Input Diagram

I/O Diagram

Electronic Signature Word

There are 64 bits of programmable memory that are al-

ways available to the user, even if the device is secured.

These bits can be used for user-specific data.

Programming/Erasing

Programming/erasing is performed using standard PLD

programmers. See

CMOS PLD Programming Hardware &

ming.

Input and I/O Pin Keeper Circuits

The ATF16V8C contains internal input and I/O pin keeper

circuits. These circuits allow each ATF16V8C 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 feed-

back inverters, as shown in the Input Diagram below.

These keeper circuits can easily be overdriven by stand-

ard TTL- or CMOS-compatible drivers. The typical over-

drive current required is 40

µA.

Preload of Registered Outputs

The ATF22V10C’s registers are provided with circuitry to

allow loading of each register with either a high or a low.

This feature will simplify testing since any state can be

forced into the registers to control test sequencing. A

JEDEC file with preload is generated when a source file

with vectors is compiled. Once downloaded, the JEDEC

file preload sequence will be done automatically by most

of the approved programmers after the programming.

Security Fuse Usage

A single fuse is provided to prevent unauthorized copying

of the ATF22V10C fuse patterns. Once programmed, fuse

verify and preload are inhibited. However, the 64-bit User

Signature remains accessible.

The security fuse should be programmed last, as its effect

is immediate.

Parameter Description

Typ

Max

Units

Power-Up

Reset Time

600

1,000

ns

Power-Up

Reset

Voltage

3.8

4.5

V

C

LOCK

POWER

REGISTERED

OUTPUTS

6

ATF22V10C