Chapter 1: Cyclone III Device Datasheet

1–29

Glossary

July 2012

Altera Corporation

Cyclone III Device Handbook

Volume 2

S

Single-ended

Voltage

referenced I/O

Standard

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.

T

High-speed receiver/transmitter input and output clock period.

TCCS (Channel-

to-channel-skew)

HIGH-SPEED I/O Block: The timing difference between the fastest and slowest output edges,

tcin

Delay from clock pad to I/O input register.

Delay from clock pad to I/O output.

tcout

Delay from clock pad to I/O output register.

HIGH-SPEED I/O Block: Duty cycle on high-speed transmitter output clock.

Signal High-to-low transition time (80–20%).

Input register hold time.

Timing Unit

Interval (TUI)

HIGH-SPEED I/O block: The timing budget allowed for skew, propagation delays, and data

Period jitter on PLL clock input.

Period jitter on dedicated clock output driven by a PLL.

Period jitter on general purpose I/O driven by a PLL.

tpllcin

Delay from PLL inclk pad to I/O input register.

tpllcout

Delay from PLL inclk pad to I/O output register.

Table 1–39. Glossary (Part 3 of 5)

Letter

Term

Definitions