ATMEL AT45DB041B User Manual
Features
• Single 2.5V - 3.6V or 2.7V - 3.6V Supply
• Serial Peripheral Interface (SPI) Compatible
• 20 MHz Max Clock Frequency
• Page Program Operation
– Single Cycle Reprogram (Erase and Program)
– 2048 Pages (264 Bytes/Page) Main Memory
• Supports Page and Block Erase Operations
• Two 264-byte SRAM Data Buffers – Allows Receiving of Data
while Reprogramming the Flash Memory Array
• Continuous Read Capability through Entire Array
– Ideal for Code Shadowing Applications
• Low Power Dissipation
– 4 mA Active Read Current Typical
– 2 µA CMOS Standby Current Typical
• Hardware Data Protection Feature
• 5.0V-tolerant Inputs: SI, SCK, CS, RESET, and WP Pins
• Commercial and Industrial Temperature Ranges
• Green (Pb/Halide-free/RoHS Compliant) Package Options
1. Description
The AT45DB041B is an SPI compatible serial interface Flash memory ideally suited
for a wide variety of digital voice-, image-, program code- and data-storage applications. Its 4,325,376 bits of memory are organized as 2048 pages of 264 bytes each. In
addition to the main memory, the AT45DB041B also contains two SRAM data buffers
of 264 bytes each.
4-megabit
2.5-volt or
2.7-volt
DataFlash
®
AT45DB041B
The buffers allow receiving of data while a page in the main memory is being reprogrammed, as well as reading or writing a continuous data stream. EEPROM emulation
(bit or byte alterability) is easily handled with a self-contained three step Read-ModifyWrite operation. Unlike conventional Flash memories that are accessed randomly with
multiple address lines and a parallel interface, the DataFlash uses a SPI serial interface to sequentially access its data. DataFlash supports SPI mode 0 and mode 3. The
simple serial interface facilitates hardware layout, increases system reliability, minimizes switching noise, and reduces package size and active pin count. The device is
optimized for use in many commercial and industrial applications where high density,
low pin count, low voltage, and low power are essential. The device operates at clock
frequencies up to 20 MHz with a typical active read current consumption of 4 mA.
To allow for simple in-system reprogrammability, the AT45DB041B does not require
high input voltages for programming. The device operates from a single power supply,
2.5V to 3.6V or 2.7V to 3.6V, for both the program and read operations. The
AT45DB041B is enabled through the chip select pin (CS
wire interface consisting of the Serial Input (SI), Serial Output (SO), and the Serial
Clock (SCK).
All programming cycles are self-timed, and no separate erase cycle is required before
programming.
) and accessed via a three-
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ATMEL CONFIDENTIAL
When the device is shipped from Atmel, the most significant page of the memory array may not
be erased. In other words, the contents of the last page may not be filled with FFH.
2. Pin Configurations and Packages
Table 2-1. Pin Configurations
Pin Name Function
CS
Chip Select
SCK Serial Clock
SI Serial Input
SO Serial Output
WP
RESET
RDY/BUSY
Hardware Page Write Protect Pin
Chip Reset
Ready/Busy
Figure 2-1. TSOP Top View Type 1
RESET
WP
VCC
GND
SCK
1
2
3
4
NC
5
NC
6
7
8
NC
9
NC
10
NC
11
CS
12
13
SI
14
SO
28
NC
27
NC
26
NC
25
NC
24
NC
23
NC
22
NC
21
NC
20
NC
19
NC
18
NC
17
NC
16
NC
15
NC
RDY/BUSY
Figure 2-2. CASON – Top View through Package Figure 2-3. 8-SOIC
SI
SCK
RESET
CS
Figure 2-4. 28-SOIC
GND
NC
NC
CS
SCK
SI
SO
NC
NC
NC
NC
NC
NC
NC
1
2
3
4
(1)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
8
SO
7
GND
6
VCC
5
WP
SCK
RESET
1
SI
2
3
4
CS
Figure 2-5. CBGA Top View
28
VCC
27
NC
26
NC
25
WP
24
RESET
23
RDY/BUSY
22
NC
21
NC
20
NC
19
NC
18
NC
17
NC
16
NC
15
NC
through Package
123
A
B
C
D
E
SCK
CS
SO
NC
NC
GND
RDY/BSY
SI
NC
RESET
SO
8
GND
7
VCC
6
WP
5
NC
VCC
WP
NC
Note: 1. The next generation DataFlash devices will not be
offered in 28-SOIC package, therefore, this package is not recommended for new designs.
