ATF1508ASVL datasheet(5/22 Pages) ATMEL

5 / 22 page

ATF1508ASV(L)

Figure 1. ATF1508ASV(L) Macrocell

Output Select and Enable

The ATF1508ASV(L) macrocell output can be selected as

registered or combinatorial. The buried feedback signal can

be either combinatorial or registered signal regardless of

whether the output is combinatorial or registered.

The output enable multiplexer (MOE) controls the output

enable signals. Any buffer can be permanently enabled for

simple output operation. Buffers can also be permanently

disabled to allow use of the pin as an input. In this configu-

ration. all the macrocell resources are still available,

including the buried feedback, expander and CASCADE

logic. The output enable for each macrocell can be

selected as one of the global OUTPUT enable signals. The

device has six global OE signals.

Global Bus/Switch Matrix

The global bus contains all input and I/O pin signals as well

as the buried feedback signal from all 128 macrocells.

The switch matrix in each logic block receives as its inputs

all signals from the global bus. Under software control, up

to 40 of these signals can be selected as inputs to the logic

block.

Foldback Bus

Each macrocell also generates a foldback product term.

This signal goes to the regional bus and is available to 16

macrocells. The foldback is an inverse polarity of one of the

macrocell’s product terms. The 16 foldback terms in each

region allow generation of high fan-in sum terms (up to 21

product terms) with little additional delay.

Open-collector Output Option

This option enables the device output to provide control

signals such as an interrupt that can be asserted by any of

the several devices.

ATF1508ASVL Datasheet(PDF) 5 Page - ATMEL Corporation