Rainbow Electronics AT45DB161B User Manual

Features

• Single 2.5V - 3.6V or 2.7V - 3.6V Supply

• Serial Peripheral Interfa ce (SPI) Compati ble

• 20 MHz Max Clock Frequency

• Page Program Operation

– Single Cycle Reprogram (Erase and Program)
– 4096 Pages (528 Bytes/Page) Main Memory

• Supports Page and Block Erase Operations

• Two 528-byte SRAM Data Buffers – Allows Receiving of Data

while Reprogramming of Nonvolatile Memory

• Continuous Read Capability through Entire Array

– Ideal for Code Shadowing Applic ation s

• Low Power Dissipation

– 4 mA Active Read Current Typical
– 2 µA CMOS Standby Current Typical

• Hardware Data Protection Feature

• 100% Compatible to AT45DB161

• 5.0V-tolerant Inputs: SI, SCK, CS, RESET and WP Pins

• Commercial and Industrial Temperature Ranges

16-megabit

2.5-volt Only or

2.7-volt Only
DataFlash

®

Description

The AT45DB161B is a 2.5-volt or 2.7-volt only, serial interface Flash memory ideally
suited for a wide variety of digital voice-, image-, program code- and data-storage
applications. Its 17,301,504 bits of memory are organized as 4096 pages of 528 bytes
each. In addition to the main memor y, the AT45DB161B also con tains two SRAM
data buffers of 528 bytes each. The buffers allow receiving of data wh il e a pag e in th e
main memory is being reprogrammed, as well as reading or writing a continuous data

Pin Configurations

Pin Name Function

CS

Chip Select
SCK Serial Clock
SI Serial Input
SO Serial Output
WP

Hardware Page Write

Protect Pin
RESET
RDY/BUSY

Chip Reset

Ready/Busy

DataFlash Card

(1)

Top View through Package

7654321

RDY/BUSY

RESET

GND

NC
NC
CS

SCK

SI
SO
NC
NC
NC
NC
NC
NC
NC

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

SOIC

1
2
3
4
5
6
7
8
9
10
11
12
13
14

TSOP 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

Type 1

CBGA Top View

through Package

2345

1

A
B
C
D
E

NC

NC

NC

NC

GND

SCK

VCC

NC

RDY/BSY

CS

WP

NC

SI

SO

RESET

NC

NC

NC

NC

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

NC
NC
NC
NC
NC

AT45DB161B

Note: 1. See AT45DCB002 Datasheet.

Rev. 2224E–DFLSH–10/02

1

Block Diagram

stream. EEPRO M emulation ( bit or byte a lterability) i s easily hand led with a s elf­contained three step Read-Mo dify-Wr ite operati on.Unli ke conv entional F lash memo ries
that are accessed randomly with multiple address l ines and a parallel in terface, the
DataFlash uses a SPI se rial interface to se quentially access its data . DataFlash sup­ports SPI mode 0 and mode 3. The simple serial interfac e 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 i ndustrial
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 AT45DB161B 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
AT45DB161B 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 cycles are self-timed, and no separate erase cycle is required before
programming.

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.

WP

FLASH MEMORY ARRAY

Memory Array

PAGE (528 BYTES)

BUFFER 2 (528 BYTES)BUFFER 1 (528 BYTES)

SCK

CS

RESET

VCC

GND

RDY/BUSY

I/O INTERFACE

SOSI

To provide optimal flexibility, the memory array of the AT45DB161B is divided into three
levels of granularity comprising of sectors, blocks, and pages. The Memory Architecture
Diagram illus trates the br eakdown of eac h leve l and details the nu mber o f 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 performe d at the block or pag e
level.

