AT25DF641-S3H-B [ATMEL]
64-Megabit 2.7-volt Minimum SPI Serial Flash Memory; 64兆位2.7伏最小的SPI串行闪存
| 型号： | AT25DF641-S3H-B |
| 厂家： | 
ATMEL |
| 描述： | 64-Megabit 2.7-volt Minimum SPI Serial Flash Memory |
| 文件： | 总59页 (文件大小：1167K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Features
• Single 2.7V - 3.6V Supply
• Serial Peripheral Interface (SPI) Compatible
– Supports SPI Modes 0 and 3
– Supports RapidS® Operation
– Supports Dual-Input Program and Dual-Output Read
• Very High Operating Frequencies
– 100 MHz for RapidS
– 85 MHz for SPI
64-Megabit
2.7-volt
Minimum
SPI Serial Flash
Memory
– Clock-to-Output (tV) of 5 ns Maximum
• Flexible, Optimized Erase Architecture for Code + Data Storage Applications
– Uniform 4-Kbyte Block Erase
– Uniform 32-Kbyte Block Erase
– Uniform 64-Kbyte Block Erase
– Full Chip Erase
• Individual Sector Protection with Global Protect/Unprotect Feature
– 128 Sectors of 64-Kbytes Each
• Hardware Controlled Locking of Protected Sectors via WP Pin
• Sector Lockdown
– Make Any Combination of 64-Kbyte Sectors Permanently Read-Only
• 128-Byte Programmable OTP Security Register
• Flexible Programming
– Byte/Page Program (1 to 256 Bytes)
• Fast Program and Erase Times
– 1.0 ms Typical Page Program (256 Bytes) Time
– 50 ms Typical 4-Kbyte Block Erase Time
– 250 ms Typical 32-Kbyte Block Erase Time
– 400 ms Typical 64-Kbyte Block Erase Time
• Program and Erase Suspend/Resume
• Automatic Checking and Reporting of Erase/Program Failures
• Software Controlled Reset
AT25DF641
Preliminary
See applicable errata
in Section 18.
• JEDEC Standard Manufacturer and Device ID Read Methodology
• Low Power Dissipation
– 5 mA Active Read Current (Typical at 20 MHz)
– 5 µA Deep Power-Down Current (Typical)
• Endurance: 100,000 Program/Erase Cycles
• Data Retention: 20 Years
• Complies with Full Industrial Temperature Range
• Industry Standard Green (Pb/Halide-free/RoHS Compliant) Package Options
– 16-Lead SOIC (300-mil wide)
– 8-Contact Very Thin DFN (6 x 8 mm)
1. Description
The AT25DF641 is a serial interface Flash memory device designed for use in a wide
variety of high-volume consumer based applications in which program code is shad-
owed from Flash memory into embedded or external RAM for execution. The flexible
erase architecture of the AT25DF641, with its erase granularity as small as 4-Kbytes,
makes it ideal for data storage as well, eliminating the need for additional data storage
EEPROM devices.
3680E–DFLASH–12/08
The physical sectoring and the erase block sizes of the AT25DF641 have been optimized to
meet the needs of today's code and data storage applications. By optimizing the size of the
physical sectors and erase blocks, the memory space can be used much more efficiently.
Because certain code modules and data storage segments must reside by themselves in their
own protected sectors, the wasted and unused memory space that occurs with large sectored
and large block erase Flash memory devices can be greatly reduced. This increased memory
space efficiency allows additional code routines and data storage segments to be added while
still maintaining the same overall device density.
The AT25DF641 also offers a sophisticated method for protecting individual sectors against
erroneous or malicious program and erase operations. By providing the ability to individually pro-
tect and unprotect sectors, a system can unprotect a specific sector to modify its contents while
keeping the remaining sectors of the memory array securely protected. This is useful in applica-
tions where program code is patched or updated on a subroutine or module basis, or in
applications where data storage segments need to be modified without running the risk of errant
modifications to the program code segments. In addition to individual sector protection capabili-
ties, the AT25DF641 incorporates Global Protect and Global Unprotect features that allow the
entire memory array to be either protected or unprotected all at once. This reduces overhead
during the manufacturing process since sectors do not have to be unprotected one-by-one prior
to initial programming.
To take code and data protection to the next level, the AT25DF641 incorporates a sector lock-
down mechanism that allows any combination of individual 64-Kbyte sectors to be locked down
and become permanently read-only. This addresses the need of certain secure applications that
require portions of the Flash memory array to be permanently protected against malicious
attempts at altering program code, data modules, security information, or encryption/decryption
algorithms, keys, and routines. The device also contains a specialized OTP (One-Time Pro-
grammable) Security Register that can be used for purposes such as unique device
serialization, system-level Electronic Serial Number (ESN) storage, locked key storage, etc.
Specifically designed for use in 3-volt systems, the AT25DF641 supports read, program, and
erase operations with a supply voltage range of 2.7V to 3.6V. No separate voltage is required for
programming and erasing.
2
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
2. Pin Descriptions and Pinouts
Table 2-1.
Pin Descriptions
Asserted
Symbol
Name and Function
State
Type
CHIP SELECT: Asserting the CS pin selects the device. When the CS pin is deasserted,
the device will be deselected and normally be placed in standby mode (not Deep Power-
Down mode), and the SO pin will be in a high-impedance state. When the device is
deselected, data will not be accepted on the SI pin.
CS
Low
Input
A high-to-low transition on the CS pin is required to start an operation, and a low-to-high
transition is required to end an operation. When ending an internally self-timed operation
such as a program or erase cycle, the device will not enter the standby mode until the
completion of the operation.
SERIAL CLOCK: This pin is used to provide a clock to the device and is used to control the
flow of data to and from the device. Command, address, and input data present on the SI pin
is always latched in on the rising edge of SCK, while output data on the SO pin is always
clocked out on the falling edge of SCK.
SCK
-
-
Input
SERIAL INPUT (SERIAL INPUT/OUTPUT): The SI pin is used to shift data into the device.
The SI pin is used for all data input including command and address sequences. Data on the
SI pin is always latched in on the rising edge of SCK.
With the Dual-Output Read Array command, the SI pin becomes an output pin (SIO) to allow
two bits of data (on the SO and SIO pins) to be clocked out on every falling edge of SCK. To
maintain consistency with SPI nomenclature, the SIO pin will be referenced as SI throughout
the document with exception to sections dealing with the Dual-Output Read Array command
in which it will be referenced as SIO.
SI (SIO)
Input/Output
Data present on the SI pin will be ignored whenever the device is deselected (CS is
deasserted).
SERIAL OUTPUT (SERIAL OUTPUT/INPUT): The SO pin is used to shift data out from the
device. Data on the SO pin is always clocked out on the falling edge of SCK.
With the Dual-Input Byte/Page Program command, the SO pin becomes an input pin (SOI)
to allow two bits of data (on the SOI and SI pins) to be clocked in on every rising edge of
SO (SOI) SCK. To maintain consistency with SPI nomenclature, the SOI pin will be referenced as SO
throughout the document with exception to sections dealing with the Dual-Input Byte/Page
Program command in which it will be referenced as SOI.
-
Output/Input
The SO pin will be in a high-impedance state whenever the device is deselected (CS is
deasserted).
WRITE PROTECT: The WP pin controls the hardware locking feature of the device. Please
refer to “Protection Commands and Features” on page 21 for more details on protection
features and the WP pin.
WP
Low
Input
The WP pin is internally pulled-high and may be left floating if hardware controlled protection
will not be used. However, it is recommended that the WP pin also be externally connected
to VCC whenever possible.
3
3680E–DFLASH–12/08
Table 2-1.
Symbol
Pin Descriptions (Continued)
Asserted
State
Name and Function
Type
HOLD: The HOLD pin is used to temporarily pause serial communication without
deselecting or resetting the device. While the HOLD pin is asserted, transitions on the SCK
pin and data on the SI pin will be ignored, and the SO pin will be in a high-impedance state.
The CS pin must be asserted, and the SCK pin must be in the low state in order for a Hold
condition to start. A Hold condition pauses serial communication only and does not have an
effect on internally self-timed operations such as a program or erase cycle. Please refer to
“Hold” on page 46 for additional details on the Hold operation.
HOLD
Low
Input
The HOLD pin is internally pulled-high and may be left floating if the Hold function will not be
used. However, it is recommended that the HOLD pin also be externally connected to VCC
whenever possible.
DEVICE POWER SUPPLY: The VCC pin is used to supply the source voltage to the device.
VCC
-
-
Power
Power
Operations at invalid VCC voltages may produce spurious results and should not be
attempted.
GROUND: The ground reference for the power supply. GND should be connected to the
system ground.
GND
Figure 2-1. 8-VDFN (Top View)
Figure 2-2. 16-SOIC (Top View)
1
8
7
6
5
CS
VCC
HOLD
VCC
NC
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
SCK
SI (SIO)
2
SO (SOI)
HOLD
SCK
3
WP
NC
4
GND
SI (SIO)
NC
NC
NC
NC
NC
NC
CS
GND
WP
SO (SOI)
4
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
3. Block Diagram
Figure 3-1. Block Diagram
CONTROL AND
I/O BUFFERS
PROTECTION LOGIC
AND LATCHES
CS
SRAM
DATA BUFFER
SCK
INTERFACE
CONTROL
AND
LOGIC
SI (SIO)
Y-DECODER
Y-GATING
SO (SOI)
FLASH
MEMORY
ARRAY
WP
X-DECODER
HOLD
4. Memory Array
To provide the greatest flexibility, the memory array of the AT25DF641 can be erased in four lev-
els of granularity including a full chip erase. In addition, the array has been divided into physical
sectors of uniform size, of which each sector can be individually protected from program and
erase operations. The size of the physical sectors is optimized for both code and data storage
applications, allowing both code and data segments to reside in their own isolated regions. The
Memory Architecture Diagram illustrates the breakdown of each erase level as well as the
breakdown of each physical sector.
5
3680E–DFLASH–12/08
Figure 4-1. Memory Architecture Diagram
Block Erase Detail
Page Program Detail
Internal Sectoring for
Protection, Lockdown,
and Suspend Functions
64KB
Block Erase
32KB
Block Erase
4KB
Block Erase
1-256 Byte
Page Program
(02h Command)
Block Address
Range
Page Address
Range
(D8h Command) (52h Command) (20h Command)
4KB
4KB
4KB
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
7FFFFFh – 7FF000h
7FEFFFh– 7FE000h
7FDFFFh – 7FD000h
7FCFFFh– 7FC000h
7FBFFFh – 7FB000h
7FAFFFh – 7FA000h
7F9FFFh – 7F9000h
7F8FFFh – 7F8000h
7F7FFFh – 7F7000h
7F6FFFh – 7F6000h
7F5FFFh – 7F5000h
7F4FFFh – 7F4000h
7F3FFFh – 7F3000h
7F2FFFh – 7F2000h
7F1FFFh – 7F1000h
7F0FFFh – 7F0000h
7EFFFFh– 7EF000h
7EEFFFh– 7EE000h
7EDFFFh – 7ED000h
7ECFFFh– 7EC000h
7EBFFFh– 7EB000h
7EAFFFh – 7EA000h
7E9FFFh – 7E9000h
7E8FFFh – 7E8000h
7E7FFFh – 7E7000h
7E6FFFh – 7E6000h
7E5FFFh – 7E5000h
7E4FFFh – 7E4000h
7E3FFFh – 7E3000h
7E2FFFh – 7E2000h
7E1FFFh – 7E1000h
7E0FFFh – 7E0000h
7FFFFFh – 7FFF00h
7FFEFFh– 7FFE00h
7FFDFFh – 7FFD00h
7FFCFFh– 7FFC00h
7FFBFFh – 7FFB00h
7FFAFFh – 7FFA00h
7FF9FFh – 7FF900h
7FF8FFh – 7FF800h
7FF7FFh – 7FF700h
7FF6FFh – 7FF600h
7FF5FFh – 7FF500h
7FF4FFh – 7FF400h
7FF3FFh – 7FF300h
7FF2FFh – 7FF200h
7FF1FFh – 7FF100h
7FF0FFh – 7FF000h
7FEFFFh– 7FEF00h
7FEEFFh– 7FEE00h
7FEDFFh – 7FED00h
7FECFFh– 7FEC00h
7FEBFFh– 7FEB00h
7FEAFFh – 7FEA00h
7FE9FFh – 7FE900h
7FE8FFh – 7FE800h
4KB
32KB
4KB
4KB
4KB
4KB
4KB
4KB
4KB
64KB
(Sector 127)
64KB
4KB
32KB
4KB
4KB
4KB
4KB
4KB
4KB
4KB
4KB
32KB
4KB
4KB
4KB
4KB
4KB
4KB
4KB
64KB
(Sector 126)
64KB
4KB
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
256 Bytes
0017FFh – 001700h
0016FFh – 001600h
0015FFh – 001500h
0014FFh – 001400h
0013FFh – 001300h
0012FFh – 001200h
0011FFh – 001100h
0010FFh – 001000h
000FFFh – 000F00h
000EFFh – 000E00h
000DFFh – 000D00h
000CFFh – 000C00h
000BFFh – 000B00h
000AFFh – 000A00h
0009FFh – 000900h
0008FFh – 000800h
0007FFh – 000700h
0006FFh – 000600h
0005FFh – 000500h
0004FFh – 000400h
0003FFh – 000300h
0002FFh – 000200h
0001FFh – 000100h
0000FFh – 000000h
32KB
4KB
4KB
4KB
4KB
4KB
4KB
4KB
00FFFFh – 00F000h
00EFFFh – 00E000h
00DFFFh – 00D000h
00CFFFh – 00C000h
00BFFFh – 00B000h
00AFFFh – 00A000h
009FFFh – 009000h
008FFFh – 008000h
007FFFh – 007000h
006FFFh – 006000h
005FFFh – 005000h
004FFFh – 004000h
003FFFh – 003000h
002FFFh – 002000h
001FFFh – 001000h
000FFFh – 000000h
4KB
32KB
4KB
4KB
4KB
4KB
4KB
4KB
4KB
64KB
(Sector 0)
64KB
4KB
32KB
4KB
4KB
4KB
4KB
6
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
5. Device Operation
The AT25DF641 is controlled by a set of instructions that are sent from a host controller, com-
monly referred to as the SPI Master. The SPI Master communicates with the AT25DF641 via the
SPI bus which is comprised of four signal lines: Chip Select (CS), Serial Clock (SCK), Serial
Input (SI), and Serial Output (SO).
The AT25DF641 features a dual-input program mode in which the SO pin becomes an input.
Similarly, the device also features a dual-output read mode in which the SI pin becomes an out-
put. In the Dual-Input Byte/Page Program command description, the SO pin will be referred to as
the SOI (Serial Output/Input) pin, and in the Dual-Output Read Array command, the SI pin will be
referenced as the SIO (Serial Input/Output) pin.