2
AT45DB041B
3443C–DFLSH–5/05
3. Block Diagram
AT45DB041B
4. Memory Array
WP
FLASH MEMORY ARRAY
PAGE (264 BYTES)
BUFFER 2 (264 BYTES)BUFFER 1 (264 BYTES)
SCK
CS
I/O INTERFACE
RESET
VCC
GND
RDY/BUSY
SOSI
To provide optimal flexibility, the memory array of the AT45DB041B is divided into three levels of
granularity comprising of sectors, blocks, and pages. The Memory Architecture Diagram illustrates the breakdown of each level and details the number of pages per sector and block. All
program operations to the DataFlash occur on a page-by-page basis; however, the optional
erase operations can be performed at the block or page level.
Figure 4-1. Memory Architecture Diagram
SECTOR ARCHITECTURE BLOCK ARCHITECTURE PAGE ARCHITECTURE
SECTOR 0 = 8 Pages
2112 bytes (2K + 64)
SECTOR 1 = 248 Pages
65,472 bytes (62K + 1984)
SECTOR 2 = 256 Pages
67,584 bytes (64K + 2K)
SECTOR 3 = 512 Pages
135,168 bytes (128K + 4K)
SECTOR 4 = 512 Pages
135,168 bytes (128K + 4K)
SECTOR 5 = 512 Pages
135,168 bytes (128K + 4K)
SECTOR 0
SECTOR 1
SECTOR 2
BLOCK 0
BLOCK 1
BLOCK 2
BLOCK 30
BLOCK 31
BLOCK 32
BLOCK 33
BLOCK 62
BLOCK 63
BLOCK 64
BLOCK 65
BLOCK 254
BLOCK 255
Block = 2112 bytes
(2K + 64)
8 Pages
BLOCK 0
BLOCK 1
PAGE 0
PAGE 1
PAGE 6
PAGE 7
PAGE 8
PAGE 9
PAGE 14
PAGE 15
PAGE 16
PAGE 17
PAGE 18
PAGE 2045
PAGE 2046
PAGE 2047
Page = 264 bytes
(256 + 8)
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ATMEL CONFIDENTIAL
5. Device Operation
The device operation is controlled by instructions from the host processor. The list of instructions
and their associated opcodes are contained in Tables 1 through 4. A valid instruction starts with
the falling edge of CS
memory address location. While the CS
the opcode and the desired buffer or main memory address location through the SI (serial input)
pin. All instructions, addresses and data are transferred with the most significant bit (MSB) first.
Buffer addressing is referenced in the datasheet using the terminology BFA8 - BFA0 to denote
the nine address bits required to designate a byte address within a buffer. Main memory
addressing is referenced using the terminology PA10 - PA0 and BA8 - BA0 where PA10 - PA0
denotes the 11 address bits required to designate a page address and BA8 - BA0 denotes the
nine address bits required to designate a byte address within the page.
