EN25P20
Status Register.
The Status Register contains a number of status and control bits that can be read or set
(as appropriate) by specific instructions.
BUSY bit.
The BUSY 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.
BP1, BP0 bits.
The Block Protect (BP1, BP0) bits are non-volatile. They define the size of the area to be
software protected against Program and Erase instructions.
SRP 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, BP1, BP0)
become read-only bits.
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 EN25P20
provides the following data protection mechanisms:
Power-On Reset and an internal timer (t
PUW
) 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 Bulk Erase (BE) instruction completion or
The Block Protect (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 (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).
Table 3. Protected Area Sizes Sector Organization
Memory Content
BP1
Bit
1
1
0
0
BP0
Bit
1
0
1
0
Protected Sectors
All ( Sector 0 to 3)
Sector 2 to 3
Sector 3
None
Addresses
000000h-03FFFFh
020000h-03FFFFh
030000h-03FFFFh
None
Density(KB)
256KB
128KB
64KB
None
Portion
All sectors
Upper 1/2
Upper 1/4
None
Hold Function
The Hold (HOLD) signal is used to pause any serial communications with the device without resetting the
clocking sequence. However, taking this signal Low does not terminate any Write Status Register,
Program or Erase cycle that is currently in progress.
This Data Sheet may be revised by subsequent versions
or modifications due to changes in technical specifications.
6
©2004 Eon Silicon Solution, Inc., www.essi.com.tw
Rev. D, Issue Date: 2007/05/07
EON [ EON SILICON SOLUTION INC. ]
