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LMK04610: Power supply current calculation

DEEPAK V14
Intellectual 810 points

Part Number: LMK04610

Hi,

Q1. LMK04610 is used for designing clock tree for our system. We have a 100MHz LVCMOS VCXO at OSCIN input with AC-Coupled Single-Ended Termination.
       The expected LVDS clocks at the output are as follows

    1. 200MHz x2
    2. 40MHz x4
    3. 2.5MHz

            How to calculate the worst case power supply current required for the above configuration with exploring all the features of LMK04610?

 

Q2. Is it possible to operate LMK04610 with LDOs having following specifications

    1. 3.3V output @ 200mA
    2. 1.8V output @ 100mA

 

Q3. In table 7.16 the value of IDDO_X is given as 41.1mA. If our system has 7 clocks at the output, does this value have to be multiplied by 7? So that total IDDO_X will be 287.7mA.

Thanks and regards
DEEPAK V

  • 0
    TI__Expert 8865 points

    Hi Deepak

    In the datasheet table "7.16 Power Supply Characteristics" can be used to find the current consumption for each supply pin listed on the device pin table. IDDOx is for each output supply pin. For yor case, 100mA for 1.8V is not sufficient.

    Best regards

    Puneet

  • 0 in reply to Puneet Sareen
    Intellectual 810 points

    Hi Punnet,

    Thank you for valuable suggestions!


    The worst case total supply current calculation for 3.3V rail and 1.8V rail is shown as below

    3.3V rail current = core supply current + PLL1 supply current + PLL2 core supply current + PLL2 OSC supply current
    = 28.6 mA + 16.1 mA + 52.0 mA + 64.9mA
    =161.6mA

    1.8V rail current = IO supply current + OSC supply current + (CLKoutx supply current * NO: of clock output)
    = 8.4 mA + 4.1 mA + (49.1 mA * 6)
    =307.1mA


    Please check whether the calculations are right? If not please correct me.

    Is it possible to use LDOs with rating shown below to power LMK04610?
    3.3V output @ 200mA
    1.8V output @500mA

    Thanks and regards
    DEEPAK V

  • 0 in reply to DEEPAK V14
    TI__Expert 8865 points
    Hello Deepak,

    Your calculation is correct and the LDOs you mentioned can be used.

    Best regards
    Puneet
  • 0 in reply to Puneet Sareen
    Intellectual 810 points
    Hi Puneet,

    Thanks once again

    Thanks and regards
    DEEPAK V