Download Xilinx Virtex-4 User Guide

R
Specific Guidelines for Virtex-4 I/O Supported Standards
Table 6-20 lists the HSTL Class II (1.8V) DC voltage specifications.
Table 6-20:
HSTL Class II (1.8V) DC Voltage Specifications
Min
Typ
Max
1.7
1.8
1.9
VREF (2)
–
0.9
–
VTT
–
VCCO × 0.5
–
VIH
VREF + 0.1
–
–
VIL
–
–
VREF – 0.1
VOH
VCCO – 0.4
–
–
VOL
–
–
0.4
IOH at VOH (mA)(1)
–16
–
–
IOL at VOL (mA)(1)
16
–
–
VCCO
Notes:
1. VOL and VOH for lower drive currents are sample tested.
2. Per EIA/JESD8-6, "The value of VREF is to be selected by the user to provide optimum noise margin in
the use conditions specified by the user."
Complementary Single-Ended (CSE) Differential HSTL Class II (1.8V)
Figure 6-52 shows a sample circuit illustrating a valid termination technique for
differential HSTL Class II (1.8V) with unidirectional termination.
External Termination
IOB
DIFF_HSTL_II_18
VTT = 0.9V
VTT = 0.9V
50Ω
50Ω
IOB
Z0
DIFF_HSTL_II_18
DIFF_HSTL_II_18
VTT = 0.9V
VTT = 0.9V
50Ω
50Ω
+
`
Z0
ug070_6_50_71904
Figure 6-52:
Virtex-4 User Guide
UG070 (v1.5) March 21, 2006
Differential HSTL (1.8V) Class II Unidirectional Termination
www.xilinx.com
261