ATF1532AE ATMEL Corporation, ATF1532AE Datasheet - Page 5

• Manufacturer Part Number: ATF1532AE
• Description: (ATF15xxAE) 2nd Generation EE Complex Programmable Logic Devices
• Manufacturer: ATMEL Corporation

Figure 2. ATF15xxAE Family Macrocell with Enhanced Features In Red
Product Terms and
Select Mux
OR/XOR/
CASCADE Logic
Foldback Bus
2398E–12/01
Within each macrocell are five product terms. Each product term may receive as its inputs any
combination of the signals from the switch matrix or regional foldback 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 determined by the fitter software,
which selects the optimum macrocell configuration.
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 many as 40 product terms with little additional delay.
The macrocell’s XOR gate allows efficient implementation of compare and arithmetic func-
tions. 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 combinatorial outputs, the fixed level input
allows polarity selection. For registered functions, the fixed levels allow DeMorgan minimiza-
tion of product terms. The XOR gate may be fed from the flip-flop output to emulate T- and JK-
type flip-flops, or fed to the buried feedback to synthesize an extra latch.
Each macrocell can also generate a foldback product term. This signal goes to the regional
bus and is available to the 16 macrocells in a given logic block. The foldback is an inverse
polarity of one of the macrocell’s product terms. Although Cascade Logic is the preferred
method for expanding the number of macrocell inputs to as many as 40, the 16 foldback terms
in each region can also generate additional fan-in sum terms with nominal additional delay.
ATF15xxAE Family
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