2

AT45DB161B

2224E–DFLSH–10/02

Memory Architectur e Diagram

AT45DB161B

SECTOR ARCHITECTURE

SECTOR 0 = 8 Pages

4,224 bytes (4K + 128)

SECTOR 1 = 248 Pages

130,944 bytes (124K + 3,968)

SECTOR 2 = 256 Pages

135,168 bytes (128K + 4K)

SECTOR 3 = 256 Pages

135,168 bytes (128K + 4K)

SECTOR 16 = 256 Pages

135,168 bytes (128K + 4K)

SECTOR 0

BLOCK ARCHITECTURE PAGE ARCHITECTURE

SECTOR 1SECTOR 2

BLOCK 0
BLOCK 1

BLOCK 30
BLOCK 31
BLOCK 32
BLOCK 33

BLOCK 62
BLOCK 63
BLOCK 64
BLOCK 65
BLOCK 66

BLOCK 509
BLOCK 510
BLOCK 511

Block = 4224 bytes

(4K + 128)

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 4093
PAGE 4094
PAGE 4095

Page = 528 bytes

(512 + 16)

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 wit h the falling ed ge of CS
and the desired buffer or main memory address location. While the CS
gling the SCK pin controls the loading of the opcode and the desired buffer or main
memory address loc ation thro ugh the SI (seri al input) pin . All instr uctions, addr esses
and data are transferred with the most significant bit (MSB) first.

Buffer addressing is reference d in the datas heet usin g the termin ology BFA 9 - BFA0 to
denote the ten address bits required to designate a byte address within a buffer. Main
memory addressing is referenced using the terminology PA11 - PA0 and BA9 - BA0
where PA11 - PA0 denotes the 12 address bits r equired to designate a page address
and BA9 - BA0 denotes the ten address bits required to designate a byte address within
the page.

followed by th e appr opriate 8 -bit opc ode

pin is low, tog-

Read Commands By specifying the appro priate opcode, data c an be read from the main mem ory or from

either one of the two data buffers. The DataFlash supports two categories of read
modes in relation to th e SCK s ignal . The dif ferenc es be tween the modes are in res pect
to the inactive state of the SCK si gnal as well as whi ch cloc k cycl e data wi ll 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 1 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 i n this datasheet fo r details on the clock cycle sequences for
each mode.

CONTINUOUS ARRAY READ: By supplyin g an initial sta rting address for the main
memory array, the Continuous Array Read command can b e utilized to sequentially
read a continuous strea m of data from the device by simp ly pro viding a cl ock sig nal; 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

2224E–DFLSH–10/02

3

cycle, allowing one con tinuous read ope ration without th e need of addition al 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 two 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 Operatio ns” d ia gram) . T he next 12 address bits (PA11 - PA0) specify which
page of the main memory array to read, and the last ten bits (BA9 - BA0) of the 24-bit
address sequence specify the starting byte address within the page. The 32 don’t care
bits that follow t he 24 a ddr ess bi ts are nee ded to initialize the re ad oper at ion . F ol lo win g
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
care bits, and the read ing of data. When the en d of a page in ma in memor y is reache d
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 pag e to the beginn ing of the nex t page). When th e 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 boundar ies, no dela ys will
be incurred when wrapping around from the end of the array to the beginning of the
array.

A low-to-high tran sition on the CS
SO pin. The maximum SCK frequency allowable for the Continuous Array Read is
defined by the f
ers and leaves the contents of the buffers unchanged.

MAIN MEMORY PAGE READ: A Main Memory Page Read allows the user to read data
directly from any one of the 4096 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 D2 H m us t b e cl oc ke d i nto th e d ev ice fol low ed by 24 a ddres s bi ts an d
32 don’t care bits. The first two bits of the 24-bit address sequence are reserved bits, the
next 12 address bits (PA11 - PA0) specify the page address, and the next ten address
bits (BA9 - 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, addi ti onal pul s es on S CK r esul t in serial data being ou tput 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
terminate the read operation and tri-state the SO pin.

