M25P20 ,2 MBIT, LOW VOLTAGE, SERIAL FLASH MEMORY WITH 25 MHZ SPI BUS INTERFACELogic DiagramVCCD QNote: 1. See page 30 (onwards) for package dimensions, and howto identify pin-1. ..
M25P20VMN6 ,512 Kbit to 32 Mbit, Low Voltage, Serial Flash Memory With 40 MHz or 50 MHz SPI Bus InterfaceM25PXX512 Kbit to 32 Mbit, Low Voltage, Serial Flash MemoryWith 40 MHz or 50 MHz SPI Bus InterfaceD ..
M25P20-VMN6 ,2 Mbit, Low Voltage, Serial Flash Memory With 40MHz SPI Bus InterfaceBlock Diagram . 11INSTRUCTIONS . . 12Table 4. Instruction Set . 12Write Enabl ..
M25P20-VMN6G ,512 Kbit to 32 Mbit, Low Voltage, Serial Flash Memory With 40 MHz or 50 MHz SPI Bus InterfaceFEATURES SUMMARY■ 512Kbit to 32Mbit of Flash Memory Figure 1. Packages■ Page Program (up to 256 Byt ..
M25P20VMN6P ,512 Kbit to 32 Mbit, Low Voltage, Serial Flash Memory With 40 MHz or 50 MHz SPI Bus InterfaceM25PXX512 Kbit to 32 Mbit, Low Voltage, Serial Flash MemoryWith 40 MHz or 50 MHz SPI Bus InterfaceD ..
M25P20-VMN6P ,2 Mbit, Low Voltage, Serial Flash Memory With 40MHz SPI Bus InterfaceFEATURES . . . . 8Page Programming . . . . . 8Sector Erase and Bulk Erase . . . ..
M38254M6-125FP , SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
M38254M6-125FP , SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
M38254M6-175GP , SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
M38254M6-304FP , SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
M38257E8FP , SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
M38257E8FP , SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
M25P20
2 MBIT, LOW VOLTAGE, SERIAL FLASH MEMORY WITH 25 MHZ SPI BUS INTERFACE
1/34December 2002
M25P202 Mbit, Low Voltage, Serial Flash Memory
With 25 MHz SPI Bus Interface
FEATURES SUMMARY 2 Mbit of Flash Memory Page Program (up to 256 Bytes) in 1.5ms
(typical) Sector Erase (512 Kbit) in 2 s (typical) Bulk Erase (2 Mbit) in 3 s (typical) 2.7 V to 3.6 V Single Supply Voltage SPI Bus Compatible Serial Interface 25 MHz Clock Rate (maximum) Deep Power-down Mode 1 μA (typical) Electronic Signature (11h) More than 100,000 Erase/Program Cycles per
Sector More than 20 Year Data Retention
Figure 1. Packages
M25P20
SUMMARY DESCRIPTIONThe M25P20 is a 2 Mbit (256K x 8) Serial Flash
Memory, with advanced write protection mecha-
nisms, accessed by a high speed SPI-compatible
bus.
The memory can be programmed 1 to 256 bytes at
a time, using the Page Program instruction.
The memory is organized as 4 sectors, each con-
taining 256 pages. Each page is 256 bytes wide.
Thus, the whole memory can be viewed as con-
sisting of 1024 pages, or 262,144 bytes.
The whole memory can be erased using the Bulk
Erase instruction, or a sector at a time, using the
Sector Erase instruction.
Figure 2. Logic Diagram
Figure 3. SO and VFQFPN ConnectionsNote:1. See page 30 (onwards) for package dimensions, and how
to identify pin-1.
Table 1. Signal Names
3/34
M25P20
SIGNAL DESCRIPTION
Serial Data Output (Q). This output signal is
used to transfer data serially out of the device.
Data is shifted out on the falling edge of Serial
Clock (C).
Serial Data Input (D). This input signal is used to
transfer data serially into the device. It receives in-
structions, addresses, and the data to be pro-
grammed. Values are latched on the rising edge of
Serial Clock (C).
Serial Clock (C). This input signal provides the
timing of the serial interface. Instructions, address-
es, or data present at Serial Data Input (D) are
latched on the rising edge of Serial Clock (C). Data
on Serial Data Output (Q) changes after the falling
edge of Serial Clock (C).
