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SN74LVT16244B: SN74LVT16244B structure

Part Number: SN74LVT16244B

Hello Team,

Can you share the internal input and output circuit structure? Is it push-pull structure? is there pull-up resistors? Thanks.

Regards,

Nanfang

  • Hello Nanfang,

    The input structure is a TTL compatible input that is overvoltage tolerant.
    The device can only be powered from 2.7V to 3.6V, and its designed for LVTTL and TTL levels, meaning VIH >2V, VIL of <0.8V. It can also accept 5V inputs.

    The output is just a simple push-pull buffered output. No pull up resistors. The output will drive the output actively high or low.
    Is there some concern? Do you need a part suggestion for a particular application?

    Best,
    Michael
  • Hello Michael,

    Thanks for your quick response, can you draw a picture to show the internal structure? The input signal is non-monotonous between VIL and VIH, is there any risk about this application?

    Regards,
    Nanfang
  • Hello Nanfang,

    The device you are using works on a the 3.3V LVTTL threshold level as shown in the image below.
    While the switching threshold is typically 1.5V, as shown, the threshold could theoretically exist anywhere between 0.8 an 2V.

    If your signal is non-monotonic between VIL and VIH, this is not going to be ideal, as the device could have oscillations or multiple switches on the output of the device.

    Furthermore, it is best to keep in mind that the input transition rate of 10ns/V needs to be met as a recommended operating condition. In other words the input signal needs to rise from GND to 3.3V in less than 33ns. If you have a non-monotonic signal, that would seem to suggest to me that it is not rising quickly. If the input isn't rising quickly, then the output is likely to oscillate anyway. Please refer to the following app note:

    http://www.ti.com/lit/wp/slla364a/slla364a.pdf 

    If you have slow rising inputs into this device, then it is best if you use schmitt trigger input devices to help clean up the slow rising signal. A schmitt trigger would also help to reduce any oscillations or retriggering that could happen during a non-monotonic signal. Based on how the input signal looks, it would be best to use a schmitt trigger that has a hysteresis which is defined to be larger than the noise on the signal.

    Does this make sense? Please let me know how I can help further.

    Best,
    Michael

  • Hello Michael,

    Got it, thank you very much. Do you have the internal input and output circuit? can you share with me? Thanks

    Regards,
    Nanfang
  • Hello Nanfang,

    Please find the output structure in the following application note:
    www.ti.com/.../scea002a.pdf

    Please see the input structure in the following app note:
    www.ti.com/.../scaa029.pdf

    Best,
    Michael