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SN74LV393A: Max. frequency at CLK input

Part Number: SN74LV393A

Dear team,

Our customers has question below:

// it's not clear to me what the guaranteed maximum possible frequency is at the CLK input at 3.3V. The data sheet is not clear for me here. Since it is an input it cannot be fmax, which is given in the tables with different C loads.

Is the device faster at lower or higher temperatures (than 25°C)?

//

Please help us to fix it, thank you in advance !

  • The maximum clock frequency is limited neither by the input nor by any internal processing, but by the drive strength of the output.

    MOSFETs have a positive temperature coefficient, i.e., their resistance increases with temperature. So it should be faster at lower temperatures. (There is no guarantee.)

  • Hello,

    I agree that this is particularly confusing and it's something we're working to improve in future datasheets.

    The values provided in f_max are specifically in regards to the input frequency at the clock pin. For example, in the above table, with a 50pF load this device can have a clock input of 25 MHz. This will result in a slower output frequency (12.5 MHz max) because of the internal logic.

    We do guarantee operation within the datasheet specs -- at 2.5V supply, 25 MHz clock input with a 50pF load, the device will function properly. You can likely use it much faster, but we only guarantee up to 25 MHz across the full temperature range.