5.1 Read Commands
By specifying the appropriate opcode, data can be read from the main memory or from either
one of the two data buffers. The DataFlash supports two categories of read modes in relation to
the SCK signal. The differences between the modes are in respect to the inactive state of the
SCK signal as well as which clock cycle data will begin to be output. The two categories, which
are comprised of four modes total, are defined as Inactive Clock Polarity Low or Inactive Clock
Polarity High and SPI Mode 0 or SPI Mode 3. A separate opcode (refer to Table 5-3 on page 10
for a complete list) is used to select which category will be used for reading. Please refer to the
“Detailed Bit-level Read Timing” diagrams in this datasheet for details on the clock cycle
sequences for each mode.
followed by the appropriate 8-bit opcode and the desired buffer or main
pin is low, toggling the SCK pin controls the loading of
5.1.1 Continuous Array Read
By supplying an initial starting address for the main memory array, the Continuous Array Read
command can be utilized to sequentially read a continuous stream of data from the device by
simply providing a clock signal; no additional addressing information or control signals need to
be provided. The DataFlash incorporates an internal address counter that will automatically
increment on every clock cycle, allowing one continuous read operation without the need of
additional address sequences. To perform a continuous read, an opcode of 68H or E8H must be
clocked into the device followed by 24 address bits and 32 don’t care bits. The first four bits of
the 24-bit address sequence are reserved for upward and downward compatibility to larger and
smaller density devices (see Notes under “Command Sequence for Read/Write Operations” diagram). The next 11 address bits (PA10 - PA0) specify which page of the main memory array to
read, and the last nine bits (BA8 - BA0) of the 24-bit address sequence specify the starting byte
address within the page. The 32 don’t care bits that follow the 24 address bits are needed to initialize the read operation. Following the 32 don’t care bits, additional clock pulses on the SCK
pin will result in serial data being output on the SO (serial output) pin.
The CS
bits, and the reading of data. When the end of a page in main memory is reached during a Continuous Array Read, the device will continue reading at the beginning of the next page with no
delays incurred during the page boundary crossover (the crossover from the end of one page to
the beginning of the next page). When the last bit in the main memory array has been read, the
device will continue reading back at the beginning of the first page of memory. As with crossing
over page boundaries, no delays will be incurred when wrapping around from the end of the
array to the beginning of the array.
pin must remain low during the loading of the opcode, the address bits, the don’t care
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3443C–DFLSH–5/05
A low-to-high transition on the CS pin will terminate the read operation and tri-state the SO pin.
The maximum SCK frequency allowable for the Continuous Array Read is defined by the f
specification. The Continuous Array Read bypasses both data buffers and leaves the contents
of the buffers unchanged.
5.1.2 Main Memory Page Read
A Main Memory Page Read allows the user to read data directly from any one of the 2048 pages
in the main memory, bypassing both of the data buffers and leaving the contents of the buffers
unchanged. To start a page read, an opcode of 52H or D2H must be clocked into the device followed by 24 address bits and 32 don’t care bits. The first four bits of the 24-bit address
sequence are reserved bits, the next 11 address bits (PA10 - PA0) specify the page address,
and the next nine address bits (BA8 - BA0) specify the starting byte address within the page.
The 32 don’t care bits which follow the 24 address bits are sent to initialize the read operation.
Following the 32 don’t care bits, additional pulses on SCK result in serial data being output on
the SO (serial output) pin. The CS
address bits, the don’t care bits, and the reading of data. When the end of a page in main memory is reached during a Main Memory Page Read, the device will continue reading at the
beginning of the same page. A low-to-high transition on the CS
ation and tri-state the SO pin.
5.1.3 Buffer Read
Data can be read from either one of the two buffers, using different opcodes to specify which
buffer to read from. An opcode of 54H or D4H is used to read data from buffer 1, and an opcode
of 56H or D6H is used to read data from buffer 2. To perform a Buffer Read, the eight bits of the
opcode must be followed by 15 don’t care bits, nine address bits, and eight don’t care bits. Since
the buffer size is 264 bytes, nine address bits (BFA8 - BFA0) are required to specify the first byte
of data to be read from the buffer. The CS
the address bits, the don’t care bits, and the reading of data. When the end of a buffer is
reached, the device will continue reading back at the beginning of the buffer. A low-to-high transition on the CS
AT45DB041B
CAR
pin must remain low during the loading of the opcode, the
pin will terminate the read oper-
pin must remain low during the loading of the opcode,
pin will terminate the read operation and tri-state the SO pin.
