8

0453H–PLD–7/05

ATF16V8CZ

6.

Input and I/O Pin-keeper Circuits

The ATF16V8CZ contains internal input and I/O pin-keeper circuits. These circuits allow each

ATF16V8CZ pin to hold its previous value even when it is not being driven by an external source

or by the device’s output buffer. This helps insure that all logic array inputs are at known, valid

logic levels. This reduces system power by preventing pins from floating to indeterminate levels.

By using pin-keeper circuits rather than pull-up resistors, there is no DC current required to hold

the pins in either logic state (high or low).

These pin-keeper circuits are implemented as weak feedback inverters, as shown in the Input

Diagram below. These keeper circuits can easily be overdriven by standard TTL- or CMOS-com-

patible drivers. The typical overdrive current required is 40 µA.

Figure 6-1.

Input Diagram

Figure 6-2.

I/O Diagram