Features
•
Single 2.7V to 3.6V Supply
•
RapidS
®
Serial Interface: 66 MHz Maximum Clock Frequency
•
– SPI Compatible Modes 0 and 3
User Configurable Page Size
– 256 Bytes per Page
– 264 Bytes per Page
– Page Size Can Be Factory Pre-configured for 256 Bytes
Page Program Operation
– Intelligent Programming Operation
– 1,024 Pages (256/264 Bytes/Page) Main Memory
Flexible Erase Options
– Page Erase (256 Bytes)
– Block Erase (2 Kbytes)
– Sector Erase (32 Kbytes)
– Chip Erase (2 Mbits)
One SRAM Data Buffer (256/264 Bytes)
Continuous Read Capability through Entire Array
– Ideal for Code Shadowing Applications
Low-power Dissipation
– 7 mA Active Read Current Typical
– 25 µA Standby Current Typical
– 5 µA Deep Power-down Typical
Hardware and Software Data Protection Features
– Individual Sector
Sector Lockdown for Secure Code and Data Storage
– Individual Sector
Security: 128-byte Security Register
– 64-byte User Programmable Space
– Unique 64-byte Device Identifier
JEDEC Standard Manufacturer and Device ID Read
100,000 Program/Erase Cycles Per Page Minimum
Data Retention – 20 Years
Industrial Temperature Range
Green (Pb/Halide-free/RoHS Compliant) Packaging Options
•
•
2-megabit
2.7-volt
Minimum
DataFlash
®
AT45DB021D
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•
•
•
•
•
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1. Description
The AT45DB021D is a 2.7V, serial-interface Flash memory ideally suited for a wide
variety of digital voice-, image-, program code- and data-storage applications. The
AT45DB021D supports RapidS serial interface for applications requiring very high
speed operations. RapidS serial interface is SPI compatible for frequencies up to 66
MHz. Its 2,162,688 bits of memory are organized as 1,024 pages of 256 bytes or 264
bytes each. In addition to the main memory, the AT45DB021D also contains one
SRAM buffer of 256/264 bytes. EEPROM emulation (bit or byte alterability) is easily
handled with a self-contained three step read-modify-write operation. Unlike conven-
tional Flash memories that are accessed randomly with multiple address lines and a
parallel interface, the DataFlash
®
uses a RapidS serial interface to sequentially
access its data. The simple sequential access dramatically reduces active pin count,
facilitates hardware layout, increases system reliability, minimizes switching noise,
and reduces package size.
3638F–DFLASH–4/08
The device is optimized for use in many commercial and industrial applications where high-den-
sity, low-pin count, low-voltage and low-power are essential.
To allow for simple in-system reprogrammability, the AT45DB021D does not require high input
voltages for programming. The device operates from a single power supply, 2.7V to 3.6V, for
both the program and read operations. The AT45DB021D is enabled through the chip select pin
(CS) and accessed via a three-wire interface consisting of the Serial Input (SI), Serial Output
(SO), and the Serial Clock (SCK).
All programming and erase cycles are self-timed.
2. Pin Configurations and Pinouts
Table 2-1.
Symbol
Pin Configurations
Asserted
State
Type
Name and Function
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 the standby mode (not Deep Power-Down mode), and the output pin (SO) will be in a
high-impedance state. When the device is deselected, data will not be accepted on the input pin (SI).
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 on the rising edge of SCK,
while output data on the SO pin is always clocked out on the falling edge of SCK.
Serial Input:
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 on the rising edge of SCK.
Serial Output:
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.
Write Protect:
When the WP pin is asserted, all sectors specified for protection by the Sector Protection Register will
be protected against program and erase operations regardless of whether the Enable Sector Protection command
has been issued or not. The WP pin functions independently of the software controlled protection method. After the
WP pin goes low, the content of the Sector Protection Register cannot be modified.
CS
Low
Input
SCK
–
Input
SI
SO
–
–
Input
Output
WP
If a program or erase command is issued to the device while the WP pin is asserted, the device will simply ignore
the command and perform no operation. The device will return to the idle state once the CS pin has been
deasserted. The Enable Sector Protection command and Sector Lockdown command, however, will be
recognized by the device when the WP pin is asserted.
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 V
CC
whenever possible.
Reset:
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
pin. Normal operation can resume once the RESET pin is brought back to a high level.
The device incorporates an internal power-on reset circuit, so there are no restrictions on the RESET pin during
power-on sequences. If this pin and feature are not utilized it is recommended that the RESET pin be driven high
externally.
Device Power Supply:
The V
CC
pin is used to supply the source voltage to the device.
Operations at invalid V
CC
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.
Low
Input
RESET
Low
Input
V
CC
GND
–
–
Power
Ground
2
AT45DB021D
3638F–DFLASH–4/08
AT45DB021D
Figure 2-1.
SOIC Top View
SI
SCK
RESET
CS
1
2
3
4
8
7
6
5
SO
GND
VCC
WP
Figure 2-2.
UDFN Top View
(1)
SI
SCK
RESET
CS
1
2
3
4
SO
7
GND
6
VCC
5
WP
8
Note:
1. The metal pad on the bottom of the UDFN package is floating. This pad can be a “No Connect” or connected to GND.
3. Block Diagram
WP
FLASH MEMORY ARRAY
PAGE (256/264 BYTES)
BUFFER (256/264 BYTES)
SCK
CS
RESET
VCC
GND
SI
I/O INTERFACE
SO
3
3638F–DFLASH–4/08
4. Memory Array
To provide optimal flexibility, the memory array of the AT45DB021D is divided into three levels of
granularity comprising of sectors, blocks, and pages. The “Memory Architecture Diagram” illus-
trates 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. The erase operations can
be performed at the chip, sector, block or page level.
