DS100RT410 in 1.25Gbps mode

Andrey Ampelonov

Other Parts Discussed in Thread: DS100RT410

Hello!

Is a question about DS100RT410 1.25Gbps mode: is a CDR unit lock to 1.25GHz and retimes a data?

Or data bypassed through IC without retiming in this case?

P.S. I try to give on DS100RT410 input 1.25Gbps and 10.3 Gbps data stream - it locket on it (LOCK signal becomes high). But I also try 2.5Gbps stream - it work well too (with high LOCK). I slightly confused about it.

Thank you!

over 12 years ago

0 Nasser Mohammadi over 12 years ago

TI__Guru* 93670 points

Hi Andrey,

For 1GbE the retimer is bypassed. If you are able to lock to 10.3G signal it means you could have a relatively good signal and thus at much lower data rate like 1.25GbE there is no need for the retimer.

Regards,,nasser

0 Andrey Ampelonov over 12 years ago in reply to Nasser Mohammadi

Prodigy 75 points

It's sad news because we have plans to use this IC for regeneration on both speeds...

What about 2.5G, why it work but non-declared?

0 Nasser Mohammadi over 12 years ago in reply to Andrey Ampelonov

TI__Guru* 93670 points

Hi Andrey,

Sorry for the late response, i was on a business travel.

There are two modes of operation: Reference mode and Referenceless mode.

In reference mode, the device locks to 10.3G or 1.25G. The device VCO block has divide by 1 or divide 8 to enable locking to these two rates automatically. However, in reference less mode we recommed bypassing when operating at 1.25G since this may cause false lock.

Regards,,nasser

0 Andrey Ampelonov over 12 years ago in reply to Nasser Mohammadi

Prodigy 75 points

Hello!

What is Reference mode? Is it automatically involved when applied external clock to IC?

I.e. if 25MHz reference clock from external oscillator provided, IC can lock and retime both 1.25G and 10.3G speeds? With automatic switching between it?

Not only 10.3G, as you wrote above "For 1GbE the retimer is bypassed."?

0 Nasser Mohammadi over 12 years ago in reply to Andrey Ampelonov

TI__Guru* 93670 points

Andrey,

You are correct. The device goes into the reference mode when 25MHz clock is applied to REFCLK_IN pin. In this mode the device locks, automatically, to either 1.25G or 10.3G data rates. The device does not lock to other rates(i.e 2G data rate).

Regards,,nasser

0 Andrey Ampelonov over 12 years ago in reply to Nasser Mohammadi

Prodigy 75 points

Thank you for helpful answer!

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DS100RT410 in 1.25Gbps mode