The SPI protocol defines a total of four modes of operation (mode 0, 1, 2, or 3) with each mode
differing in respect to the SCK polarity and phase and how the polarity and phase control the
flow of data on the SPI bus. The AT25DF641 supports the two most common modes, SPI
Modes 0 and 3. The only difference between SPI Modes 0 and 3 is the polarity of the SCK signal
when in the inactive state (when the SPI Master is in standby mode and not transferring any
data). With SPI Modes 0 and 3, data is always latched in on the rising edge of SCK and always
output on the falling edge of SCK.
Figure 5-1. SPI Mode 0 and 3
CS
SCK
MSB
LSB
SI
MSB
LSB
SO
6. Commands and Addressing
A valid instruction or operation must always be started by first asserting the CS pin. After the CS
pin has been asserted, the host controller must then clock out a valid 8-bit opcode on the SPI
bus. Following the opcode, instruction dependent information such as address and data bytes
would then be clocked out by the host controller. All opcode, address, and data bytes are trans-
ferred with the most-significant bit (MSB) first. An operation is ended by deasserting the CS pin.
Opcodes not supported by the AT25DF641 will be ignored by the device and no operation will be
started. The device will continue to ignore any data presented on the SI pin until the start of the
next operation (CS pin being deasserted and then reasserted). In addition, if the CS pin is deas-
serted before complete opcode and address information is sent to the device, then no operation
will be performed and the device will simply return to the idle state and wait for the next
operation.
Addressing of the device requires a total of three bytes of information to be sent, representing
address bits A23-A0. Since the upper address limit of the AT25DF641 memory array is
7FFFFFh, address bit A23 is always ignored by the device.
7
3680E–DFLASH–12/08
Table 6-1.
Command
Command Listing
Clock
Frequency
Address
Bytes
Dummy
Bytes
Data
Bytes
Opcode
Read Commands
1Bh
0Bh
03h
3Bh
0001 1011
Up to 100 MHz
Up to 85 MHz
Up to 50 MHz
Up to 85 MHz
3
3
3
3
2
1
0
1
1+
1+
1+
1+
Read Array
0000 1011
0000 0011
0011 1011
Dual-Output Read Array
Program and Erase Commands
Block Erase (4-KBytes)
20h
52h
D8h
60h
C7h
02h
A2h
B0h
D0h
0010 0000
0101 0010
1101 1000
0110 0000
1100 0111
0000 0010
1010 0010
1011 0000
1101 0000
Up to 100 MHz
Up to 100 MHz
Up to 100 MHz
Up to 100 MHz
Up to 100 MHz
Up to 100 MHz
Up to 100 MHz
Up to 100 MHz
Up to 100 MHz
3
3
3
0
0
3
3
0
0
0
0
0
0
0
0
0
0
0
0
0
Block Erase (32-KBytes)
Block Erase (64-KBytes)
0
0
Chip Erase
0
Byte/Page Program (1 to 256 Bytes)
Dual-Input Byte/Page Program (1 to 256 Bytes)
Program/Erase Suspend
Program/Erase Resume
Protection Commands
Write Enable
1+
1+
0
0
06h
04h
36h
39h
0000 0110
0000 0100
0011 0110
0011 1001
Up to 100 MHz
Up to 100 MHz
Up to 100 MHz
Up to 100 MHz
0
0
3
3
0
0
0
0
0
0
0
0
Write Disable
Protect Sector
Unprotect Sector
Global Protect/Unprotect
Read Sector Protection Registers
Security Commands
Use Write Status Register Byte 1 Command
3Ch
0011 1100
Up to 100 MHz
3
0
1+
Sector Lockdown
33h
34h
35h
9Bh
77h
0011 0011
0011 0100
0011 0101
1001 1011
0111 0111
Up to 100 MHz
Up to 100 MHz
Up to 100 MHz
Up to 100 MHz
Up to 100 MHz
3
3
3
3
3
0
0
0
0
2
1
Freeze Sector Lockdown State
Read Sector Lockdown Registers
Program OTP Security Register
Read OTP Security Register
Status Register Commands
Read Status Register
1
1+
1+
1+
05h
01h
31h
0000 0101
0000 0001
0011 0001
Up to 100 MHz
Up to 100 MHz
Up to 100 MHz
0
0
0
0
0
0
1+
1
Write Status Register Byte 1
Write Status Register Byte 2
Miscellaneous Commands
Reset
1
F0h
9Fh
B9h
ABh
1111 0000
1001 1111
1011 1001
1010 1011
Up to 100 MHz
Up to 85 MHz
Up to 100 MHz
Up to 100 MHz
0
0
0
0
0
0
0
0
1
1 to 4
0
Read Manufacturer and Device ID
Deep Power-Down
Resume from Deep Power-Down
0
8
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
7. Read Commands
7.1
Read Array
The Read Array command can be used to sequentially read a continuous stream of data from
the device by simply providing the clock signal once the initial starting address has been speci-
fied. The device incorporates an internal address counter that automatically increments on every
clock cycle.
Three opcodes (1Bh, 0Bh, and 03h) can be used for the Read Array command. The use of each
opcode depends on the maximum clock frequency that will be used to read data from the device.
The 0Bh opcode can be used at any clock frequency up to the maximum specified by fCLK, and
the 03h opcode can be used for lower frequency read operations up to the maximum specified
by fRDLF. The 1Bh opcode allows the highest read performance possible and can be used at any
clock frequency up to the maximum specified by fMAX; however, use of the 1Bh opcode at clock
frequencies above fCLK should be reserved to systems employing the RapidS protocol.
To perform the Read Array operation, the CS pin must first be asserted and the appropriate
opcode (1Bh, 0Bh, or 03h) must be clocked into the device. After the opcode has been clocked
in, the three address bytes must be clocked in to specify the starting address location of the first
byte to read within the memory array. Following the three address bytes, additional dummy
bytes may need to be clocked into the device depending on which opcode is used for the Read
Array operation. If the 1Bh opcode is used, then two dummy bytes must be clocked into the
device after the three address bytes. If the 0Bh opcode is used, then a single dummy byte must
be clocked in after the address bytes.
After the three address bytes (and the dummy bytes or byte if using opcodes 1Bh or 0Bh) have
been clocked in, additional clock cycles will result in data being output on the SO pin. The data is
always output with the MSB of a byte first. When the last byte (7FFFFFh) of the memory array
has been read, the device will continue reading back at the beginning of the array (000000h). No
delays will be incurred when wrapping around from the end of the array to the beginning of the
array.
Deasserting the CS pin will terminate the read operation and put the SO pin into a high-imped-
ance state. The CS pin can be deasserted at any time and does not require that a full byte of
data be read.
Figure 7-1. Read Array - 1Bh Opcode
CS
0
1
2
3
4
5
6
7
8
9
10 11 12
29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56
SCK
SI
OPCODE
ADDRESS BITS A23-A0
DON'T CARE
DON'T CARE
0
0
0
1
1
0
1
1
A
A
A
A
A
A
A
A
A
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
MSB
MSB
MSB
MSB
DATA BYTE 1
HIGH-IMPEDANCE
D
D
D
D
D
D
D
D
D
D
SO
MSB
MSB
9
3680E–DFLASH–12/08
Figure 7-2. Read Array - 0Bh Opcode
CS
0
1
2
3
4
5
6
7
8
9
10 11 12
29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
SCK
SI
OPCODE
ADDRESS BITS A23-A0
DON'T CARE
0
0
0
0
1
0
1
1
A
A
A
A
A
A
A
A
A
X
X
X
X
X
X
X
X
MSB
MSB
MSB
DATA BYTE 1
HIGH-IMPEDANCE
D
D
D
D
D
D
D
D
D
D
SO
MSB
MSB
Figure 7-3. Read Array - 03h Opcode
CS
0
1
2
3
4
5
6
7
8
9
10 11 12
29 30 31 32 33 34 35 36 37 38 39 40
SCK
SI
OPCODE
ADDRESS BITS A23-A0
0
0
0
0
0
0
1
1
A
A
A
A
A
A
A
A
A
MSB
MSB
DATA BYTE 1
HIGH-IMPEDANCE
D
D
D
D
D
D
D
D
D
D
SO
MSB
MSB
7.2
Dual-Output Read Array
The Dual-Output Read Array command is similar to the standard Read Array command and can
be used to sequentially read a continuous stream of data from the device by simply providing the
clock signal once the initial starting address has been specified. Unlike the standard Read Array
command, however, the Dual-Output Read Array command allows two bits of data to be clocked
out of the device on every clock cycle rather than just one.
The Dual-Output Read Array command can be used at any clock frequency up to the maximum
specified by fRDDO. To perform the Dual-Output Read Array operation, the CS pin must first be
asserted and the opcode of 3Bh must be clocked into the device. After the opcode has been
clocked in, the three address bytes must be clocked in to specify the starting address location of
the first byte to read within the memory array. Following the three address bytes, a single
dummy byte must also be clocked into the device.
After the three address bytes and the dummy byte have been clocked in, additional clock cycles
will result in data being output on both the SO and SIO pins. The data is always output with the
MSB of a byte first, and the MSB is always output on the SO pin. During the first clock cycle, bit
7 of the first data byte will be output on the SO pin while bit 6 of the same data byte will be output
on the SIO pin. During the next clock cycle, bits 5 and 4 of the first data byte will be output on the
SO and SIO pins, respectively. The sequence continues with each byte of data being output
after every four clock cycles. When the last byte (7FFFFFh) of the memory array has been read,
10
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
the device will continue reading back at the beginning of the array (000000h). No delays will be
incurred when wrapping around from the end of the array to the beginning of the array.
Deasserting the CS pin will terminate the read operation and put the SO and SIO pins into a
high-impedance state. The CS pin can be deasserted at any time and does not require that a full
byte of data be read.
Figure 7-4. Dual-Output Read Array
CS
SCK
SIO
SO
0
1
2
3
4
5
6
7
8
9
10 11 12
29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
OUTPUT
DATA BYTE 1
OUTPUT
DATA BYTE 2
OPCODE
ADDRESS BITS A23-A0
DON'T CARE
D
D
D
D
D
D
D
D
D
D
D
D
D
D
0
0
1
1
1
0
1
1
A
A
A
A
A
A
A
A
A
X
X
X
X
X
X
X
X
6
4
2
0
1
6
4
2
0
1
6
7
4
5
MSB
MSB
MSB
HIGH-IMPEDANCE
D
D
D
D
D
5
D
7
5
3
7
3
MSB
MSB
MSB
11
3680E–DFLASH–12/08
8. Program and Erase Commands
8.1
Byte/Page Program
The Byte/Page Program command allows anywhere from a single byte of data to 256 bytes of
data to be programmed into previously erased memory locations. An erased memory location is
one that has all eight bits set to the logical “1” state (a byte value of FFh). Before a Byte/Page
Program command can be started, the Write Enable command must have been previously
issued to the device (see “Write Enable” on page 21) to set the Write Enable Latch (WEL) bit of
the Status Register to a logical “1” state.
To perform a Byte/Page Program command, an opcode of 02h must be clocked into the device
followed by the three address bytes denoting the first byte location of the memory array to begin
programming at. After the address bytes have been clocked in, data can then be clocked into the
device and will be stored in an internal buffer.
If the starting memory address denoted by A23-A0 does not fall on an even 256-byte page
boundary (A7-A0 are not all 0), then special circumstances regarding which memory locations to
be programmed will apply. In this situation, any data that is sent to the device that goes beyond
the end of the page will wrap around back to the beginning of the same page. For example, if the
starting address denoted by A23-A0 is 0000FEh, and three bytes of data are sent to the device,
then the first two bytes of data will be programmed at addresses 0000FEh and 0000FFh while
the last byte of data will be programmed at address 000000h. The remaining bytes in the page
(addresses 000001h through 0000FDh) will not be programmed and will remain in the erased
state (FFh). In addition, if more than 256 bytes of data are sent to the device, then only the last
256 bytes sent will be latched into the internal buffer.
When the CS pin is deasserted, the device will take the data stored in the internal buffer and pro-
gram it into the appropriate memory array locations based on the starting address specified by
A23-A0 and the number of data bytes sent to the device. If less than 256 bytes of data were sent
to the device, then the remaining bytes within the page will not be programmed and will remain
in the erased state (FFh). The programming of the data bytes is internally self-timed and should
take place in a time of tPP or tBP if only programming a single byte.
The three address bytes and at least one complete byte of data must be clocked into the device
before the CS pin is deasserted, and the CS pin must be deasserted on even byte boundaries
(multiples of eight bits); otherwise, the device will abort the operation and no data will be pro-
grammed into the memory array. In addition, if the address specified by A23-A0 points to a
memory location within a sector that is in the protected state (see “Protect Sector” on page 22)
or locked down (see “Sector Lockdown” on page 29), then the Byte/Page Program command will
not be executed, and the device will return to the idle state once the CS pin has been deas-
serted. The WEL bit in the Status Register will be reset back to the logical “0” state if the
program cycle aborts due to an incomplete address being sent, an incomplete byte of data being
sent, the CS pin being deasserted on uneven byte boundaries, or because the memory location
to be programmed is protected or locked down.
While the device is programming, the Status Register can be read and will indicate that the
device is busy. For faster throughput, it is recommended that the Status Register be polled
rather than waiting the tBP or tPP time to determine if the data bytes have finished programming.
At some point before the program cycle completes, the WEL bit in the Status Register will be
reset back to the logical “0” state.
The device also incorporates an intelligent programming algorithm that can detect when a byte
location fails to program properly. If a programming error arises, it will be indicated by the EPE
bit in the Status Register.
12
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
Figure 8-1. Byte Program
CS
0
1
2
3
4
5
6
7
8
9
10 11 12
29 30 31 32 33 34 35 36 37 38 39
SCK
SI
OPCODE
ADDRESS BITS A23-A0
DATA IN
0
0
0
0
0
0
1
0
A
A
A
A
A
A
A
A
A
D
D
D
D
D
D
D
D
MSB
MSB
MSB
HIGH-IMPEDANCE
SO
Figure 8-2. Page Program
CS
0
1
2
3
4
5
6
7
8
9
29 30 31 32 33 34 35 36 37 38 39
SCK
SI
OPCODE
ADDRESS BITS A23-A0
DATA IN BYTE 1
DATA IN BYTE n
0
0
0
0
0
0
1
0
A
A
A
A
A
A
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
MSB
MSB
MSB
MSB
HIGH-IMPEDANCE
SO
8.2
Dual-Input Byte/Page Program
The Dual-Input Byte/Page Program command is similar to the standard Byte/Page Program
command and can be used to program anywhere from a single byte of data up to 256 bytes of
data into previously erased memory locations. Unlike the standard Byte/Page Program com-
mand, however, the Dual-Input Byte/Page Program command allows two bits of data to be
clocked into the device on every clock cycle rather than just one.
Before the Dual-Input Byte/Page Program command can be started, the Write Enable command
must have been previously issued to the device (see “Write Enable” on page 21) to set the Write
Enable Latch (WEL) bit of the Status Register to a logical “1” state. To perform a Dual-Input
Byte/Page Program command, an opcode of A2h must be clocked into the device followed by
the three address bytes denoting the first byte location of the memory array to begin program-
ming at. After the address bytes have been clocked in, data can then be clocked into the device
two bits at a time on both the SOI and SI pins.
