LMK00308: CLKout can support DC voltage?

Noriyuki Takahashi

Genius 10210 points

Part Number: LMK00308

Hi team,

Could you confirm that CLKout can support DC voltage?

It seems that fCLKin supports DC but I can see no description about CLKout.

Regards,

Noriyuki Takahashi

over 3 years ago

0 Aaron Black over 3 years ago

TI__Expert 8405 points

Hello Takahashi-san,

Please see section 7.5: Electrical Characteristics for the different voltages of terminations for LVPECL, LVDS, HCSL and pertaining to REFout LCVMOS.

0 Noriyuki Takahashi over 3 years ago in reply to Aaron Black

TI__Genius 10210 points

Aaron,

Thanks. Please let me ask an additional question.

Could you tell the min output frequency of LVDS and LVPECL?

It seems that the datasheet specifies the output frequency range of HCSL. And the min output frequency is DC. But I can't find the min output frequency of LVDSS and LVPECL in the datasheet.

Regards,

Noriyuki Takahashi

0 Aaron Black over 3 years ago in reply to Noriyuki Takahashi

TI__Expert 8405 points

Hello Takakashi-san,

The specified output frequency range of HCSL as f_CLKout. Please find either f_CLKout_FS or f_CLKout_RS under LVPECL as well as LVDS to find the minimum output frequency.

Please pay attention to the 'Test Conditions' column as different Vod ranges will associate with different frequency ranges.

0 Noriyuki Takahashi over 3 years ago in reply to Aaron Black

TI__Genius 10210 points

Aaron,

I think that f_CLKout_FS or f_CLKout_RS is the maximum output frequency at the certain condition and doesn't specify the output frequency range.

Customer's question is to know the min output frequency.

Regards,

Noriyuki Takahashi

0 Aaron Black over 3 years ago in reply to Noriyuki Takahashi

TI__Expert 8405 points

Hello Takahashi-san,

You are correct, below any of these settings this device will act as a buffer. The only time we have to worry about output frequency not operating as intended is within these maximum cases.

Sorry for the initial confusion, thank you!

0 Noriyuki Takahashi over 3 years ago in reply to Aaron Black

TI__Genius 10210 points

Hi Aaron,

Sorry, I still don't understand yet. Do you mean that the output frequency range of LVDS & LVPECL is from DC to Maximum Output Frequency?

Regards,

Noriyuki Takahashi

0 Aaron Black over 3 years ago in reply to Noriyuki Takahashi

TI__Expert 8405 points

Hello Takahashi-san,

Anything below 800MHz should not be an issue for this buffer in any output settings.

When higher frequencies are used is the only time when specific settings should be followed as discussed earlier.

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LMK00308: CLKout can support DC voltage?