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david900
Guest
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| output low or high impedance only |
 Posted: Sat Apr 07, 2007 2:35 pm |
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| How do I configure an IO pin to have high impedance when not outputting low (0V)? Basically I want the pin to have just two state: low or high impedance. |
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Ttelmah
Guest
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| Posted: Sat Apr 07, 2007 2:43 pm |
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output_float.
It basically turns the pin into an input, without reading the data, leaving it in a high impedance state.
Best Wishes |
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david9000
Guest
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| Posted: Sat Apr 07, 2007 2:47 pm |
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| bingo. Thanks |
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david9000
Guest
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| Posted: Sat Apr 07, 2007 9:17 pm |
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I know it's high voltage for an io pin, but when I input 9V from my battery, I can see 25mA is flowing into the high Z pin. Why?
I don't see any current flow when I input 5V from the regulator into the HIgh Z pin which is expected and good. |
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dyeatman
Joined: 06 Sep 2003
Posts: 1933
Location: Norman, OK
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| Posted: Sat Apr 07, 2007 10:24 pm |
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You are seeing junction breakdown because you are greatly exceeeding the chip maximum ratings (5.5VDC).. I'm surprised you didn't blow the chip.
From the manufacturer manual.
# Input voltage: Vin
Maximum voltage that may be applied to input pins.
This voltage is determined by the punch-through breakdown voltage of the input transistors or the breakdown voltage of input diodes, and therefore voltage exceeding this rating may destroy these transistors or diodes. |
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