ATV2500B ATMEL Corporation, ATV2500B Datasheet - Page 3

• Manufacturer Part Number: ATV2500B
• Description: High-Speed High-Density UV Erasable Programmable Logic Device
• Manufacturer: ATMEL Corporation

Description
The ATV2500Bs are the highest density PLDs available in
a 40- or 44-pin package. With their fully connected logic
array and flexible macrocell structure, high gate utilization
is easily obtainable.
The ATV2500Bs are organized around a single universal
and-or array . All pin and feedback terms are always avail-
able to every macrocell. Each of the 38 logic pins are array
inputs, as are the outputs of each flip-flop.
In the ATV2500Bs, four product terms are input to each
sum term. Furthermore, each macrocell's three sum terms
can be combined to provide up to 12 product terms per
sum term with no performance penalty . Each flip-flop is
individually selectable to be either D- or T-type, providing
further logic compaction. Also, 24 of the flip-flops may be
bypassed to provide internal combinatorial feedback to the
logic array.
Product terms provide individual clocks and asynchronous
resets for each flip-flop. The flip-flops may also be individu-
ally configured to have direct input pin clocking. Each out-
put has its own enable product term. Eight synchronous
preset product terms serve local groups of either four or
eight flip-flops. Register preload functions are provided to
simplify testing. All registers automatically reset upon
power up.
Several low power device options allow selection of the
optimum solution for many power-sensitive applications.
Each of the options significantly reduces total system
power and enhances system reliability.
Functional Logic Diagram Description
The ATV2500B functional logic diagram describes the
interconnections between the input, feedback pins and
logic cells. All interconnections are routed through the sin-
gle global bus.
The ATV2500Bs are straightforward and uniform PLDs.
The 24 macrocells are numbered 0 through 23. Each mac-
rocell contains 17 AND gates. All AND gates have 172
inputs. The five lower product terms provide AR1, CK1,
CK2, AR2, and OE. These are: one asynchronous reset
and clock per flip-flop, and an output enable. The top 12
product terms are grouped into three sum terms, which are
used as shown in the macrocell diagrams.
Eight synchronous preset terms are distributed in a 2/4 pat-
tern. The first four macrocells share Preset 0, the next two
share Preset 1, and so on, ending with the last two macro-
cells sharing Preset 7.
The 14 dedicated inputs and their complements use the
numbered positions in the global bus as shown. Each
macrocell provides six inputs to the global bus: (left to
right) feedback F2
false, and the pin true and false. The positions occupied by
these signals in the global bus are the six numbers in the
bus diagram next to each macrocell.
Note:
1. Either the flip-flop input (D/T2) or output (Q2) may
be fed back in the ATV2500Bs.
(1)
true and false, flip-flop Q1 true and
3