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White Electronic Designs Corporation • (602) 437-1520 • www.wedc.com

White Electronic Designs

WE128K32-XXX

March 2006

Rev. 10

White Electronic Designs Corp. reserves the right to change products or specifications without notice.

HARDWARE DATA PROTECTION

These features protect against inadvertent writes to the

WE128K32-XXX. These are included to improve reliability

during normal operation:

a)

5msec typical before allowing write cycles.

b)

While below 3.8V typical write cycles are inhibited.

c)

Write inhibiting

Holding OE# low and either CS# or WE# high

inhibits write cycles.

d)

Noise filter

Pulses of <8ns (typ) on WE# or CS# will not initiate

a write cycle.

SOFTWARE DATA PROTECTION

A software write protection feature may be enabled

or disabled by the user. When shipped by White

Microelectronics, the WE-128K32-XXX has the feature

disabled. Write access to the device is unrestricted.

To enable software write protection, the user writes three

access code bytes to three special internal locations.

Once write protection has been enabled, each write to the

EEPROM must use the same three byte write sequence

to permit writing. After setting software data protection,

any attempt to write to the device without the three-byte

command sequence will start the internal write timers. No

data will be written to the device, however, for the duration

a six byte write sequence of specific data to specific

locations. Power transitions will not reset the software

write protection.

Each 128K byte block of the EEPROM has independent

write protection. One or more blocks may be enabled and

the rest disabled in any combination. The software write

protection guards against inadvertent writes during power

transitions, or unauthorized modification using a PROM

programmer.

NOTES:

1. Data Format: D7 - D0 (Hex);

Address Format: A16 - A0 (Hex).

2. Write Protect state will be activated at end of write even if

no other data is loaded.

3. Write Protect state will be deactivated at end of write

period even if no other data is loaded.

4. 1 to 128 bytes of data may be loaded.

LOAD DATA AA

TO

ADDRESS 5555

LOAD DATA 55

TO

ADDRESS 2AAA

LOAD DATA 80

TO

ADDRESS 5555

LOAD DATA AA

TO

ADDRESS 5555

LOAD DATA 55

TO

ADDRESS 2AAA

LOAD DATA 20

TO

ADDRESS 5555

LOAD DATA XX

TO

LOAD LAST BYTE

TO

LAST ADDRESS

FIGURE 10 –

SOFTWARE BLOCK DATA PROTECTION

EXIT DATA