MX26L6420TC-12 Просмотр технического описания (PDF) - Macronix International

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MX26L6420TC-12

64M-BIT [4M x 16] CMOS MULTIPLE-TIME-PROGRAMMABLE EPROM

Macronix International 

MX26L6420

sion has the secured sector Indicator Bit permanently

set to a "0". Therefore, the Secured Silicon Sector Indi-

cator Bit permanently set to a "0". Therefore, the Second

Silicon Sector Indicator Bit prevents customer, lockable

device from being used to replace devices that are fac-

tory locked.

The system access the Secured Silicon Sector through

a command sequence (refer to "Enter Secured Silicon/

Exit Secured Silicon Sector command Sequence). After

the system has written the Enter Secured Silicon Sector

command sequence, it may read the Secured Silicon

Sector by using the address normally occupied by the

address 000000h-0001FFh. This mode of operation con-

tinues until the system issues the Exit Secured Silicon

Sector command sequence, or until power is removed

from the device. On power-up, or following a hardware

reset, the device reverts to sending command to ad-

dress 000000h-0001FFFh.

LOW VCC WRITE INHIBIT

When VCC is less than VLKO the device does not ac-

cept any write cycles. This protects dataduring VCC

power-up and power-down. The command register and

all internal program/erase circuits are disabled, and the

device resets. Subsequent writes are ignored until VCC

is greater thanVLKO. The system must provide the proper

signals to the control pins to prevent unintentional write

when VCC is greater than VLKO.

WRITE PULSE "GLITCH" PROTECTION

Noise pulses of less than 5ns(typical) on CE or WE will

not initiate a write cycle.

FACTORY LOCKED:Secured Silicon Sector

Programmed and Protected At the Factory

In device with an ESN, the Secured Silicon Sector is

protected when the device is shipped from the factory.

The Secured Silicon Sector cannot be modified in any

way. A factory locked device has an 8-word random ESN

at address 000000h-000007h.

CUSTOMER LOCKABLE:Secured Silicon

Sector NOT Programmed or Protected At the

Factory

As an alternative to the factory-locked version, the device

may be ordered such that the customer may program

and protect the 512-word Secured Silicon Sector.

Programming and protecting the Secured Silicon Sector

must be used with caution since, once protected, there

is no procedure available for unprotecting the Secured

Silicon Sector area and none of the bits in the Secured

Silicon Sector memory space can be modified in any

way.

The Secured Silicon Sector area can be protected using

the following procedures:

Write the three-cycle Enter Secured Silicon Sector Region

command sequence. This allows in-system protection

of the Secured Silicon Sector without raising any device

pin to a high voltage. Note that method is only applicable

to the Secured Silicon Sector.

Once the Secured Silicon Sector is programmed, locked

and verified, the system must write the Exit Secured

Silicon Sector Region command sequence to return to

reading and writing the remainder of the array.

LOGICAL INHIBIT

Writing is inhibited by holding any one of OE = VIL, CE =

VIH or WE = VIH. To initiate a write cycle CE and WE

must be a logical zero while OE is a logical one.

POWER-UP SEQUENCE

The MX26L6420 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.

P/N:PM0823

9

REV. 0.5, JAN. 29, 2002

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