ProASIC3 Device Family Overview
In addition, every SRAM block has an embedded FIFO control unit. The control unit allows the
SRAM block to be configured as a synchronous FIFO without using additional core VersaTiles. The
FIFO width and depth are programmable. The FIFO also features programmable Almost Empty
(AEMPTY) and Almost Full (AFULL) flags in addition to the normal Empty and Full flags. The
embedded FIFO control unit contains the counters necessary for generation of the read and write
address pointers. The embedded SRAM/FIFO blocks can be cascaded to create larger configurations.
PLL and CCC
ProASIC3 devices provide designers with very flexible clock conditioning capabilities. Each member
of the ProASIC3 family contains six CCCs. One CCC (center west side) has a PLL. The A3P015 and
A3P030 devices do not have a PLL.
The six CCC blocks are located at the four corners and the centers of the east and west sides.
All six CCC blocks are usable; the four corner CCCs and the east CCC allow simple clock delay
operations as well as clock spine access.
The inputs of the six CCC blocks are accessible from the FPGA core or from one of several inputs
located near the CCC that have dedicated connections to the CCC block.
The CCC block has these key features:
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Wide input frequency range (f
IN_CCC
) = 1.5 MHz to 350 MHz
Output frequency range (f
OUT_CCC
) = 0.75 MHz to 350 MHz
Clock delay adjustment via programmable and fixed delays from –7.56 ns to +11.12 ns
2 programmable delay types for clock skew minimization
Clock frequency synthesis (for PLL only)
Internal phase shift = 0°, 90°, 180°, and 270°. Output phase shift depends on the output
divider configuration (for PLL only).
Output duty cycle = 50% ± 1.5% or better (for PLL only)
Low output jitter: worst case < 2.5% × clock period peak-to-peak period jitter when single
global network used (for PLL only)
Maximum acquisition time = 300 µs (for PLL only)
Low power consumption of 5 mW
Exceptional tolerance to input period jitter— allowable input jitter is up to 1.5 ns (for PLL
only)
Four precise phases; maximum misalignment between adjacent phases of 40 ps × (350 MHz /
f
OUT_CCC
) (for PLL only)
Additional CCC specifications:
Global Clocking
ProASIC3 devices have extensive support for multiple clocking domains. In addition to the CCC and
PLL support described above, there is a comprehensive global clock distribution network.
Each VersaTile input and output port has access to nine VersaNets: six chip (main) and three
quadrant global networks. The VersaNets can be driven by the CCC or directly accessed from the
core via multiplexers (MUXes). The VersaNets can be used to distribute low-skew clock signals or for
rapid distribution of high fanout nets.
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ACTEL [ Actel Corporation ]
