ATF20V8B(Q)(L)

5

Input Test Waveforms and

Measurement Levels

t

Output Test Loads

Commercial

Note:

1. Typical values for nominal supply voltage. This parameter is only sampled and is not 100% tested.

Power-up Reset

The registers in the ATF20V8Bs are designed to reset dur-

ing power-up. At a point delayed slightly from V

V

the registered output state will always be high on power-up.

This feature is critical for state machine initialization. How-

ever, due to the asynchronous nature of reset and the

uncertainty of how V

lowing conditions are required:

1.

The V

2.

After reset occurs, all input and feedback setup

times must be met before driving the clock pin high,

and

3.

The clock must remain stable during t

Preload of Registered Outputs

The ATF16V8B’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.

Electronic Signature Word

There are 64 bits of programmable memory that are always

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

bits can be used for user-specific data.

Security Fuse Usage

A single fuse is provided to prevent unauthorized copying

of the ATF20V8B 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.

Programming/Erasing

Programming/erasing is performed using standard PLD

programmers. For further information, see the Configurable

Logic Databook, section titled, “CMOS PLD Programming

Hardware and Software Support.”

Pin Capacitance

f = 1 MHz, T = 25°C

(1)

Typ

Max

Units

Conditions

58

pF

C

OUT

68

pF

V

Parameter

Description

Typ

Max

Units

Power-up Reset Time

600

1,000

ns

V

RST

Power-up Reset Voltage

3.8

4.5

V