XPLA3 Datasheet, PDF (2/11 Pages) Xilinx, Inc – Excellent pin retention during design changes

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occur. The XPLA3 CPLD is electrically reprogrammable
using industry standard device programmers from vendors
such as Data I/O, BP Microsystems, and SMS.
XPLA3 Architecture
Figure 1 shows a high-level block diagram of a 128 macro-
cell device implementing the XPLA3 architecture. The
XPLA3 architecture consists of logic blocks that are inter-
connected by a Zero-power Interconnect Array (ZIA). The
ZIA is a virtual crosspoint switch. Each logic block has 36
inputs from the ZIA and 16 macrocells.
From this point of view, this architecture looks like many
other CPLD architectures. What makes the XPLA3 family
unique is logic allocation inside each logic block and the
design technique used to implement these logic blocks.
Logic Block Architecture
Figure 2 illustrates the logic block architecture. Each logic
block contains a PLA array that generates control terms,
CoolRunner™ XPLA3 CPLD
clock terms, and logic cells. There are 36 pairs of true and
complement inputs from the ZIA that feed the 48 product
terms in the array. Within the 48 P-terms there are eight
local control terms (LCT[0:7]) available as control inputs to
each macrocell for use as asynchronous clocks, resets,
presets and output enables. The other P-terms serve as
additional single inputs into each macrocell.
There are eight foldback NAND P-terms that are available
for ease of fitting and pin locking. Sixteen product terms are
coupled with the associated programmable OR gate into
the VFM (Variable Function Multiplexer). The VFM
increases logic optimization by implementing any two input
logic funtion before entering the macrocell (see Figure 3).
Each macrocell can support combinatorial or registered
inputs, preset and reset on a per macrocell basis and con-
figurable D, T registers, or latch function. If a macrocell
needs more product terms, it simply gets the additional
product terms from the PLA array.
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Figure 1: Xilinx XPLA3 CPLD Architecture
DS012 (v1.1) March 3, 2000
www.xilinx.com
1-800-255-7778
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