5.1.4 Status Register Read
The status register can be used to determine the device’s Ready/Busy status, the result of a
Main Memory Page to Buffer Compare operation, or the device density. To read the status register, an opcode of 57H or D7H must be loaded into the device. After the last bit of the opcode is
shifted in, the eight bits of the status register, starting with the MSB (bit 7), will be shifted out on
the SO pin during the next eight clock cycles. The five most significant bits of the status register
will contain device information, while the remaining three least-significant bits are reserved for
future use and will have undefined values. After bit 0 of the status register has been shifted out,
the sequence will repeat itself (as long as CS
again with bit 7. The data in the status register is constantly updated, so each repeating
sequence will output new data.
Table 5-1. Status Register Format
RDY/BUSY
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remains low and SCK is being toggled) starting
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
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ATMEL CONFIDENTIAL
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ATMEL CONFIDENTIAL
Ready/Busy status is indicated using bit 7 of the status register. If bit 7 is a 1, then the device is
not busy and is ready to accept the next command. If bit 7 is a 0, then the device is in a busy
state. The user can continuously poll bit 7 of the status register by stopping SCK at a low level
once bit 7 has been output. The status of bit 7 will continue to be output on the SO pin, and once
the device is no longer busy, the state of SO will change from 0 to 1. There are eight operations
which can cause the device to be in a busy state: Main Memory Page to Buffer Transfer, Main
Memory Page to Buffer Compare, Buffer to Main Memory Page Program with Built-in Erase,
Buffer to Main Memory Page Program without Built-in Erase, Page Erase, Block Erase, Main
Memory Page Program, and Auto Page Rewrite.
The result of the most recent Main Memory Page to Buffer Compare operation is indicated using
bit 6 of the status register. If bit 6 is a 0, then the data in the main memory page matches the
data in the buffer. If bit 6 is a 1, then at least one bit of the data in the main memory page does
not match the data in the buffer.
The device density is indicated using bits 5, 4, 3 and 2 of the status register. For the
AT45DB041B, the four bits are 0, 1, 1 and 1. The decimal value of these four binary bits does
not equate to the device density; the four bits represent a combinational code relating to differing
densities of Serial DataFlash devices, allowing a total of sixteen different density configurations.
5.2 Program and Erase Commands
5.2.1 Buffer Write
Data can be shifted in from the SI pin into either buffer 1 or buffer 2. To load data into either
buffer, an 8-bit opcode, 84H for buffer 1 or 87H for buffer 2, must be followed by 15 don’t care
bits and nine address bits (BFA8 - BFA0). The nine address bits specify the first byte in the
buffer to be written. The data is entered following the address bits. If the end of the data buffer is
reached, the device will wrap around back to the beginning of the buffer. Data will continue to be
loaded into the buffer until a low-to-high transition is detected on the CS
5.2.2 Buffer to Main Memory Page Program with Built-in Erase
Data written into either buffer 1 or buffer 2 can be programmed into the main memory. To start
the operation, an 8-bit opcode, 83H for buffer 1 or 86H for buffer 2, must be followed by the four
reserved bits, 11 address bits (PA10 - PA0) that specify the page in the main memory to be written, and nine additional don’t care bits. When a low-to-high transition occurs on the CS
part will first erase the selected page in main memory to all 1s and then program the data stored
in the buffer into the specified page in the main memory. Both the erase and the programming of
the page are internally self-timed and should take place in a maximum time of t
time, the status register will indicate that the part is busy.
