DS250DF810 / about the input timing of REFCLK(CLK_CAL_IN)

Toshiyuki

Mastermind 7075 points

Other Parts Discussed in Thread: DS250DF810

Hi,

Customer is considering DS250DF810. And they have some questions.Please let me know the details.

Are there time constraints between power up VDD and input 25MHz at CLK_CAL_IN?

Before power up VDD, could CLK_CAL_IN accept 25MHz?

Could the unused pins(RX*P,RX*N,TX*P,TX*N) be open?

Best Regards,

Kato

over 9 years ago

0 Rodrigo Natal over 9 years ago

TI__Mastermind 19235 points

Hi Kato-san,

Are there time constraints between power up VDD and input 25MHz at CLK_CAL_IN?

There's no particular time constraint. If VDD is present but CAL_CLK_IN is not the device will remain in static mode and not attempt CDR lock on any channel. Once CAL_CLK_IN is available channels with input signal will attempt to lock CDR.

Before power up VDD, could CLK_CAL_IN accept 25MHz?

Yes, I don't expect issue with that scenario.

Cordially,

Rodrigo Natal

DPS Applications Engineer

0 Toshiyuki over 9 years ago in reply to Rodrigo Natal

Mastermind 7075 points

Hello Rodrigo - san,

Thank you for the reply. How about Q2? I understand that the unused pins(RX*P,RX*N,TX*P,TX*N) could be open.

Best Regards,

Kato

0 Rodrigo Natal over 9 years ago in reply to Toshiyuki

TI__Mastermind 19235 points

Hi Kato-san, that is correct. On unused channel the Tx output will be muted by default. So you may leave I/O pins floating.

Regards,

Rodrigo Natal

DPS Applications Engineer

0 Mizanur Chowdhury over 9 years ago in reply to Rodrigo Natal

TI__Genius 17270 points

Hello Rodrigo,

I understand one can leave the unused input pairs (and output pairs) floating, is that correct?
You mentioned the TX pairs on unused channels will be muted. Any concerns/comments on unused RX pairs?

Best regards,
Mizanur

0 Rodrigo Natal over 9 years ago in reply to Mizanur Chowdhury

TI__Mastermind 19235 points

I understand one can leave the unused input pairs (and output pairs) floating, is that correct?
- Correct
You mentioned the TX pairs on unused channels will be muted. Any concerns/comments on unused RX pairs?
- No concern.
- If desired, you can force disable the Rx by on a given channel by setting channel 0x14[6]=1

Regards,

Rodrigo Natal

DPS Applications Engineer

0 Mizanur Chowdhury over 9 years ago in reply to Rodrigo Natal

TI__Genius 17270 points

Thanks, that helps.
BR,
Mizanur

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DS250DF810 / about the input timing of REFCLK(CLK_CAL_IN)