The data is always input with the MSB of a byte first, and the MSB is always input on the SOI
pin. During the first clock cycle, bit 7 of the first data byte would be input on the SOI pin while bit
6 of the same data byte would be input on the SI pin. During the next clock cycle, bits 5 and 4 of
the first data byte would be input on the SOI and SI pins, respectively. The sequence would con-
tinue with each byte of data being input after every four clock cycles. Like the standard
Byte/Page Program command, all data clocked into the device is stored in an internal buffer.
If the starting memory address denoted by A23-A0 does not fall on an even 256-byte page
boundary (A7-A0 are not all 0), then special circumstances regarding which memory locations to
13
3680E–DFLASH–12/08
be programmed will apply. In this situation, any data that is sent to the device that goes beyond
the end of the page will wrap around back to the beginning of the same page. For example, if the
starting address denoted by A23-A0 is 0000FEh, and three bytes of data are sent to the device,
then the first two bytes of data will be programmed at addresses 0000FEh and 0000FFh while
the last byte of data will be programmed at address 000000h. The remaining bytes in the page
(addresses 000001h through 0000FDh) will not be programmed and will remain in the erased
state (FFh). In addition, if more than 256 bytes of data are sent to the device, then only the last
256 bytes sent will be latched into the internal buffer.
When the CS pin is deasserted, the device will take the data stored in the internal buffer and pro-
gram it into the appropriate memory array locations based on the starting address specified by
A23-A0 and the number of data bytes sent to the device. If less than 256 bytes of data were sent
to the device, then the remaining bytes within the page will not be programmed and will remain
in the erased state (FFh). The programming of the data bytes is internally self-timed and should
take place in a time of tPP or tBP if only programming a single byte.
The three address bytes and at least one complete byte of data must be clocked into the device
before the CS pin is deasserted, and the CS pin must be deasserted on even byte boundaries
(multiples of eight bits); otherwise, the device will abort the operation and no data will be pro-
grammed into the memory array. In addition, if the address specified by A23-A0 points to a
memory location within a sector that is in the protected state (see “Protect Sector” on page 22)
or locked down (see “Sector Lockdown” on page 29), then the Byte/Page Program command will
not be executed, and the device will return to the idle state once the CS pin has been deas-
serted. The WEL bit in the Status Register will be reset back to the logical “0” state if the
program cycle aborts due to an incomplete address being sent, an incomplete byte of data being
sent, the CS pin being deasserted on uneven byte boundaries, or because the memory location
to be programmed is protected or locked down.
While the device is programming, the Status Register can be read and will indicate that the
device is busy. For faster throughput, it is recommended that the Status Register be polled
rather than waiting the tBP or tPP time to determine if the data bytes have finished programming.
At some point before the program cycle completes, the WEL bit in the Status Register will be
reset back to the logical “0” state.
The device also incorporates an intelligent programming algorithm that can detect when a byte
location fails to program properly. If a programming error arises, it will be indicated by the EPE
bit in the Status Register.
Figure 8-3. Dual-Input Byte Program
CS
0
1
2
3
4
5
6
7
8
9
10 11 12
29 30 31 32 33 34 35
SCK
SI
INPUT
DATA BYTE
OPCODE
ADDRESS BITS A23-A0
D
D
D
D
2 0
1
0
1
0
0
0
1
0
A
A
A
A
A
A
A
A
A
6
4
MSB
MSB
HIGH-IMPEDANCE
D
D
D
D
3 1
7
5
SOI
MSB
14
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
Figure 8-4. Dual-Input Page Program
CS
0
1
2
3
4
5
6
7
8
9
10 11 12
29 30 31 32 33 34 35 36 37 38 39
SCK
SI
INPUT
INPUT
INPUT
DATA BYTE n
OPCODE
ADDRESS BITS A23-A0
DATA BYTE 1 DATA BYTE 2
D
D
D
D
D
D
D
D
D
D
D
D
2 0
1
0
1
0
0
0
1
0
A
A
A
A
A
A
A
A
A
6
4
2
0
6
4
2
0
6
4
MSB
MSB
HIGH-IMPEDANCE
D
D
D
D
D
D
D
D
D
D
D
D
3 1
7
5
3
1
7
5
3
1
7
5
SOI
MSB
MSB
MSB
8.3
Block Erase
A block of 4, 32, or 64 Kbytes can be erased (all bits set to the logical “1” state) in a single oper-
ation by using one of three different opcodes for the Block Erase command. An opcode of 20h is
used for a 4-Kbyte erase, an opcode of 52h is used for a 32-Kbyte erase, and an opcode of D8h
is used for a 64-Kbyte erase. Before a Block Erase command can be started, the Write Enable
command must have been previously issued to the device to set the WEL bit of the Status Reg-
ister to a logical “1” state.
To perform a Block Erase, the CS pin must first be asserted and the appropriate opcode (20h,
52h, or D8h) must be clocked into the device. After the opcode has been clocked in, the three
address bytes specifying an address within the 4-, 32-, or 64-Kbyte block to be erased must be
clocked in. Any additional data clocked into the device will be ignored. When the CS pin is deas-
serted, the device will erase the appropriate block. The erasing of the block is internally self-
timed and should take place in a time of tBLKE
.
Since the Block Erase command erases a region of bytes, the lower order address bits do not
need to be decoded by the device. Therefore, for a 4-Kbyte erase, address bits A11-A0 will be
ignored by the device and their values can be either a logical “1” or “0”. For a 32-Kbyte erase,
address bits A14-A0 will be ignored, and for a 64-Kbyte erase, address bits A15-A0 will be
ignored by the device. Despite the lower order address bits not being decoded by the device, the
complete three address bytes must still be clocked into the device before the CS pin is deas-
serted, and the CS pin must be deasserted on an even byte boundary (multiples of eight bits);
otherwise, the device will abort the operation and no erase operation will be performed.
If the address specified by A23-A0 points to a memory location within a sector that is in the pro-
tected or locked down state, then the Block Erase command will not be executed, and the device
will return to the idle state once the CS pin has been deasserted.
The WEL bit in the Status Register will be reset back to the logical “0” state if the erase cycle
aborts due to an incomplete address being sent, the CS pin being deasserted on uneven byte
boundaries, or because a memory location within the region to be erased is protected or locked
down.
While the device is executing a successful erase cycle, the Status Register can be read and will
indicate that the device is busy. For faster throughput, it is recommended that the Status Regis-
ter be polled rather than waiting the tBLKE time to determine if the device has finished erasing. At
some point before the erase cycle completes, the WEL bit in the Status Register will be reset
back to the logical “0” state.
15
3680E–DFLASH–12/08
The device also incorporates an intelligent erase algorithm that can detect when a byte location
fails to erase properly. If an erase error occurs, it will be indicated by the EPE bit in the Status
Register.
Figure 8-5. Block Erase
CS
0
1
2
3
4
5
6
7
8
9
10 11 12
26 27 28 29 30 31
SCK
SI
OPCODE
ADDRESS BITS A23-A0
C
C
C
C
C
C
C
C
A
A
A
A
A
A
A
A
A
A
A
A
MSB
MSB
HIGH-IMPEDANCE
SO
8.4
Chip Erase
The entire memory array can be erased in a single operation by using the Chip Erase command.
Before a Chip Erase command can be started, the Write Enable command must have been pre-
viously issued to the device to set the WEL bit of the Status Register to a logical “1” state.
Two opcodes, 60h and C7h, can be used for the Chip Erase command. There is no difference in
device functionality when utilizing the two opcodes, so they can be used interchangeably. To
perform a Chip Erase, one of the two opcodes (60h or C7h) must be clocked into the device.
Since the entire memory array is to be erased, no address bytes need to be clocked into the
device, and any data clocked in after the opcode will be ignored. When the CS pin is deas-
serted, the device will erase the entire memory array. The erasing of the device is internally self-
timed and should take place in a time of tCHPE
.
The complete opcode must be clocked into the device before the CS pin is deasserted, and the
CS pin must be deasserted on an even byte boundary (multiples of eight bits); otherwise, no
erase will be performed. In addition, if any sector of the memory array is in the protected or
locked down state, then the Chip Erase command will not be executed, and the device will return
to the idle state once the CS pin has been deasserted. The WEL bit in the Status Register will be
reset back to the logical “0” state if the CS pin is deasserted on uneven byte boundaries or if a
sector is in the protected or locked down state.
While the device is executing a successful erase cycle, the Status Register can be read and will
indicate that the device is busy. For faster throughput, it is recommended that the Status Regis-
ter be polled rather than waiting the tCHPE time to determine if the device has finished erasing. At
some point before the erase cycle completes, the WEL bit in the Status Register will be reset
back to the logical “0” state.
The device also incorporates an intelligent erase algorithm that can detect when a byte location
fails to erase properly. If an erase error occurs, it will be indicated by the EPE bit in the Status
Register.
16
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
Figure 8-6. Chip Erase
CS
0
1
2
3
4
5
6
7
SCK
SI
OPCODE
C
C
C
C
C
C
C
C
MSB
HIGH-IMPEDANCE
SO
8.5
Program/Erase Suspend
In some code plus data storage applications, it is often necessary to process certain high-level
system interrupts that require relatively immediate reading of code or data from the Flash mem-
ory. In such an instance, it may not be possible for the system to wait the microseconds or
milliseconds required for the Flash memory to complete a program or erase cycle. The Pro-
gram/Erase Suspend command allows a program or erase operation in progress to a particular
64-Kbyte sector of the Flash memory array to be suspended so that other device operations can
be performed. For example, by suspending an erase operation to a particular sector, the system
can perform functions such as a program or read operation within another 64-Kbyte sector in the
device. Other device operations, such as a Read Status Register, can also be performed while a
program or erase operation is suspended. Table 8-1 outlines the operations that are allowed and
not allowed during a program or erase suspend.
Since the need to suspend a program or erase operation is immediate, the Write Enable com-
mand does not need to be issued prior to the Program/Erase Suspend command being issued.
Therefore, the Program/Erase Suspend command operates independently of the state of the
WEL bit in the Status Register.
To perform a Program/Erase Suspend, the CS pin must first be asserted and the opcode of B0h
must be clocked into the device. No address bytes need to be clocked into the device, and any
data clocked in after the opcode will be ignored. When the CS pin is deasserted, the program or
erase operation currently in progress will be suspended within a time of tSUSP. The Program Sus-
pend (PS) bit or the Erase Suspend (ES) bit in the Status Register will then be set to the logical
“1” state to indicate that the program or erase operation has been suspended. In addition, the
RDY/BSY bit in the Status Register will indicate that the device is ready for another operation.
The complete opcode must be clocked into the device before the CS pin is deasserted, and the
CS pin must be deasserted on an even byte boundary (multiples of eight bits); otherwise, no
suspend operation will be performed.
Read operations are not allowed to a 64-Kbyte sector that has had its program or erase opera-
tion suspended. If a read is attempted to a suspended sector, then the device will output
undefined data. Therefore, when performing a Read Array operation to an unsuspended sector
and the device’s internal address counter increments and crosses the sector boundary to a sus-
pended sector, the device will then start outputting undefined data continuously until the address
counter increments and crosses a sector boundary to an unsuspended sector.
A program operation is not allowed to a sector that has been erase suspended. If a program
operation is attempted to an erase suspended sector, then the program operation will abort and
the WEL bit in the Status Register will be reset back to the logical “0” state. Likewise, an erase
17
3680E–DFLASH–12/08
operation is not allowed to a sector that has been program suspended. If attempted, the erase
operation will abort and the WEL bit in the Status Register will be reset to a logical “0” state.
During an Erase Suspend, a program operation to a different 64-Kbyte sector can be started and
subsequently suspended. This results in a simultaneous Erase Suspend/Program Suspend con-
dition and will be indicated by the states of both the ES and PS bits in the Status Register being
set to the logical “1” state.
If a Reset operation (see “Reset” on page 42) is performed while a sector is erase suspended,
the suspend operation will abort and the contents of the block in the suspended sector will be left
in an undefined state. However, if a Reset is performed while a sector is program suspended,
the suspend operation will abort but only the contents of the page that was being programmed
and subsequently suspended will be undefined. The remaining pages in the 64-Kbyte sector will
retain their previous contents.
If an attempt is made to perform an operation that is not allowed during a program or erase sus-
pend, such as a Protect Sector operation, then the device will simply ignore the opcode and no
operation will be performed. The state of the WEL bit in the Status Register, as well as the SPRL
(Sector Protection Registers Locked) and SLE (Sector Lockdown Enabled) bits, will not be
affected.
18
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
.
Table 8-1.
Operations Allowed and Not Allowed During a Program or Erase Suspend
Operation During
Program Suspend
Operation During
Erase Suspend
Command
Read Commands
Read Array (All Opcodes)
Allowed
Allowed
Program and Erase Commands
Block Erase
Not Allowed
Not Allowed
Not Allowed
Not Allowed
Allowed
Not Allowed
Not Allowed
Allowed
Chip Erase
Byte/Page Program (All Opcodes)
Program/Erase Suspend
Program/Erase Resume
Protection Commands
Write Enable
Allowed
Allowed
Not Allowed
Not Allowed
Not Allowed
Not Allowed
Not Allowed
Allowed
Allowed
Allowed
Write Disable
Protect Sector
Not Allowed
Not Allowed
Not Allowed
Allowed
Unprotect Sector
Global Protect/Unprotect
Read Sector Protection Registers
Security Commands
Sector Lockdown
Not Allowed
Not Allowed
Allowed
Not Allowed
Not Allowed
Allowed
Freeze Sector Lockdown State
Read Sector Lockdown Registers
Program OTP Security Register
Read OTP Security Register
Status Register Commands
Read Status Register
Not Allowed
Allowed
Not Allowed
Allowed
Allowed
Allowed
Write Status Register (All Opcodes)
Miscellaneous Commands
Reset
Not Allowed
Not Allowed
Allowed
Allowed
Allowed
Allowed
Read Manufacturer and Device ID
Deep Power-Down
Not Allowed
Not Allowed
Not Allowed
Not Allowed
Resume from Deep Power-Down
19
3680E–DFLASH–12/08
Figure 8-7. Program/Erase Suspend
CS
0
1
2
3
4
5
6
7
SCK
SI
OPCODE
1
0
1
1
0
0
0
0
MSB
HIGH-IMPEDANCE
SO
8.6
Program/Erase Resume
The Program/Erase Resume command allows a suspended program or erase operation to be
resumed and continue programming a Flash page or erasing a Flash memory block where it left
off. As with the Program/Erase Suspend command, the Write Enable command does not need
to be issued prior to the Program/Erase Resume command being issued. Therefore, the Pro-
gram/Erase Resume command operates independently of the state of the WEL bit in the Status
Register.
