EN25F20 Datasheet, PDF (5/31 Pages) Eon Silicon Solution Inc. – 2 Mbit Serial Flash Memory with 4Kbytes Uniform Sector

Figure 3. SPI Modes
EN25F20
Page Programming
To program one data byte, two instructions are required: Write Enable (WREN), which is one byte, and a
Page Program (PP) sequence, which consists of four bytes plus data. This is followed by the internal
Program cycle (of duration tPP).
To spread this overhead, the Page Program (PP) instruction allows up to 256 bytes to be programmed at
a time (changing bits from 1 to 0), provided that they lie in consecutive addresses on the same page of
memory.
Sector Erase, Block Erase and Chip Erase
The Page Program (PP) instruction allows bits to be reset from 1 to 0. Before this can be applied, the
bytes of memory need to have been erased to all 1s (FFh). This can be achieved a sector at a time, using
the Sector Erase (SE) instruction, a block at a time using the Block Erase (BE) instruction or throughout
the entire memory, using the Chip Erase (CE) instruction. This starts an internal Erase cycle (of duration
tSE tBE or tCE). The Erase instruction must be preceded by a Write Enable (WREN) instruction.
Polling During a Write, Program or Erase Cycle
A further improvement in the time to Write Status Register (WRSR), Program (PP) or Erase (SE, BE or
CE ) can be achieved by not waiting for the worst case delay (tW, tPP, tSE, tBEor tCE). The Write In
Progress (WIP) bit is provided in the Status Register so that the application program can monitor its value,
polling it to establish when the previous Write cycle, Program cycle or Erase cycle is complete.
Active Power, Stand-by Power and Deep Power-Down Modes
When Chip Select (CS#) is Low, the device is enabled, and in the Active Power mode. When Chip Select
(CS#) is High, the device is disabled, but could remain in the Active Power mode until all internal cycles
have completed (Program, Erase, Write Status Register). The device then goes into the Stand-by Power
mode. The device consumption drops to I_CC1.
The Deep Power-down mode is entered when the specific instruction (the Enter Deep Power-down Mode
(DP) instruction) is executed. The device consumption drops further to I_CC2. The device remains in this
mode until another specific instruction (the Release from Deep Power-down Mode and Read Device ID
(RDI) instruction) is executed.
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.
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 / 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
This Data Sheet may be revised by subsequent versions
5
or modifications due to changes in technical specifications.
©2004 Eon Silicon Solution, Inc., www.essi.com.tw
Rev. B, Issue Date: 2007/05/15