Chip Select (S). When this input signal is High,
the device is deselected and Serial Data Output
(Q) is at high impedance. Unless an internal Pro-
gram, Erase or Write Status Register cycle is in
progress, the device will be in the Standby mode
(this is not the Deep Power-down mode). Driving
Chip Select (S) Low enables the device, placing it
in the active power mode.
After Power-up, a falling edge on Chip Select (S)
is required prior to the start of any instruction.
Hold (HOLD). The Hold (HOLD) signal is used to
pause any serial communications with the device
without deselecting the device.
During the Hold condition, the Serial Data Output
(Q) is high impedance, and Serial Data Input (D)
and Serial Clock (C) are Don’t Care.
To start the Hold condition, the device must be se-
lected, with Chip Select (S) driven Low.
Write Protect (W). The main purpose of this in-
put signal is to freeze the size of the area of mem-
ory that is protected against program or erase
instructions (as specified by the values in the BP1
and BP0 bits of the Status Register).
M25P20
SPI MODESThese devices can be driven by a microcontroller
with its SPI peripheral running in either of the two
following modes: CPOL=0, CPHA=0 CPOL=1, CPHA=1
For these two modes, input data is latched in on
the rising edge of Serial Clock (C), and output data
is available from the falling edge of Serial Clock
(C).
The difference between the two modes, as shown
in Figure 5, is the clock polarity when the bus mas-
ter is in Stand-by mode and not transferring data: C remains at 0 for (CPOL=0, CPHA=0) C remains at 1 for (CPOL=1, CPHA=1)
Figure 4. Bus Master and Memory Devices on the SPI BusNote:1. The Write Protect (W) and Hold (HOLD) signals should be driven, High or Low as appropriate.
Figure 5. SPI Modes Supported
5/34
M25P20
OPERATING FEATURES
Page ProgrammingTo program one data byte, two instructions are re-
quired: Write Enable (WREN), which is one byte,
and a Page Program (PP) sequence, which con-
sists 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 pro-
grammed at a time (changing bits from 1 to 0), pro-
vided that they lie in consecutive addresses on the
same page of memory.
Sector Erase and Bulk EraseThe 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 either a sector at a
time, using the Sector Erase (SE) instruction, or
throughout the entire memory, using the Bulk
Erase (BE) instruction. This starts an internal
Erase cycle (of duration tSE or tBE).
The Erase instruction must be preceeded by a
Write Enable (WREN) instruction.
Polling During a Write, Program or Erase CycleA further improvement in the time to Write Status
Register (WRSR), Program (PP) or Erase (SE or
BE) can be achieved by not waiting for the worst
case delay (tW, tPP, tSE, or tBE). The Write In
Progress (WIP) bit is provided in the Status Regis-
ter so that the application program can monitor its
value, polling it to establish when the previous
Write cycle, Program cycle or Erase cycle is com-
plete.
Active Power, Stand-by Power and Deep
Power-Down ModesWhen Chip Select (S) is Low, the device is en-
abled, and in the Active Power mode.
When Chip Select (S) is High, the device is dis-
abled, but could remain in the Active Power mode
until all internal cycles have completed (Program,
Erase, Write Status Register). The device then
goes in to the Stand-by Power mode. The device
consumption drops to ICC1.
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 ICC2. The device re-
mains in this mode until another specific instruc-
tion (the Release from Deep Power-down Mode
and Read Electronic Signature (RES) 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 inadvertant Write, Program or Erase
instructions.
Status RegisterThe Status Register contains a number of status
and control bits, as shown in Table 5, that can be
read or set (as appropriate) by specific instruc-
tions.
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 indi-
cates 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.
SRWD bit. The Status Register Write Disable
(SRWD) bit is operated in conjunction with the
Write Protect (W) signal. The Status Register
Write Disable (SRWD) bit and Write Protect (W)
signal allow the device to be put in the Hardware
Protected mode. In this mode, the non-volatile bits
of the Status Register (SRWD, BP1, BP0) become
read-only bits.
M25P20
Protection ModesThe environments where non-volatile memory de-
vices are used can be very noisy. No SPI device
can operate correctly in the presence of excessive
noise. To help combat this, the M25P20 boasts the
following data protection mechanisms: Power-On Reset and an internal timer (tPUW)
can provide protection against inadvertant
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 Write Status Register (WRSR) instruction
completion Page Program (PP) instruction completion Sector Erase (SE) instruction completion Bulk Erase (BE) instruction completion 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 (W) signal, in co-operation
with the Status Register Write Disable (SRWD)
bit, allows the Block Protect (BP1, BP0) bits and
Status Register Write Disable (SRWD) bit to be
write-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 inadvertant
Write, Program and Erase instructions, as all
instructions are ignored except one particular
instruction (the Release from Deep Power-
down instruction).
