1.8v SpartanIIE

[CW]

This is a question related to input pin on 1.8V Spartan IIE. Datasheets said
it is "5V tolerant with external resistor." What should the value of this
external resistor be? What value in the datasheet are you based on to
calculate the necessary voltage drop on this resistor? I am mainly a
firmware person, just start looking into FPGAs...
Thanks!

 

[Egads]

In article <W9rNb.1068$vK3.331@fe02.usenetserver.com>,
ching_wang@REMOVE.THE.OBVIOUS.alltel.net says...

This is a question related to input pin on 1.8V Spartan IIE. Datasheets said
it is "5V tolerant with external resistor." What should the value of this
external resistor be? What value in the datasheet are you based on to
calculate the necessary voltage drop on this resistor? I am mainly a
firmware person, just start looking into FPGAs...
Thanks!

100 Ohms...

--
Greg Deuerling
Fermi National Accelerator Laboratory
P.O.Box 500 MS368 Batavia, IL 60510
(630)840-4629 FAX (630)840-5406
Electronic Systems Engineering Group
Work: egads_AT_fnal.gov, remove '_AT_'

 

[Peter Alfke]

100 Ohms of you are after speed. Any higher value, let's say up to 1
kilohm, if the RC delay (C of the connection and input capacitance) is acceptable.
1 kilohm times 20 pF = 20 ns
Peter Alfke, Xilinx
==========
Egads wrote:

In article <W9rNb.1068$vK3.331@fe02.usenetserver.com>,
ching_wang@REMOVE.THE.OBVIOUS.alltel.net says...
This is a question related to input pin on 1.8V Spartan IIE. Datasheets said
it is "5V tolerant with external resistor." What should the value of this
external resistor be? What value in the datasheet are you based on to
calculate the necessary voltage drop on this resistor? I am mainly a
firmware person, just start looking into FPGAs...
Thanks!

100 Ohms...
--
Greg Deuerling
Fermi National Accelerator Laboratory
P.O.Box 500 MS368 Batavia, IL 60510
(630)840-4629 FAX (630)840-5406
Electronic Systems Engineering Group
Work: egads_AT_fnal.gov, remove '_AT_'