To perform a Program/Erase Resume, the CS pin must first be asserted and the opcode of D0h
must be clocked into the device. No address bytes need to be clocked into the device, and any
data clocked in after the opcode will be ignored. When the CS pin is deasserted, the program or
erase operation currently suspended will be resumed within a time of tRES. The PS bit or the ES
bit in the Status Register will then be reset back to the logical “0” state to indicate that the pro-
gram or erase operation is no longer suspended. In addition, the RDY/BSY bit in the Status
Register will indicate that the device is busy performing a program or erase operation. The com-
plete opcode must be clocked into the device before the CS pin is deasserted, and the CS pin
must be deasserted on an even byte boundary (multiples of eight bits); otherwise, no resume
operation will be performed.
During a simultaneous Erase Suspend/Program Suspend condition, issuing the Program/Erase
Resume command will result in the program operation resuming first. After the program opera-
tion has been completed, the Program/Erase Resume command must be issued again in order
for the erase operation to be resumed.
While the device is busy resuming a program or erase operation, any attempts at issuing the
Program/Erase Suspend command will be ignored. Therefore, if a resumed program or erase
operation needs to be subsequently suspended again, the system must either wait the entire
t
RES time before issuing the Program/Erase Suspend command, or it must check the status of
the RDY/BSY bit or the appropriate PS or ES bit in the Status Register to determine if the previ-
ously suspended program or erase operation has resumed.
20
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
Figure 8-8. Program/Erase Resume
CS
0
1
2
3
4
5
6
7
SCK
SI
OPCODE
1
1
0
1
0
0
0
0
MSB
HIGH-IMPEDANCE
SO
9. Protection Commands and Features
9.1
Write Enable
The Write Enable command is used to set the Write Enable Latch (WEL) bit in the Status Regis-
ter to a logical “1” state. The WEL bit must be set before a Byte/Page Program, erase, Protect
Sector, Unprotect Sector, Sector Lockdown, Freeze Sector Lockdown State, Program OTP
Security Register, or Write Status Register command can be executed. This makes the issuance
of these commands a two step process, thereby reducing the chances of a command being
accidentally or erroneously executed. If the WEL bit in the Status Register is not set prior to the
issuance of one of these commands, then the command will not be executed.
To issue the Write Enable command, the CS pin must first be asserted and the opcode of 06h
must be clocked into the device. No address bytes need to be clocked into the device, and any
data clocked in after the opcode will be ignored. When the CS pin is deasserted, the WEL bit in
the Status Register will be set to a logical “1”. The complete opcode must be clocked into the
device before the CS pin is deasserted, and the CS pin must be deasserted on an even byte
boundary (multiples of eight bits); otherwise, the device will abort the operation and the state of
the WEL bit will not change.
Figure 9-1. Write Enable
CS
0
1
2
3
4
5
6
7
SCK
SI
OPCODE
0
0
0
0
0
1
1
0
MSB
HIGH-IMPEDANCE
SO
21
3680E–DFLASH–12/08
9.2
Write Disable
The Write Disable command is used to reset the Write Enable Latch (WEL) bit in the Status Reg-
ister to the logical "0" state. With the WEL bit reset, all Byte/Page Program, erase, Protect
Sector, Unprotect Sector, Sector Lockdown, Freeze Sector Lockdown State, Program OTP
Security Register, and Write Status Register commands will not be executed. Other conditions
can also cause the WEL bit to be reset; for more details, refer to the WEL bit section of the Sta-
tus Register description.
To issue the Write Disable command, the CS pin must first be asserted and the opcode of 04h
must be clocked into the device. No address bytes need to be clocked into the device, and any
data clocked in after the opcode will be ignored. When the CS pin is deasserted, the WEL bit in
the Status Register will be reset to a logical “0”. The complete opcode must be clocked into the
device before the CS pin is deasserted, and the CS pin must be deasserted on an even byte
boundary (multiples of eight bits); otherwise, the device will abort the operation and the state of
the WEL bit will not change.
Figure 9-2. Write Disable
CS
0
1
2
3
4
5
6
7
SCK
SI
OPCODE
0
0
0
0
0
1
0
0
MSB
HIGH-IMPEDANCE
SO
9.3
Protect Sector
Every physical 64-Kbyte sector of the device has a corresponding single-bit Sector Protection
Register that is used to control the software protection of a sector. Upon device power-up, each
Sector Protection Register will default to the logical “1” state indicating that all sectors are pro-
tected and cannot be programmed or erased.
Issuing the Protect Sector command to a particular sector address will set the corresponding
Sector Protection Register to the logical “1” state. The following table outlines the two states of
the Sector Protection Registers.
Table 9-1.
Sector Protection Register Values
Value
Sector Protection Status
0
1
Sector is unprotected and can be programmed and erased.
Sector is protected and cannot be programmed or erased. This is the default state.
Before the Protect Sector command can be issued, the Write Enable command must have been
previously issued to set the WEL bit in the Status Register to a logical “1”. To issue the Protect
Sector command, the CS pin must first be asserted and the opcode of 36h must be clocked into
the device followed by three address bytes designating any address within the sector to be pro-
tected. Any additional data clocked into the device will be ignored. When the CS pin is
deasserted, the Sector Protection Register corresponding to the physical sector addressed by
22
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
A23-A0 will be set to the logical “1” state, and the sector itself will then be protected from pro-
gram and erase operations. In addition, the WEL bit in the Status Register will be reset back to
the logical “0” state.
The complete three address bytes must be clocked into the device before the CS pin is deas-
serted, and the CS pin must be deasserted on an even byte boundary (multiples of eight bits);
otherwise, the device will abort the operation. When the device aborts the Protect Sector opera-
tion, the state of the Sector Protection Register will be unchanged, and the WEL bit in the Status
Register will be reset to a logical “0”.
As a safeguard against accidental or erroneous protecting or unprotecting of sectors, the Sector
Protection Registers can themselves be locked from updates by using the SPRL (Sector Protec-
tion Registers Locked) bit of the Status Register (please refer to the Status Register description
for more details). If the Sector Protection Registers are locked, then any attempts to issue the
Protect Sector command will be ignored, and the device will reset the WEL bit in the Status Reg-
ister back to a logical “0” and return to the idle state once the CS pin has been deasserted.
Figure 9-3. Protect Sector
CS
0
1
2
3
4
5
6
7
8
9
10 11 12
26 27 28 29 30 31
SCK
SI
OPCODE
ADDRESS BITS A23-A0
0
0
1
1
0
1
1
0
A
A
A
A
A
A
A
A
A
A
A
A
MSB
MSB
HIGH-IMPEDANCE
SO
9.4
Unprotect Sector
Issuing the Unprotect Sector command to a particular sector address will reset the correspond-
ing Sector Protection Register to the logical “0” state (see Table 9-1 for Sector Protection
Register values). Every physical sector of the device has a corresponding single-bit Sector Pro-
tection Register that is used to control the software protection of a sector.
Before the Unprotect Sector command can be issued, the Write Enable command must have
been previously issued to set the WEL bit in the Status Register to a logical “1”. To issue the
Unprotect Sector command, the CS pin must first be asserted and the opcode of 39h must be
clocked into the device. After the opcode has been clocked in, the three address bytes designat-
ing any address within the sector to be unprotected must be clocked in. Any additional data
clocked into the device after the address bytes will be ignored. When the CS pin is deasserted,
the Sector Protection Register corresponding to the sector addressed by A23-A0 will be reset to
the logical “0” state, and the sector itself will be unprotected. In addition, the WEL bit in the Sta-
tus Register will be reset back to the logical “0” state.
The complete three address bytes must be clocked into the device before the CS pin is deas-
serted, and the CS pin must be deasserted on an even byte boundary (multiples of eight bits);
otherwise, the device will abort the operation, the state of the Sector Protection Register will be
unchanged, and the WEL bit in the Status Register will be reset to a logical “0”.
23
3680E–DFLASH–12/08
As a safeguard against accidental or erroneous locking or unlocking of sectors, the Sector Pro-
tection Registers can themselves be locked from updates by using the SPRL (Sector Protection
Registers Locked) bit of the Status Register (please refer to the Status Register description for
more details). If the Sector Protection Registers are locked, then any attempts to issue the
Unprotect Sector command will be ignored, and the device will reset the WEL bit in the Status
Register back to a logical “0” and return to the idle state once the CS pin has been deasserted.
Figure 9-4. Unprotect Sector
CS
0
1
2
3
4
5
6
7
8
9
10 11 12
26 27 28 29 30 31
SCK
SI
OPCODE
ADDRESS BITS A23-A0
0
0
1
1
1
0
0
1
A
A
A
A
A
A
A
A
A
A
A
A
MSB
MSB
HIGH-IMPEDANCE
SO
9.5
Global Protect/Unprotect
The Global Protect and Global Unprotect features can work in conjunction with the Protect Sec-
tor and Unprotect Sector functions. For example, a system can globally protect the entire
memory array and then use the Unprotect Sector command to individually unprotect certain sec-
tors and individually reprotect them later by using the Protect Sector command. Likewise, a
system can globally unprotect the entire memory array and then individually protect certain sec-
tors as needed.
Performing a Global Protect or Global Unprotect is accomplished by writing a certain combina-
tion of data to the Status Register using the Write Status Register Byte 1 command (see “Write
Status Register Byte 1” on page 40 for command execution details). The Write Status Register
command is also used to modify the SPRL (Sector Protection Registers Locked) bit to control
hardware and software locking.
To perform a Global Protect, the appropriate WP pin and SPRL conditions must be met, and the
system must write a logical “1” to bits 5, 4, 3, and 2 of the first byte of the Status Register. Con-
versely, to perform a Global Unprotect, the same WP and SPRL conditions must be met but the
system must write a logical “0” to bits 5, 4, 3, and 2 of the first byte of the Status Register. Table
9-2 details the conditions necessary for a Global Protect or Global Unprotect to be performed.
Sectors that have been erase or program suspended must remain in the unprotected state. If a
Global Protect operation is attempted while a sector is erase or program suspended, the protec-
tion operation will abort, the protection states of all sectors in the Flash memory array will not
change, and WEL bit in the Status Register will be reset back to a logical “0”.
24
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
Table 9-2.
Valid SPRL and Global Protect/Unprotect Conditions
New Write Status
Register Byte 1
Data
Current
SPRL
Value
New
SPRL
Value
WP
State
Bit
7 6 5 4 3 2 1 0
Protection Operation
0 x 0 0 0 0 x x
0 x 0 0 0 1 x x
↕
Global Unprotect – all Sector Protection Registers reset to 0
No change to current protection.
No change to current protection.
No change to current protection.
Global Protect – all Sector Protection Registers set to 1
0
0
0
0
0
0 x 1 1 1 0 x x
0 x 1 1 1 1 x x
0
0
1
0
1
0
1 x 0 0 0 0 x x
1 x 0 0 0 1 x x
↕
Global Unprotect – all Sector Protection Registers reset to 0
No change to current protection.
No change to current protection.
No change to current protection.
Global Protect – all Sector Protection Registers set to 1
1
1
1
1
1
1 x 1 1 1 0 x x
1 x 1 1 1 1 x x
No change to the current protection level. All sectors currently
protected will remain protected and all sectors currently unprotected
will remain unprotected.
x x x x x x x x
The Sector Protection Registers are hard-locked and cannot be
changed when the WP pin is LOW and the current state of SPRL is 1.
Therefore, a Global Protect/Unprotect will not occur. In addition, the
SPRL bit cannot be changed (the WP pin must be HIGH in order to
change SPRL back to a 0).
0 x 0 0 0 0 x x
0 x 0 0 0 1 x x
↕
Global Unprotect – all Sector Protection Registers reset to 0
No change to current protection.
No change to current protection.
No change to current protection.
Global Protect – all Sector Protection Registers set to 1
0
0
0
0
0
0 x 1 1 1 0 x x
0 x 1 1 1 1 x x
1 x 0 0 0 0 x x
1 x 0 0 0 1 x x
↕
Global Unprotect – all Sector Protection Registers reset to 0
No change to current protection.
No change to current protection.
No change to current protection.
Global Protect – all Sector Protection Registers set to 1
1
1
1
1
1
1 x 1 1 1 0 x x
1 x 1 1 1 1 x x
0 x 0 0 0 0 x x
0 x 0 0 0 1 x x
↕
No change to the current protection level. All sectors
currently protected will remain protected, and all sectors
currently unprotected will remain unprotected.
0
0
0
0
0
0 x 1 1 1 0 x x
0 x 1 1 1 1 x x
The Sector Protection Registers are soft-locked and cannot
be changed when the current state of SPRL is 1. Therefore,
a Global Protect/Unprotect will not occur. However, the
SPRL bit can be changed back to a 0 from a 1 since the WP
pin is HIGH. To perform a Global Protect/Unprotect, the
Write Status Register command must be issued again after
the SPRL bit has been changed from a 1 to a 0.
1
1
1 x 0 0 0 0 x x
1 x 0 0 0 1 x x
↕
1
1
1
1
1
1 x 1 1 1 0 x x
1 x 1 1 1 1 x x
Essentially, if the SPRL bit of the Status Register is in the logical “0” state (Sector Protection
Registers are not locked), then writing a 00h to the first byte of the Status Register will perform a
Global Unprotect without changing the state of the SPRL bit. Similarly, writing a 7Fh to the first
byte of the Status Register will perform a Global Protect and keep the SPRL bit in the logical “0”
state. The SPRL bit can, of course, be changed to a logical “1” by writing an FFh if software-lock-
ing or hardware-locking is desired along with the Global Protect.
25
3680E–DFLASH–12/08
If the desire is to only change the SPRL bit without performing a Global Protect or Global Unpro-
tect, then the system can simply write a 0Fh to the first byte of the Status Register to change the
SPRL bit from a logical “1” to a logical “0” provided the WP pin is deasserted. Likewise, the sys-
tem can write an F0h to change the SPRL bit from a logical “0” to a logical “1” without affecting
the current sector protection status (no changes will be made to the Sector Protection
Registers).
When writing to the first byte of the Status Register, bits 5, 4, 3, and 2 will not actually be modi-
fied but will be decoded by the device for the purposes of the Global Protect and Global
Unprotect functions. Only bit 7, the SPRL bit, will actually be modified. Therefore, when reading
the first byte of the Status Register, bits 5, 4, 3, and 2 will not reflect the values written to them
but will instead indicate the status of the WP pin and the sector protection status. Please refer to
“Read Status Register” on page 35 and Table 11-1 on page 36 for details on the Status Register
format and what values can be read for bits 5, 4, 3, and 2.
9.6
Read Sector Protection Registers
The Sector Protection Registers can be read to determine the current software protection status
of each sector. Reading the Sector Protection Registers, however, will not determine the status
of the WP pin.
To read the Sector Protection Register for a particular sector, the CS pin must first be asserted
and the opcode of 3Ch must be clocked in. Once the opcode has been clocked in, three address
bytes designating any address within the sector must be clocked in. After the last address byte
has been clocked in, the device will begin outputting data on the SO pin during every subse-
quent clock cycle. The data being output will be a repeating byte of either FFh or 00h to denote
the value of the appropriate Sector Protection Register.
