DS90UB928Q-Q1: DS90UB928 + DS90UB929 eye diagram question

AJ Cheng

Genius 3615 points

Part Number: DS90UB928Q-Q1

Hello

We measure the Tx side and Rx side then found that the waveform is unstable. So we can't measure the eye diagram.

But DS90UB928 CLM out eye diagram is good. May I ask if this is normal? Thanks for kindly help~

UB928 CML out

DS90UB929 Tx

DS90UB928 Rx

over 6 years ago

0 Palaniappan Manickam over 6 years ago

TI__Genius 10475 points

Hello,
The 928 CMLOUT spec is 0.4UI eye width and 300 mV eye height (typical), so the eye looks like it is within the typical spec.
Where are you measuring the 929 TX and RX at?

0 AJ Cheng over 6 years ago in reply to Palaniappan Manickam

Genius 3615 points

Dear Palaniappan

Thanks for your reply.

We measure the 929 Tx / 928 Rx / 928 CMLOUT. Only CMLOUT eye diagram is good.

Please reference on below 929 Tx / 928 Rx measuring position. We need to know if it is normal or not. Thanks for help~

929 Tx

928 Rx

0 Steven(Shenzhen) Shi over 6 years ago in reply to AJ Cheng

TI__Mastermind 30515 points

as the link between 929 and 928 has high speed FC signal and low speed BC signal, it is normal that you get the above signal. for CML output, the low speed is filtered so you can get the FC signal only which is stable.

regards,
Steven

Interface

Interface forum

DS90UB928Q-Q1: DS90UB928 + DS90UB929 eye diagram question