5.2.3 Buffer to Main Memory Page Program without Built-in Erase
A previously erased page within main memory can be programmed with the contents of either
buffer 1 or buffer 2. To start the operation, an 8-bit opcode, 88H for buffer 1 or 89H for buffer 2,
must be followed by the four reserved bits, 11 address bits (PA10 - PA0) that specify the page in
the main memory to be written, and nine additional don’t care bits. When a low-to-high transition
occurs on the CS
the main memory. It is necessary that the page in main memory that is being programmed has
been previously erased. The programming of the page is internally self-timed and should take
place in a maximum time of t
busy.
pin, the part will program the data stored in the buffer into the specified page in
. During this time, the status register will indicate that the part is
P
pin.
pin, the
. During this
EP
6
AT45DB041B
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5.2.4 Page Erase
5.2.5 Block Erase
AT45DB041B
Successive page programming operations without doing a page erase are not recommended. In
other words, changing bytes within a page from a “1” to a “0” during multiple page programming
operations without erasing that page is not recommended.
The optional Page Erase command can be used to individually erase any page in the main
memory array allowing the Buffer to Main Memory Page Program without Built-in Erase command to be utilized at a later time. To perform a Page Erase, an opcode of 81H must be loaded
into the device, followed by four reserved bits, 11 address bits (PA10 - PA0), and nine don’t care
bits. The 11 address bits are used to specify which page of the memory array is to be erased.
When a low-to-high transition occurs on the CS
The erase operation is internally self-timed and should take place in a maximum time of t
ing this time, the status register will indicate that the part is busy.
A block of eight pages can be erased at one time allowing the Buffer to Main Memory Page Program without Built-in Erase command to be utilized to reduce programming times when writing
large amounts of data to the device. To perform a Block Erase, an opcode of 50H must be
loaded into the device, followed by four reserved bits, eight address bits (PA10 - PA3), and 12
don’t care bits. The eight address bits are used to specify which block of eight pages is to be
erased. When a low-to-high transition occurs on the CS
block of eight pages to 1s. The erase operation is internally self-timed and should take place in a
maximum time of t
. During this time, the status register will indicate that the part is busy.
BE
pin, the part will erase the selected page to 1s.
. Dur-
PE
pin, the part will erase the selected
Table 5-2. Block Erase Addressing
PA1 0 PA 9 PA8 PA7 PA6 PA 5 PA 4 PA 3 PA 2 PA 1 PA0 Bl oc k
0 0000000XXX 0
0 0000001XXX 1
0 0000010XXX 2
0 0000011XXX 3
•
•
•
1 1111100XXX252
1 1111101XXX253
1 1111110XXX254
1 1111111XXX255
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
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ATMEL CONFIDENTIAL
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ATMEL CONFIDENTIAL
5.2.6 Main Memory Page Program Through Buffer
This operation is a combination of the Buffer Write and Buffer to Main Memory Page Program
with Built-in Erase operations. Data is first shifted into buffer 1 or buffer 2 from the SI pin and
then programmed into a specified page in the main memory. To initiate the operation, an 8-bit
opcode, 82H for buffer 1 or 85H for buffer 2, must be followed by the four reserved bits and 20
address bits. The 11 most significant address bits (PA10 - PA0) select the page in the main
memory where data is to be written, and the next nine address bits (BFA8 - BFA0) select the first
byte in the buffer to be written. After all address bits are shifted in, the part will take data from the
SI pin and store it in one of the data buffers. If the end of the buffer is reached, the device will
wrap around back to the beginning of the buffer. When there is a low-to-high transition on the CS
pin, the part will first erase the selected page in main memory to all 1s and then program the
data stored in the buffer into the specified page in the main memory. Both the erase and the programming of the page are internally self-timed and should take place in a maximum of time t
During this time, the status register will indicate that the part is busy.
5.3 Additional Commands
5.3.1 Main Memory Page to Buffer Transfer
A page of data can be transferred from the main memory to either buffer 1 or buffer 2. To start
the operation, an 8-bit opcode, 53H for buffer 1 and 55H for buffer 2, must be followed by the
four reserved bits, 11 address bits (PA10 - PA0) which specify the page in main memory that is
to be transferred, and nine don’t care bits. The CS
load the opcode, the address bits, and the don’t care bits from the SI pin. The transfer of the
page of data from the main memory to the buffer will begin when the CS
low to a high state. During the transfer of a page of data (t
determine whether the transfer has been completed or not.
