5

0776L–PLD–11/08

ATF750C(L)

9.

Bus-friendly Pin-keeper Input and I/Os

All input and I/O pins on the ATF750C(L) have programmable “pin-keeper” circuits. If activated,

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.

Enabling or disabling of the pin-keeper circuits is controlled by the device type chosen in the

logic compiler device selection menu. Please refer to the software compiler table for more

details. Once the pin-keeper circuits are disabled, normal termination procedures are required

for unused inputs and I/Os.

10. Input Diagram

11. I/O Diagram

100K

V

CC

ESD

PROTECTION

CIRCUIT

INPUT

PROGRAMMABLE

OPTION

100K

V

CC

V

CC

DATA

OE

I/O

PROGRAMMABLE

OPTION