Rainbow Electronics ATF22V10CQ - Manual (Page 7)

7
ATF22V10C(Q)
0735P–PLD–01/02
Input and I/O Pin-
keeper Circuits
The ATF22V10C contains internal input and I/O pin-keeper circuits. These circuits allow
each ATF22V10C 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 to ensure 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-compatible drivers. The typical overdrive current required is 40 µA.
Input Diagram
I/O Diagram