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MAX14434: Interpreting Supply Current Values in Datasheet

Category: Datasheet/Specs
Product Number: MAX14434

Hello, I want to calculate power dissipation for a digital isolator I am using (MAX14434EAWE+). However, the supply current numbers in the datasheet don't seem consistent with each other so I'm not sure which ones to use.

Just for an example, Sheet 3 of the datasheet has a table with typical values. The table is unclear but I believe this should be showing current per active channel? Looking at IDDA at 12.5MHz, CL = 0pf, VDDA = 5V, it says 1.63 mA typical. Looking at IDDB at 12.5 MHz, CL = 0pF, VDDB = 5V, it says 2.97 mA typical.

However, when I look at the curves on Sheet 13, they give quite different values. IDDA for 12.5MHz, VDDA = 5V is around 0.65mA. IDDB for 12.5MHz, VDDB = 5V is around 1mA. 

Then when I look at Sheet 21-22 it says to use Figure 8 and Figure 9 which also give completely different values.

Questions:

What is the relationship between the table on Sheet 3 and the curves on Sheet 13? Which should I use for calculating power dissipation in the part? Can you confirm that both of these are showing "current per channel"?

Thank you for any help.

  • If you are calculating an estimated power dissipation for the part, I would suggest that you follow the guidance and charts on pages 21 and 22. 

    The author of the datasheet was very likely aware of any unstated details/considerations behind the different supply current values in the other sections of the data sheet and specifically made the effort to generate the figures and application instructions for how to estimate the power dissipation on pages 21 and 22.

    Eric