SST38VF6401B datasheet(13/58 Pages) MICROCHIP

13 / 58 page

 2013 Microchip Technology Inc.

Preliminary

DS25002B-page 13

SST38VF6401B / SST38VF6402B / SST38VF6403B / SST38VF6404B

The Read-Irreversible Block-Lock Status command

indicates if the Irreversible Block Command has been

issued. If DQ0 = 0, then the Irreversible Lock command

has been previously issued.

In order to return to the standard Read mode, the soft-

ware Product Identification mode must be exited. The

exit is accomplished by issuing the software ID Exit

command sequence, which returns the device to the

Read mode. See Table 5-2 for software command

codes, Figure 6-13 for timing waveform, and Figures 6-

22 and 6-23 for flowcharts.

4.12

Security ID

The SST38VF6401B/6402B/6403B/6404B devices offer

a Security ID feature. The Secure ID space is divided

into two segments — one factory programmed 128 bit

segment and one user programmable 248 word seg-

ment. See Table 4-4 for address information. The first

segment is programmed and locked at Microchip and

contains a 128 bit Unique ID which uniquely identifies

the device. The user segment is left un-programmed

for the customer to program as desired.

The user segment of the Security ID can be pro-

grammed by first using the SEC ID Entry command to

enter the Secure ID space. Once in the Secure ID

space, for smaller data sets, use the Word-Program

command to program data. To program larger sets of

data more quickly, use the Write-Buffer Programming

feature. Note that Bypass Mode is not available.

To detect end-of-write for the SEC ID, read the toggle

bits. Do not use Data# Polling to detect end of Write.

Once the programming is complete, lock the Sec ID by

programming bit ‘0’ in the PSR with the PSR Program

command. Locking the Sec ID disables any corruption of

this space. Note that regardless of whether or not the Sec

ID is locked, the Sec ID segments can not be erased.

The Secure ID space can be queried by executing a

three-byte command sequence with Enter Sec ID com-

mand (88H) at address 555H in the last byte sequence.

To exit this mode, the Exit Sec ID command should be

executed. Refer to Table 5-2 for software commands

and Figures 6-22 and 6-23 for flow charts.

4.13

Bypass Mode

Bypass mode shortens the time needed to issue pro-

gram and erase commands by reducing these com-

mands to two write cycles each. After using the Bypass

Entry command to enter the Bypass mode, only the

Bypass Word-Program, Bypass Block Erase, Bypass

Chip Erase, Erase-Suspend, and Erase-Resume com-

mands are available. The Bypass Exit command exits

Bypass mode. See Table 5-2 for further details.

Entering Bypass Mode while already in Erase-Suspend

limits the available commands. See “Erase-Suspend/

Erase-Resume Commands” on page 9 for more infor-

mation.

4.14

Protection Settings Register (PSR)

The Protection Settings Register (PSR) is a user-pro-

grammable register that allows for further customiza-

tion

the

SST38VF6401B/6402B/6403B/6404B

protection features. The 16-bit PSR provides four One

Time Programmable (OTP) bits for users, each of

which can be programmed individually. However, once

an OTP bit is programmed to ‘0’, the value cannot be

changed back to a ‘1’. The other 12 bits of the PSR are

reserved. See Table 4-5 for the definition of all 16-bits

of the PSR.

Note that DQ4, DQ2, DQ1, DQ0 do not have to be pro-

grammed at the same time. In addition, DQ2 and DQ1

cannot both be programmed to ‘0’. The valid combina-

tions of states of DQ2 and DQ1 are shown in Table 4-6.

TABLE 4-4:

ADDRESS RANGE FOR SEC ID

Size

Address

Microchip Unique ID

128 bits

000H – 007H

User

248 W

008H – 0FFH

TABLE 4-5:

PSR BIT DEFINITIONS

Bit

Default

from

Factory

Definition

DQ15-

DQ5

FFFh

Reserved

DQ4

VPB power-up / hardware reset state

0 = all protected

1 = all unprotected

DQ3

Reserved

DQ2

Password mode

0 = Password only mode

1 = Pass-Through mode

DQ1

Pass-Through mode

0 = Pass-Through only mode

1 = Pass-Through mode

DQ0

SEC ID Lock Out Bit

0 = locked

1 = unlocked

TABLE 4-6:

VALID DQ2 AND DQ1

COMBINATIONS

Combination

Definition

DQ2, DQ1 = 11

Pass-Through mode (factory

default)

DQ2, DQ1 = 10

Pass-Through only mode

DQ2, DQ1 = 01

Password only mode

DQ2, DQ1 = 00

Not Allowed

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