M45PE20-VMN6TP ,2 Mbit, Low Voltage, Page-Erasable Serial Flash Memory With Byte-Alterability and a 25 MHz SPI Bus InterfaceFEATURES SUMMARY■ 2Mbit of Page-Erasable Flash Memory Figure 1. Packages■ Page Write (up to 256 Byt ..
M45PE20-VMP6G ,2 Mbit, Low Voltage, Page-Erasable Serial Flash Memory With Byte-Alterability and a 25 MHz SPI Bus InterfaceBlock Diagram . 10INSTRUCTIONS . . 11Table 4. Instruction Set . 11Write Enabl ..
M45PE20-VMP6TG ,2 Mbit, Low Voltage, Page-Erasable Serial Flash Memory With Byte-Alterability and a 25 MHz SPI Bus InterfaceM45PE202 Mbit, Low Voltage, Page-Erasable Serial Flash MemoryWith Byte-Alterability and a 25 MHz SP ..
M45PE40-VMN6TP , 4 Mbit, low voltage, Page-Erasable Serial Flash memory with byte-alterability and a 50 MHz SPI bus interface
M45PE40-VMP6G ,4 Mbit, Low Voltage, Page-Erasable Serial Flash Memory With Byte-Alterability and a 25 MHz SPI Bus InterfaceAbsolute Maximum Ratings . . . . . . . 26DC AND AC PARAMETERS . 27Table 8. Operating Cond ..
M45PE40-VMW6G , 4 Mbit, Low Voltage, Page-Erasable Serial Flash Memory With Byte-Alterability and a 33 MHz SPI Bus Interface
M6045C , Dual Common-Cathode Schottky Rectifier
M6045P , Dual Common-Cathode Schottky Rectifier
M6045P. , Dual Common-Cathode Schottky Rectifier
M6060P , Dual Common-Cathode Schottky Rectifier
M6060P. , Dual Common-Cathode Schottky Rectifier
M-608T , DC Line Fileters
M45PE20VMN6P-M45PE20-VMN6P-M45PE20VMN6TP-M45PE20-VMN6TP-M45PE20-VMP6G-M45PE20-VMP6TG
2 Mbit, Low Voltage, Page-Erasable Serial Flash Memory With Byte-Alterability and a 25 MHz SPI Bus Interface
1/35October 2004
M45PE202 Mbit, Low Voltage, Page-Erasable Serial Flash Memory
With Byte-Alterability and a 25 MHz SPI Bus Interface
FEATURES SUMMARY 2Mbit of Page-Erasable Flash Memory Page Write (up to 256 Bytes) in 11ms (typical) Page Program (up to 256 Bytes) in 1.2ms
(typical) Page Erase (256 Bytes) in 10ms (typical) Sector Erase (512 Kbit) 2.7 to 3.6V Single Supply Voltage SPI Bus Compatible Serial Interface 25MHz Clock Rate (maximum) Deep Power-down Mode 1µA (typical) Electronic Signature JEDEC Standard Two-Byte Signature
(4012h) More than 100,000 Write Cycles More than 20 Year Data Retention
Figure 1. Packages
M45PE20
TABLE OF CONTENTS
FEATURES SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Figure 1. Packages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
SUMMARY DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5Figure 2. Logic Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Figure 3. SO and VDFPN Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Table 1. Signal Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
SIGNAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Serial Data Output (Q). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Serial Data Input (D) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Serial Clock (C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Chip Select (S) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Reset (Reset). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Write Protect (W) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
SPI MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7Figure 4. Bus Master and Memory Devices on the SPI Bus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Figure 5. SPI Modes Supported . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
OPERATING FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Sharing the Overhead of Modifying Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
An Easy Way to Modify Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
A Fast Way to Modify Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Polling During a Write, Program or Erase Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Active Power, Standby Power and Deep Power-Down Modes . . . . . . . . . . . . . . . . . . . . . . . . . .8
Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9WIP bit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
WEL bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Table 2. Status Register Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Protection Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
MEMORY ORGANIZATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10Table 3. Memory Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Figure 6. Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11Table 4. Instruction Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Write Enable (WREN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12Figure 7. Write Enable (WREN) Instruction Sequence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Write Disable (WRDI). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12Figure 8. Write Disable (WRDI) Instruction Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
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M45PE20
Read Identification (RDID) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Table 5. Read Identification (RDID) Data-Out Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Figure 9. Read Identification (RDID) Instruction Sequence and Data-Out Sequence . . . . . . . . . .13
