Thread: 4V - 5V signal on Digital Input
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Unread 06-03-2008, 09:49
dcbrown dcbrown is offline
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Re: 4V - 5V signal on Digital Input
The first thing that comes to mind is a simple level triggering opamp circuit? For example LM339s or LM139s? Set up a resistor divider so that 4.1v is Vref, apply your 4v-5v to Vin, Vout should be ~0v if Vin is less than 4.1v and ~5v is greater than 4.1v...

See National Semi AN-74.pdf application note for more info.
Last edited by dcbrown : 06-03-2008 at 10:02.