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参数资料
| 型号： | M28C256-12KA6T |
| 厂商： | 意法半导体 |
| 元件分类： | EEPROM |
| 英文描述： | 256 Kbit (32Kb x8) Parallel EEPROM with Software Data Protection |
| 中文描述： | 256千位（的32KB × 8）与软件数据保护并行的EEPROM |
| 文件页数： | 5/21页 |
| 文件大小： | 132K |
| 代理商： | M28C256-12KA6T |
Status Register
ThedevicesprovideseveralWriteoperationstatus
flags that can be used to minimizethe application
write time. These signals are available on the I/O
port bits during programming cycleonly.
Data Polling bit (DQ7).
During the internal write
cycle, any attemptto read the last bytewritten will
produceon DQ7 the complementary value of the
previously latched bit. Once the write cycle is fin-
ished the true logic value appears on DQ7 in the
read cycle.
Toggle bit (DQ6).
The devices offer another way
for determining when the internal write cycle is
completed. During the internal Erase/Write cycle,
DQ6 will toggle from ”0” to ”1” and ”1” to ”0” (the
first read value is ”0”) on subsequent attempts to
read any byte of the memory. When the internal
cycle is completed the toggling will stop and the
data read on DQ7-DQ0 is the addressed memory
byte.The deviceis nowaccessiblefor anewRead
or Writeoperation.
PageLoadTimerStatusbit(DQ5).
Duringa Page
Write instruction,the devicesexpectto receivethe
stream of data with a minimum period of time
between each data byte. This period of time
(t
WHWH
) is defined by the on-chipPage Load timer
whichrunning/overflowstatusis availableon DQ5.
DQ5 Low indicates that the timer is running, DQ5
Highindicatesthe time-outafter whichthe internal
writecycle will start.
Software Data Protection
The devices offer a software controlled write pro-
tectionfacility thatallowstheusertoinhibitallwrite
modesto the device.This can be usefulin protect-
ing the memory from inadvertentwrite cyclesthat
may occur due to uncontrolledbus conditions.
Thedevicesareshippedasstandardinthe”unpro-
tected” state meaning that the memory contents
canbe changedas required by the user.After the
Software Data Protection enable algorithm is is-
sued, the device
enters the ”Protect Mode” of
operationwhere no further write commands have
any effect on the memorycontents.
The devices remain in this
SoftwareData Protection(SDP) disablesequence
is received whereby the device reverts to its ”un-
protected”state. The Software Data Protection is
fully non-volatile and is not changed by power
on/off sequences. To enable the Software Data
Protection (SDP) the device requires the user to
write (with a Page Write addressingthree specific
databytestothreespecificmemorylocations,each
location in a different page) as per Figure 6. Simi-
larly to disable the Software Data Protection the
userhas to write specificdata bytes intosix differ-
ent locations as per Figure 5 (with a Page Write
adressingdifferent bytes in differentpages).
Thiscomplexseriesensuresthattheuserwillnever
enable or disable the Software Data Protection
accidentally.
To write into the devices when SDP is set, the
sequence shown in Figure 6 must be used. This
sequence provides an unlock key to enable the
write action, and at the same time SDP continues
to be set.
Anextension tothis is where SDPis requiredto be
set, and data is to be written.
Using the same sequenceas above, the data can
be writtenand SDP is set at the same time, giving
boththese actions in the same Write cycle (t
WC
).
mode until a valid
DQ7
DQ6 DQ5 DQ4 DQ3 DQ2
DQ1 DQ0
DP
TB
PLTS
X
X
X
X
X
DP
TB
PLTS = PageLoad Timer Status
= Data Polling
= Toggle Bit
Figure 4. StatusBit Assignment
5/21
M28256
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| M28C256-12MS1T | 256 Kbit (32Kb x8) Parallel EEPROM with Software Data Protection |
| M28C256-12MS6T | 256 Kbit (32Kb x8) Parallel EEPROM with Software Data Protection |
| M28C256-12NS1T | 256 Kbit (32Kb x8) Parallel EEPROM with Software Data Protection |
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相关代理商/技术参数 |
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|---|---|
| M28C256-12MS1T | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:256 Kbit (32Kb x8) Parallel EEPROM with Software Data Protection |
| M28C256-12MS6T | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:256 Kbit (32Kb x8) Parallel EEPROM with Software Data Protection |
| M28C256-12NS1T | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:256 Kbit (32Kb x8) Parallel EEPROM with Software Data Protection |
| M28C256-12NS6T | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:256 Kbit (32Kb x8) Parallel EEPROM with Software Data Protection |
| M28C256-12WBS1T | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:256 Kbit (32Kb x8) Parallel EEPROM with Software Data Protection |
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