Read Status Register (RDSR). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14WIP bit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
WEL bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Figure 10.Read Status Register (RDSR) Instruction Sequence and Data-Out Sequence . . . . . . .14
Read Data Bytes (READ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15Figure 11.Read Data Bytes (READ) Instruction Sequence and Data-Out Sequence . . . . . . . . . . .15
Read Data Bytes at Higher Speed (FAST_READ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16Figure 12.Read Data Bytes at Higher Speed (FAST_READ) Instruction Sequence and Data-Out Se-
quence 16
Page Write (PW). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17Figure 13.Page Write (PW) Instruction Sequence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Page Program (PP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18Figure 14.Page Program (PP) Instruction Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Page Erase (PE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19Figure 15.Page Erase (PE) Instruction Sequence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Sector Erase (SE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20Figure 16.Sector Erase (SE) Instruction Sequence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Deep Power-down (DP). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21Figure 17.Deep Power-down (DP) Instruction Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Release from Deep Power-down (RDP). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22Figure 18.Release from Deep Power-down (RDP) Instruction Sequence. . . . . . . . . . . . . . . . . . . .22
POWER-UP AND POWER-DOWN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23Figure 19.Power-up Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Table 6. Power-Up Timing and VWI Threshold. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
INITIAL DELIVERY STATE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
MAXIMUM RATING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25Table 7. Absolute Maximum Ratings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
DC AND AC PARAMETERS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26Table 8. Operating Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Table 9. AC Measurement Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Figure 20.AC Measurement I/O Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Table 10. Capacitance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Table 11. DC Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Table 12. AC Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Figure 21.Serial Input Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Figure 22.Write Protect Setup and Hold Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Figure 23.Output Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Figure 24.Reset AC Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
M45PE20
PACKAGE MECHANICAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31Figure 25.SO8 narrow – 8 lead Plastic Small Outline, 150 mils body width, Package Outline . . . .31
Table 13. SO8 narrow – 8 lead Plastic Small Outline, 150 mils body width, Package Mechanical Data
Figure 26.MLP8, 8-lead Very thin Dual Flat Package No lead, 6x5mm, Package Outline . . . . . . .32
Table 14. MLP8, 8-lead Very thin Dual Flat Package No lead, 6x5mm, Package Mechanical Data32
PART NUMBERING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33Table 15. Ordering Information Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
REVISION HISTORY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34Table 16. Document Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
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M45PE20
SUMMARY DESCRIPTIONThe M45PE20 is a 2Mbit (256K x 8 bit) Serial
Paged Flash Memory accessed by a high speed
SPI-compatible bus.
The memory can be written or programmed 1 to
256 bytes at a time, using the Page Write or Page
Program instruction. The Page Write instruction
consists of an integrated Page Erase cycle fol-
lowed by a Page Program cycle.
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 memory can be erased a page at a time, using
the Page Erase instruction, or a sector at a time,
using the Sector Erase instruction.
Figure 2. Logic Diagram
Figure 3. SO and VDFPN ConnectionsNote:1. There is an exposed die paddle on the underside of the
MLP8 package. This is pulled, internally, to VSS, and
must not be allowed to be connected to any other voltage
or signal line on the PCB. See PACKAGE MECHANICAL section for package di-
mensions, and how to identify pin-1.
Table 1. Signal Names
M45PE20
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 Read,
Program, Erase or Write cycle is in progress, the
device will be in the Standby Power mode (this is
not the Deep Power-down mode). Driving Chip
Select (S) Low selects 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.
Reset (Reset). The Reset (Reset) input provides
a hardware reset for the memory. In this mode, the
outputs are high impedance.
