n25q256 Numonyx, n25q256 Datasheet - Page 52

• Manufacturer Part Number: n25q256
• Description: 256-mbit 3 V, Multiple I/o, 4-kbyte Subsector Erase, Xip Enabled, Serial Flash Memory With 108 Mhz Spi Bus Interface
• Manufacturer: Numonyx

Protection modes
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7.1
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Protection modes
There are protocol-related and specific hardware and software protection modes. They are
described below.
SPI Protocol-related protections
This applies to all three protocols. The environments where non-volatile memory devices
are used can be very noisy. No SPI device can operate correctly in the presence of
excessive noise. To help combat this, the N25Q256 features the following data protection
mechanisms:
This bit is also returned to its reset state after all the analogous events in DIO-SPI and QIO-
SPI protocol modes.
Specific hardware and software protection
There are two software protected modes, SPM1 and SPM2, that can be combined to protect
the memory array as required. The SPM2 can be locked by hardware with the help of the W
input pin.
SPM1
The first software protected mode (SPM1) is managed by specific Lock Registers assigned
to each 64 Kbyte sector.
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 to ensure the
instruction includes a number of clock pulses that is a multiple of a byte 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 (in Extended SPI protocol mode):
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–
–
–
–
–
–
–
–
–
–
–
–
Power-up
Write Disable (WRDI) instruction completion
Write Status Register (WRSR) instruction completion
Write to Lock Register (WRLR) instruction completion
Program OTP (POTP) instruction completion
Page Program (PP) instruction completion
Dual Input Fast Program (DIFP) instruction completion
Dual Input Extended Fast Program (DIEFP) instruction completion
Quad Input Fast Program (QIFP) instruction completion
Quad Input Extended Fast Program (QIEFP) instruction completion
Subsector Erase (SSE) instruction completion
Sector Erase (SE) instruction completion
Bulk Erase (BE) instruction completion
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N25Q256 - 3 V