EP
pin must be low while toggling the SCK pin to
pin transitions from a
), the status register can be read to
XFR
.
5.3.2 Main Memory Page to Buffer Compare
A page of data in main memory can be compared to the data in buffer 1 or buffer 2. To initiate
the operation, an 8-bit opcode, 60H for buffer 1 and 61H for buffer 2, must be followed by 24
address bits consisting of the four reserved bits, 11 address bits (PA10 - PA0) which specify the
page in the main memory that is to be compared to the buffer, and nine don’t care bits. The CS
pin must be low while toggling the SCK pin to load the opcode, the address bits, and the don’t
care bits from the SI pin. On the low-to-high transition of the CS
selected main memory page will be compared with the 264 bytes in buffer 1 or buffer 2. During
this time (t
pare operation, bit 6 of the status register is updated with the result of the compare.
5.3.3 Auto Page Rewrite
This mode is only needed if multiple bytes within a page or multiple pages of data are modified in
a random fashion. This mode is a combination of two operations: Main Memory Page to Buffer
Transfer and Buffer to Main Memory Page Program with Built-in Erase. A page of data is first
transferred from the main memory to buffer 1 or buffer 2, and then the same data (from buffer 1
or buffer 2) is programmed back into its original page of main memory. To start the rewrite operation, an 8-bit opcode, 58H for buffer 1 or 59H for buffer 2, must be followed by the four reserved
bits, 11 address bits (PA10 - PA0) that specify the page in main memory to be rewritten, and
nine additional don’t care bits. When a low-to-high transition occurs on the CS
first transfer data from the page in main memory to a buffer and then program the data from the
buffer back into same page of main memory. The operation is internally self-timed and should
), the status register will indicate that the part is busy. On completion of the com-
XFR
pin, the 264 bytes in the
pin, the part will
8
AT45DB041B
3443C–DFLSH–5/05
take place in a maximum time of tEP. During this time, the status register will indicate that the
part is busy.
If a sector is programmed or reprogrammed sequentially page-by-page, then the programming
algorithm shown in Figure 17-1 on page 27 is recommended. Otherwise, if multiple bytes in a
page or several pages are programmed randomly in a sector, then the programming algorithm
shown in Figure 17-2 on page 28 is recommended. Each page within a sector must be
updated/rewritten at least once within every 10,000 cumulative page erase/program operations
in that sector.
5.4 Operation Mode Summary
The modes described can be separated into two groups – modes which make use of the Flash
memory array (Group A) and modes which do not make use of the Flash memory array (Group
B).
Group A modes consist of:
1. Main Memory Page Read
2. Main Memory Page to Buffer 1 (or 2) Transfer
3. Main Memory Page to Buffer 1 (or 2) Compare
4. Buffer 1 (or 2) to Main Memory Page Program with Built-in Erase
5. Buffer 1 (or 2) to Main Memory Page Program without Built-in Erase
6. Page Erase
7. Block Erase
8. Main Memory Page Program through Buffer
9. Auto Page Rewrite
AT45DB041B
Group B modes consist of:
1. Buffer 1 (or 2) Read
2. Buffer 1 (or 2) Write
3. Status Register Read
If a Group A mode is in progress (not fully completed) then another mode in Group A should not
be started. However, during this time in which a Group A mode is in progress, modes in Group B
can be started.
This gives the Serial DataFlash the ability to virtually accommodate a continuous data stream.
While data is being programmed into main memory from buffer 1, data can be loaded into buffer
2 (or vice versa). See application note AN-4 (“Using Atmel’s Serial DataFlash”) for more details.