pin must remain low during the loading of the opcode, the address bits, the don’t

pin will terminate the rea d operation and tri-state the

specification. T he Contin uous Array Read bypass es both da ta buff-

CAR

pin must remain lo w during the loading of the opcod e, the

pin will

BUFFER READ: Data can be read from either one of the two bu ffers, usin g different
opcodes to specif y whi ch bu ffer t o r ea d fro m. A n opc od e o f 5 4H o r D4H is u sed to read
data from buffer 1, an d a n o pco de of 5 6H or D6H is used to re ad data from buffer 2. To
perform a Buffer Read, the eight bits of the opcode must be followed by 14 don’t care
bits, ten address bits, and eight don’t care bits. Since the buffer size is 528 bytes, ten
address bits (BFA9 - B F A0 ) ar e required to specify t he fir s t by te of d ata to be read from
the buffer. The CS
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

STATUS REGISTER RE AD: The st atus regi ster c an b e us ed to deter mine the device ’s
Ready/Busy statu s, the resu lt of a Ma in Memory Page to Buf fer Compa re operati on, or
the device density. To read the status register, an opcode of 57H or D7H must be

4

AT45DB161B

pin must remain low during the loading of the opcode, the address

pin will terminate the read operation and tri-state the SO pin.

2224E–DFLSH–10/02

AT45DB161B

loaded into the device. After the last bit of the opcode is shifted in, the eight bits of the
status register, startin g with the MSB (bi t 7), will be shift ed out on the SO pin dur ing 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 value s. After bit 0 of the status register has been shifted
out, the sequence will repeat itself (as long as CS
gled) starting again with bit 7. The data in the status register is constantly updated, so
each repeating sequence will output new data.

Status Register Format

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

RDY/BUSY COMP1011XX

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 s tatus register by
stopping SCK at a l ow lev el on ce bi t 7 has b een ou tput . T he status o f b it 7 wi ll 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 Ma in Me mory P age P rogram with Buil t-in E rase, Buff er to M ain M emory
Page Program without Built-in Erase, Page Erase, Block Erase, Main Memory Page
Program, and Auto Page Rewrite.

remains low and SCK is being tog-

Program and Erase Commands

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
AT45DB161B, the four bits are 1, 0, 1 and 1. The decimal value of these four binary bits
does not equate to the device density; the fou r bits represent a c ombinational code
relating to differ ing d ensiti es of S erial DataFl ash device s, all owing a to tal of s ixt een d if­ferent density configurations.

BUFFER WRITE: Data can be shifted in fr om the SI pi n into eith er buffe r 1 or buffe r 2.
To load data into either buffer, an 8-bit opcode, 84H for buffer 1 or 87H for buffer 2, must
be followed by 14 don ’t care bit s and ten ad dress bits (BFA9 - BFA0). The ten address
bits specify th e first byt e in the buffer to be writ ten. The dat a is entere d followin g the
address bits. If the end of the data buffer is reached, the device will wrap around back to
the beginning of the buffer. Dat a will cont inue to be loaded i nto the buf fer until a low- to­high transition is detected on the CS

BUFFER TO MAIN MEMORY PAGE PROGRAM WITH BUILT-IN ERASE: Data writte n
into either buffer 1 or buffer 2 can be programmed into the main memory. To start the
operation, an 8-bit opcode , 83H fo r buffe r 1 or 8 6H for bu ffer 2, m ust be fol lo wed by th e
two reserved bits, 12 address bits (PA 11 - PA0) that specify the page in the main
memory to be written, and ten additional don’t care bits. When a low-to-high transition
occurs on the CS
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
cate that the part is busy.

pin, the part will first erase the selected page in main memory to all 1s

pin.

. During this time, the status register will indi-

EP

2224E–DFLSH–10/02

5

BUFFER TO MAIN MEMORY PAGE PROGRAM WITHOUT BUILT-IN ERASE: A

previously erased page within m ain memory can be programmed with the c ontents of
either buffer 1 or buffer 2. To start the operat ion, an 8-bit opcod e, 88H for buffer 1 or
89H for buffer 2, must be followed by the two reserved bits, 12 address bits
(PA11 - PA0) that specify the page i n the m ain memo ry to be written , and ten additional
don’t care bits. When a low-to-high transition occurs on the CS

pin, the part will program
the data stored in the buffer into the specifi ed p age in the main memory. It is n ec essa ry
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

. During this time, the status register will indicate that the part is busy.

