ATF1502AS ATMEL [ATMEL Corporation], ATF1502AS Datasheet - Page 3

• Manufacturer Part Number: ATF1502AS
• Description: High Performance E2PROM CPLD
• Manufacturer: ATMEL [ATMEL Corporation]

Each macrocell also generates a foldback logic term, which
goes to a regional bus. Cascade logic between macrocells
in the ATF1502AS allows fast, efficient generation of com-
plex logic functions. The ATF1502AS contains four such
logic chains, each capable of creating sum term logic with a
fan in of up to 40 product terms.
The ATF1502AS macrocell shown in Figure 1, is flexible
enough to support highly complex logic functions operating
at high speed. The macrocell consists of five sections:
product terms and product term select multiplexer;
OR/XOR/CASCADE logic; a flip-flop; output select and
enable; and logic array inputs.
Unused product terms are automatically disabled by the
compiler to decrease power consumption. A Security Fuse,
Figure 1. ATF1502AS Macrocell
Product Terms and Select MUX
Each ATF1502AS macrocell has five product terms. Each
product term receives as its inputs all signals from both the
global bus and regional bus.
The product term select multiplexer (PTMUX) allocates the
five product terms as needed to the macrocell logic gates
and control signals. The PTMUX programming is deter-
mined by the design compiler, which selects the optimum
macrocell configuration.
OR/XOR/CASCADE Logic
The ATF1502AS’s logic structure is designed to efficiently
support all types of logic. Within a single macrocell, all the
product terms can be routed to the OR gate, creating a 5-
input AND/OR sum term. With the addition of the CASIN
from neighboring macrocells, this can be expanded to as
w h e n p r o g r a m m e d , p r o t e c t s t h e c o n t e n t s o f t h e
ATF1502AS. Two bytes (16-bits) of User Signature are
accessible to the user for purposes such as storing project
name, part number, revision or date. The User Signature is
accessible regardless of the state of the Security Fuse.
The ATF1502AS device is an In-System Programmable
(ISP) device. It uses the industry standard 4-pin JTAG
interface (IEEE Std. 1149.1), and is fully compliant with
JTAG’s Boundary Scan Description Language (BSDL). ISP
allows the device to be programmed without removing it
from the printed circuit board. In addition to simplifying the
manufacturing flow, ISP also allows design modifications to
be made in the field via software.
many as 40 product terms with a very small additional
delay.
The macrocell’s XOR gate allows efficient implementation
of compare and arithmetic functions. One input to the XOR
comes from the OR sum term. The other XOR input can be
a product term or a fixed high or low level. For combinato-
rial outputs, the fixed level input allows polarity selection.
For registered functions, the fixed levels allow DeMorgan
minimization of product terms. The XOR gate is also used
to emulate T- and JK-type flip-flops.
Flip Flop
The ATF1502AS’s flip flop has very flexible data and con-
trol functions. The data input can come from either the XOR
gate, from a separate product term or directly from the I/O
pin. Selecting the separate product term allows creation of
a buried registered feedback within a combinatorial output
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