At clock frequencies above fCLK, the first byte of data output will not be valid. Therefore, if operat-
ing at clock frequencies above fCLK, at least two bytes of data must be clocked out from the
device in order to determine the correct status of the appropriate Sector Protection Register.
Table 9-3.
Output Data
Read Sector Protection Register - Output Data
Sector Protection Register Value
00h
FFh
Sector Protection Register value is 0 (sector is unprotected).
Sector Protection Register value is 1 (sector is protected).
Deasserting the CS pin will terminate the read operation and put the SO pin into a high-imped-
ance state. The CS pin can be deasserted at any time and does not require that a full byte of
data be read.
In addition to reading the individual Sector Protection Registers, the Software Protection Status
(SWP) bits in the Status Register can be read to determine if all, some, or none of the sectors
are software protected (refer to “Read Status Register” on page 35 for more details).
26
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
Figure 9-5. Read Sector Protection Register
CS
0
1
2
3
4
5
6
7
8
9
10 11 12
29 30 31 32 33 34 35 36 37 38 39 40
SCK
SI
OPCODE
ADDRESS BITS A23-A0
0
0
1
1
1
1
0
0
A
A
A
A
A
A
A
A
A
MSB
MSB
DATA BYTE
HIGH-IMPEDANCE
D
D
D
D
D
D
D
D
D
D
SO
MSB
MSB
9.7
Protected States and the Write Protect (WP) Pin
The WP pin is not linked to the memory array itself and has no direct effect on the protection sta-
tus or lockdown status of the memory array. Instead, the WP pin, in conjunction with the SPRL
(Sector Protection Registers Locked) bit in the Status Register, is used to control the hardware
locking mechanism of the device. For hardware locking to be active, two conditions must be met-
the WP pin must be asserted and the SPRL bit must be in the logical “1” state.
When hardware locking is active, the Sector Protection Registers are locked and the SPRL bit
itself is also locked. Therefore, sectors that are protected will be locked in the protected state,
and sectors that are unprotected will be locked in the unprotected state. These states cannot be
changed as long as hardware locking is active, so the Protect Sector, Unprotect Sector, and
Write Status Register commands will be ignored. In order to modify the protection status of a
sector, the WP pin must first be deasserted, and the SPRL bit in the Status Register must be
reset back to the logical “0” state using the Write Status Register command. When resetting the
SPRL bit back to a logical “0”, it is not possible to perform a Global Protect or Global Unprotect
at the same time since the Sector Protection Registers remain soft-locked until after the Write
Status Register command has been executed.
If the WP pin is permanently connected to GND, then once the SPRL bit is set to a logical “1”,
the only way to reset the bit back to the logical “0” state is to power-cycle the device. This allows
a system to power-up with all sectors software protected but not hardware locked. Therefore,
sectors can be unprotected and protected as needed and then hardware locked at a later time
by simply setting the SPRL bit in the Status Register.
When the WP pin is deasserted, or if the WP pin is permanently connected to VCC, the SPRL bit
in the Status Register can still be set to a logical “1” to lock the Sector Protection Registers. This
provides a software locking ability to prevent erroneous Protect Sector or Unprotect Sector com-
mands from being processed. When changing the SPRL bit to a logical “1” from a logical “0”, it is
also possible to perform a Global Protect or Global Unprotect at the same time by writing the
appropriate values into bits 5, 4, 3, and 2 of the first byte of the Status Register.
Tables 9-4 and 9-5 detail the various protection and locking states of the device.
27
3680E–DFLASH–12/08
Table 9-4.
Sector Protection Register States
Sector Protection Register
Sector
n(1)
WP
n(1)
0
Unprotected
Protected
X
(Don't Care)
1
Note:
1. “n” represents a sector number
Table 9-5.
Hardware and Software Locking
WP
SPRL
Locking
SPRL Change Allowed
Sector Protection Registers
Unlocked and modifiable using the
Protect and Unprotect Sector commands.
Global Protect and Unprotect can also be
performed.
0
0
1
0
1
Can be modified from 0 to 1
Locked in current state. Protect and
Unprotect Sector commands will be
ignored. Global Protect and Unprotect
cannot be performed.
Hardware
Locked
0
1
1
Locked
Unlocked and modifiable using the
Protect and Unprotect Sector commands.
Global Protect and Unprotect can also be
performed.
Can be modified from 0 to 1
Can be modified from 1 to 0
Locked in current state. Protect and
Unprotect Sector commands will be
ignored. Global Protect and Unprotect
cannot be performed.
Software
Locked
28
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
10. Security Commands
10.1 Sector Lockdown
Certain applications require that portions of the Flash memory array be permanently protected
against malicious attempts at altering program code, data modules, security information, or
encryption/decryption algorithms, keys, and routines. To address these applications, the device
incorporates a sector lockdown mechanism that allows any combination of individual 64-Kbyte
sectors to be permanently locked so that they become read only. Once a sector is locked down,
it can never be erased or programmed again, and it can never be unlocked from the locked
down state.
Each 64-Kbyte physical sector has a corresponding single-bit Sector Lockdown Register that is
used to control the lockdown status of that sector. These registers are nonvolatile and will retain
their state even after a device power-cycle or reset operation. The following table outlines the
two states of the Sector Lockdown Registers.
Table 10-1. Sector Lockdown Register Values
Value
Sector Lockdown Status
0
1
Sector is not locked down and can be programmed and erased. This is the default state.
Sector is permanently locked down and can never be programmed or erased again.
Issuing the Sector Lockdown command to a particular sector address will set the corresponding
Sector Lockdown Register to the logical “1” state. Each Sector Lockdown Register can only be
set once; therefore, once set to the logical “1” state, a Sector Lockdown Register cannot be reset
back to the logical “0” state.
Before the Sector Lockdown command can be issued, the Write Enable command must have
been previously issued to set the WEL bit in the Status Register to a logical “1”. In addition, the
Sector Lockdown Enabled (SLE) bit in the Status Register must have also been previously set to
the logical “1” state by using the Write Status Register Byte 2 command (see “Write Status Reg-
ister Byte 2” on page 41). To issue the Sector Lockdown command, the CS pin must first be
asserted and the opcode of 33h must be clocked into the device followed by three address bytes
designating any address within the 64-Kbyte sector to be locked down. After the three address
bytes have been clocked in, a confirmation byte of D0h must also be clocked in immediately fol-
lowing the three address bytes. Any additional data clocked into the device after the first byte of
data will be ignored. When the CS pin is deasserted, the Sector Lockdown Register correspond-
ing to the sector addressed by A23-A0 will be set to the logical “1” state, and the sector itself will
then be permanently locked down from program and erase operations within a time of tLOCK. In
addition, the WEL bit in the Status Register will be reset back to the logical “0” state.
The complete three address bytes and the correct confirmation byte value of D0h must be
clocked into the device before the CS pin is deasserted, and the CS pin must be deasserted on
an even byte boundary (multiples of eight bits); otherwise, the device will abort the operation.
When the device aborts the Sector Lockdown operation, the state of the corresponding Sector
Lockdown Register as well as the SLE bit in the Status Register will be unchanged; however, the
WEL bit in the Status Register will be reset to a logical “0”.
As a safeguard against accidental or erroneous locking down of sectors, the Sector Lockdown
command can be enabled and disabled as needed by using the SLE bit in the Status Register.
In addition, the current sector lockdown state can be frozen so that no further modifications to
29
3680E–DFLASH–12/08
the Sector Lockdown Registers can be made (see “Freeze Sector Lockdown State” below). If
the Sector Lockdown command is disabled or if the sector lockdown state is frozen, then any
attempts to issue the Sector Lockdown command will be ignored, and the device will reset the
WEL bit in the Status Register back to a logical “0” and return to the idle state once the CS pin
has been deasserted.
Figure 10-1. Sector Lockdown
CS
0
1
2
3
4
5
6
7
8
9
29 30 31 32 33 34 35 36 37 38 39
SCK
SI
OPCODE
ADDRESS BITS A23-A0 CONFIRMATION BYTE IN
0
0
1
1
0
0
1
1
A
A
A
A
A
A
1
1
0
1
0
0
0
0
MSB
MSB
MSB
HIGH-IMPEDANCE
SO
10.2 Freeze Sector Lockdown State
The current sector lockdown state can be permanently frozen so that no further modifications to
the Sector Lockdown Registers can be made; therefore, the Sector Lockdown command will be
permanently disabled, and no additional sectors can be locked down aside from those already
locked down. Any attempts to issue the Sector Lockdown command after the sector lockdown
state has been frozen will be ignored.
Before the Freeze Sector Lockdown State command can be issued, the Write Enable command
must have been previously issued to set the WEL bit in the Status Register to a logical “1”. In
addition, the Sector Lockdown Enabled (SLE) bit in the Status Register must have also been
previously set to the logical “1” state. To issue the Freeze Sector Lockdown State command, the
CS pin must first be asserted and the opcode of 34h must be clocked into the device followed by
three command specific address bytes of 55AA40h. After the three address bytes have been
clocked in, a confirmation byte of D0h must be clocked in immediately following the three
address bytes. Any additional data clocked into the device will be ignored. When the CS pin is
deasserted, the current sector lockdown state will be permanently frozen within a time of tLOCK
.
In addition, the WEL bit in the Status Register will be reset back to the logical “0” state, and the
SLE bit will be permanently reset to a logical “0” to indicate that the Sector Lockdown command
is permanently disabled.
The complete and correct three address bytes and the confirmation byte must be clocked into
the device before the CS pin is deasserted, and the CS pin must be deasserted on an even byte
boundary (multiples of eight bits); otherwise, the device will abort the operation. When the
device aborts the Freeze Sector Lockdown State operation, the WEL bit in the Status Register
will be reset to a logical “0”; however, the state of the SLE bit will be unchanged.
30
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
Figure 10-2. Freeze Sector Lockdown State
CS
0
1
2
3
4
5
6
7
8
9
29 30 31 32 33 34 35 36 37 38 39
SCK
SI
OPCODE
ADDRESS BITS A23-A0 CONFIRMATION BYTE IN
0
0
1
1
0
1
0
0
0
1
0
0
0
0
1
1
0
1
0
0
0
0
MSB
MSB
MSB
HIGH-IMPEDANCE
SO
10.3 Read Sector Lockdown Registers
The Sector Lockdown Registers can be read to determine the current lockdown status of each
physical 64-Kbyte sector. To read the Sector Lockdown Register for a particular 64-Kbyte sec-
tor, the CS pin must first be asserted and the opcode of 35h must be clocked in. Once the
opcode has been clocked in, three address bytes designating any address within the 64-Kbyte
sector must be clocked in. After the address bytes have been clocked in, data will be output on
the SO pin during every subsequent clock cycle. The data being output will be a repeating byte
of either FFh or 00h to denote the value of the appropriate Sector Lockdown Register.
At clock frequencies above fCLK, the first byte of data output will not be valid. Therefore, if operat-
ing at clock frequencies above fCLK, at least two bytes of data must be clocked out from the
device in order to determine the correct status of the appropriate Sector Lockdown Register.
Table 10-2. Read Sector Lockdown Register – Output Data
Output Data
00h
Sector Lockdown Register Value
Sector Lockdown Register value is 0 (sector is not locked down).
Sector Lockdown Register value is 1 (sector is permanently locked down).
FFh
Deasserting the CS pin will terminate the read operation and put the SO pin into a high-imped-
ance state. The CS pin can be deasserted at any time and does not require that a full byte of
data be read.
Figure 10-3. Read Sector Lockdown Register
CS
SCK
SI
0
1
2
3
4
5
6
7
8
9
10 11 12
29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
OPCODE
ADDRESS BITS A23-A0
DON'T CARE
0
0
1
1
0
1
0
1
A
A
A
A
A
A
A
A
A
X
X
X
X
X
X
X
X
MSB
MSB
MSB
DATA BYTE
HIGH-IMPEDANCE
D
D
D
D
D
D
D
D
D
D
SO
MSB
MSB
31
3680E–DFLASH–12/08
10.4 Program OTP Security Register
The device contains a specialized OTP (One-Time Programmable) Security Register that can be
used for purposes such as unique device serialization, system-level Electronic Serial Number
(ESN) storage, locked key storage, etc. The OTP Security Register is independent of the main
Flash memory array and is comprised of a total of 128 bytes of memory divided into two por-
tions. The first 64 bytes (byte locations 0 through 63) of the OTP Security Register are allocated
as a one-time user-programmable space. Once these 64 bytes have been programmed, they
cannot be erased or reprogrammed. The remaining 64 bytes of the OTP Security Register (byte
locations 64 through 127) are factory programmed by Atmel and will contain a unique value for
each device. The factory programmed data is fixed and cannot be changed.
Table 10-3. OTP Security Register
Security Register
Byte Number
0
1
. . .
62
63
64
65
. . .
126
127
One-Time User Programmable
Factory Programmed by Atmel
The user-programmable portion of the OTP Security Register does not need to be erased before
it is programmed. In addition, the Program OTP Security Register command operates on the
entire 64-byte user-programmable portion of the OTP Security Register at one time. Once the
user-programmable space has been programmed with any number of bytes, the user-program-
mable space cannot be programmed again; therefore, it is not possible to only program the first
two bytes of the register and then program the remaining 62 bytes at a later time.
Before the Program OTP Security Register command can be issued, the Write Enable command
must have been previously issued to set the WEL bit in the Status Register to a logical “1”. To
program the OTP Security Register, the CS pin must first be asserted and an opcode of 9Bh
must be clocked into the device followed by the three address bytes denoting the first byte loca-
tion of the OTP Security Register to begin programming at. Since the size of the user-
programmable portion of the OTP Security Register is 64 bytes, the upper order address bits do
not need to be decoded by the device. Therefore, address bits A23-A6 will be ignored by the
device and their values can be either a logical “1” or “0”. After the address bytes have been
clocked in, data can then be clocked into the device and will be stored in the internal buffer.
If the starting memory address denoted by A23-A0 does not start at the beginning of the OTP
Security Register memory space (A5-A0 are not all 0), then special circumstances regarding
which OTP Security Register locations to be programmed will apply. In this situation, any data
that is sent to the device that goes beyond the end of the 64-byte user-programmable space will
wrap around back to the beginning of the OTP Security Register. For example, if the starting
address denoted by A23-A0 is 00003Eh, and three bytes of data are sent to the device, then the
first two bytes of data will be programmed at OTP Security Register addresses 00003Eh and
00003Fh while the last byte of data will be programmed at address 000000h. The remaining
bytes in the OTP Security Register (addresses 000001h through 00003Dh) will not be pro-
grammed and will remain in the erased state (FFh). In addition, if more than 64 bytes of data are
sent to the device, then only the last 64 bytes sent will be latched into the internal buffer.
