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DM8168 minimum Vio question

Bill Argabright
Intellectual 270 points

Looking at the DM8168 datasheet, page 139 shows the "Electrical Characteristics" table.  It lists a minimum Voh (for 3.3V I/O) of 2.4V at the maximum output current (6mA).  I am not operating anywhere near that - I'm more like 100uA instead.

My problem is that one of the devices the DM8168 is talking to has a minimum Vih of Vcc-0.3V (or 3.0V in my case).  Therefore, I can't guarantee operation when using 2.4V Voh for the DM8168.

My main question is, what is the DM8168's minimum Voh (for 3.3V I/O) for a 100uA output current?

Thanks!

-Bill

  • 0
    TI__Mastermind 43875 points

    Bill,

    What this is really saying is that the output drivers can drive 6mA from a 3.3V supply and will have a maximum drop of 0.9V.

    Effectively this translates then to an effective output impedance of about 150 ohms (R = V/I = 0.9/0.006 = 150).

    In reality it is not quite this simple but it is OK for your calculations here...

    The maximum voltage drop will therefore be in the region of 15mV for your 100uA.

    BR,

    Steve