When Reset (Reset) is driven High, the memory is
in the normal operating mode. When Reset (Re-
set) is driven Low, the memory will enter the Reset
mode, provided that no internal operation is cur-
rently in progress. Driving Reset (Reset) Low while
an internal operation is in progress has no effect
on that internal operation (a write cycle, program
cycle, or erase cycle).
Write Protect (W). This input signal puts the de-
vice in the Hardware Protected mode, when Write
Protect (W) is connected to VSS, causing the first
256 pages of memory to become read-only by pro-
tecting them from write, program and erase oper-
ations. When Write Protect (W) is connected to
VCC, the first 256 pages of memory behave like
the other pages of memory.
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M45PE20
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
master 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: The Write Protect (W) signal should be driven, High or Low as appropriate.
Figure 5. SPI Modes Supported
M45PE20
OPERATING FEATURES
Sharing the Overhead of Modifying DataTo write or program one (or more) data bytes, two
instructions are required: Write Enable (WREN),
which is one byte, and a Page Write (PW) or Page
Program (PP) sequence, which consists of four
bytes plus data. This is followed by the internal cy-
cle (of duration tPW or tPP).
To share this overhead, the Page Write (PW) or
Page Program (PP) instruction allows up to 256
bytes to be programmed (changing bits from 1 to
0) or written (changing bits to 0 or 1) at a time, pro-
vided that they lie in consecutive addresses on the
same page of memory.
An Easy Way to Modify DataThe Page Write (PW) instruction provides a con-
venient way of modifying data (up to 256 contigu-
ous bytes at a time), and simply requires the start
address, and the new data in the instruction se-
quence.
The Page Write (PW) instruction is entered by
driving Chip Select (S) Low, and then transmitting
the instruction byte, three address bytes (A23-A0)
and at least one data byte, and then driving Chip
Select (S) High. While Chip Select (S) is being
held Low, the data bytes are written to the data
buffer, starting at the address given in the third ad-
dress byte (A7-A0). When Chip Select (S) is driven
High, the Write cycle starts. The remaining, un-
changed, bytes of the data buffer are automatically
loaded with the values of the corresponding bytes
of the addressed memory page. The addressed
memory page then automatically put into an Erase
cycle. Finally, the addressed memory page is pro-
grammed with the contents of the data buffer.
All of this buffer management is handled internally,
and is transparent to the user. The user is given
the facility of being able to alter the contents of the
memory on a byte-by-byte basis.
A Fast Way to Modify DataThe Page Program (PP) instruction provides a fast
way of modifying data (up to 256 contiguous bytes
at a time), provided that it only involves resetting
bits to 0 that had previously been set to 1.
This might be: when the designer is programming the device
for the first time when the designer knows that the page has
already been erased by an earlier Page Erase
(PE) or Sector Erase (SE) instruction. This is
useful, for example, when storing a fast
stream of data, having first performed the
erase cycle when time was available when the designer knows that the only
changes involve resetting bits to 0 that are still
set to 1. When this method is possible, it has
the additional advantage of minimising the
number of unnecessary erase operations, and
the extra stress incurred by each page.
Polling During a Write, Program or Erase CycleA further improvement in the write, program or
erase time can be achieved by not waiting for the
worst case delay (tPW, tPP, tPE, or tSE). The Write
In Progress (WIP) bit is provided in the Status
Register so that the application program can mon-
itor its value, polling it to establish when the previ-
ous cycle is complete.
ResetAn internal Power On Reset circuit helps protect
against inadvertent data writes. Addition protec-
tion is provided by driving Reset (Reset) Low dur-
ing the Power-on process, and only driving it High
when VCC has reached the correct voltage level,
VCC(min).
Active Power, Standby Power and Deep
Power-Down ModesWhen Chip Select (S) is Low, the device is select-
ed, and in the Active Power mode.
When Chip Select (S) is High, the device is dese-
lected, but could remain in the Active Power mode
until all internal cycles have completed (Program,
Erase, Write). The device then goes in to the
Standby Power mode. The device consumption
drops to ICC1.