P

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.

PAGE ER AS E: The op tional P age Erase command can be used to individua lly er ase
any page in the main mem ory array a llowing th e Buffer to Mai n Memo ry Page Progra m
without Built-in Eras e com mand t o be utilize d at a later tim e. To perfo rm a Page Er ase,
an opcode of 81H must be loaded into the device, followed by two reserved bits,
12 address bits (PA11 - PA0), and ten don’t care bits. The 12 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
internally self-timed and should take place in a maximum time of t

pin, the part will erase the selected page to 1s. The erase operation is

. During this time,

PE

the status register will indicate that the part is busy.
BLOCK ERASE: A block of eight pa ges ca n be eras ed at on e time al lowi ng the Bu ffer

to Main Memory Page Pr ogra m wi thou t B uil t- in Eras e c om man d to be u til iz ed to r ed uc e
programming times when writi ng large amounts o f data to the d evice. To perform a
Block Erase, an opcode of 50H must be loaded into the device, followed by two
reserved bits, nine address bits (PA 11 - PA3 ), and 13 don ’t care bits. T he nine addre ss
bits are used t o spe cify wh ich block of ei ght p ages is to be erased . Whe n a low-to -hig h
transition occurs on the CS

pin, the part will erase the selected 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

Block Erase Addressi ng

PA11 PA10 PA9 PA8 PA7 PA6 PA5 PA4 PA3 PA2 PA1 PA0 Block

000000000XXX0
000000001XXX1
000000010XXX2
000000011XXX3

•

•

•
111111100XXX508
111111101XXX509
111111110XXX510
111111111XXX511

6

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•

AT45DB161B

•

•

•

•

•

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2224E–DFLSH–10/02

•

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AT45DB161B

MAIN MEMORY PAGE PROGRAM THROUGH BUFFER: This operation is a combina-

tion of the Buffer Write and Buffer to Main Memor y Page Program wi th 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 two reserved bits
and 22 address bits. The 12 most signifi cant add ress bits (P A11 - PA 0) se lect th e page
in the main memory where data is to be written, and the next ten address bits
(BFA9 - BFA0) select the first byte in the buffer to be written. After all address bits are
shifted in, the part w ill ta ke dat a fr om the SI pi n an d s tor e it in one of t he d ata 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
selected pag e in main m emory t o all 1s and the n progr am the da ta sto red 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
this time, the status register will indicate that the part is busy.

Additional Commands MAIN MEMORY PAGE TO BUFFER TRANSFER: A page of data can be transferred

from the main memory t o either buffer 1 or buffer 2. To sta rt the operation, an 8-bit
opcode, 53H for buffer 1 and 55H for buffer 2, must be followed by the two reserved bits,
12 address bits (PA11 - PA0) which specify the page in main memory that is to be trans­ferred, and ten don ’t care bits. Th e 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
tions from a low to a high state. During the transfer of a page of data (t
register can be read to determine whether the transfer has been completed or not.

pin must be low while tog gling the SCK pi n to

pin, the part will first erase the

. During

EP

pin transi-

), the sta tus

XFR

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, mus t be foll owed by 24 address bits consis ting of
the two reserved bits, 12 ad dress bits (P A11 - PA0 ) which specify the page in the mai n
memory that is to be compared to the buffer, and ten don’t care bits. The CS

pin must be
low while toggling the SCK pin to load the opcode, t he address bi ts, and th e don’t ca re
bits from the SI pin. On the low-to-high transition of the CS

pin, the 528 bytes in the
selected main me mory pa ge w il l b e compared with the 528 by tes i n b uffe r 1 or buffer 2.
During this time (t

), the statu s reg iste r wil l indi cate that the part is b usy . On c ompl e-

XFR

tion of the compare operation, bit 6 of the status register is updated with the result of the
compare.

