINC 818 at the 2.125 Gbps rate (essential Fibre Channel physically) over 100 ohm cable if the standard intended 150 ohm differential impedance?

Are all receiver circuits 100 ohm diff impedance or could I have a mis-match with a receiver that is designed for 150 ohm diff impedance?

0 Rodrigo Natal over 4 years ago in reply to Michael Moon1

TI__Mastermind 19235 points

From the TI repeater perspective, if both the Tx SerDes I/O and the cable have 100 ohm differential impedance then there should not be an issue. If the repeater is interfaced to 150ohm cable and/or SerDes I/O then you would have a problem.

Cordially,

Rodrigo Natal

HSSC Applications Engineer

Because of the holidays, TI E2E™ design support forum responses will be delayed from Dec. 25 through Jan. 2. Thank you for your patience.

Interface

Interface forum

DS280MB810: ARINC 818 over 100 Ohm STP Cabling