cancel
Showing results for 
Search instead for 
Did you mean: 
Highlighted
Visitor
Visitor
6,480 Views
Registered: ‎01-29-2013

Spartan 6, maximum IO voltage

Jump to solution

Hello,

 

I am working on a design with a Spartan 6.

Can I connect a 3.3v signal to 1.5 v IO bank in spartan 6 ?

I read the related doucuments, bus I cound not find a clear describe about maximum IO voltage in Spartan 6.

 

Thank you for your help,

Alex

Tags (2)
0 Kudos
1 Solution

Accepted Solutions
Highlighted
Scholar
Scholar
8,199 Views
Registered: ‎02-27-2008

Re: Spartan 6, maximum IO voltage

Jump to solution

Alex,

 

Generally, no, you can't do that.  Most devices allow you to use a series resistor to limit the current (100 ohms is often used).

 

S6 does have the ability to turn off the clamp diode to Vcco,  so I believe it is possible, but you have to configure it properly (clamp = off).

 

Or, you could use a series resistor.



Austin Lesea
Principal Engineer
Xilinx San Jose

View solution in original post

7 Replies
Highlighted
Xilinx Employee
Xilinx Employee
6,454 Views
Registered: ‎01-03-2008

Re: Spartan 6, maximum IO voltage

Jump to solution

> Can I connect a 3.3v signal to 1.5 v IO bank in spartan 6 ?

 

Yes, you can do this.

 

> I cound not find a clear describe about maximum IO voltage in Spartan 6.

 

This is documented in Table 2 of the Spartan-6 data sheet.

------Have you tried typing your question into Google? If not you should before posting.
Too many results? Try adding site:www.xilinx.com
0 Kudos
Highlighted
Scholar
Scholar
8,200 Views
Registered: ‎02-27-2008

Re: Spartan 6, maximum IO voltage

Jump to solution

Alex,

 

Generally, no, you can't do that.  Most devices allow you to use a series resistor to limit the current (100 ohms is often used).

 

S6 does have the ability to turn off the clamp diode to Vcco,  so I believe it is possible, but you have to configure it properly (clamp = off).

 

Or, you could use a series resistor.



Austin Lesea
Principal Engineer
Xilinx San Jose

View solution in original post

Highlighted
Visitor
Visitor
6,434 Views
Registered: ‎01-29-2013

Re: Spartan 6, maximum IO voltage

Jump to solution

Thanks for you reply.

0 Kudos
Highlighted
Visitor
Visitor
6,384 Views
Registered: ‎01-25-2011

Re: Spartan 6, maximum IO voltage

Jump to solution

Tables 1 and 2 in ds162 don't say anything about having to turn off clamp diodes. They do say the specification doesn't apply when driving the I/O as an output.

 

This only seems to apply to Spartan-6; other families (including Series 7) clearly do have clamp diodes.

0 Kudos
Highlighted
Xilinx Employee
Xilinx Employee
6,378 Views
Registered: ‎01-03-2008

Re: Spartan 6, maximum IO voltage

Jump to solution

Table 2 in DS162 lists two conditions for the Vin specification.  One condition is for the PCI IOSTANDARD and the other is for everything else.  In Spartan-6 the clamp diode is only enable for PCI.

------Have you tried typing your question into Google? If not you should before posting.
Too many results? Try adding site:www.xilinx.com
0 Kudos
Highlighted
Anonymous
Not applicable
3,692 Views

Re: Spartan 6, maximum IO voltage

Jump to solution

Hello,

I have the same question but about artix 7 XC7A35T

If i configure a IO in High Impedance, can i connect a 3.3volts input in a 1.8v bank?

In high impedance, serie resistor is very big and current very low. So normally, they are no problems.

I have a mistake with my second clock powered in 3.3v connected in a 1.8v bank

Thanks

0 Kudos
Highlighted
Scholar
Scholar
3,607 Views
Registered: ‎02-27-2008

Re: Spartan 6, maximum IO voltage

Jump to solution

f,

 

All 7 series have diodes to vcco and ground, that are not configurable.

 

Driving 3.3v to a 1.8v input will damage the device.

 

You need a level shifter, or at least a series resistor to limit the current into the pin through the forward biased pmos fet intrinsic diode to the Vcco.

 

 

 

 

Austin Lesea
Principal Engineer
Xilinx San Jose
0 Kudos