When the CS pin is deasserted, the device will take the data stored in the internal buffer and pro-
gram it into the appropriate OTP Security Register locations based on the starting address
specified by A23-A0 and the number of data bytes sent to the device. If less than 64 bytes of
data were sent to the device, then the remaining bytes within the OTP Security Register will not
32
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
be programmed and will remain in the erased state (FFh). The programming of the data bytes is
internally self-timed and should take place in a time of tOTPP. It is not possible to suspend the
programming of the OTP Security Register.
The three address bytes and at least one complete byte of data must be clocked into the device
before the CS pin is deasserted, and the CS pin must be deasserted on even byte boundaries
(multiples of eight bits); otherwise, the device will abort the operation and the user-programma-
ble portion of the OTP Security Register will not be programmed. The WEL bit in the Status
Register will be reset back to the logical “0” state if the OTP Security Register program cycle
aborts due to an incomplete address being sent, an incomplete byte of data being sent, the CS
pin being deasserted on uneven byte boundaries, or because the user-programmable portion of
the OTP Security Register was previously programmed.
While the device is programming the OTP Security Register, the Status Register can be read
and will indicate that the device is busy. For faster throughput, it is recommended that the Status
Register be polled rather than waiting the tOTPP time to determine if the data bytes have finished
programming. At some point before the OTP Security Register programming completes, the
WEL bit in the Status Register will be reset back to the logical “0” state.
If the device is powered-down during the OTP Security Register program cycle, then the con-
tents of the 64-byte user programmable portion of the OTP Security Register cannot be
guaranteed and cannot be programmed again.
The Program OTP Security Register command utilizes the internal 256-buffer for processing.
Therefore, the contents of the buffer will be altered from its previous state when this command is
issued.
Figure 10-4. Program OTP Security Register
CS
SCK
SI
0
1
2
3
4
5
6
7
8
9
29 30 31 32 33 34 35 36 37 38 39
OPCODE
ADDRESS BITS A23-A0
DATA IN BYTE 1
DATA IN BYTE n
1
0
0
1
1
0
1
1
A
A
A
A
A
A
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
MSB
MSB
MSB
MSB
HIGH-IMPEDANCE
SO
33
3680E–DFLASH–12/08
10.5 Read OTP Security Register
The OTP Security Register can be sequentially read in a similar fashion to the Read Array oper-
ation up to the maximum clock frequency specified by fMAX. To read the OTP Security Register,
the CS pin must first be asserted and the opcode of 77h must be clocked into the device. After
the opcode has been clocked in, the three address bytes must be clocked in to specify the start-
ing address location of the first byte to read within the OTP Security Register. Following the
three address bytes, two dummy bytes must be clocked into the device before data can be
output.
After the three address bytes and the dummy bytes have been clocked in, additional clock
cycles will result in OTP Security Register data being output on the SO pin. When the last byte
(00007Fh) of the OTP Security Register has been read, the device will continue reading back at
the beginning of the register (000000h). No delays will be incurred when wrapping around from
the end of the register to the beginning of the register.
Deasserting the CS pin will terminate the read operation and put the SO pin into a high-imped-
ance state. The CS pin can be deasserted at any time and does not require that a full byte of
data be read.
Figure 10-5. Read OTP Security Register
CS
SCK
SI
0
1
2
3
4
5
6
7
8
9
10 11 12
29 30 31 32 33 34 35 36
OPCODE
ADDRESS BITS A23-A0
DON'T CARE
0
1
1
1
0
1
1
1
A
A
A
A
A
A
A
A
A
X
X
X
X
X
X
X
X
X
MSB
MSB
MSB
DATA BYTE 1
HIGH-IMPEDANCE
D
D
D
D
D
D
D
D
D
D
SO
MSB
MSB
34
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
11. Status Register Commands
11.1 Read Status Register
The two-byte Status Register can be read to determine the device’s ready/busy status, as well
as the status of many other functions such as Hardware Locking and Software Protection. The
Status Register can be read at any time, including during an internally self-timed program or
erase operation.
To read the Status Register, the CS pin must first be asserted and the opcode of 05h must be
clocked into the device. After the opcode has been clocked in, the device will begin outputting
Status Register data on the SO pin during every subsequent clock cycle. After the second byte
of the Status Register has been clocked out, the sequence will repeat itself starting again with
the first byte of the Status Register as long as the CS pin remains asserted and the clock pin is
being pulsed. The data in the Status Register is constantly being updated, so each repeating
sequence will output new data. The RDY/BSY status is available for both bytes of the Status
Register and is updated for each byte.
At clock frequencies above fCLK, the first two bytes of data output from the Status Register will
not be valid. Therefore, if operating at clock frequencies above fCLK, at least four bytes of data
must be clocked out from the device in order to read the correct values of both bytes of the Sta-
tus Register.
Deasserting the CS pin will terminate the Read Status Register operation and put the SO pin
into a high-impedance state. The CS pin can be deasserted at any time and does not require
that a full byte of data be read.
35
3680E–DFLASH–12/08
Table 11-1. Status Register Format – Byte 1
Bit(1)
Name
Type(2)
R/W
R
Description
0
1
0
0
1
0
1
Sector Protection Registers are unlocked (default).
Sector Protection Registers are locked.
Reserved for future use.
7
6
5
SPRL
RES
EPE
Sector Protection Registers Locked
Reserved for future use
Erase/Program Error
Erase or program operation was successful.
Erase or program error detected.
WP is asserted.
R
4
WPP
SWP
WEL
Write Protect (WP) Pin Status
Software Protection Status
Write Enable Latch Status
R
R
WP is deasserted.
All sectors are software unprotected (all Sector
Protection Registers are 0).
00
01
Some sectors are software protected. Read
individual Sector Protection Registers to determine
which sectors are protected.
3:2
10
11
Reserved for future use.
All sectors are software protected (all Sector
Protection Registers are 1 – default).
0
1
0
1
Device is not write enabled (default).
Device is write enabled.
1
0
R
R
Device is ready.
RDY/BSY Ready/Busy Status
Device is busy with an internal operation.
Notes: 1. Only bit 7 of Status Register Byte 1 will be modified when using the Write Status Register Byte 1 command.
2. R/W = Readable and writeable
R = Readable only
36
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
Table 11-2. Status Register Format – Byte 2
Bit(1)
Name
Type(2)
Description
Reserved for future use.
7
6
5
RES
RES
RES
Reserved for future use
Reserved for future use
Reserved for future use
R
R
R
0
0
0
0
1
Reserved for future use.
Reserved for future use.
Reset command is disabled (default).
Reset command is enabled.
4
RSTE
Reset Enabled
R/W
Sector Lockdown and Freeze Sector Lockdown State
commands are disabled (default).
0
1
3
SLE
Sector Lockdown Enabled
R/W
Sector Lockdown and Freeze Sector Lockdown State
commands are enabled.
0
1
0
1
0
1
No sectors are program suspended (default).
A sector is program suspended.
No sectors are erase suspended (default).
A sector is erase suspended.
2
1
0
PS
ES
Program Suspend Status
Erase Suspend Status
R
R
R
Device is ready.
RDY/BSY Ready/Busy Status
Device is busy with an internal operation.
Notes: 1. Only bits 4 and 3 of Status Register Byte 2 will be modified when using the Write Status Register Byte 2 command.
2. R/W = Readable and writeable
R = Readable only
11.1.1
SPRL Bit
The SPRL bit is used to control whether the Sector Protection Registers can be modified or not.
When the SPRL bit is in the logical “1” state, all Sector Protection Registers are locked and can-
not be modified with the Protect Sector and Unprotect Sector commands (the device will ignore
these commands). In addition, the Global Protect and Global Unprotect features cannot be per-
formed. Any sectors that are presently protected will remain protected, and any sectors that are
presently unprotected will remain unprotected.
When the SPRL bit is in the logical “0” state, all Sector Protection Registers are unlocked and
can be modified (the Protect Sector and Unprotect Sector commands, as well as the Global Pro-
tect and Global Unprotect features, will be processed as normal). The SPRL bit defaults to the
logical “0” state after device power-up. The Reset command has no effect on the SPRL bit.
The SPRL bit can be modified freely whenever the WP pin is deasserted. However, if the WP pin
is asserted, then the SPRL bit may only be changed from a logical “0” (Sector Protection Regis-
ters are unlocked) to a logical “1” (Sector Protection Registers are locked). In order to reset the
SPRL bit back to a logical “0” using the Write Status Register Byte 1 command, the WP pin will
have to first be deasserted.
The SPRL bit is the only bit of Status Register Byte 1 that can be user modified via the Write Sta-
tus Register Byte 1 command.
11.1.2
EPE Bit
The EPE bit indicates whether the last erase or program operation completed successfully or
not. If at least one byte during the erase or program operation did not erase or program properly,
then the EPE bit will be set to the logical “1” state. The EPE bit will not be set if an erase or pro-
37
3680E–DFLASH–12/08
gram operation aborts for any reason such as an attempt to erase or program a protected region
or a locked down sector, an attempt to erase or program a suspended sector, or if the WEL bit is
not set prior to an erase or program operation. The EPE bit will be updated after every erase and
program operation.
11.1.3
11.1.4
WPP Bit
The WPP bit can be read to determine if the WP pin has been asserted or not.
SWP Bits
The SWP bits provide feedback on the software protection status for the device. There are three
possible combinations of the SWP bits that indicate whether none, some, or all of the sectors
have been protected using the Protect Sector command or the Global Protect feature. If the
SWP bits indicate that some of the sectors have been protected, then the individual Sector Pro-
tection Registers can be read with the Read Sector Protection Registers command to determine
which sectors are in fact protected.
11.1.5
WEL Bit
The WEL bit indicates the current status of the internal Write Enable Latch. When the WEL bit is
in the logical “0” state, the device will not accept any Byte/Page Program, erase, Protect Sector,
Unprotect Sector, Sector Lockdown, Freeze Sector Lockdown State, Program OTP Security
Register, or Write Status Register commands. The WEL bit defaults to the logical “0” state after
a device power-up or reset operation. In addition, the WEL bit will be reset to the logical “0” state
automatically under the following conditions:
• Write Disable operation completes successfully
• Write Status Register operation completes successfully or aborts
• Protect Sector operation completes successfully or aborts
• Unprotect Sector operation completes successfully or aborts
• Sector Lockdown operation completes successfully or aborts
• Freeze Sector Lockdown State operation completes successfully or aborts
• Program OTP Security Register operation completes successfully or aborts
• Byte/Page Program operation completes successfully or aborts
• Block Erase operation completes successfully or aborts
• Chip Erase operation completes successfully or aborts
• Hold condition aborts
If the WEL bit is in the logical “1” state, it will not be reset to a logical “0” if an operation aborts
due to an incomplete or unrecognized opcode being clocked into the device before the CS pin is
deasserted. In order for the WEL bit to be reset when an operation aborts prematurely, the entire
opcode for a Byte/Page Program, erase, Protect Sector, Unprotect Sector, Sector Lockdown,
Freeze Sector Lockdown State, Program OTP Security Register, or Write Status Register com-
mand must have been clocked into the device.
11.1.6
RSTE Bit
The RSTE bit is used to enable or disable the Reset command. When the RSTE bit is in the log-
ical “0” state (the default state after power-up), the Reset command is disabled and any attempts
to reset the device using the Reset command will be ignored. When the RSTE bit is in the logical
“1” state, the Reset command is enabled.
38
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
The RSTE bit will retain its state as long as power is applied to the device. Once set to the logi-
cal “1” state, the RSTE bit will remain in that state until it is modified using the Write Status
Register Byte 2 command or until the device has been power cycled. The Reset command itself
will not change the state of the RSTE bit.
11.1.7
SLE Bit
The SLE bit is used to enable and disable the Sector Lockdown and Freeze Sector Lockdown
State commands. When the SLE bit is in the logical “0” state (the default state after power-up),
the Sector Lockdown and Freeze Sector Lockdown commands are disabled. If the Sector Lock-
down and Freeze Sector Lockdown commands are disabled, then any attempts to issue the
commands will be ignored. This provides a safeguard for these commands against accidental or
erroneous execution. When the SLE bit is in the logical “1” state, the Sector Lockdown and
Freeze Sector Lockdown State commands are enabled.
Unlike the WEL bit, the SLE bit does not automatically reset after certain device operations.
Therefore, once set, the SLE bit will remain in the logical “1” state until it is modified using the
Write Status Register Byte 2 command or until the device has been power cycled. The Reset
command has no effect on the SLE bit.
If the Freeze Sector Lockdown State command has been issued, then the SLE bit will be perma-
nently reset in the logical “0” state to indicate that the Sector Lockdown command has been
disabled.
11.1.8
11.1.9
PS Bit
ES Bit
The PS bit indicates whether or not a sector is in the Program Suspend state.
The ES bit indicates whether or not a sector is in the Erase Suspend state.
11.1.10 RDY/BSY Bit
The RDY/BSY bit is used to determine whether or not an internal operation, such as a program
or erase, is in progress. To poll the RDY/BSY bit to detect the completion of a program or erase
cycle, new Status Register data must be continually clocked out of the device until the state of
the RDY/BSY bit changes from a logical “1” to a logical “0”.
Figure 11-1. Read Status Register
CS
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
SCK
SI
OPCODE
0
0
0
0
0
1
0
1
MSB
STATUS REGISTER
BYTE 1
STATUS REGISTER
BYTE 2
STATUS REGISTER
BYTE 1
HIGH-IMPEDANCE
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
SO
MSB
MSB
MSB
39
3680E–DFLASH–12/08
11.2 Write Status Register Byte 1
The Write Status Register Byte 1 command is used to modify the SPRL bit of the Status Regis-
ter and/or to perform a Global Protect or Global Unprotect operation. Before the Write Status
Register Byte 1 command can be issued, the Write Enable command must have been previ-
ously issued to set the WEL bit in the Status Register to a logical “1”.
To issue the Write Status Register Byte 1 command, the CS pin must first be asserted and the
opcode of 01h must be clocked into the device followed by one byte of data. The one byte of
data consists of the SPRL bit value, a don’t care bit, four data bits to denote whether a Global
Protect or Unprotect should be performed, and two additional don’t care bits (see Table 11-3).
Any additional data bytes that are sent to the device will be ignored. When the CS pin is deas-
serted, the SPRL bit in the Status Register will be modified, and the WEL bit in the Status
Register will be reset back to a logical “0”. The values of bits 5, 4, 3, and 2 and the state of the
SPRL bit before the Write Status Register Byte 1 command was executed (the prior state of the
SPRL bit) will determine whether or not a Global Protect or Global Unprotect will be performed.
Please refer to “Global Protect/Unprotect” on page 24 for more details.
The complete one byte of data must be clocked into the device before the CS pin is deasserted,
and the CS pin must be deasserted on even byte boundaries (multiples of eight bits); otherwise,
the device will abort the operation, the state of the SPRL bit will not change, no potential Global
Protect or Unprotect will be performed, and the WEL bit in the Status Register will be reset back
to the logical “0” state.
