MACH111SP5JC データシートの表示（PDF） - Lattice Semiconductor

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MACH111SP5JC

High-Performance EE CMOS Programmable Logic

Lattice Semiconductor 

Each PAL block consists of the following elements:

x Product-term array

x Logic Allocator

x Macrocells

x I/O cells

Each PAL block additionally contains an asynchronous reset product term and an asynchronous

preset product term. This allows the flip-flops within a single PAL block to be initialized as a bank.

There are also output enable product terms that provide tri-state control for the I/O cells.

Product-Term Array

The product-term array consists of a number of product terms that form the basis of the logic being

implemented. The inputs to the AND gates come from the switch matrix (Table 4), and are

provided in both true and complement forms for efficient logic implementation.

Because the number of product terms available for a given function is not fixed, the full sum of

products is not realized in the array. The product terms drive the logic allocator, which allocates

the appropriate number of product terms to generate the function.

Table 4. PAL Block Inputs

Device

MACH111

MACH111SP

MACH131

MACH131SP

MACH211

Number of Inputs to PAL Block

26

26

26

26

26

Device

MACH211SP

MACH221

MACH221SP

MACH231

MACH231SP

Number of Inputs to PAL Block

26

26

26

32

32

Logic Allocator

The logic allocator (Figure 2) is a block within which different product terms are allocated to the

appropriate macrocells in groups of four product terms called “product term clusters”. The

availability and distribution of product term clusters is automatically considered by the software as

it fits functions within the PAL block. The size of the product term clusters has been designed to

provide high utilization of product terms. Complex functions using many product terms are

possible, and when few product terms are used, there will be a minimal number of unused, or

wasted, product terms left over.

The product term clusters do not “wrap” around the logic block. This means that the macrocells

at the ends of the block have fewer product terms available (Tables 5, 6, 7, 8).

MACH 1 & 2 Families

5

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