uln2803 & inverted logic
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Posts: 46,084
In a message dated 8/19/2003 6:32:48 PM Pacific Daylight Time,
manwithapipe@y... writes:
> Hello...
>
> I'm using an opto22 I/O rack and the current for switching each relay
> is 12mA, creating dangerous current totals with more than 3 outputs.
> So I've decided to use a ULN2803 to protect my stamp.
>
> Here's the confusing part: the opto22 uses inverted logic. So does
> the ULN2803. Does inverted + inverted = normal? Or is there some
> catch?
>
>
Not confusing at all......YES, the ULN2803 does invert your input. Click on
the link to the PDF spec sheet. A high input is a low output and visa versa.
If both devices are inverting logic, then by the time you get to the final
output, there should no longer be inversion.
<A
HREF="http://www.onsemi.com/pub/Collateral/ULN2803-D.PDF">http://www.onsemi.com/\
pub/Collateral/ULN2803-D.PDF</A>
[noparse][[/noparse]Non-text portions of this message have been removed]
manwithapipe@y... writes:
> Hello...
>
> I'm using an opto22 I/O rack and the current for switching each relay
> is 12mA, creating dangerous current totals with more than 3 outputs.
> So I've decided to use a ULN2803 to protect my stamp.
>
> Here's the confusing part: the opto22 uses inverted logic. So does
> the ULN2803. Does inverted + inverted = normal? Or is there some
> catch?
>
>
Not confusing at all......YES, the ULN2803 does invert your input. Click on
the link to the PDF spec sheet. A high input is a low output and visa versa.
If both devices are inverting logic, then by the time you get to the final
output, there should no longer be inversion.
<A
HREF="http://www.onsemi.com/pub/Collateral/ULN2803-D.PDF">http://www.onsemi.com/\
pub/Collateral/ULN2803-D.PDF</A>
[noparse][[/noparse]Non-text portions of this message have been removed]