XQ2V3000 Xilinx, XQ2V3000 Datasheet - Page 9

• Manufacturer Part Number: XQ2V3000
• Description: QPro Virtex-II 1.5V Military QML Platform FPGAs
• Manufacturer: Xilinx

The DDR mechanism shown in
ror a copy of the clock on the output. This is useful for prop-
agating a clock along the data that has an identical delay. It
is also useful for multiple clock generation, where there is a
unique clock driver for every clock load. Virtex-II devices
can produce many copies of a clock with very little skew.
Each group of two registers has a clock enable signal (ICE
for the input registers, OCE for the output registers, and
TCE for the 3-state registers). The clock enable signals are
active High by default. If left unconnected, the clock enable
for that storage element defaults to the active state.
Each IOB block has common synchronous or asynchronous
set and reset (SR and REV signals).
SR forces the storage element into the state specified by the
SRHIGH or SRLOW attribute. SRHIGH forces a logic “1”.
SRLOW forces a logic “0”. When SR is used, a second input
(REV) forces the storage element into the opposite state. The
reset condition predominates over the set condition. The ini-
tial state after configuration or global initialization state is
defined by a separate INIT0 and INIT1 attribute. By default,
DS122 (v1.1) January 7, 2004
Product Specification
CLOCK
R
D1
D2
CLK1
CLK2
Figure 4
(50/50 duty cycle clock)
Q1
Q2
can be used to mir-
Figure 4: Double Data Rate Registers
DDR MUX
FDDR
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Q
the SRLOW attribute forces INIT0, and the SRHIGH attribute
forces INIT1.
For each storage element, the SRHIGH, SRLOW, INIT0,
and INIT1 attributes are independent. Synchronous or
asynchronous set/reset is consistent in an IOB block.
All the control signals have independent polarities. Any
inverter placed on a control input is automatically absorbed.
Each register or latch (independent of all other registers or
latches) (see
•
•
•
•
•
•
•
The synchronous reset overrides a set, and an asynchro-
nous clear overrides a preset.
180° 0°
No set or reset
Synchronous set
Synchronous reset
Synchronous set and reset
Asynchronous set (preset)
Asynchronous reset (clear)
Asynchronous set and reset (preset and clear)
DCM
QPro Virtex-II 1.5V Military QML Platform FPGAs
Figure
D1
D2
CLK1
CLK2
5) can be configured as follows:
Q1
Q2
DDR MUX
FDDR
DS031_26_100900
Q
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