MICRON MT28F400B5WG-8T, MT28F400B5CG-8TET, MT28F004B5WG-8T, MT28F004B5WG-8TET, MT28F400B5CG-8T Datasheet

PRODUCTS AND SPECIFICATIONS DISCUSSED HEREIN ARE SUBJECT TO CHANGE BY MICRON WITHOUT NOTICE.

4Mb Smart 5 Boot Block Flash Memory ©2002, Micron Technology Inc.
MT28F004B5_3.fm - Rev. 3, Pub. 8/2002

1

4Mb

SMART 5 BOOT BLOCK FLASH MEMORY

FLASH MEMORY

MT28F004B5
MT28F400B5

5V Only, Dual Supply (Smart 5)

0.18µm Process Technology

FEATURES

• Seven erase blocks:
16KB/8K-word boot block (protected)
Two 8KB/4K-word parameter blocks
Four main memory blocks

• Smart 5 technology (B5):
5V ±10% V

CC

5V ±10% VPP application/production
programming

1

• Advanced 0.18µm CMOS floating-gate process

• Compatible with 0.3µm Smart 5 device

• Address access time: 80ns

• 100,000 ERASE cycles

• Industry-standard pinouts

• Inputs and outputs are fully TTL-compatible

• Automated write and erase algorithm

• Two-cycle WRITE/ERASE sequence

• Byte- or word-wide READ and WRITE

(MT28F400B5, 256K x 16/512K x 8)

•Byte-wide READ and WRITE only
(MT28F004B5, 512K x 8)

• TSOP and SOP packaging options

Notes: 1. This generation of devices does not support 12V VPP

compatibility production programming; however, 5V
V

PP application production programming can be used

with no loss of performance.

2. Contact factory for availability.

Part Number Example:

MT28F400B5WG-8 T

GENERAL DESCRIPTION

The MT28F004B5 (x8) and MT28F400B5 (x16, x8)
are nonvolatile, electrically block-erasable (Flash),
programmable, read-only memories containing
4,194,304 bits organized as 262,144 words (16 bits) or
524,288 bytes (8 bits). Writing or erasing the device is
done with a 5V V

PP voltage, while all operations are

performed with a 5V V

CC. Due to process technology

advances, 5V V

PP is optimal for application and pro-

duction programming. These devices are fabricated
with Micron’s advanced 0.18µm CMOS floating-gate
process.

The MT28F004B5 and MT28F400B5 are organized
into seven separately erasable blocks. To ensure that
critical firmware is protected from accidental erasure
or overwrite, the devices feature a hardware-protected
boot block. Writing or erasing the boot block requires
either applying a super-voltage to the RP# pin or driv­ing WP# HIGH in addition to executing the normal
write or erase sequences. This block may be used to
store code implemented in low-level system recovery.
The remaining blocks vary in density and are written
and erased with no additional security measures.

Please refer to Micron’s Web site (www.micron.com/

flash) for the latest data sheet.

OPTIONS MARKING

• Timing
80ns access -8

• Configurations
512K x 8 MT28F004B5
256K x 16/512K x 8 MT28F400B5

• Boot Block Starting Word Address
Top (3FFFFh) T
Bottom (00000h) B

•Operating Temperature Range
Commercial (0ºC to +70ºC) None
Extended (-40ºC to +85ºC) ET

•Packages
MT28F400B5
Plastic 44-pin SOP (600 mil) SG

2

Plastic 48-pin TSOP Type I WG
MT28F004B5
Plastic 40-pin TSOP Type I VG

40-Pin TSOP Type I

44-Pin SOP

2

48-Pin TSOP Type I

4Mb

SMART 5 BOOT BLOCK FLASH MEMORY

4Mb Smart 5 Boot Block Flash Memory ©2002, Micron Technology Inc.
MT28F004B5_3.fm - Rev. 3, Pub. 8/2002

2

Pin Assignment (Top View)

48-Pin TSOP Type I

Order Number and Part Marking

MT28F400B5WG-8 B
MT28F400B5WG-8 T
MT28F400B5WG-8 BET
MT28F400B5WG-8 TET

44-PIN SOP

1

Order Number and Part Marking

MT28F400B5SG-8 B
MT28F400B5SG-8 T
MT28F400B5SG-8 BET
MT28F400B5SG-8 TET

40-Pin TSOP Type I

Order Number and Part Marking

MT28F004B5VG-8 B
MT28F004B5VG-8 T
MT28F004B5VG-8 BET
MT28F004B5VG-8 TET

Notes: 1. Contact factory for availability.

