Cascading two HD3SS3412 devices

Steve Manolis79

Other Parts Discussed in Thread: HD3SS3412

We need to implement a function that requires cascading two HD3SS3412 devices for a PCIE application where the TX lanes are AC coupled (standard PCIE implementations). Is there any biasing required between the two cascaded device?

over 10 years ago

0 Elias Villegas M. over 10 years ago

TI__Guru* 76130 points

Hello,

The HD3SS3412 requires bias voltage, typically this biasing is provided either by the host or the endpoint, if the available bias voltage is higher than 2V then you have to provide a controlled bias voltage lower than 2V.

The location of the AC coupling caps is also relevant for the biasing.

Please see the attached app note.

Regards.

HD3SS3412_application_note.pdf

0 Steve Manolis79 over 10 years ago in reply to Elias Villegas M.

Prodigy 30 points

Thank you for the response and the application note. However, the cascading device question still remains. When we have 2 devices back-to-back between the system and end points we are not clear if the biasing from the system and/or end point propagate to bias the second stage device.

0 Elias Villegas M. over 10 years ago in reply to Steve Manolis79

TI__Guru* 76130 points

Yes,
The biasing will be propagated to the cascaded device, extra care should be taken on the layout as these switches are passive and the channel loss will be added between devices.
Regards.

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Cascading two HD3SS3412 devices