Figure 4-1.
Memory Architecture Diagram
BLOCK ARCHITECTURE
SECTOR
0a
SECTOR
0b
BLOCK 0
BLOCK 1
BLOCK 2
SECTOR
ARCHITECTURE
SECTOR
0a =
8
Pages
2,048/2,112 bytes
PAGE ARCHITECTURE
8
Pages
BLOCK 0
PAGE 0
PAGE 1
SECTOR
0b = 120 Pages
31,744/32,726
bytes
PAGE 6
PAGE 7
PAGE
8
BLOCK 14
BLOCK 15
BLOCK 17
SECTOR
1
BLOCK 1
SECTOR
1 = 128 Pages
32,768/33,792
bytes
BLOCK 16
PAGE 9
PAGE 14
PAGE 15
BLOCK
30
BLOCK
31
SECTOR
6 = 128 Pages
32,768/33,792
bytes
BLOCK
32
BLOCK
33
PAGE 16
PAGE 17
PAGE 18
SECTOR
7 = 128 Pages
32,768/33,792
bytes
BLOCK 126
BLOCK 127
PAGE 1,022
PAGE 1,023
Block = 1,024/1,056 bytes
Page = 256/264 bytes
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 15-1 through 15-7.
A valid instruction
starts with the falling edge of CS followed by the appropriate 8-bit opcode and the desired buffer
or main memory address location. While the CS pin is low, toggling the SCK pin controls the
loading of 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 for the DataFlash standard page size (264 bytes) is referenced in the
datasheet using the terminology BFA8 - BFA0 to denote the 9 address bits required to designate
a byte address within a buffer. Main memory addressing is referenced using the terminology
PA9 - PA0 and BA8 - BA0, where PA9 - PA0 denotes the 10 address bits required to designate
a page address and BA8 - BA0 denotes the 9 address bits required to designate a byte address
within the page.
For the “Power of 2” binary page size (256 bytes), the Buffer addressing is referenced in the
datasheet using the conventional terminology BFA7 - BFA0 to denote the 8 address bits
required to designate a byte address within a buffer. Main memory addressing is referenced
using the terminology A17 - A0, where A17 - A8 denotes the 10 address bits required to desig-
nate a page address and A7 - A0 denotes the 8 address bits required to designate a byte
address within a page.
4
AT45DB021D
3638F–DFLASH–4/08
AT45DB021D
6. Read Commands
By specifying the appropriate opcode, data can be read from the main memory or from the
SRAM data buffer. The DataFlash supports RapidS protocols for Mode 0 and Mode 3. Please
refer to the “Detailed Bit-level Read Timing” diagrams in this datasheet for details on the clock
cycle sequences for each mode.
6.1
Continuous Array Read (Legacy Command – E8H): Up to 66 MHz
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 from the DataFlash standard page
size (264 bytes), an opcode of E8H must be clocked into the device followed by three address
bytes (which comprise the 24-bit page and byte address sequence) and 4 don’t care bytes. The
first 10 bits (PA9 - PA0) of the 19-bit address sequence specify which page of the main memory
array to read, and the last 9 bits (BA8 - BA0) of the 19-bit address sequence specify the starting
byte address within the page. To perform a continuous read from the binary page size (256
bytes), the opcode (E8H) must be clocked into the device followed by three address bytes and 4
don’t care bytes. The first 10 bits (A17 - A8) of the 18-bits sequence specify which page of the
main memory array to read, and the last 8 bits (A7 - A0) of the 18-bits address sequence specify
the starting byte address within the page. The don’t care bytes that follow the address bytes are
needed to initialize the read operation. Following the don’t care bytes, additional clock pulses on
the SCK pin will result in data being output on the SO (serial output) pin.
The CS pin must remain low during the loading of the opcode, the address bytes, the don’t care
bytes, 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 cross-
ing over page boundaries, no delays will be incurred when wrapping around from the end of the
array to the beginning of the array.
A low-to-high transition on the CS pin will terminate the read operation and tri-state the output
pin (SO). The maximum SCK frequency allowable for the Continuous Array Read is defined by
the f
CAR1
specification. The Continuous Array Read bypasses the data buffer and leaves the
contents of the buffer unchanged.
6.2
Continuous Array Read (High Frequency Mode – 0BH): Up to 66 MHz
This command can be used with the serial interface to read the main memory array sequentially
in high speed mode for any clock frequency up to the maximum specified by f
CAR1
. To perform a
continuous read array with the page size set to 264 bytes, the CS must first be asserted then an
opcode 0BH must be clocked into the device followed by three address bytes and a dummy
byte. The first 10 bits (PA9 - PA0) of the 19-bit address sequence specify which page of the
main memory array to read, and the last 9 bits (BA8 - BA0) of the 19-bit address sequence spec-
ify the starting byte address within the page. To perform a continuous read with the page size
set to 256 bytes, the opcode, 0BH, must be clocked into the device followed by three address
bytes (A17 - A0) and a dummy byte. Following the dummy byte, additional clock pulses on the
SCK pin will result in data being output on the SO (serial output) pin.
5
3638F–DFLASH–4/08
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