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Author Topic: I2C Voltage 5V or 3,3V?  (Read 1012 times)
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Normally the due IO pins only can stand 3.3 V, but what about the I2C? Can i use the bus with 5V? i cannot find a good documentation about the I2c specification for the due.

i found this thread: http://arduino.cc/forum/index.php/topic,141237.0.html

but could not find out if it is possible without damaging the due.

sorry for this noob question but i soldered my hardware for 5 V and now it would be fine to operate the i2c bus at 5V.

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I2C is normally open drain (or open collector) for all devices that are connected.
You'll have to look at the specifics for PB-12, 13 for I2C to see what they will accept in I2C mode.
I only have the Summary datasheet downloaded, and it doesn't have the Electrical Characterstics section in it.
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According to my reading of the datasheet, ALL IO pins are strictly 3.3V, no exceptions smiley-sad
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Normally the due IO pins only can stand 3.3 V, but what about the I2C? Can i use the bus with 5V? i cannot find a good documentation about the I2c specification for the due.

The I2C bus itself is voltage agnostic.

It depends on the specific I2C devices you pick and use. Some will work like the TI ADS1110 I2C ADC chip from 2.7V to 5.5V, other I2C chips may not work at over 3.3vdc. Some like the popular RTC DS1307 is a 5 volt only device.

Lefty

« Last Edit: January 24, 2013, 04:24:21 pm by retrolefty » Logged

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Why do say DS1307 is 5V only? Datasheet indicates it will work much lower:

Logic 1 Input, VIH: 2.2 to VCC + 0.3V
Logic 0 Input, VIL: -0.3 to +0.8V

Looks like a 3.3V capable part to me.
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Why do say DS1307 is 5V only? Datasheet indicates it will work much lower:

Logic 1 Input, VIH: 2.2 to VCC + 0.3V
Logic 0 Input, VIL: -0.3 to +0.8V

Looks like a 3.3V capable part to me.

I was just looking at the datasheet at it's Vcc rating. But your right in that even though needing +5vdc Vcc power, it will still work on a 3.3volt I2C bus.

Lefty
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