EN25F40 Datasheet, PDF (6/33 Pages) Eon Silicon Solution Inc. – 4 Mbit Serial Flash Memory with 4Kbytes Uniform Sector

EN25F40
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.
SRP bit / OTP_LOCK bit The Status Register Protect (SRP) bit is operated 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 is served as OTP_LOCK bit, user can read/program/erase OTP sector as normal
sector while OTP_LOCK 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 enter 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 EN25F40
provides the following data protection mechanisms:
z Power-On Reset and an internal timer (t_PUW) can provide protection against inadvertent changes
while the power supply is outside the operating specification.
z 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.
z 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
z 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).
z 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).
z 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
6
or modifications due to changes in technical specifications.
©2004 Eon Silicon Solution, Inc., www.essi.com.tw
Rev. B, Issue Date: 2007/05/09