3443C–DFLSH–5/05
ATMEL CONFIDENTIAL
9
ATMEL CONFIDENTIAL
Table 5-3. Read Commands
Command SCK Mode Opcode
Continuous Array Read
Main Memory Page Read
Buffer 1 Read
Buffer 2 Read
Status Register Read
Inactive Clock Polarity Low or High 68H
SPI Mode 0 or 3 E8H
Inactive Clock Polarity Low or High 52H
SPI Mode 0 or 3 D2H
Inactive Clock Polarity Low or High 54H
SPI Mode 0 or 3 D4H
Inactive Clock Polarity Low or High 56H
SPI Mode 0 or 3 D6H
Inactive Clock Polarity Low or High 57H
SPI Mode 0 or 3 D7H
Table 5-4. Program and Erase Commands
Command SCK Mode Opcode
Buffer 1 Write Any 84H
Buffer 2 Write Any 87H
Buffer 1 to Main Memory Page Program with Built-in Erase Any 83H
Buffer 2 to Main Memory Page Program with Built-in Erase Any 86H
Buffer 1 to Main Memory Page Program without Built-in Erase Any 88H
Buffer 2 to Main Memory Page Program without Built-in Erase Any 89H
Page Erase Any 81H
Block Erase Any 50H
Main Memory Page Program through Buffer 1 Any 82H
Main Memory Page Program through Buffer 2 Any 85H
Table 5-5. Additional Commands
Command SCK Mode Opcode
Main Memory Page to Buffer 1 Transfer Any 53H
Main Memory Page to Buffer 2 Transfer Any 55H
Main Memory Page to Buffer 1 Compare Any 60H
Main Memory Page to Buffer 2 Compare Any 61H
Auto Page Rewrite through Buffer 1 Any 58H
Auto Page Rewrite through Buffer 2 Any 59H
Note: In Tables 2 and 3, an SCK mode designation of “Any” denotes any one of the four modes of operation (Inactive Clock Polarity
Low, Inactive Clock Polarity High, SPI Mode 0, or SPI Mode 3).
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AT45DB041B
3443C–DFLSH–5/05
5.5 Pin Descriptions
5.5.1 Serial Input (SI)
The SI pin is an input-only pin and is used to shift data into the device. The SI pin is used for all
data input including opcodes and address sequences.
5.5.2 Serial Output (SO)
The SO pin is an output-only pin and is used to shift data out from the device.
5.5.3 Serial Clock (SCK)
The SCK pin is an input-only pin and is used to control the flow of data to and from the
DataFlash. Data is always clocked into the device on the rising edge of SCK and clocked out of
the device on the falling edge of SCK.
AT45DB041B
5.5.4 Chip Select (CS
5.5.5 Write Protect (WP
5.5.6 RESET
5.5.7 READY/BUSY
)
The DataFlash is selected when the CS
be accepted on the SI pin, and the SO pin will remain in a high-impedance state. A high-to-low
transition on the CS
pin is required to end an operation.
If the WP
only way to reprogram the first 256 pages is to first drive the protect pin high and then use the
program commands previously mentioned. If this pin and feature are not utilized it is recommended that the WP
A low state on the reset pin (RESET) will terminate the operation in progress and reset the internal state machine to an idle state. The device will remain in the reset condition as long as a low
level is present on the RESET
back to a high level.
The device incorporates an internal power-on reset circuit, so there are no restrictions on the
RESET
that the RESET
This open drain output pin will be driven low when the device is busy in an internally self-timed
operation. This pin, which is normally in a high state (through a 1 kΩ external pull-up resistor),
will be pulled low during programming operations, compare operations, and during page-tobuffer transfers.
pin is low. When the device is not selected, data will not
pin is required to start an operation, and a low-to-high transition on the CS
)
pin is held low, the first 256 pages of the main memory cannot be reprogrammed. The
pin be driven high externally.
pin. Normal operation can resume once the RESET pin is brought
pin during power-on sequences. If this pin and feature are not utilized it is recommended
pin be driven high externally.
3443C–DFLSH–5/05
The busy status indicates that the Flash memory array and one of the buffers cannot be
accessed; read and write operations to the other buffer can still be performed.
ATMEL CONFIDENTIAL
11
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