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SN74LVC244A: Rise time and fall time specifications

Madhu Sharma
Expert 2915 points
Part Number: SN74LVC244A

Hi,

I am using SN74LVC244A buffer for keystone II SOC JTAG interface.

In the buffer datasheet, it is mentioned to refer Recommended operating conditions table for rise and fall time specifications, but that table doesn't contain that information.

So please let me know what is the rise time and fall time specifications of the buffer. Keystone II requires the rise time to be between 500ps to 1500ps.

Thanks & Regards,

Madhu

  • 0
    Guru 287090 points
    Where did you get these 500ps/1500ps numbers from?

    The recommended operating conditions table would contain the requirements for the buffers' inputs. (For LVC devices at 1.8 V, the upper limit typically is 20 ns/V, i.e., 36 ns.)
    The output rise/fall time depends on the capacitances and parasitic inductances of your cicruit; to minimize it, make the trace between the buffer and the SOC as short as possible.