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SN74LV14A: How many Load-Capacitance can Y (output pin) drive?

cafain
Mastermind 6365 points
Part Number: SN74LV14A

Hi,

From the data sheet of SN74LV14A,
Switching timing is specified for LOAD CAPACITANCE with CL=15pF and 50pF.

It is a question.
1.Is it possible to connect (drive) CL=1000pF to Y-pin (output)?
2.When 1000pF is connected, if the rising / falling time linearly increases, will the device be damaged?
3.How many "xxxpF" can Y(output pin) drive?

Best regards
cafain

  • 0
    TI__Guru* 96591 points

    Hi cafain,

    1:

    You will be limited by current before anything else.  The device has a rated maximum of 25mA.  By adding a series output resistor (220 ohms) the output current will be limited to <25mA, and the  size of the output capacitor becomes irrelevant. You could theoretically connect a 1 F capacitor and it would not damage the device... of course, with such a large capacitor, the charge time would be quite ridiculous.

    With small capacitances (ie < 100pF) the amount of charge required is low and won't cause any damage to the device, even if the current momentarily increases beyond 25mA.

    2: Rise/Fall time at the output of a logic device will not damage it in and of itself. Damage is caused by excessive current or voltage.

    3: A good rule of thumb is to limit to 70 pF.