The Deep Power-down mode is entered when the
specific instruction (the Deep Power-down (DP) in-
struction) is executed. The device consumption
drops further to ICC2. The device remains in this
mode until another specific instruction (the Re-
lease from Deep Power-down and Read Electron-
ic 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 inadvertent Write, Program or Erase
instructions.
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M45PE20
Status RegisterThe Status Register contains two status bits that
can be read by the Read Status Register (RDSR)
instruction.
WIP bit. The Write In Progress (WIP) bit indicates
whether the memory is busy with a Write, Program
or Erase cycle.
WEL bit. The Write Enable Latch (WEL) bit indi-
cates the status of the internal Write Enable Latch.
Table 2. Status Register FormatNote: WEL and WIP are volatile read-only bits (WEL is set and re-
set by specific instructions; WIP is automatically set and re-
set by the internal logic of the device).
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 M45PE20 features
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 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 Reset (RESET) driven Low Write Disable (WRDI) instruction
completion Page Write (PW) instruction completion Page Program (PP) instruction completion Page Erase (PE) instruction completion Sector Erase (SE) instruction completion The Hardware Protected mode is entered
when Write Protect (W) is driven Low, causing
the first 256 pages of memory to become
read-only. When Write Protect (W) is driven
High, the first 256 pages of memory behave
like the other pages of memory The Reset (Reset) signal can be driven Low to
protect the contents of the memory during any
critical time, not just during Power-up and
Power-down. In addition to the low power consumption
feature, the Deep Power-down mode offers
extra software protection from inadvertant
Write, Program and Erase instructions while
the device is not in active use.
b7 b0
M45PE20
MEMORY ORGANIZATIONThe memory is organized as: 1024 pages (256 bytes each). 262,144 bytes (8 bits each) 4 sectors (512 Kbits, 65536 bytes each)
Each page can be individually: programmed (bits are programmed from 1 to erased (bits are erased from 0 to 1) written (bits are changed to either 0 or 1)
The device is Page or Sector Erasable (bits are
erased from 0 to 1).
Table 3. Memory Organization
Figure 6. Block Diagram
11/35
M45PE20
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.
In the case of a Read Data Bytes (READ), Read
Data Bytes at Higher Speed (Fast_Read) or Read
Status Register (RDSR) instruction, the shifted-in
instruction sequence is followed by a data-out se-
quence. 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 Write (PW), Page Program
(PP), Page Erase (PE), Sector Erase (SE), Write
Enable (WREN), Write Disable (WRDI), Deep
Power-down (DP) or Release from Deep Power-
down (RDP) instruction, Chip Select (S) must be
driven High exactly at a byte boundary, otherwise
the instruction is rejected, 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 cycle, Program cycle or Erase cycle are ig-
nored, and the internal Write cycle, Program cycle
or Erase cycle continues unaffected.
Table 4. Instruction Set
M45PE20
Write Enable (WREN)The Write Enable (WREN) instruction (Figure 7.)
sets the Write Enable Latch (WEL) bit.
The Write Enable Latch (WEL) bit must be set pri-
or to every Page Write (PW), Page Program (PP),
Page Erase (PE), and Sector Erase (SE) instruc-
tion.
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.
Write Disable (WRDI)The Write Disable (WRDI) instruction (Figure 8.)
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 Page Write (PW) instruction completion Page Program (PP) instruction completion Page Erase (PE) instruction completion Sector Erase (SE) instruction completion
13/35
M45PE20
Read Identification (RDID)The Read Identification (RDID) instruction allows
the 8-bit manufacturer identification to be read, fol-
lowed by two bytes of device identification. The
manufacturer identification is assigned by JEDEC,
and has the value 20h for STMicroelectronics. The
device identification is assigned by the device
manufacturer, and indicates the memory type in
the first byte (40h), and the memory capacity of the
device in the second byte (12h).
Any Read Identification (RDID) instruction while
an Erase or Program cycle is in progress, is not
decoded, and has no effect on the cycle that is in
progress.
