CDCM6208: LVPECL output matching network

Lacey Lin

Intellectual 2900 points

Part Number: CDCM6208

Hi team,

For the LVPECL output, does the CDCM6208 only support the AC coupling?

If I use the DC coupling to connect the CDCM6208 output to a LVPECL receiver, will this cause issue?

Lacey

Thanks a lot!

over 7 years ago

0 Lane Boyd over 7 years ago

TI__Genius 16845 points

Hi Lacey,

Yes, the output only supports AC-coupling for LVDS or LVPECL outputs. DC coupling can cause issues.

Kind regards,
Lane

0 Lacey Lin over 7 years ago in reply to Lane Boyd

TI__Intellectual 2900 points

Hi Lane，
Can you help to share the detail structure or reason for why the DC coupling will cause issue?
And what's the issue?
Customer need the detail information to evaluate the solution.
Lacey
Thanks a lot!

0 Madhu Balasubramanian over 7 years ago in reply to Lacey Lin

TI__Expert 4400 points

Hi Lacey, there is no device issue with DC coupling but we need to recommend the right interface if customer prefer to DC couple in order to support both the output common mode voltage for CDCM6208 as well as the input common mode voltage for the LVPECL receiver. Can you share the specifications of the LVPECL receiver, like Vicm, Vid etc so that we can look into the correct recommendation. AC coupling will always be the easiest.

0 Lacey Lin over 7 years ago in reply to Madhu Balasubramanian

TI__Intellectual 2900 points

Hi Madhu，
For my understanding, the CDCM6208 can support DC LVPECL, because the common mode voltage of the CDCM6208 in LVPECL-Like is not the same as the standard LVPECL. right?
So what's the common mode voltage of CDCM6208 in the LVPECL-Like output?
Customer said they need to double check with the receiver vendor to make sure the LVPECL receiver specs.
Lacey
Thanks a lot!

0 Shawn Han over 7 years ago in reply to Lacey Lin

TI__Genius 9920 points

Hi Lacey,

Datasheet shows it as below. Notice it is a CML driver internal for this LVPECL-like output.

Best Regards,

Shawn

Clock & timing

Clock & timing forum

CDCM6208: LVPECL output matching network