Chapter 1: Cyclone IV Device Datasheet
1–39
Glossary
Table 1–46. Glossary (Part 3 of 5)
Letter
Term
Definitions
RL
Receiver differential input discrete resistor (external to Cyclone IV devices).
Receiver input waveform for LVDS and LVPECL differential standards:
Single-Ended Waveform
Positive Channel (p) = VIH
VID
Negative Channel (n) = VIL
VCM
Ground
Receiver Input
Waveform
R
Differential Waveform (Mathematical Function of Positive & Negative Channel)
VID
0 V
VID
p - n
Receiver input
skew margin
(RSKM)
High-speed I/O block: The total margin left after accounting for the sampling window and TCCS.
RSKM = (TUI – SW – TCCS) / 2.
VCCIO
VOH
VIH AC
(
)
VIH(DC)
VREF
VIL(DC)
VIL(AC
)
Single-ended
voltage-
referenced I/O
Standard
VOL
S
VSS
The JEDEC standard for SSTl and HSTL I/O standards defines both the AC and DC input signal
values. The AC values indicate the voltage levels at which the receiver must meet its timing
specifications. The DC values indicate the voltage levels at which the final logic state of the
receiver is unambiguously defined. After the receiver input crosses the AC value, the receiver
changes to the new logic state. The new logic state is then maintained as long as the input stays
beyond the DC threshold. This approach is intended to provide predictable receiver timing in the
presence of input waveform ringing.
SW (Sampling
Window)
High-speed I/O block: The period of time during which the data must be valid to capture it
correctly. The setup and hold times determine the ideal strobe position in the sampling window.
December 2013 Altera Corporation
Cyclone IV Device Handbook,
Volume 3
ALTERA [ ALTERA CORPORATION ]
