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Electronics => Electronics => Topic started by: airman00 on June 08, 2009, 06:03:06 AM

Title: Connecting Comparator to Axon
Post by: airman00 on June 08, 2009, 06:03:06 AM

I've set up a comparator circuit and it's all working, now I want to connect the output of the comparator to an Axon digital input pin. What is the maximum voltage a digital pin can handle?

Title: Re: Connecting Comparator to Axon
Post by: Soeren on June 08, 2009, 11:52:58 AM

Hi,

This is a generic input protection useable for up to more than 30V
(http://That.Homepage.dk/Img/Inp_Protect.png).

If your comparator is the kind with an open collector output it's even easier - just connect the pull up between the output and the controllers Vdd (that's what open collector outputs are specifically made for.

Title: Re: Connecting Comparator to Axon
Post by: Admin on June 09, 2009, 06:26:31 PM

Quote

What is the maximum voltage a digital pin can handle?

ATmega640 datasheet, silly :P

Without a protection circuit, it has to be less than the mcu voltage. Otherwise you'd get negative current. Although I'm sure it has some un-spec'd tolerance . . .