The device is first selected by driving Chip Select
(S) Low. Then, the 8-bit instruction code for the in-
struction is shifted in. This is followed by the 24-bit
device identification, stored in the memory, being
shifted out on Serial Data Output (Q), each bit be-
ing shifted out during the falling edge of Serial
Clock (C).
The instruction sequence is shown in Figure 9..
The Read Identification (RDID) instruction is termi-
nated by driving Chip Select (S) High at any time
during data output.
When Chip Select (S) is driven High, the device is
put in the Standby Power mode. Once in the
Standby Power mode, the device waits to be se-
lected, so that it can receive, decode and execute
instructions.
M45PE20
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 cycle is in progress.
When one of these cycles is in progress, it is rec-
ommended to check the Write In Progress (WIP)
bit before sending a new instruction to the device.
It is also possible to read the Status Register con-
tinuously, as shown in Figure 10..
The status bits of the Status Register are as fol-
lows:
WIP bit. The Write In Progress (WIP) bit indicates
whether the memory is busy with a Write, 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, Program or Erase instruction
is accepted.
15/35
M45PE20
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 11..
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.
Figure 11. Read Data Bytes (READ) Instruction Sequence and Data-Out SequenceNote: Address bits A23 to A18 are Don’t Care.
M45PE20
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 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 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.
Figure 12. Read Data Bytes at Higher Speed (FAST_READ) Instruction Sequence and Data-Out
SequenceNote: Address bits A23 to A18 are Don’t Care.
17/35
M45PE20
Page Write (PW)The Page Write (PW) instruction allows bytes to
be written in the memory. Before it can be accept-
ed, a Write Enable (WREN) instruction must previ-
ously have been executed. After the Write Enable
(WREN) instruction has been decoded, the device
sets the Write Enable Latch (WEL).
The Page Write (PW) 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). The rest of
the page remains unchanged if no power failure
occurs during this write cycle.
The Page Write (PW) instruction performs a page
erase cycle even if only one byte is updated.
If the 8 least significant address bits (A7-A0) are
not all zero, all transmitted data exceeding the ad-
dressed page boundary wrap round, and are writ-
ten from the start address of the same page (the
one whose 8 least significant address 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 13..
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 written correctly
within the same page. If less than 256 Data bytes
are sent to device, they are correctly written at the
requested addresses without having 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 Write (PW) instruction is not
executed.
As soon as Chip Select (S) is driven High, the self-
timed Page Write cycle (whose duration is tPW) is
initiated. While the Page Write cycle is in progress,
the Status Register may be read to check the val-
ue of the Write In Progress (WIP) bit. The Write In
Progress (WIP) bit is 1 during the self-timed Page
Write cycle, and is 0 when it is completed. At some
unspecified time before the cycle is complete, the
Write Enable Latch (WEL) bit is reset.
A Page Write (PW) instruction applied to a page
that is Hardware Protected is not executed.
Any Page Write (PW) instruction, while an Erase,
Program or Write cycle is in progress, is rejected
without having any effects on the cycle that is in
progress.
Figure 13. Page Write (PW) Instruction SequenceNote:1. Address bits A23 to A18 are Don’t Care 1 ≤ n ≤ 256
M45PE20
Page Program (PP)The Page Program (PP) instruction allows bytes to
be programmed in the memory (changing bits from
1 to 0, only). Before it can be accepted, a Write En-
able (WREN) instruction must previously have
been executed. After the Write Enable (WREN) in-
struction has been decoded, the device sets the
Write Enable 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 exceeding the ad-
dressed page boundary wrap round, and are pro-
grammed from the start address of the same page
(the one whose 8 least significant address bits
(A7-A0) are all zero). Chip Select (S) must be driv-
en 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 complete, the Write Enable Latch (WEL)
bit is reset.
A Page Program (PP) instruction applied to a page
that is Hardware Protected is not executed.
Any Page Program (PP) instruction, while an
Erase, Program or Write cycle is in progress, is re-
jected without having any effects on the cycle that
is in progress.
Figure 14. Page Program (PP) Instruction SequenceNote:1. Address bits A23 to A18 are Don’t Care 1 ≤ n ≤ 256
