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SN74LVC2G125: About input maximum frequency

Tao_2199
Genius 5770 points
Part Number: SN74LVC2G125

Hello,

 

Regarding to the input maximum frequency on SN74LVC2G125, my customer is asking a question.

(Question)

Is it up to 100MHz(max) regardless of output voltages(1.8/2.5/3.3/5V)?

Or is it difference by output voltages?

 

Regards,

Tao2199

  • 0
    Guru 317060 points

    Figure 6 does not go above 75 MHz.

    A tpd value of 10 ns would correspond to 50 MHz. (The propagation delay times are not necessarily directly related with the frequency, but the quoted 100 MHz value at 3.3 V fits with that tpd value.)

  • 0 in reply to Clemens Ladisch
    TI__Mastermind 24975 points
    Hello Tao,

    Clemens is correct. At different voltages there are different propagation delay times but that does not necessarily mean the device can't create a signal that is clean, it just means there might be additional delay longer than a single clock cycle.

    At lower voltages, the output driver is not able to drive the output as quickly, hence the increase in tpd, but at higher voltages the output has to drive the output higher, which may take longer to get to a valid VIH level for the next stage.

    All things considered, the device should be able to do upwards of 100MHz across VCC depending on the circuit conditions. You would need to ensure that the PCB was optimized for such a high speed single-ended signal (trace length minimized, output capacitance minimized, and trace layout optimized) to be able to get the frequencies required.

    I know that this is not exactly a yes or no answer, but there are too many external variables that need to be controlled to ensure that the system will operate well at 100MHz, even including your tolerance to noise and signal integrity on the output. Under ideal conditions this device should be able to support it, but bench testing is best to test whether or not the signal will work in your system.

    Best,
    Michael