Re: [avr-gcc-list] I/O input pin current

[Joerg Wunsch]

As Jamie Morken <address@hidden> wrote:

>When an AVR I/O pin is set to input how much current will it draw
>from the signal?  In the atmega8 datasheet under electrical
>characteristics it states 3uA as the max I/O pin leakage current for
>pin low and pin high, but this would give an input resistance of
>5V/3uA=1.6Mohms which seems .. great! :)

Sure, it's a MOS input which has a high input resistance.

However, don't forget to examine the dynamic behaviour (i. e. the
influence of re-charging the input capacitance) unless you're running
at only very low frequencies.  Also, if you exceed the cutoff voltage
of the protection diodes (i. e. your input voltage goes below GND or
above Vcc), the input will start drawing current.
-- 
J"org Wunsch                                           Unix support engineer
address@hidden        http://www.interface-systems.de/~j/

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