CDCLVC1104: Can't find any oscillator for this device

Kei Kuwahara

Part Number: CDCLVC1104

Tool/software:

Hello team,

My customer can't find any oscillator which satisfy input slew rate spec (1V/ns - 4V/ns)

Is CDCLVC1104 not developped to be used with oscillator as input clock?
Can you recommend any oscillator which can be used with CDCLVC1104?

Best Regards,
Kei Kuwahara

5 months ago

+1 Kadeem Samuel 5 months ago

TI__Mastermind 23220 points

Kuwahara-san,

The CDC6Cx BAW oscillator (https://www.ti.com/product/CDC6C) can meet this input requirement using a 3.3V supply voltage, "normal mode" for the slew rate, and a 15pF load capacitor:

Thanks,
Kadeem

0 Kei Kuwahara 5 months ago in reply to Kadeem Samuel

TI__Expert 8110 points

Hi Kadeem-san,

Thank you for the quick answer.

I have calculated slew rate for rise/fall time of 2.2ns for 3.3V supply (20% to 80%).
It will be 3.3V * 0.6 / 2.2ns = 0.9V/ns correnct?

If so, it will violate the minimum slew rate requirement of CDCLVC1104. (1V/ns min)

Best Regards,
Kei Kuwahara

0 Kei Kuwahara 5 months ago in reply to Kei Kuwahara

TI__Expert 8110 points

Hello Kadeem-san,

I have similar question before (thread below) but what spec parameter might be affected if input slew rate is violated?

My guess is jitter spec might get affected, is this correct?

https://e2e.ti.com/support/clock-timing-group/clock-timing-internal/f/clock-timing---internal-forum/1484810/cdclvc1104-input-slew-rate-max-limit?tisearch=e2e-sitesearch&keymatch=CDCLVC1104%2520kuwahara#

Best Regards,
Kei Kuwahara

+1 Michael Srinivasan 5 months ago in reply to Kei Kuwahara

TI__Genius 10600 points

Kuwahara-san,

For these clock buffers, if the input slew rate is less than the minimum spec, then as you said, there will be considerable phase noise degradation. However, it is possible to increase the slew rate by simply decreasing the load capacitance (i.e. decreasing from 15 pF to 5 pF should roughly double the slew rate according to the CDC6Cx datasheet, and if that is too aggressive of an increase, then you can use 10 pF).

Thanks,

Michael

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CDCLVC1104: Can't find any oscillator for this device