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0735U–PLD–7/10

Atmel ATF22V10C(Q)

8.

Input and I/O Pin-keeper Circuits

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 40µA.

Figure 8-1.

Input Diagram

Figure 8-2.

I/O Diagram