Input Trip Voltage

Hardware questions and issues with the FV-1

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amz-fx
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Input Trip Voltage

Post by amz-fx »

Frank,

What is the voltage at which the address pins, S0-S2, will switch?

I'm guessing that they are cmos and it is around 1/2Vcc? I'm really interested in how close to ground I have to pull the address lines for them to flip to zero (assuming a 20k-47k pullup).

Thanks, Jack
frank
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Post by frank »

Well, normally input pins have schmitt triggers to avoid false triggering due to noise so you probably want to target 70/30 for the switching points. I.e. about 2.3V or greater for switching high and 1V or less for switching low.

If you are using a 20K pull up on the pin and just switching the pin to gnd when necessary (like in the datasheet) that should be no problem.
Frank Thomson
Experimental Noize
amz-fx
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Post by amz-fx »

I want to pull it low through a diode. So the pin will be about 0.65v above ground.

Should work?

Thanks, Jack
frank
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Post by frank »

That should probably work OK. Why through a diode?
amz-fx wrote:I want to pull it low through a diode. So the pin will be about 0.65v above ground.

Should work?

Thanks, Jack
Frank Thomson
Experimental Noize
djmalan
Posts: 36
Joined: Fri Mar 06, 2009 8:22 am

Post by djmalan »

Why through a diode?
I guess; :D
Couldn't find an encoder and tries to make own ,by using some kind of switches,is it. :D
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