If the WP pin is asserted, then the SPRL bit can only be set to a logical “1”. If an attempt is made
to reset the SPRL bit to a logical “0” while the WP pin is asserted, then the Write Status Register
Byte 1 command will be ignored, and the WEL bit in the Status Register will be reset back to the
logical “0” state. In order to reset the SPRL bit to a logical “0”, the WP pin must be deasserted.
Table 11-3. Write Status Register Byte 1 Format
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
SPRL
X
Global Protect/Unprotect
X
X
Figure 11-2. Write Status Register Byte 1
CS
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15
SCK
SI
STATUS REGISTER IN
BYTE 1
OPCODE
0
0
0
0
0
0
0
1
D
X
D
D
D
D
X
X
MSB
MSB
HIGH-IMPEDANCE
SO
40
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
11.3 Write Status Register Byte 2
The Write Status Register Byte 2 command is used to modify the RSTE and SLE bits of the Sta-
tus Register. Using the Write Status Register Byte 2 command is the only way to modify the
RSTE and SLE bits in the Status Register during normal device operation, and the SLE bit can
only be modified if the sector lockdown state has not been frozen. Before the Write Status Reg-
ister Byte 2 command can be issued, the Write Enable command must have been previously
issued to set the WEL bit in the Status Register to a logical “1”.
To issue the Write Status Register Byte 2 command, the CS pin must first be asserted and the
opcode of 31h must be clocked into the device followed by one byte of data. The one byte of
data consists of three don’t care bits, the RSTE bit value, the SLE bit value, and three additional
don’t care bits (see Table 11-4). Any additional data bytes that are sent to the device will be
ignored. When the CS pin is deasserted, the RSTE and SLE bits in the Status Register will be
modified, and the WEL bit in the Status Register will be reset back to a logical “0”. The SLE bit
will only be modified if the Freeze Sector Lockdown State command has not been previously
issued.
The complete one byte of data must be clocked into the device before the CS pin is deasserted,
and the CS pin must be deasserted on even byte boundaries (multiples of eight bits); otherwise,
the device will abort the operation, the state of the RSTE and SLE bits will not change, and the
WEL bit in the Status Register will be reset back to the logical “0” state.
Table 11-4. Write Status Register Byte 2 Format
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
X
X
X
RSTE
SLE
X
X
X
Figure 11-3. Write Status Register Byte 2
CS
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15
SCK
SI
STATUS REGISTER IN
BYTE 2
OPCODE
0
0
1
1
0
0
0
1
X
X
X
D
D
X
X
X
MSB
MSB
HIGH-IMPEDANCE
SO
41
3680E–DFLASH–12/08
12. Other Commands and Functions
12.1 Reset
In some applications, it may be necessary to prematurely terminate a program or erase cycle
early rather than wait the hundreds of microseconds or milliseconds necessary for the program
or erase operation to complete normally. The Reset command allows a program or erase opera-
tion in progress to be ended abruptly and returns the device to an idle state. Since the need to
reset the device is immediate, the Write Enable command does not need to be issued prior to
the Reset command being issued. Therefore, the Reset command operates independently of
the state of the WEL bit in the Status Register.
The Reset command can only be executed if the command has been enabled by setting the
Reset Enabled (RSTE) bit in the Status Register to a logical “1”. If the Reset command has not
been enabled (the RSTE bit is in the logical “0” state), then any attempts at executing the Reset
command will be ignored.
To perform a Reset, the CS pin must first be asserted and the opcode of F0h must be clocked
into the device. No address bytes need to be clocked in, but a confirmation byte of D0h must be
clocked into the device immediately after the opcode. Any additional data clocked into the device
after the confirmation byte will be ignored. When the CS pin is deasserted, the program or erase
operation currently in progress will be terminated within a time of tRST. Since the program or
erase operation may not complete before the device is reset, the contents of the page being pro-
grammed or the block being erased cannot be guaranteed to be valid.
The Reset command has no effect on the states of the Sector Protection Registers, the Sector
Lockdown Registers, or the SPRL, RSTE, and SLE bits in the Status Register. The WEL, PS,
and ES bits, however, will be reset back to their default states. If a Reset operation is performed
while a sector is erase suspended, the suspend operation will abort, and the contents of the
block being erased in the suspended sector will be left in an undefined state. If a Reset is per-
formed while a sector is program suspended, the suspend operation will abort, and the contents
of the page that was being programmed and subsequently suspended will be undefined. The
remaining pages in the 64-Kbyte sector will retain their previous contents.
The complete opcode and confirmation byte must be clocked into the device before the CS pin is
deasserted, and the CS pin must be deasserted on an even byte boundary (multiples of eight
bits); otherwise, no Reset operation will be performed.
Figure 12-1. Reset
CS
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15
SCK
SI
OPCODE
CONFIRMATION BYTE IN
1
1
1
1
0
0
0
0
1
1
0
1
0
0
0
0
MSB
MSB
HIGH-IMPEDANCE
SO
42
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
12.2 Read Manufacturer and Device ID
Identification information can be read from the device to enable systems to electronically query
and identify the device while it is in system. The identification method and the command opcode
comply with the JEDEC standard for “Manufacturer and Device ID Read Methodology for SPI
Compatible Serial Interface Memory Devices”. The type of information that can be read from the
device includes the JEDEC defined Manufacturer ID, the vendor specific Device ID, and the ven-
dor specific Extended Device Information.
The Read Manufacturer and Device ID command is limited to a maximum clock frequency of
fCLK. Since not all Flash devices are capable of operating at very high clock frequencies, applica-
tions should be designed to read the identification information from the devices at a reasonably
low clock frequency to ensure that all devices to be used in the application can be identified
properly. Once the identification process is complete, the application can then increase the clock
frequency to accommodate specific Flash devices that are capable of operating at the higher
clock frequencies.
To read the identification information, the CS pin must first be asserted and the opcode of 9Fh
must be clocked into the device. After the opcode has been clocked in, the device will begin out-
putting the identification data on the SO pin during the subsequent clock cycles. The first byte
that will be output will be the Manufacturer ID followed by two bytes of Device ID information.
The fourth byte output will be the Extended Device Information String Length, which will be 00h
indicating that no Extended Device Information follows. After the Extended Device Information
String Length byte is output, the SO pin will go into a high-impedance state; therefore, additional
clock cycles will have no affect on the SO pin and no data will be output. As indicated in the
JEDEC standard, reading the Extended Device Information String Length and any subsequent
data is optional.
Deasserting the CS pin will terminate the Manufacturer and Device ID read operation and put
the SO pin into a high-impedance state. The CS pin can be deasserted at any time and does not
require that a full byte of data be read.
Table 12-1. Manufacturer and Device ID Information
Byte No.
Data Type
Value
1Fh
48h
1
2
3
4
Manufacturer ID
Device ID (Part 1)
Device ID (Part 2)
00h
Extended Device Information String Length
00h
Table 12-2. Manufacturer and Device ID Details
Hex
Data Type
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0 Value Details
JEDEC Assigned Code
Manufacturer ID
1Fh
48h
00h
JEDEC Code:
0001 1111 (1Fh for Atmel)
0
0
0
0
0
0
0
1
0
0
1
1
1
1
0
0
Family Code
Density Code
0
Family Code:
Density Code:
010 (AT25DF/26DFxxx series)
01000 (64-Mbit)
Device ID (Part 1)
Device ID (Part 2)
1
Sub Code
0
1
0
Product Version Code
Sub Code:
Product Version: 00000 (Initial version)
000 (Standard series)
0
0
0
43
3680E–DFLASH–12/08
Figure 12-2. Read Manufacturer and Device ID
CS
0
6
7
8
14 15 16
22 23 24
30 31 32
38
SCK
SI
OPCODE
9Fh
HIGH-IMPEDANCE
1Fh
48h
00h
00h
SO
MANUFACTURER ID
DEVICE ID
BYTE 1
DEVICE ID
BYTE 2
EXTENDED
DEVICE
INFORMATION
STRING LENGTH
Note: Each transition
shown for SI and SO represents one byte (8 bits)
12.3 Deep Power-Down
During normal operation, the device will be placed in the standby mode to consume less power
as long as the CS pin remains deasserted and no internal operation is in progress. The Deep
Power-Down command offers the ability to place the device into an even lower power consump-
tion state called the Deep Power-Down mode.
When the device is in the Deep Power-Down mode, all commands including the Read Status
Register command will be ignored with the exception of the Resume from Deep Power-Down
command. Since all commands will be ignored, the mode can be used as an extra protection
mechanism against program and erase operations.
Entering the Deep Power-Down mode is accomplished by simply asserting the CS pin, clocking
in the opcode of B9h, and then deasserting the CS pin. Any additional data clocked into the
device after the opcode will be ignored. When the CS pin is deasserted, the device will enter the
Deep Power-Down mode within the maximum time of tEDPD
.
The complete opcode must be clocked in before the CS pin is deasserted, and the CS pin must
be deasserted on an even byte boundary (multiples of eight bits); otherwise, the device will abort
the operation and return to the standby mode once the CS pin is deasserted. In addition, the
device will default to the standby mode after a power-cycle.
The Deep Power-Down command will be ignored if an internally self-timed operation such as a
program or erase cycle is in progress. The Deep Power-Down command must be reissued after
the internally self-timed operation has been completed in order for the device to enter the Deep
Power-Down mode.
44
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
Figure 12-3. Deep Power-Down
CS
tEDPD
0
1
2
3
4
5
6
7
SCK
OPCODE
1
0
1
1
1
0
0
1
SI
MSB
HIGH-IMPEDANCE
Active Current
SO
ICC
Standby Mode Current
Deep Power-Down Mode Current
12.4 Resume from Deep Power-Down
In order to exit the Deep Power-Down mode and resume normal device operation, the Resume
from Deep Power-Down command must be issued. The Resume from Deep Power-Down com-
mand is the only command that the device will recognized while in the Deep Power-Down mode.
To resume from the Deep Power-Down mode, the CS pin must first be asserted and opcode of
ABh must be clocked into the device. Any additional data clocked into the device after the
opcode will be ignored. When the CS pin is deasserted, the device will exit the Deep Power-
Down mode within the maximum time of tRDPD and return to the standby mode. After the device
has returned to the standby mode, normal command operations such as Read Array can be
resumed.
If the complete opcode is not clocked in before the CS pin is deasserted, or if the CS pin is not
deasserted on an even byte boundary (multiples of eight bits), then the device will abort the
operation and return to the Deep Power-Down mode.
Figure 12-4. Resume from Deep Power-Down
CS
tRDPD
0
1
2
3
4
5
6
7
SCK
SI
OPCODE
1
0
1
0
1
0
1
1
MSB
HIGH-IMPEDANCE
Active Current
SO
ICC
Standby Mode Current
Deep Power-Down Mode Current
45
3680E–DFLASH–12/08
12.5 Hold
The HOLD pin is used to pause the serial communication with the device without having to stop
or reset the clock sequence. The Hold mode, however, does not have an affect on any internally
self-timed operations such as a program or erase cycle. Therefore, if an erase cycle is in prog-
ress, asserting the HOLD pin will not pause the operation, and the erase cycle will continue until
it is finished.
The Hold mode can only be entered while the CS pin is asserted. The Hold mode is activated
simply by asserting the HOLD pin during the SCK low pulse. If the HOLD pin is asserted during
the SCK high pulse, then the Hold mode won’t be started until the beginning of the next SCK low
pulse. The device will remain in the Hold mode as long as the HOLD pin and CS pin are
asserted.
While in the Hold mode, the SO pin will be in a high-impedance state. In addition, both the SI pin
and the SCK pin will be ignored. The WP pin, however, can still be asserted or deasserted while
in the Hold mode.
To end the Hold mode and resume serial communication, the HOLD pin must be deasserted
during the SCK low pulse. If the HOLD pin is deasserted during the SCK high pulse, then the
Hold mode won’t end until the beginning of the next SCK low pulse.
If the CS pin is deasserted while the HOLD pin is still asserted, then any operation that may
have been started will be aborted, and the device will reset the WEL bit in the Status Register
back to the logical “0” state.
Figure 12-5. Hold Mode
CS
SCK
HOLD
Hold
Hold
Hold
46
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
13. RapidS Implementation
To implement RapidS and operate at clock frequencies higher than what can be achieved in a
viable SPI implementation, a full clock cycle can be used to transmit data back and forth across
the serial bus. The AT25DF641 is designed to always clock its data out on the falling edge of the
SCK signal and clock data in on the rising edge of SCK.
For full clock cycle operation to be achieved, when the AT25DF641 is clocking data out on the
falling edge of SCK, the host controller should wait until the next falling edge of SCK to latch the
data in. Similarly, the host controller should clock its data out on the rising edge of SCK in order
to give the AT25DF641 a full clock cycle to latch the incoming data in on the next rising edge of
SCK.
Implementing RapidS allows a system to run at higher clock frequencies since a full clock cycle
is used to accommodate a device’s clock-to-output time, input setup time, and associated
rise/fall times. For example, if the system clock frequency is 100 MHz (10 ns cycle time) with a
50% duty cycle, and the host controller has an input setup time of 2 ns, then a standard SPI
implementation would require that the slave device be capable of outputting its data in less than
3 ns to meet the 2 ns host controller setup time [(10 ns x 50%) - 2 ns] not accounting for rise/fall
times. In an SPI mode 0 or 3 implementation, the SPI master is designed to clock in data on the
next immediate rising edge of SCK after the SPI slave has clocked its data out on the preceding
falling edge. This essentially makes SPI a half-clock cycle protocol and requires extremely fast
clock-to-output times and input setup times in order to run at high clock frequencies. With
a RapidS implementation of this example, however, the full 10 ns cycle time is available which
gives the slave device up to 8 ns, not accounting for rise/fall times, to clock its data out. Like-
wise, with RapidS, the host controller has more time available to output its data to the slave
since the slave device would be clocking that data in a full clock cycle later.
Figure 13-1. RapidS Operation
Slave CS
1
8
1
8
1
2
3
4
5
6
7
2
3
4
5
6
7
SCK
B
E
tV
A
C
D
MSB
LSB
MOSI
MISO
BYTE A
H
G
I
F
MSB
LSB
BYTE B
MOSI = Master Out, Slave In
MISO = Master In, Slave Out
The Master is the ASIC/MCU and the Slave is the memory device.
The Master always clocks data out on the rising edge of SCK and always clocks data in on the falling edge of SCK.
The Slave always clocks data out on the falling edge of SCK and always clocks data in on the rising edge of SCK.
A. Master clocks out first bit of BYTE A on the rising edge of SCK.
B. Slave clocks in first bit of BYTE A on the next rising edge of SCK.
C. Master clocks out second bit of BYTE A on the same rising edge of SCK.
D. Last bit of BYTE A is clocked out from the Master.
E. Last bit of BYTE A is clocked into the slave.
F. Slave clocks out first bit of BYTE B.
G. Master clocks in first bit of BYTE B.
H. Slave clocks out second bit of BYTE B.
I. Master clocks in last bit of BYTE B.
47
3680E–DFLASH–12/08
14. Electrical Specifications
14.1 Absolute Maximum Ratings*
Temperature under Bias ............................... -55°C to +125° C
*NOTICE:
Stresses beyond those listed under “Absolute
Maximum Ratings” may cause permanent dam-
age to the device. This is a stress rating only and
functional operation of the device at these or any
other conditions beyond those indicated in the
operational sections of this specification is not
implied. Exposure to absolute maximum rating
conditions for extended periods may affect device
reliability.
