OSCin, OSCin* LMK03806

Jochen Pruess

Prodigy 10 points

Other Parts Discussed in Thread: LMK03806

I want to use LMK03806 with a XO. In the datasheet I read:

— A XO, TCXO, or other external clock. Must be AC
Coupled.

But if I look at the schematics of the Ti eval board, I found a DC coupled situation.

How "hard" is your datasheet must?

over 13 years ago

0 Jonathan Kolbrak over 13 years ago

TI__Intellectual 915 points

The correct configuration is AC coupled. This is how the device is tested so this it the recommended configuration.

Regards,

Jon

0 ALeksey Chistyakov over 12 years ago in reply to Jonathan Kolbrak

Prodigy 30 points

I want to drive LMK by sine wave source 50 ohm. Can i do it, and wich termination scheme can i use?

0 Arvind Sridhar over 12 years ago in reply to ALeksey Chistyakov

TI__Mastermind 24205 points

Hi Chistyakov,

In order to meet the jitter performance listed in the LMK03806 data sheet, the minimum recommended slew rate for the input clock is 0.5 V/ns. This is especially true for single-ended clocks. Phase noise performance will begin to degrade as the clock input slew rate is reduced. The device will function at slew rates down to the minimum listed.

Regards

Arvind Sridhar

0 ALeksey Chistyakov over 12 years ago in reply to Arvind Sridhar

Prodigy 30 points

I understood correctly, what do you recommend to place at input circuit LOGIC CONVERTER such as LTC6957, for better phase noise performance? Such scheme not found at input on LMK03806 ?

0 Arvind Sridhar over 12 years ago in reply to ALeksey Chistyakov

TI__Mastermind 24205 points

Hi Chistyakov,

A good choice to speed up edges would be to use a limiting amplifier like the ONET1191P

(http://www.ti.com/product/onet1191p)

Regards

Arvind Sridhar

Clock & timing

Clock & timing forum

OSCin, OSCin* LMK03806