MCP23S17 question

Log in or register to post comments
Go To Last Post
5 posts / 0 new
Author
Message
mike32217
mike32217's picture
Level: Hangaround
Joined: Sun. Feb 28, 2010
Posts: 380 View posts
Location: St. Johns, FL
#1
Posted by mike32217: Fri. Oct 31, 2014 - 07:59 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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

Tags:

Learning and Information, General Electronics
Top
Chuck99
Chuck99's picture
Level: Posting Freak
Joined: Sat. Oct 31, 2009
Posts: 1424 View posts
Location: Vancouver, WA, USA
Posted by Chuck99: Fri. Oct 31, 2014 - 09:38 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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

 

Top
keith v
keith v's picture
Level: Hangaround
Joined: Fri. Oct 24, 2014
Posts: 176 View posts
Posted by keith v: Fri. Oct 31, 2014 - 09:42 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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

Top
mike32217
mike32217's picture
Level: Hangaround
Joined: Sun. Feb 28, 2010
Posts: 380 View posts
Location: St. Johns, FL
Posted by mike32217: Fri. Oct 31, 2014 - 09:59 PM (Reply to #2)
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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

Top
valusoft
valusoft's picture
Level: Moderator
Joined: Sat. Jul 2, 2005
Posts: 15137 View posts
Location: Melbourne, Australia
Posted by valusoft: Fri. Oct 31, 2014 - 10:57 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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 ValuSoft Melbourne Australia

Top