Rainbow Electronics ATF1508ASL - Manual (Page 6)

6
ATF1508AS(L)
0784O–PLD–09/02
Figure 1. ATF1508AS Macrocell
Programmable
Pin-keeper
Option for
Inputs and I/Os
The ATF1508AS offers the option of programming all input and I/O pins so that “pin-keeper”
circuits can be utilized. When any pin is driven high or low and then subsequently left floating,
it will stay at that previous high- or low-level. This circuitry prevents unused input and I/O lines
from floating to intermediate voltage levels, which causes unnecessary power consumption
and system noise. The keeper circuits eliminate the need for external pull-up resistors and
eliminate their DC power consumption.
Input Diagram