LMK1D1204: CMOS 3.3V Single ended input

Seung-Gon Hong

Part Number: LMK1D1204

Hi,

I am going to use a 3.3V CMOS single-ended input as clock input for LMK1D1204.

How should I configure the input circuit? I've found a similar reference design for the 3.3V CMOS single-ended clock input.

Can I use the recommended application setting for single-ended input signals?

Thanks,

over 4 years ago

0 Julian Hagedorn over 4 years ago

TI__Mastermind 20900 points

Hello,

you cannot AC couple an 3.3V LVCMOS signal into LMK1D1204. See the datasheet recommendation below:

Vth can be set with resistor divider.

Regards,

Julian

0 Seung-Gon Hong over 4 years ago in reply to Julian Hagedorn

Prodigy 170 points

Thank you for your reply.

I can't find the electrical characteristics of VIH and VIL for single-ended LVCMOS clock input in the datasheet. Only the highlighted part can be checked as shown in the table below.

Can I calculate Vth using VDD as VIH and 0V as VIL?

And can I leave the unused Vac-ref pin floating?

Thanks

+1 Julian Hagedorn over 4 years ago in reply to Seung-Gon Hong

TI__Mastermind 20900 points

Hello,

the requirement for the input swing is stated as VIN_S-E.

You'll need to check the actual input signal and take the VIH and VIL levels from that signal.

See section 9.2.1 for further details:

If V_AC_REF is not used you can leave it floating.

regards,

Julian

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LMK1D1204: CMOS 3.3V Single ended input