AR# 1575: XC4000XL: 1996 DATA BOOK: Page 4-24 table 10.Supported Source for XC4000-Series Device Inputs is incorrect
XC4000XL: 1996 DATA BOOK: Page 4-24 table 10.Supported Source for XC4000-Series Device Inputs is incorrect
Keywords: 3.3V, 4000XL, DATA BOOK, VTT, 5V
In the table it shows that, in order to have a 5V CMOS device sourcing a 3.3V CMOS device(specificly 4000XL), it will require Vtt pin to 5V.
That is incorrect, the new design puts an internal protection circuitry that can stand 5V CMOS input to 3.3V XL parts. Therefore driving a 5V CMOS output into a 4000XL input (with CMOS inputs specified) is not be a problem.