SN74LVC2G79: Clarification on CPD for LVC2G79 needed

Bo Gao

Part Number: SN74LVC2G79

Hi,

Is there a CPD for each of F_clk and F_data for LVC2G79? There is a CPD in datasheet, but I don't know if it is F_clk related or F_data related.

AUC2G79 has CPD for both F_clk and F_data, but I need this number for LVC2G79.

Thanks,

Bo Gao

over 6 years ago

0 Emrys Maier over 6 years ago

TI__Guru* 96681 points

Hi Bo Gao,
The Cpd value given in the SN74LVC2G79 datasheet is tested with the given frequency on the clock pin and a phase-shifted half-frequency signal on the data pin (which causes the output to switch on every clock). This is the worst case and is what you should use for power calculations.

0 Bo Gao over 6 years ago in reply to Emrys Maier

Prodigy 140 points

Thank you, Emrys,

I'm working on a low power design which uses DFFs to latch data to a known, synchronized clock. Here, input data rate is 10MHz, and the clock is exactly 80MHz. Therefore, my data toggles at most 10M times per second, and my clock toggles exactly 80M times per second.

Since it's a low power design, I would like to know exactly how much power will this device consume.

Thanks,

Bo Gao

0 Emrys Maier over 6 years ago in reply to Bo Gao

TI__Guru* 96681 points

Hi Bo Gao,

I would recommend measuring the Cpd under your conditions.

The test for this is relatively easy and can be done with a simple RMS multimeter.

The details for the test are located here:

Starting on page 6.

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SN74LVC2G79: Clarification on CPD for LVC2G79 needed