Table 2. Protected Area SizesNote:1. The device is ready to accept a Bulk Erase instruction if, and only if, both Block Protect (BP1, BP0) are 0.
7/34
M25P20
Hold ConditionThe Hold (HOLD) signal is used to pause any se-
rial communications with the device without reset-
ting the clocking sequence. However, taking this
signal Low does not terminate any Write Status
Register, Program or Erase cycle that is currently
in progress.
To enter the Hold condition, the device must be
selected, with Chip Select (S) Low.
The Hold condition starts on the falling edge of the
Hold (HOLD) signal, provided that this coincides
with Serial Clock (C) being Low (as shown in Fig-
ure 6).
The Hold condition ends on the rising edge of the
Hold (HOLD) signal, provided that this coincides
with Serial Clock (C) being Low.
If the falling edge does not coincide with Serial
Clock (C) being Low, the Hold condition starts af-
ter Serial Clock (C) next goes Low. Similarly, if the
rising edge does not coincide with Serial Clock (C)
being Low, the Hold condition ends after Serial
Clock (C) next goes Low. (This is shown in Figure
6).
During the Hold condition, the Serial Data Output
(Q) is high impedance, and Serial Data Input (D)
and Serial Clock (C) are Don’t Care.
Normally, the device is kept selected, with Chip
Select (S) driven Low, for the whole duration of the
Hold condition. This is to ensure that the state of
the internal logic remains unchanged from the mo-
ment of entering the Hold condition.
If Chip Select (S) goes High while the device is in
the Hold condition, this has the effect of resetting
the internal logic of the device. To restart commu-
nication with the device, it is necessary to drive
Hold (HOLD) High, and then to drive Chip Select
(S) Low. This prevents the device from going back
to the Hold condition.
Figure 6. Hold Condition Activation
M25P20
MEMORY ORGANIZATIONThe memory is organized as: 262,144 bytes (8 bits each) 4 sectors (512 Kbits, 65536 bytes each) 1024 pages (256 bytes each).
Each page can be individually programmed (bits
are programmed from 1 to 0). The device is Sector
or Bulk Erasable (bits are erased from 0 to 1) but
not Page Erasable.
Table 3. Memory Organization
Figure 7. Block Diagram
9/34
M25P20
INSTRUCTIONSAll instructions, addresses and data are shifted in
and out of the device, most significant bit first.
Serial Data Input (D) is sampled on the first rising
edge of Serial Clock (C) after Chip Select (S) is
driven Low. Then, the one-byte instruction code
must be shifted in to the device, most significant bit
first, on Serial Data Input (D), each bit being
latched on the rising edges of Serial Clock (C).
The instruction set is listed in Table 4.
Every instruction sequence starts with a one-byte
instruction code. Depending on the instruction,
this might be followed by address bytes, or by data
bytes, or by both or none. Chip Select (S) must be
driven High after the last bit of the instruction se-
quence has been shifted in.
In the case of a Read Data Bytes (READ), Read
Data Bytes at Higher Speed (Fast_Read), Read
Status Register (RDSR) or Release from Deep
Power-down, and Read Electronic Signature
(RES) instruction, the shifted-in instruction se-
quence is followed by a data-out sequence. Chip
Select (S) can be driven High after any bit of the
data-out sequence is being shifted out.
In the case of a Page Program (PP), Sector Erase
(SE), Bulk Erase (BE), Write Status Register
(WRSR), Write Enable (WREN), Write Disable
(WRDI) or Deep Power-down (DP) instruction,
Chip Select (S) must be driven High exactly at a
byte boundary, otherwise the instruction is reject-
ed, and is not executed. That is, Chip Select (S)
must driven High when the number of clock pulses
after Chip Select (S) being driven Low is an exact
multiple of eight.
All attempts to access the memory array during a
Write Status Register cycle, Program cycle or
Erase cycle are ignored, and the internal Write
Status Register cycle, Program cycle or Erase cy-
cle continues unaffected.
Table 4. Instruction Set
M25P20
Figure 8. Write Enable (WREN) Instruction Sequence
Write Enable (WREN)The Write Enable (WREN) instruction (Figure 8)
sets the Write Enable Latch (WEL) bit.
