Altera ALTDLL - Manual (Page 6)

1–2 Chapter 1: About these Megafunctions
Features
ALTDLL and ALTDQ_DQS Megafunctions User Guide © February 2012 Altera Corporation
Features
The ALTDLL and ALTDQ_DQS megafunctions offer the following features:
■ ALTDLL
■ A delay-locked loop (DLL) block to center-align the read strobe with read data.
■ Phase offset control blocks to fine-tune the delay time on the read strobe using
static or dynamic offset.
■ ALTDQ_DQS
■ Supports RLDRAM II memory interface.
■ DDR registers on the input and output paths to read or write to an external
DDR interface.
■ Half-rate registers to enable successful data transfers between the I/O registers
and the core logic.
■ Access to dynamic on-chip termination (OCT) controls to switch between
parallel termination during reads to series termination during writes.
■ Access to I/O delay chains to fine-tune delays on the data or strobe signals
statically or dynamically.
Figure 1–1 shows a high-level overview of how you can connect the ALTDQ_DQS
megafunction with other megafunctions such as ALTPLL, ALTDLL, and ALTIOBUF,
to create a full custom external memory interface.
Figure 1–1 shows a 36-bit interface
created with ALTDQ_DQS instantiations, where each instantiation is configured in
the ×9 mode.
Figure 1–1. System-Level View
ALTIOBUF (DQS/DQSN)
ALTIOBUF (BIDIR_DQ)
ALTIOBUF (INPUT_DQ)
ALTIOBUF (OUTPUT_DQ)
ALTDQ_DQS
x9
ALTDQ_DQS
x9
ALTDQ_DQS
x9
ALTDQ_DQS
x9
ALTDLL
ALTPLL