MCP23S17 question

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mike32217
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Posted by mike32217: Fri. Oct 31, 2014 - 07:59 PM
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I'm basically a programmer so parts of data sheets are difficult for me to read.

 

My question is I've ordered some MCP23S17 devices and if I'm reading the data sheet correctly I can power with 3.3V and 5V on the I/O pins won't hurt it?

 

 

Voltage on VDD with respect to VSS .......................................................................................................... -0.3V to +5.5V

 

Voltage on all other pins with respect to VSS (except VDD)............................................................. -0.6V to (VDD + 0.6V)
 

It's a little confusing because further down in the DC Characteristics there are entries for Input Low/High voltage that seem to conflict?

 

Happy Trails,

Mike

JaxCoder.com

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Learning and Information, General Electronics
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Chuck99
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Posted by Chuck99: Fri. Oct 31, 2014 - 09:38 PM
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mike32217 wrote:
I can power with 3.3V and 5V on the I/O pins won't hurt it?

 

Voltage on all other pins with respect to VSS (except VDD)............................................................. -0.6V to (VDD + 0.6V)

 

Vdd = 3.3V

Any other pin: max voltage is 3.3V + 0.6V = 3.9V

 

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keith v
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Posted by keith v: Fri. Oct 31, 2014 - 09:42 PM
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General rule is to never exceed the supply voltage on any pin.

If you do the part my latch up and be stuck till you power cycle it ( if you're lucky )

 

from what you posted you can run it at 5v, or 3.3, but if you run it at 3.3, your inputs should not exceed 3.3

 

The IO levels are probably a max for a low level and a min for a high level?

Keith Vasilakes

Firmware engineer

Minnesota

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mike32217
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Posted by mike32217: Fri. Oct 31, 2014 - 09:59 PM (Reply to #2)
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Chuck99 wrote:

 

mike32217 wrote:

I can power with 3.3V and 5V on the I/O pins won't hurt it?

 

 

Voltage on all other pins with respect to VSS (except VDD)............................................................. -0.6V to (VDD + 0.6V)

 

 

Vdd = 3.3V

Any other pin: max voltage is 3.3V + 0.6V = 3.9V

 

Ah I see, thanks for the wisdom!

Happy Trails,

Mike

JaxCoder.com

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valusoft
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Posted by valusoft: Fri. Oct 31, 2014 - 10:57 PM
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Hi Mike.

 

And for future reference, there are some parts that have inputs that are "tolerant" of having higher voltages applied. The maker usually uses the "tolerant" word which is handy for Google searches and within datasheets.

 

Cheers,

 

Ross

 

Ross McKenzie, Melbourne Australia

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