ep2c35 Altera Corporation, ep2c35 Datasheet - Page 159

• Manufacturer Part Number: ep2c35
• Description: Cyclone Ii Device Family Data Sheet
• Manufacturer: Altera Corporation

Figure 5–10. DCD Measurement Technique for DDIO (Double-Data Rate) Outputs
Altera Corporation
February 2008
clk
INPUT
VCC
When an FPGA PLL generates the internal clock, the PLL output clocks
the IOE block. As the PLL only monitors the positive edge of the reference
clock input and internally re-creates the output clock signal, any DCD
present on the reference clock is filtered out. Therefore, the DCD for a
DDIO output with PLL in the clock path is better than the DCD for a
DDIO output without PLL in the clock path.
Tables 5–55
derivation for different I/O standards on Cyclone II devices. Examples
are also provided that show how to calculate DCD as a percentage.
LVCMOS
LVTTL
2.5-V
1.8-V
1.5-V
SSTL-2 Class I
SSTL-2 Class II
SSTL-18 Class I
HSTL-15 Class I
HSTL-18 Class I
Table 5–55. Maximum DCD for Single Data Outputs (SDR) on Row I/O
Pins
Row I/O Output Standard
Notes
through
(1),
GND
V
CC
(2)
DFF
DFF
5–58
(Part 1 of 2)
D
D
CLRN
CLRN
PRN
PRN
give the maximum DCD in absolution
Q
Q
DC Characteristics and Timing Specifications
145
165
195
120
115
130
Cyclone II Device Handbook, Volume 1
C6
60
65
90
85
1
0
230
255
120
115
130
165
145
155
C7
90
75
230
255
135
175
135
165
205
155
output
C8
90
75
Unit
ps
ps
ps
ps
ps
ps
ps
ps
ps
ps
5–69