AUT O PAG E RE WR IT E: This mode is only needed if multiple bytes within a page or
multiple pages of data are mod ified in a random fashion . This mode is a comb ina tion of
two operations: Main Memory Page to Buffer Transfer and Buffer to Main Memory Page
Program with Built-in Er as e. A pa ge o f dat a is fi rst tr an sf er red fr om the m ain mem or y 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 5 9H for buffer 2, must be followe d by the two r eserv ed bits,
12 address bits (PA11 - PA0) that specify the page in main memory to be rewritten, and
ten additional don’t care bits. When a low-to-hi gh transition oc curs on the CS

pin, the
part will 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 s hould take place in a ma ximum time of t

. During this time, the

EP

status register will indicate that the part is busy.

2224E–DFLSH–10/02

7

If a sector is programmed or reprogrammed sequentiall y page-by-pa ge, then the pr o­gramming algorithm shown in Figure 1 on page 26 is recommended. Otherwise, if
multiple bytes in a page or several pages are programmed randomly in a sector, then
the programming alg orithm s hown i n Fig ure 2 on page 27 is r ecom mended. Each page
within a sector must be updated/rewritten at least once within every 10,000 cumulative
page erase/program operations in that sector.

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
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 pr ogress (n ot fully completed) then another mo de in Group A

should not be started. However, during this time in which a Gr oup 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 b uffer 2 (or v ice ver sa). S ee appl icatio n note AN-4 (“Using Atmel ’s Ser ial
DataFlash”) for more details.

Pin Descriptions 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.
SERIAL OUTPUT (SO): The SO pin is an output-only pin and is used to shift data out

from the device.
SERIAL CLOCK (SCK): The SCK pin is an input-only pin and is used to control the flow

of data to and fr om the Da taFlas h. Data is alw ays cloc ked in to the de vice on the risi ng
edge of SCK and clocked out of the device on the falling edge of SCK.

CHIP SELECT (CS

device is not selected, data will not 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
start an operation, and a low-to-high transition on the CS
operation.

8

AT45DB161B

): The DataFlash is selected when the CS pin is low. When the

pin is required to

pin is required to end an

2224E–DFLSH–10/02

AT45DB161B

WRITE PROTECT: If the WP pin is held low, the first 25 6 page s of the main memo ry

cannot be reprogrammed. T he on ly way to repro gram the first 256 pages is to first dr ive
the protect pin high and the n use the program co mmands previo usly mentio ned. The

pin is internally pulled hi gh; ther efore , connecti on of the WP pin is not necessary if

WP
this pin and feature wi ll not be util ized . Howeve r, it is reco mmende d that th e WP
driven high externally whenever possible.

RESET: A low state on the reset pin (RESET) will terminate the operation in progress
and reset the interna l state machi ne to a n id le sta te. Th e device will r emai n in the reset
condition as long as a low level is present on the RESET
resume once the RESET

The device incorporates an internal power-on reset circuit, so there are no restrictions
on the RESET pin during power-on sequences. The RESET pin is also internally pulled
high; therefore, conne ct ion of th e RE SE T
not be utilized. However, it is recommended that the RESET
nally whenever possible.

READY/BUSY: This open drain output pin will be dr iven low w hen the dev ice is bus y in
an internally self-timed operation. This pin, which is normally in a high state (through

W external pull-up resistor), will be pulled low during programming operations, com-

a1k
pare operations, and during page-to-buffer transfers.

pin is brought back to a high level.

pin is not necessary if thi s pi n a nd fe atur e w ill

pin. Normal operation can

pin be driven high exter-

pin be

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.

Power-on/Reset State When power is first applied to the device, or when recovering from a reset condition, the

device will defau lt to S PI Mode 3. In add ition, th e SO pin will be i n a high -impedanc e
state, and a high-to -low tran sition on the CS
tion. The SPI mode wil l be automatically sel ected on every falli ng edge of CS
sampling the inactive clock state.

pin will be required to start a valid instruc-

by

2224E–DFLSH–10/02

9

Table 1. 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 2. 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 3. 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).

10

AT45DB161B

2224E–DFLSH–10/02