MX29F080 datasheet(13/38 Pages) MCNIX

13 / 38 page

P/N:PM0579

REV. 1.6, NOV. 21, 2002

MX29F080

SECTOR GROUP PROTECTION

The MX29F080 features hardware sector group protec-

tion. This feature will disable both program and erase

operations for these group sector protected. To activate

this mode, the programming equipment must force VID

on address pin A9 and control pin OE, (suggest VID =

12V) A6 = VIL and CE = VIL. (see Table 2) Program-

ming of the protection circuitry begins on the falling edge

of the WE or CE, whichever happens later pulse and is

terminated on the rising edge. Please refer to group sector

protect algorithm and waveform.

To verify programming of the protection circuitry, the pro-

gramming equipment must force VID on address pin A9

( with CE and OE at VIL and WE at VIH). When A1=1, it

will produce a logical "1" code at device output Q0 for a

protected sector. Otherwise the device will produce 00H

for the unprotected sector. In this mode, the addresses,

except for A1, are don't care. Address locations with A1

= VIL are reserved to read manufacturer and device codes.

(Read Silicon ID)

It is also possible to determine if the group is protected

in the system by writing a Read Silicon ID command.

Performing a read operation with A1=VIH, it will produce

a logical "1" at Q0 for the protected sector.

CHIP UNPROTECT

The MX29F080 also features the chip unprotect mode,

so that all sectors are unprotected after chip unprotect

is completed to incorporate any changes in the code. It

is recommended to protect all sectors before activating

chip unprotect mode.

To activate this mode, the programming equipment must

force VID on control pin OE and address pin A9. The CE

pins must be set at VIL. Pins A6 must be set to VIH.

(see Table 2) Refer to chip unprotect algorithm and wave-

form for the chip unprotect algorithm. The unprotection

mechanism begins on the falling edge of the WE or CE,

whichever happens later pulse and is terminated on the

rising edge.

POWER-UP SEQUENCE

The MX29F080 powers up in the Read only mode. In

addition, the memory contents may only be altered after

successful completion of the predefined command se-

quences.

POWER SUPPLY DECOUPLING

In order to reduce power switching effect, each device

should have a 0.1uF ceramic capacitor connected be-

tween its VCC and GND.

It is also possible to determine if the chip is unprotected

in the system by writing the Read Silicon ID command.

Performing a read operation with A1=VIH, it will produce

00H at data outputs (Q0-Q7) for an unprotected sector. It

is noted that all sectors are unprotected after the chip

unprotect algorithm is completed.

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