ProASIC3L Low Power Flash FPGAs
Revision 13
1-7
The CCC block has these key features:
Wide input frequency range (fIN_CCC) = 1.5 MHz up to 250 MHz
Output frequency range (fOUT_CCC) = 0.75 MHz up to 250 MHz
2 programmable delay types for clock skew minimization
Clock frequency synthesis
Additional CCC specifications:
Internal phase shift = 0°, 90°, 180°, and 270°. Output phase shift depends on the output divider
configuration.
Output duty cycle = 50% ± 1.5% or better
Low output jitter: worst case < 2.5% × clock period peak-to-peak period jitter when single global
network used
Maximum acquisition time is 300 s
Exceptional tolerance to input period jitter— allowable input jitter is up to 1.5 ns
Four precise phases; maximum misalignment between adjacent phases of 40 ps × 250 MHz /
fOUT_CCC
Global Clocking
ProASIC3L 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.
I/Os with Advanced I/O Standards
The ProASIC3L family of FPGAs features a flexible I/O structure, supporting a range of voltages (1.2 V,
1.5 V, 1.8 V, 2.5 V, 3.0 V wide range, and 3.3 V). ProASIC3L FPGAs support different I/O standards,
including single-ended, differential, and voltage-referenced (ProASIC3EL only). The I/Os are organized
into banks, with two, four, or eight (ProASIC3EL only) banks per device. The configuration of these banks
determines the I/O standards supported
(Table 1-1). For ProASIC3EL, each I/O bank is subdivided into
VREF minibanks, which are used by voltage-referenced I/Os. VREF minibanks contain 8 to 18 I/Os. All
the I/Os in a given minibank share a common VREF line. Therefore, if any I/O in a given VREF minibank
is configured as a VREF pin, the remaining I/Os in that minibank will be able to use that reference
voltage.
Each I/O module contains several input, output, and enable registers. These registers allow the
implementation of the following:
Single-data-rate applications (e.g., PCI 66 MHz, bidirectional SSTL 2 and 3, Class I and II)
Double-data-Rate applications (e.g., DDR LVDS, B-LVDS, and M-LVDS I/Os for point-to-point
communications, and DDR 200 MHz SRAM using bidirectional HSTL Class II).
ProASIC3L banks support LVPECL, LVDS, B-LVDS, and M-LVDS. B-LVDS and M-LVDS can support up
to 20 loads.
Table 1-1 I/O Standards Supported
I/O Bank Type
Device and
Bank
Location
I/O Standards Supported
LVTTL/
LVCMOS
PCI/
PCI-X
LVPECL, LVDS,
B-LVDS, M-LVDS
GTL+ 2.5 V/3.3 V, GTL
2.5 V/3.3 V, HSTL I and II,
SSTL2 I and II, SSTL3 I and II
Pro I/Os
A3PE3000L
33
3
Advanced I/Os
A3P250L,
A3P600L,
A3P1000L
33
3
Not supported