5V tolerant I/O?

Go To Last Post
7 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

My Wiznet812MJ is 5V tolerant I/O (according to datasheet). I'm using SPI. My Atmega is running at 5V and Wiznet812MJ is 3V. Does that mean I can connect the Wiznet812MJ I/O to my Atmega directly without damaging the Wiznet812MJ or shorten its life?

I cant run my Atmega at 3V because other devices running at 5V too.

The word "tolerant" makes me a bit worry. If it say 5V-compatible, then I pretty sure it is no problem.

cs

I'm happy ytd, today, and tmr :)

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

"5 V tolerant I/O" is a common term meaning you can put 5 V on the I/O pins and it won't die. It implicitly also means that you should not put 5 V on any other pin not explicitly mentioned as 5 V tolerant (e.g. supply pins)

Stealing Proteus doesn't make you an engineer.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

ArnoldB wrote:
"5 V tolerant I/O" is a common term meaning you can put 5 V on the I/O pins and it won't die. It implicitly also means that you should not put 5 V on any other pin not explicitly mentioned as 5 V tolerant (e.g. supply pins)

It won't die is good...But I'm more concern does the 5V going to shorten its life?

Or do I need some level shifter like 74HC4050/CD4050...to make the Wiznet has a longer lifespan?

cs

I'm happy ytd, today, and tmr :)

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Quote:
It won't die is good...But I'm more concern does the 5V going to shorten its life?

No, doesnt mean That it will short it's life...

Quote:
Or do I need some level shifter like 74HC4050/CD4050...to make the Wiznet has a longer lifespan?

You don't need it...

I not experience and don't hear about that tolerant will short it's life...

Regards,

Bruno Muswieck

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

The Wiznet will not be harmed by the 5V signals from the AVR, but the AVR will be seeing a marginal signal from the WIZNET. A 3V '1' on a 5V AVR input pin is right on the ragged edge of a valid level (AVR datasheet says 0.6 * Vcc or 3V). You will have essentially -no- noise margin without some kind of level translation.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

So,

From AVR -> WIZNET, no need level translator.

From WIZNET -> AVR, need some sort of level translator, like SN74AHCT541?

cs

I'm happy ytd, today, and tmr :)

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Check out this topic: https://www.avrfreaks.net/index.p...

It will answer all you interface/level translator questions.

Felipe Maimon