DS125BR401A: DS125BR401A VDD input

David Sandler

Intellectual 1910 points

Part Number: DS125BR401A

Hi,

I am using the DS125BR401A Linear Repeater in two places. One is for a x4 PCIe. The other is only a x2 but I want to use the same part to minimize the types of parts on the BOM. To terminate the unused inputs, I was going to pull the “+” input to VDD with a 1K resistor. The “-“ input in pulled to GND with a 1K.

I didn’t see anything in the data sheet about this. Is this reasonable? If not, how should they be terminated?

Thanks,

David

over 7 years ago

0 Lee Sledjeski over 7 years ago

TI__Mastermind 43795 points

Hi David,

There is no need to pull the unused inputs to opposite voltages.

The B-side inputs will shut down automatically due to a loss of signal on the input.

The A-side inputs can just be left alone with the output terminated at 100 ohms. The A-side inputs can also be shut off if desired via the SMBus register space.

Regards,

Lee

0 David Sandler over 7 years ago in reply to Lee Sledjeski

TI__Intellectual 1910 points

Hi Lee,

Hate to be a stickler, but, when you say terminate outputs to 100 ohms. Do you mean 100 ohms to ground? With the inputs floating, will there be current passing through the 100ohm termination?

Thanks,
David

0 Lee Sledjeski over 7 years ago in reply to David Sandler

TI__Mastermind 43795 points

Hi David,

If the inputs are not connected then the outputs can be left floating. No need to terminate.

Regards,

Lee

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DS125BR401A: DS125BR401A VDD input