EN25Q40
All other instructions are ignored while the device is in the Deep Power-down mode. This can be used
as an extra software protection mechanism, when the device is not in active use, to protect the device
from inadvertent Write, Program or Erase instructions.
Status Register.
The Status Register contains a number of status and control bits that can be read or
set (as appropriate) by specific instructions.
WIP bit.
The Write In Progress (WIP) bit indicates whether the memory is busy with a Write Status
Register, Program or Erase cycle.
WEL bit.
The Write Enable Latch (WEL) bit indicates the status of the internal Write Enable Latch.
BP2, BP1, BP0 bits.
The Block Protect (BP2, BP1, BP0) bits are non-volatile. They define the size of
the area to be software protected against Program and Erase instructions.
WPDIS bit.
The Write Protect disable (WPDIS) bit, non-volatile bit, when it is reset to “0” (factory
default) to enable WP# function or is set to “1” to disable WP# function (can be floating during SPI
mode.)
SRP bit / OTP_LOCK bit
The Status Register Protect (SRP) bit operates in conjunction with the Write
Protect (WP#) signal. The Status Register Protect (SRP) bit and Write Protect (WP#) signal allow the
device to be put in the Hardware Protected mode. In this mode, the non-volatile bits of the Status
Register (SRP, BP2, BP1, BP0) become read-only bits.
In OTP mode, this bit serves as OTP_LOCK bit, user can read/program/erase OTP sector as normal
sector while OTP_LOCK bit value is equal 0, after OTP_LOCK is programmed with 1 by WRSR
command, the OTP sector is protected from program and erase operation. The OTP_LOCK bit can only
be programmed once.
Note :
In OTP mode, the WRSR command will ignore any input data and program OTP_LOCK bit to 1,
user must clear the protect bits before entering OTP mode and program the OTP code, then execute
WRSR command to lock the OTP sector before leaving OTP mode.
Write Protection
Applications that use non-volatile memory must take into consideration the possibility of noise and other
adverse system conditions that may compromise data integrity. To address this concern the EN25Q40
provides the following data protection mechanisms:
Power-On Reset and an internal timer (tPUW) can provide protection against inadvertent changes
while the power supply is outside the operating specification.
Program, Erase and Write Status Register instructions are checked that they consist of a number
of clock pulses that is a multiple of eight, before they are accepted for execution.
All instructions that modify data must be preceded by a Write Enable (WREN) instruction to set
the Write Enable Latch (WEL) bit. This bit is returned to its reset state by the following events:
– Power-up
– Write Disable (WRDI) instruction completion or Write Status Register (WRSR) instruction
completion or Page Program (PP) instruction completion or Sector Erase (SE) instruction
completion or Block Erase (BE) instruction completion or Chip Erase (CE) instruction
completion
The Block Protect (BP2, BP1, BP0) bits allow part of the memory to be configured as read-only.
This is the Software Protected Mode (SPM).
The Write Protect (WP#) signal allows the Block Protect (BP2, BP1, BP0) bits and Status Register
Protect (SRP) bit to be protected. This is the Hardware Protected Mode (HPM).
In addition to the low power consumption feature, the Deep Power-down mode offers extra
software protection from inadvertent Write, Program and Erase instructions, as all instructions are
ignored except one particular instruction (the Release from Deep Power-down instruction).
This Data Sheet may be revised by subsequent versions
or modifications due to changes in technical specifications.
8
©2004 Eon Silicon Solution, Inc.,
www.eonssi.com
Rev. C, Issue Date: 2009/10/13
EON [ EON SILICON SOLUTION INC. ]