Storage Temperature.................................... -65°C to +150° C
All Input Voltages
(including NC Pins)
with Respect to Ground.....................................-0.6V to +4.1V
All Output Voltages
with Respect to Ground.............................-0.6V to VCC + 0.5V
14.2 DC and AC Operating Range
AT25DF641
-40°C to 85° C
2.7V to 3.6V
Operating Temperature (Case)
CC Power Supply
Ind.
V
14.3 DC Characteristics
Symbol
Parameter
Condition
CS, WP, HOLD = VCC
all inputs at CMOS levels
CS, WP, HOLD = VCC
Min
Typ
Max
Units
,
ISB
Standby Current
25
50
µA
,
IDPD
Deep Power-down Current
5
12
10
8
10
19
17
14
12
10
8
µA
all inputs at CMOS levels
f = 100 MHz; IOUT = 0 mA;
CS = VIL, VCC = Max
f = 85 MHz; IOUT = 0 mA;
CS = VIL, VCC = Max
f = 66 MHz; IOUT = 0 mA;
CS = VIL, VCC = Max
ICC1
Active Current, Read Operation
mA
f = 50 MHz; IOUT = 0 mA;
CS = VIL, VCC = Max
7
f = 33 MHz; IOUT = 0 mA;
CS = VIL, VCC = Max
6
f = 20 MHz; IOUT = 0 mA;
CS = VIL, VCC = Max
5
ICC2
ICC3
ILI
Active Current, Program Operation
Active Current, Erase Operation
Input Leakage Current
Output Leakage Current
Input Low Voltage
CS = VCC, VCC = Max
CS = VCC, VCC = Max
VIN = CMOS levels
VOUT = CMOS levels
12
12
18
mA
mA
µA
µA
V
18
1
1
ILO
VIL
0.3 x VCC
VIH
VOL
VOH
Input High Voltage
0.7 x VCC
V
Output Low Voltage
IOL = 1.6 mA; VCC = Min
IOH = -100 µA; VCC = Min
0.4
V
Output High Voltage
VCC - 0.2V
V
48
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
14.4 AC Characteristics - Maximum Clock Frequencies
Symbol
RapidS and SPI Operation
Maximum Clock Frequency for All Operations – RapidS Operation Only
Parameter
Min
Max
Units
fMAX
100
85
MHz
MHz
(excluding 0Bh, 03h, 3Bh, and 9F opcodes)
Maximum Clock Frequency for All Operations
(excluding 03h and 3Bh opcodes)
fCLK
fRDLF
Maximum Clock Frequency for 03h Opcode (Read Array – Low Frequency)
Maximum Clock Frequency for 3Bh Opcode (Dual-Output Read)
50
85
MHz
MHz
fRDDO
14.5 AC Characteristics – All Other Parameters
Symbol
tCLKH
Parameter
Min
4.3
4.3
0.1
0.1
50
5
Max
Units
ns
Clock High Time
tCLKL
Clock Low Time
ns
(1)
tCLKR
Clock Rise Time, Peak-to-Peak (Slew Rate)
Clock Fall Time, Peak-to-Peak (Slew Rate)
Chip Select High Time
V/ns
V/ns
ns
(1)
tCLKF
tCSH
tCSLS
tCSLH
tCSHS
tCSHH
tDS
Chip Select Low Setup Time (relative to Clock)
Chip Select Low Hold Time (relative to Clock)
Chip Select High Setup Time (relative to Clock)
Chip Select High Hold Time (relative to Clock)
Data In Setup Time
ns
5
ns
5
ns
5
ns
2
ns
tDH
Data In Hold Time
1
ns
(1)
tDIS
Output Disable Time
5
5
ns
(2)
tV
Output Valid Time
ns
tOH
Output Hold Time
2
5
5
5
5
ns
tHLS
tHLH
tHHS
tHHH
HOLD Low Setup Time (relative to Clock)
HOLD Low Hold Time (relative to Clock)
HOLD High Setup Time (relative to Clock)
HOLD High Hold Time (relative to Clock)
HOLD Low to Output High-Z
ns
ns
ns
ns
(1)
tHLQZ
5
5
ns
(1)
tHHQX
HOLD High to Output Low-Z
ns
(1)(3)
tWPS
Write Protect Setup Time
20
ns
(1)(3)
tWPH
Write Protect Hold Time
100
ns
(1)
tSECP
Sector Protect Time (from Chip Select High)
Sector Unprotect Time (from Chip Select High)
Sector Lockdown and Freeze Sector Lockdown State Time (from Chip Select High)
20
20
ns
(1)
tSECUP
ns
(1)
tLOCK
200
µs
49
3680E–DFLASH–12/08
14.5 AC Characteristics – All Other Parameters (Continued)
Symbol
Parameter
Min
Max
1
Units
µs
(1)
tEDPD
Chip Select High to Deep Power-Down
Chip Select High to Standby Mode
Reset Time
(1)
tRDPD
30
30
µs
tRST
µs
Notes: 1. Not 100% tested (value guaranteed by design and characterization).
2. 15 pF load at frequencies above 70 MHz, 30 pF otherwise.
3. Only applicable as a constraint for the Write Status Register Byte 1 command when SPRL = 1.
14.6 Program and Erase Characteristics
Symbol
Parameter
Min
Typ
1.0
7
Max
Units
ms
(1)
tPP
Page Program Time (256 Bytes)
Byte Program Time
3.0
tBP
µs
4 Kbytes
32 Kbytes
64 Kbytes
50
200
600
950
112
20
(1)
tBLKE
Block Erase Time
250
400
64
ms
(1)(2)
tCHPE
Chip Erase Time
sec
µs
µs
µs
ns
tSUSP
tRES
Program/Erase Suspend Time
Program/Erase Resume Time
OTP Security Register Program Time
Write Status Register Time
10
10
20
(1)
tOTPP
200
500
200
(2)
tWRSR
Note:
1. Maximum values indicate worst-case performance after 100,000 erase/program cycles.
2. Not 100% tested (value guaranteed by design and characterization).
14.7 Power-up Conditions
Symbol
tVCSL
Parameter
Min
Max
Units
µs
Minimum VCC to Chip Select Low Time
Power-up Device Delay Before Program or Erase Allowed
Power-on Reset Voltage
50
tPUW
10
ms
V
VPOR
1.5
2.5
50
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
14.8 Input Test Waveforms and Measurement Levels
0.9VCC
AC
AC
DRIVING
LEVELS
VCC/2
MEASUREMENT
LEVEL
0.1VCC
tR, tF < 2 ns (10% to 90%)
14.9 Output Test Load
DEVICE
UNDER
TEST
15 pF (frequencies above 70 MHz)
or
30pF
51
3680E–DFLASH–12/08
15. AC Waveforms
Figure 15-1. Serial Input Timing
tCSH
CS
tCSLS
tCSLH
tCLKL
tCSHH
tCLKH
tCSHS
SCK
tDS
tDH
MSB
LSB
MSB
SI
HIGH-IMPEDANCE
SO
Figure 15-2. Serial Output Timing
CS
tCLKH
tCLKL
tDIS
SCK
SI
tOH
tV
tV
SO
Figure 15-3. WP Timing for Write Status Register Byte 1 Command When SPRL = 1
CS
tWPS
tWPH
WP
SCK
SI
0
0
0
X
MSB
MSB OF
LSB OF
WRITE STATUS REGISTER
DATA BYTE
MSB OF
WRITE STATUS REGISTER
BYTE 1 OPCODE
NEXT OPCODE
HIGH-IMPEDANCE
SO
52
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
Figure 15-4. HOLD Timing – Serial Input
CS
SCK
tHHH
tHLS
tHLH
tHHS
HOLD
SI
HIGH-IMPEDANCE
SO
Figure 15-5. HOLD Timing – Serial Output
CS
SCK
tHHH
tHLS
tHLH
tHHS
HOLD
SI
tHLQZ
SO
tHHQX
53
3680E–DFLASH–12/08
16. Ordering Information
16.1 Ordering Code Detail
A T 2 5 D F 6 4 1 – S 3 H – B
Atmel Designator
Product Family
Shipping Carrier Option
B = Bulk (tubes)
Y = Bulk (trays)
T = Tape and reel
Device Grade
H = Green, NiPdAu lead finish, industrial
temperature range (–40°C to +85°C)
Device Density
Package Option
64 = 64-megabit
S3 = 16-lead, 0.300" wide SOIC
MW = 8-contact, 6 mm x 8 mm VDFN
Interface
1 = Serial
16.2 Green Package Options (Pb/Halide-free/RoHS Compliant)
Max. Freq.
Ordering Code
Package
Lead Finish
Operating Voltage
(MHz)
Operation Range
AT25DF641-S3H-B
AT25DF641-S3H-T
16S
Industrial
NiPdAu
2.7V to 3.6V
100
(-40°C to +85°C)
AT25DF641-MWH-Y
AT25DF641-MWH-T
8MW1
Note:
The shipping carrier option code is not marked on the devices.
Package Type
16S
16-lead, 0.300" Wide, Plastic Gull Wing Small Outline Package (SOIC)
8-contact, 6 x 8 mm, Very Thin Dual Flat No Lead Package (VDFN)
8MW1
54
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
17. Packaging Information
17.1 16S – SOIC
1
E
H
E
End View
N
L
C
Top View
COMMON DIMENSIONS
(Unit of Measure = mm)
e
b
MIN
2.35
0.10
0.31
MAX
2.65
0.30
0.51
NOM
NOTE
SYMBOL
A
A1
b
–
A1
A
–
–
D
E
H
L
10.30 BSC
7.50 BSC
10.30 BSC
–
2
D
3
Side View
0.40
0.20
1.27
4
e
1.27 BSC
C
0.33
Notes:
1. This drawing is for general information only; refer to JEDEC Drawing MS-013, Variation AA for additional information.
2. Dimension D does not include mold Flash, protrusions or gate burrs. Mold Flash, protrusion and gate burrs shall not
exceed 0.15 mm (0.006") per side.
3. Dimension E does not include inter-lead Flash or protrusion. Inter-lead flash and protrusions shall not exceed 0.25 mm
(0.010") per side.
4. L is the length of the terminal for soldering to a substrate.
11/02/05
TITLE
DRAWING NO.
16S
REV.
2325 Orchard Parkway
San Jose, CA 95131
16S, 16-lead, 0.300" Wide Body, Plastic Gull
Wing Small Outline Package (SOIC)
A
R
55
3680E–DFLASH–12/08
17.2 8MW1 – VDFN
C
E
Pin 1 ID
D
SIDE VIEW
A1
TOP VIEW
A
E1
COMMON DIMENSIONS
(Unit of Measure = mm)
8
7
6
5
1
Pin #1 ID
MIN
0.80
–
MAX
1.00
0.05
0.48
NOM
–
NOTE
SYMBOL
Option A
Option B
Pin #1
A
Chamfer
(C 0.30)
2
A1
b
–
D1
0.35
0.40
3
C
0.203 REF
6.00
e
D
5.90
4.70
7.90
4.80
6.10
4.90
8.10
5.00
4
D1
E
4.80
b
8.00
Pin #1
Notch
E1
e
4.90
L
K
(0.20 R)
1.27
BOTTOM VIEW
L
0.45
0.50
0.55
K
0.30 REF
4/15/08
GPC
YKL
DRAWING NO.
TITLE
REV.
8MW1, 8-pad (6 x 8 x 1.0 mm Body), Thermally
Enhanced Plastic Very Thin Dual Flat No Lead
Package (VDFN)
Package Drawing Contact:
packagedrawings@atmel.com
8MW1
D
56
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
AT25DF641 [Preliminary]
18. Errata
18.1 Erase Suspend
Issue: Parts may not program correctly if a device is in the Erase Suspend state.
Workaround: None. It is recommended to not use the Byte/Page Program commands (opcodes
02h and A2h) during an Erase Suspend state. Systems should resume from Erase Suspend first
before attempting to program a device.
Resolution: The Erase Suspend feature is being fixed with a new revision of the device. Please
contact Atmel for the estimated availability of devices with the fix.
18.2 AC Characteristics – Maximum Clock Frequencies for Read Operations
Issue: Devices currently do not meet the maximum specified clock frequency for the following
read operations: Read Array, Read Sector Protection Registers, Read Sector Lockdown Regis-
ters, Read OTP Security Register, Read Status Register, and Read Manufacturer and Device
ID. Reading at clock frequencies higher than those listed below could cause read errors.
Symbol
fMAX
Opcodes Affected
Datasheet Specification
100 MHz
Errata Specification
66 MHz
1Bh, 3Ch, 35h, 77h, 05h
fCLK
0Bh, 9Fh
03h
85 MHz
66 MHz
fRDLF
fRDDO
50 MHz
33 MHz
3Bh
85 MHz
66 MHz
Workaround: None. Devices are limited to the clock frequencies specified above.
Resolution: The clock frequency issues are being fixed with a new revision of the device.
Please contact Atmel for the estimated availability of devices with the fix.
57
3680E–DFLASH–12/08
19. Revision History
Revision Level – Release Date History
A – December 2007
Initial release.
Minor text edits throughout document
Changed Standby Current values
– Increased typical value from 10 µA to 25 µA
– Increased maximum value from 20 µA to 35 µA
B – February 2008
Changed minimum Clock High Time and minimum Clock Low Time
from 3.7 ns to 4.3 ns
Replaced the technical illustration (16S2) with the correct one (16S)
on page 55.
C – June 2008
Added Errata (Section 18) regarding Erase Suspend and AC
Characteristics.
D – November 2008
Corrected clock frequency values in Table 6-1.
Changed Standby Current value
– Increased maximum value from 35 µA to 50 µA
Changed Deep Power-Down Current values
– Increased typical value from 1 µA to 5 µA
– Increased maximum value from 5 µA to 10 µA
E – December 2008
58
AT25DF641 [Preliminary]
3680E–DFLASH–12/08
Headquarters
International
Atmel Corporation
2325 Orchard Parkway
San Jose, CA 95131
USA
Tel: 1(408) 441-0311
Fax: 1(408) 487-2600
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Product Contact
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Technical Support
Sales Contact
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www.atmel.com/contacts
Literature Requests
www.atmel.com/literature
Disclaimer: The information in this document is provided in connection with Atmel products. No license, express or implied, by estoppel or otherwise, to any
intellectual property right is granted by this document or in connection with the sale of Atmel products. EXCEPT AS SET FORTH IN ATMEL’S TERMS AND CONDI-
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marks or trademarks of Atmel Corporation or its subsidiaries. Other terms and product names may be trademarks of others.
3680E–DFLASH–12/08
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