DS90LVRA2-Q1: Series Termination

Michael Ly

Part Number: DS90LVRA2-Q1
Other Parts Discussed in Thread: DS90LVRA2EVM, DS90LVRA2

Tool/software:

Hi all,

I have an application that requires me to convert a 1.8V subLVDS signal to 1.8V LVCMOS (single-ended).

I'm planning on using the DS90LVRA2-Q1 part, and I just want to make sure that I am correct in assuming that I will need series termination on the output of the differential receiver, which will feed into another board that requires the single-ended 1.8 V LVCMOS signal. I would normally use 33 ohms.

In addition to this, I've ordered a DS90LVRA2EVM to test this since there is not yet an IBIS model. I see there may be one coming in the future, though, according to other E2E threads mentioning the DS90LVRA2.

When using this EVM, I see that the reference design uses 20-ohm source terminations. Is it better to stick to this value versus 33 ohms? My current plan is to just follow the reference design with 20 ohms for now and have a 33 ohm pair handy in the same footprint for my custom design.

Regards,
Michael Ly

2 months ago

0 Amy 2 months ago

TI__Genius 15321 points

Hi Michael,

You will need a 100-ohm termination at the input to the receiver. Section 8.2 of the datasheet goes into greater detail on this.

Thanks,

Amy

0 Michael Ly 2 months ago in reply to Amy

TI__Expert 5500 points

Hi Amy,

Yes, I have an external 100-ohm termination at the input already.

Here is the design I had for the question about the output line driver resistor I was asking about:

Regards,
Michael Ly

+1 Amy 2 months ago in reply to Michael Ly

TI__Genius 15321 points

Hi Michael,

Thanks for sharing the schematic. These are not required. You can also use a 0-ohm placeholder, in case you find you need a current limiting option in the design.

Regards, Amy

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DS90LVRA2-Q1: Series Termination