The Write Enable Latch (WEL) bit must be set pri-
or to every Page Program (PP), Sector Erase
(SE), Bulk Erase (BE) and Write Status Register
(WRSR) instruction.
The Write Enable (WREN) instruction is entered
by driving Chip Select (S) Low, sending the in-
struction code, and then driving Chip Select (S)
High.
Figure 9. Write Disable (WRDI) Instruction Sequence
Write Disable (WRDI)The Write Disable (WRDI) instruction (Figure 9)
resets the Write Enable Latch (WEL) bit.
The Write Disable (WRDI) instruction is entered by
driving Chip Select (S) Low, sending the instruc-
tion code, and then driving Chip Select (S) High.
The Write Enable Latch (WEL) bit is reset under
the following conditions: Power-up Write Disable (WRDI) instruction completion Write Status Register (WRSR) instruction com-
pletion Page Program (PP) instruction completion Sector Erase (SE) instruction completion Bulk Erase (BE) instruction completion
11/34
M25P20
Figure 10. Read Status Register (RDSR) Instruction Sequence and Data-Out Sequence
Read Status Register (RDSR)The Read Status Register (RDSR) instruction al-
lows the Status Register to be read. The Status
Register may be read at any time, even while a
Program, Erase or Write Status Register cycle is in
progress. When one of these cycles is in progress,
it is recommended to check the Write In Progress
(WIP) bit before sending a new instruction to the
device. It is also possible to read the Status Reg-
ister continuously, as shown in Figure 10.
Table 5. Status Register FormatThe status and control bits of the Status Register
are as follows:
WIP bit. The Write In Progress (WIP) bit indicates
whether the memory is busy with a Write Status
Register, Program or Erase cycle. When set to 1,
such a cycle is in progress, when reset to 0 no
such cycle is in progress.
WEL bit. The Write Enable Latch (WEL) bit indi-
cates the status of the internal Write Enable Latch.
When set to 1 the internal Write Enable Latch is
set, when set to 0 the internal Write Enable Latch
is reset and no Write Status Register, Program or
Erase instruction is accepted.
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. These bits are written with the Write
Status Register (WRSR) instruction. When one or
both of the Block Protect (BP1, BP0) bits is set to
1, the relevant memory area (as defined in Table
2) becomes protected against Page Program (PP)
and Sector Erase (SE) instructions. The Block
Protect (BP1, BP0) bits can be written provided
that the Hardware Protected mode has not been
set. The Bulk Erase (BE) instruction is executed if,
and only if, both Block Protect (BP1, BP0) bits are
0.
SRWD bit. The Status Register Write Disable
(SRWD) bit is operated in conjunction with the
Write Protect (W) signal. The Status Register
Write Disable (SRWD) bit and Write Protect (W)
signal allow the device to be put in the Hardware
Protected mode (when the Status Register Write
Disable (SRWD) bit is set to 1, and Write Protect
(W) is driven Low). In this mode, the non-volatile
bits of the Status Register (SRWD, BP1, BP0) be-
come read-only bits and the Write Status Register
(WRSR) instruction is no longer accepted for exe-
cution.
b7 b0
Write In Progress Bit
M25P20
Figure 11. Write Status Register (WRSR) Instruction Sequence
Write Status Register (WRSR)The Write Status Register (WRSR) instruction al-
lows new values to be written to the Status Regis-
ter. Before it can be accepted, a Write Enable
(WREN) instruction must previously have been ex-
ecuted. After the Write Enable (WREN) instruction
has been decoded and executed, the device sets
the Write Enable Latch (WEL).
The Write Status Register (WRSR) instruction is
entered by driving Chip Select (S) Low, followed
by the instruction code and the data byte on Serial
Data Input (D).
The instruction sequence is shown in Figure 11.
The Write Status Register (WRSR) instruction has
no effect on b6, b5, b4, b1 and b0 of the Status
Register. b6, b5 and b4 are always read as 0.
Chip Select (S) must be driven High after the
eighth bit of the data byte has been latched in. If
not, the Write Status Register (WRSR) instruction
is not executed. As soon as Chip Select (S) is driv-
en High, the self-timed Write Status Register cycle
(whose duration is tW) is initiated. While the Write
Status Register cycle is in progress, the Status
Register may still be read to check the value of the
Write In Progress (WIP) bit. The Write In Progress
(WIP) bit is 1 during the self-timed Write Status
Register cycle, and is 0 when it is completed. At
some unspecified time before the cycle is complet-
ed, the Write Enable Latch (WEL) is reset.
