Interface slow 5V signals

Technical discussions around xCORE processors (e.g. General Purpose (L/G), xCORE-USB, xCORE-Analog, xCORE-XA).
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skoe
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Interface slow 5V signals

Postby skoe » Tue May 11, 2010 2:14 pm

Can I connect slow 5V signals using a series resistor of about 1 k to the XMOS' I/O ports? Will the clipping diodes be enough in this case to protect the inputs? It's just a test circuit, nevertheless I don't want to blow up my XMOS.

Regards,
Thomas
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leon_heller
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Postby leon_heller » Tue May 11, 2010 4:14 pm

Inputs are 5V compatible, see the data sheet.
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Woody
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Postby Woody » Tue May 11, 2010 5:28 pm

leon_heller wrote:Inputs are 5V compatible, see the data sheet.
Only XS1-G devices have 5V tolerant inputs. XS1-L parts have a maximum input voltage of 3.6V (~3.3+10%).

As Leon says, check the datasheets.
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leon_heller
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Postby leon_heller » Tue May 11, 2010 5:39 pm

I checked the data sheet I had for the XS1-L1, and that gave 5.5V as the maximum. The latest version gives 3.6V.

A resistor should be OK for the XS1-L1, I've seen one used with other devices.
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skoe
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Postby skoe » Tue May 11, 2010 10:45 pm

Thanks!

There must be a reason they corrected it down to 3.6 V in the latest revision :) I'll add another resistor per pin to build a voltage divider, just to be on the safe side.

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