SST38VF6401B Datasheet, PDF (13/58 Pages) Microchip Technology – 64 Mbit (x16) Advanced Multi-Purpose Flash Plus

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.
TABLE 4-4: ADDRESS RANGE FOR SEC ID
Size
Address
Microchip Unique ID 128 bits 000H – 007H
User
248 W 008H – 0FFH
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 of 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.
TABLE 4-5: PSR BIT DEFINITIONS
Default
from
Bit Factory Definition
DQ₁₅-
DQ₅
DQ₄
FFFh Reserved
1 VPB power-up / hardware reset state
0 = all protected
1 = all unprotected
DQ₃
1 Reserved
DQ₂
1 Password mode
0 = Password only mode
1 = Pass-Through mode
DQ₁
1 Pass-Through mode
0 = Pass-Through only mode
1 = Pass-Through mode
DQ₀
1 SEC ID Lock Out Bit
0 = locked
1 = unlocked
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 4-6: VALID DQ₂ AND DQ₁
COMBINATIONS
Combination Definition
DQ₂, DQ₁ = 11 Pass-Through mode (factory
default)
DQ_2, DQ₁ = 10
DQ₂, DQ₁ = 01
DQ₂, DQ₁ = 00
Pass-Through only mode
Password only mode
Not Allowed
 2013 Microchip Technology Inc.
Preliminary
DS25002B-page 13