DM74S473V datasheet(4/6 Pages) NSC

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AC Electrical Characteristics with Standard Load and Operating Conditions

COMMERCIAL TEMP RANGE

(0 Cto a70 C)

Symbol

JEDEC

Parameter

DM74S473

DM74S473A

Units

Symbol

Min

Typ

Max

Min

Typ

Max

TAA

TAVQV

Address Access Time

TEA

TEVQV

Enable Access Time

TER

TEXQX

Enable Recovery Time

TZX

TEVQX

Output Enable Time

TXZ

TEXQZ

Output Disable Time

Functional Description

TESTABILITY

The Schottky PROM die includes extra rows and columns of

fusable links for testing the programmability of each chip

These test fuses are placed at the worst-case chip locations

to provide the highest possible confidence in the program-

ming tests in the final product A ROM pattern is also per-

manently fixed in the additional circuitry and coded to pro-

vide a parity check of input address levels These and other

test circuits are used to test for correct operation of the row

and column-select circuits and functionality of input and en-

able gates All test circuits are available at both wafer and

assembled device levels to allow 100% functional and para-

metric testing at every stage of the test flow

RELIABILITY

As with all National products the Ti-W PROMs are subject-

ed to an on-going reliability evaluation by the Reliability As-

surance Department These evaluations employ accelerat-

ed life tests including dynamic high-temperature operating

life temperature-humidity life temperature cycling and ther-

mal shock To date nearly 74 million Schottky Ti-W PROM

device hours have been logged with samples in Epoxy B

molded DIP (N-package) PLCC (V-package) and CERIP (J-

package) Device performance in all package configurations

is excellent

TITANIUM-TUNGSTEN FUSES

National’s Programmable Read-Only Memories (PROMs)

feature titanuim-tungsten (Ti-W) fuse links designed to pro-

gram efficiently with only 105V applied The high perform-

ance and reliability of these PROMs are the result of fabrica-

tion by a Schottky bipolar process of which the titanium-

tungsten metallization is an integral part and the use of an

on-chip programming circuit

A major advantage of the titanium-tungsten fuse technology

is the low programming voltage of the fuse links At 105V

this virtually eliminates the need for guard-ring devices and

wide spacings required for other fuse technologies Care is

taken however to minimize voltage drops across the die

and to reduce parasitics The device is designed to ensure

that worst-case fuse operating current is low enough for

reliable long-term operation The Darlington programming

circuit is liberally designed to insure adequate power density

for blowing the fuse links The complete circuit design is

optimized to provide high performance over the entire oper-

ating ranges of VCC and temperature

DM74S473V Datasheet(PDF) 4 Page - National Semiconductor (TI)

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