The Write Status Register (WRSR) instruction al-
lows the user to change the values of the Block
Protect (BP1, BP0) bits, to define the size of the
area that is to be treated as read-only, as defined
in Table 2. The Write Status Register (WRSR) in-
struction also allows the user to set or reset the
Status Register Write Disable (SRWD) bit in ac-
cordance with the Write Protect (W) signal. The
Status Register Write Disable (SRWD) bit and
Write Protect (W) signal allow the device to be put
in the Hardware Protected Mode (HPM). The Write
Status Register (WRSR) instruction is not execut-
ed once the Hardware Protected Mode (HPM) is
entered.
13/34
M25P20
Table 6. Protection ModesNote:1. As defined by the values in the Block Protect (BP1, BP0) bits of the Status Register, as shown in Table 2.
The protection features of the device are summa-
rized in Table 6.
When the Status Register Write Disable (SRWD)
bit of the Status Register is 0 (its initial delivery
state), it is possible to write to the Status Register
provided that the Write Enable Latch (WEL) bit has
previously been set by a Write Enable (WREN) in-
struction, regardless of the whether Write Protect
(W) is driven High or Low.
When the Status Register Write Disable (SRWD)
bit of the Status Register is set to 1, two cases
need to be considered, depending on the state of
Write Protect (W): If Write Protect (W) is driven High, it is possible
to write to the Status Register provided that the
Write Enable Latch (WEL) bit has previously
been set by a Write Enable (WREN) instruction. If Write Protect (W) is driven Low, it is not pos-
sible to write to the Status Register even if the
Write Enable Latch (WEL) bit has previously
been set by a Write Enable (WREN) instruction.
(Attempts to write to the Status Register are re-
jected, and are not accepted for execution). As
a consequence, all the data bytes in the memo-
ry area that are software protected (SPM) by the
Block Protect (BP1, BP0) bits of the Status Reg-
ister, are also hardware protected against data
modification.
Regardless of the order of the two events, the
Hardware Protected Mode (HPM) can be entered: by setting the Status Register Write Disable
(SRWD) bit after driving Write Protect (W) Low or by driving Write Protect (W) Low after setting
the Status Register Write Disable (SRWD) bit.
The only way to exit the Hardware Protected Mode
(HPM) once entered is to pull Write Protect (W)
High.
If Write Protect (W) is permanently tied High, the
Hardware Protected Mode (HPM) can never be
activated, and only the Software Protected Mode
(SPM), using the Block Protect (BP1, BP0) bits of
the Status Register, can be used.
M25P20
Figure 12. Read Data Bytes (READ) Instruction Sequence and Data-Out SequenceNote:1. Address bits A23 to A18 are Don’t Care.
Read Data Bytes (READ)The device is first selected by driving Chip Select
(S) Low. The instruction code for the Read Data
Bytes (READ) instruction is followed by a 3-byte
address (A23-A0), each bit being latched-in during
the rising edge of Serial Clock (C). Then the mem-
ory contents, at that address, is shifted out on Se-
rial Data Output (Q), each bit being shifted out, at
a maximum frequency fR, during the falling edge of
Serial Clock (C).
The instruction sequence is shown in Figure 12.
The first byte addressed can be at any location.
The address is automatically incremented to the
next higher address after each byte of data is shift-
ed out. The whole memory can, therefore, be read
with a single Read Data Bytes (READ) instruction.
When the highest address is reached, the address
counter rolls over to 000000h, allowing the read
sequence to be continued indefinitely.
The Read Data Bytes (READ) instruction is termi-
nated by driving Chip Select (S) High. Chip Select
(S) can be driven High at any time during data out-
put. Any Read Data Bytes (READ) instruction,
while an Erase, Program or Write cycle is in
progress, is rejected without having any effects on
the cycle that is in progress.
15/34
M25P20
Figure 13. Read Data Bytes at Higher Speed (FAST_READ) Instruction Sequence and Data-Out
SequenceNote:1. Address bits A23 to A18 are Don’t Care.
Read Data Bytes at Higher Speed
(FAST_READ)The device is first selected by driving Chip Select
(S) Low. The instruction code for the Read Data
Bytes at Higher Speed (FAST_READ) instruction
is followed by a 3-byte address (A23-A0) and a
dummy byte, each bit being latched-in during the
rising edge of Serial Clock (C). Then the memory
contents, at that address, is shifted out on Serial
Data Output (Q), each bit being shifted out, at a
maximum frequency fC, during the falling edge of
Serial Clock (C).
