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LMK1C1104: Maximum Input Consumption Current

PAB
Prodigy 75 points
Part Number: LMK1C1104

Tool/software:

Hi everybody,

I would like to know the maximum input consumption current of this particular part, working with VDD = 3.3 V and all outputs active, 50Ohm load, 10 MHz frequency.

This parameter is usually labeled as "Total current into VDD" in other parts' datasheets.

Datasheet talks about "Core supply current" which at first I thought would be the answer to my question, but it refers a maximum of 40mA, when each output delivers 20mA.

Thanks for your help.

Regards,

  • 0
    TI__Genius 10235 points

    PAB,

    The picture below contains the core supply current used by the entire device. At 3.3V the device burns a total of ~33mA. If that's not what you're looking for, what do you mean by input consumption current? How much current was burned by the input driver alone? What is this for?

    Best,

    Andrea

  • 0 in reply to Andrea Vallenilla
    Prodigy 75 points

    Hi Andrea!

    Thanks for your reply.

    In case every output (four outputs in the case of the LMK1C1104) is loaded with 50Ohm||5pF, what would be the core supply current of the device?

    Regards,

    PAB

  • 0 in reply to PAB
    TI__Genius 10235 points

    PAB,

    Unfortunately we do not have data with a 50Ω load; however, because the data we have is across a 5pF load, I would assume the consumption across an added 50Ω would be the same since the capacitor alone acts like an open circuit. Adding the resistor in parallel would generate the same amount of current, the current would just dissipate across the resistor.

    Best,

    Andrea

  • 0 in reply to Andrea Vallenilla
    Prodigy 75 points

    Andrea, I got confused. How is it possible for this device to deliver 20mA per output (20ma x 4 outputs = 80mA), and just taking 33mA  from the supply?

  • 0 in reply to PAB
    TI__Genius 10235 points

    PAB,

    The device is NOT taking 33mA per output, the ENTIRE device (so the core, the outputs, inputs, internal circuitry, etc) will all consume 33mA. With a 5pF load each output is consuming on average ~6.3mA.

    Best,

    Andrea

  • 0 in reply to Andrea Vallenilla
    Prodigy 75 points

    Andrea, I didn't say it is taking 33mA per output.

    I understand the whole device, with all its outputs active, will consume (maximum) 33mA (40mA). That's clear.

    Now, each output, with a 50Ohm||5pF load, is able to deliver approximately 20mA. That sums up 80mA. (I asked about this in this forum).

    How is it possible, for this device, to drive 80mA when there is a maximum current through VCC or GND through the entire device of 40mA? 

  • +1 in reply to PAB
    Prodigy 75 points

    For those who this may be useful.

    I had to find the answer for myself.

    When they told me each output is able to drive up to 20mA, they didn’t mention not at the same time.

    Putting all outputs in parallel, with 50 Ohm load, it drives around 28,5mA, which perfectly correlates with those 33mA specified as typical core supply current on the datashet.

    Hope it helps.

    Regards.