EN29F002 datasheet(13/32 Pages) ETC

13 / 32 page

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EN29F002 / EN29F002N

Rev. C, Issue Date: 2001/07/05

DATA PROTECTION

Power-up Write Inhibit

During power-up, the device automatically resets to READ mode and locks out write cycles. Even

with CE = VIL, WE = VIL and OE = VIH, the device will not accept commands on the rising edge of

WE .

Low VCC Write Inhibit

During VCC power-up or power-down, the EN20F002 locks out write cycles to protect against any

unintentional writes. If VCC < VLKO, the command register is disabled and all internal program or

erase circuits are disabled. Under this condition, the device will reset to the READ mode. Subsequent

writes will be ignored until VCC > VLKO.

Write “Noise” Pulse Protection

Noise pulses less than 5ns on OE , CE or WE will neither initiate a write cycle nor change the

command register.

Logical Inhibit

If CE =VIH or WE=VIH, writing is inhibited. To initiate a write cycle, CE and WE must be a logical

“zero”. If CE , WE , and OE are all logical zero (not recommended usage), it will be considered a

write.

Sector Protection/Unprotection

When the device is shipped, all sectors are unprotected. Each sector can be separately protected

against data changes.

Using hardware protection circuitry enabled at user’s site with external

programming equipment, both program and erase operations may be disabled for any specified

sector or combination of sectors.

Verification of write protection for a specific sector can be achieved with an Auto Select ID read

command at location 02h where the address bits A17 - A13 select the defined sector (see Table 5).

A logical “1” at DQ0 means a protected sector and a logical “0” means an unprotected sector.

The Sector Unprotect disables sector protection in all sectors in one operation to implement code

changes.

All sectors must be placed in protection mode using the protection algorithm mentioned

above before unprotection can be executed.

Additional details on this feature are provided in a supplement, which can be obtained by contacting a

representative of Eon Silicon Devices, Inc.

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