The instruction sequence is shown in Figure 13.
The first byte addressed can be at any location.
The address is automatically incremented to the
next higher address after each byte of data is shift-
ed out. The whole memory can, therefore, be read
with a single Read Data Bytes at Higher Speed
(FAST_READ) instruction. When the highest ad-
dress is reached, the address counter rolls over to
000000h, allowing the read sequence to be contin-
ued indefinitely.
The Read Data Bytes at Higher Speed
(FAST_READ) instruction is terminated by driving
Chip Select (S) High. Chip Select (S) can be driv-
en High at any time during data output. Any Read
Data Bytes at Higher Speed (FAST_READ) in-
struction, while an Erase, Program or Write cycle
is in progress, is rejected without having any ef-
fects on the cycle that is in progress.
M25P20
Figure 14. Page Program (PP) Instruction SequenceNote:1. Address bits A23 to A18 are Don’t Care.
Page Program (PP)The Page Program (PP) instruction allows bytes to
be programmed in the memory (changing bits from
1 to 0). Before it can be accepted, a Write Enable
(WREN) instruction must previously have been ex-
ecuted. After the Write Enable (WREN) instruction
has been decoded, the device sets the Write En-
able Latch (WEL).
The Page Program (PP) instruction is entered by
driving Chip Select (S) Low, followed by the in-
struction code, three address bytes and at least
one data byte on Serial Data Input (D). If the 8
least significant address bits (A7-A0) are not all
zero, all transmitted data that goes beyond the end
of the current page are programmed from the start
address of the same page (from the address
whose 8 least significant bits (A7-A0) are all zero).
Chip Select (S) must be driven Low for the entire
duration of the sequence.
The instruction sequence is shown in Figure 14.
If more than 256 bytes are sent to the device, pre-
viously latched data are discarded and the last 256
data bytes are guaranteed to be programmed cor-
rectly within the same page. If less than 256 Data
bytes are sent to device, they are correctly pro-
grammed at the requested addresses without hav-
ing any effects on the other bytes of the same
page.
Chip Select (S) must be driven High after the
eighth bit of the last data byte has been latched in,
otherwise the Page Program (PP) instruction is not
executed.
As soon as Chip Select (S) is driven High, the self-
timed Page Program cycle (whose duration is tPP)
is initiated. While the Page Program cycle is in
progress, the Status Register may be read to
check the value of the Write In Progress (WIP) bit.
The Write In Progress (WIP) bit is 1 during the self-
timed Page Program cycle, and is 0 when it is
completed. At some unspecified time before the
cycle is completed, the Write Enable Latch (WEL)
bit is reset.
A Page Program (PP) instruction applied to a page
which is protected by the Block Protect (BP1, BP0)
bits (see Tables 3 and 2) is not executed.
17/34
M25P20
Figure 15. Sector Erase (SE) Instruction SequenceNote:1. Address bits A23 to A18 are Don’t Care.
Sector Erase (SE)The Sector Erase (SE) instruction sets to 1 (FFh)
all bits inside the chosen sector. Before it can be
accepted, a Write Enable (WREN) instruction
must previously have been executed. After the
Write Enable (WREN) instruction has been decod-
ed, the device sets the Write Enable Latch (WEL).
The Sector Erase (SE) instruction is entered by
driving Chip Select (S) Low, followed by the in-
struction code, and three address bytes on Serial
Data Input (D). Any address inside the Sector (see
Table 3) is a valid address for the Sector Erase
(SE) instruction. Chip Select (S) must be driven
Low for the entire duration of the sequence.
The instruction sequence is shown in Figure 15.
Chip Select (S) must be driven High after the
eighth bit of the last address byte has been latched
in, otherwise the Sector Erase (SE) instruction is
not executed. As soon as Chip Select (S) is driven
High, the self-timed Sector Erase cycle (whose du-
ration is tSE) is initiated. While the Sector Erase cy-
cle is in progress, the Status Register may be read
to check the value of the Write In Progress (WIP)
bit. The Write In Progress (WIP) bit is 1 during the
self-timed Sector Erase cycle, and is 0 when it is
completed. At some unspecified time before the
cycle is completed, the Write Enable Latch (WEL)
bit is reset.
A Sector Erase (SE) instruction applied to a page
which is protected by the Block Protect (BP1, BP0)
bits (see Tables 3 and 2) is not executed.
