PLUS
ProASIC
Flash Family FPGAs
®
User Security
Embedded Memory Configurations
ProASICPLUS devices have FlashLock protection bits that,
once programmed, block the entire programmed
contents from being read externally. Please refer to
Table 1-10 for details on the number of bits in the key for
each device. If locked, the user can only reprogram the
device employing the user-defined security key. This
protects the device from being read back and duplicated.
Since programmed data is stored in nonvolatile memory
cells (actually very small capacitors) rather than in the
wiring, physical deconstruction cannot be used to
compromise data. This type of security breach is further
discouraged by the placement of the memory cells
beneath the four metal layers (whose removal cannot be
accomplished without disturbing the charge in the
capacitor). This is the highest security provided in the
industry. For more information, refer to Actel’s Design
Security in Nonvolatile Flash and Antifuse FPGAs white
paper.
The embedded memory in the ProASICPLUS family
provides great configuration flexibility (Table 1-11). Each
ProASICPLUS block is designed and optimized as a two-
port memory (one read, one write). This provides 198
kbits of two-port and/or single port memory in the
APA1000 device.
Each memory block can be configured as FIFO or SRAM,
with independent selection of synchronous or
asynchronous read and write ports (Table 1-12).
Additional characteristics include programmable flags as
well as parity checking and generation. Figure 1-21 on
page 1-24 and Figure 1-22 on page 1-25 show the block
diagrams of the basic SRAM and FIFO blocks. Table 1-13
on page 1-24 and Table 1-14 on page 1-25 describe
memory block SRAM and FIFO interface signals,
respectively. A single memory block is designed to
operate at up to 150 MHz (standard speed grade typical
conditions). Each block is comprised of 256 9-bit words
(one read port, one write port). The memory blocks may
be cascaded in width and/or depth to create the desired
memory organization. (Figure 1-23 on page 1-26). This
provides optimal bit widths of 9 (one block), 18, 36, and
72, and optimal depths of 256, 512, 768, and 1,024. Refer
to Actel’s ACTgen User’s Guide for more information.
Table 1-10 • Flashlock Key Size by Device
Device
APA075
APA150
APA300
APA450
APA600
APA750
APA1000
Key Size
79 bits
79 bits
79 bits
Figure 1-24 on page 1-26 gives an example of optimal
memory usage. Ten blocks with 23,040 bits have been
used to generate three arrays of various widths and
depths. Figure 1-25 on page 1-26 shows how RAM blocks
can be used in parallel to create extra read ports. In this
example, using only 10 of the 88 available blocks of the
APA1000 yields an effective 6,912 bits of multiple port
RAM. The Actel ACTgen software facilitates building
wider and deeper memory configurations for optimal
memory usage.
119 bits
167 bits
191 bits
263 bits
Embedded Memory Floorplan
The embedded memory is located across the top and
bottom of the device in 256x9 blocks (Figure 1-1 on page
1-2). Depending on the device, up to 88 blocks are
available to support a variety of memory configurations.
Each block can be programmed as an independent
memory array or combined (using dedicated memory
routing resources) to form larger, more complex memory
configurations. A single memory configuration could
include blocks from both the top and bottom memory
locations.
Table 1-11 • ProASICPLUS Memory Configurations by Device
Maximum Width
Maximum Depth
Device
APA075
APA150
APA300
APA450
APA600
APA750
APA1000
Bottom
Top
12
16
16
24
28
32
44
D
W
D
W
0
256
256
256
256
256
256
256
108
144
144
216
252
288
396
1,536
2,048
2,048
3,072
3,584
4,096
5,632
9
9
9
9
9
9
9
0
16
24
28
32
44
1-22
v5.2
ACTEL [ Actel Corporation ]
