Architecture
LatticeECP2/M Family Data Sheet
Lattice Semiconductor
DQSXFER
LatticeECP2/M devices provide a DQSXFER signal to the output buffer to assist it in data transfer to DDR memo-
ries that require DQS strobe be shifted 90o. This shifted DQS strobe is generated by the DQSDEL block. The
DQSXFER signal runs the span of the data bus.
sysI/O Buffer
Each I/O is associated with a flexible buffer referred to as a sysI/O buffer. These buffers are arranged around the
periphery of the device in groups referred to as banks. The sysI/O buffers allow users to implement the wide variety
of standards that are found in today’s systems including LVCMOS, SSTL, HSTL, LVDS and LVPECL.
sysI/O Buffer Banks
LatticeECP2/M devices have nine sysI/O buffer banks: eight banks for user I/Os arranged two per side. The ninth
sysI/O buffer bank (Bank 8) is located adjacent to Bank 3 and has dedicated/shared I/Os for configuration. When a
shared pin is not used for configuration it is available as a user I/O. Each bank is capable of supporting multiple I/O
standards. Each sysI/O bank has its own I/O supply voltage (V
). In addition, each bank, except Bank 8, has
CCIO
voltage references, V
and V
, which allow it to be completely independent from the others. Bank 8 shares
REF1
REF2
two voltage references, V
plies.
and V
, with Bank 3. Figure 2-37 shows the nine banks and their associated sup-
REF1
REF2
In LatticeECP2/M devices, single-ended output buffers and ratioed input buffers (LVTTL, LVCMOS and PCI) are
powered using V
independent of V
. LVTTL, LVCMOS33, LVCMOS25 and LVCMOS12 can also be set as fixed threshold inputs
.
CCIO
CCIO
Each bank can support up to two separate V
voltages, V
and V
, that set the threshold for the refer-
REF
REF1
REF2
enced input buffers. Some dedicated I/O pins in a bank can be configured to be a reference voltage supply pin.
Each I/O is individually configurable based on the bank’s supply and reference voltages.
2-40
LATTICE [ LATTICE SEMICONDUCTOR ]