A15
A14
A13
A12
A11
A10

A9
A8

NC
NC

WE#

RP#

V

PP

WP#

NC
NC

A17

A7
A6
A5
A4
A3
A2
A1

A16

BYTE#
V

SS

DQ15/(A-1)
DQ7
DQ14
DQ6
DQ13
DQ5
DQ12
DQ4

V

CC

DQ11
DQ3
DQ10
DQ2
DQ9
DQ1
DQ8
DQ0

OE#
V

SS

CE#

A0

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24

48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25

VPP

WP#

A17

A7

A6

A5

A4

A3

A2

A1

A0

CE#

V

SS

OE#

DQ0

DQ8

DQ1

DQ9

DQ2

DQ10

DQ3

DQ11

RP#

WE#

A8

A9

A10

A11

A12

A13

A14

A15

A16

BYTE#

V

SS

DQ15/(A-1)

DQ7

DQ14

DQ6

DQ13

DQ5

DQ12

DQ4

V

CC

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

44

43

42

41

40

39

38

37

36

35

34

33

32

31

30

29

28

27

26

25

24

23

A16
A15
A14
A13
A12
A11

A9
A8

WE#

RP#

V

PP

WP#

A18

A7
A6
A5
A4
A3
A2
A1

A17

V

SS

NC
NC

A10

DQ7
DQ6
DQ5
DQ4

V

CC

V

CC

NC

DQ3
DQ2
DQ1
DQ0

OE#
V

SS

CE#

A0

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21

4Mb

SMART 5 BOOT BLOCK FLASH MEMORY

4Mb Smart 5 Boot Block Flash Memory ©2002, Micron Technology Inc.
MT28F004B5_3.fm - Rev. 3, Pub. 8/2002

3

Functional Block Diagram

Notes: 1. Does not apply to MT28F004B5.

16KB Boot Block

8KB Parameter Block
8KB Parameter Block

96KB Main Block

128KB Main Block

128KB Main Block

Y - Select Gates

Sense Amplifiers

Write/Erase-Bit

Compare and Verify

Addr.

Buffer/

Latch

Power

(Current)

Control

Addr.

Counter

Command

Execution

Logic

I/O

Control

Logic

V

PP

Switch/

Pump

Status

Register

Identification

Register

Y -

Decoder

128KB Main Block

X - Decoder/Block Erase Control

Output

Buffer

Input

Buffer

State

Machine

BYTE#

1

A

0–A17/(18)

CE#

OE#

WE#

RP#

V

PP

DQ15/(A - 1)

1

MUX

DQ15

8

8

7

DQ8–DQ14

1

DQ0–DQ7

16

8

18 (19)

7

A-1

9

(10)

9

8

Output

Buffer

Output

Buffer

Input

Buffer

Input

Buffer

Input Data
Latch/Mux

7

A9

VCC

WP#

4Mb

SMART 5 BOOT BLOCK FLASH MEMORY

4Mb Smart 5 Boot Block Flash Memory ©2002, Micron Technology Inc.
MT28F004B5_3.fm - Rev. 3, Pub. 8/2002

4

PIN DESCRIPTIONS

44-PIN SOP

NUMBERS

40-PIN

TSOP

NUMBERS

48-PIN

TSOP

NUMBERS SYMBOL TYPE DESCRIPTION

43 9 11 WE# Input

Write Enable: Determines if a given cycle is a WRITE cycle.
If WE# is LOW, the cycle is either a WRITE to the command
execution logic (CEL) or to the memory array.

2 12 14 WP# Input

Write Protect: Unlocks the boot block when HIGH if VPP =
5V and RP# = V

IH during a WRITE or ERASE. Does not affect

WRITE or ERASE operation on other blocks.

12 22 26 CE# Input

Chip Enable: Activates the device when LOW. When CE# is
HIGH, the device is disabled and goes into standby power
mode.

44 10 12 RP# Input

Reset/Power-Down: When LOW, RP# clears the status
register, sets the internal state machine (ISM) to the array
read mode and places the device in deep power-down
mode. All inputs, including CE#, are “Don’t Care,” and all
outputs are High-Z. RP# unlocks the boot block and
overrides the condition of WP# when at V

HH, and must be

held at V

IH during all other modes of operation.

14 24 28 OE# Input

Output Enable: Enables data output buffers when LOW.
When OE# is HIGH, the output buffers are disabled.

33 – 47 BYTE# Input

Byte Enable: If BYTE# = HIGH, the upper byte is active
through DQ8–DQ15. If BYTE# = LOW, DQ8–DQ14 are
High-Z, and all data is accessed through DQ0–DQ7. DQ15/
(A-1) becomes the least significant address input.

11, 10, 9, 8,

7, 6, 5, 4,
42, 41, 40,
39, 38, 37,

36, 35, 34, 3

21, 20, 19,

18, 17,

16,15, 14, 8,

7, 36, 6, 5,

4, 3, 2, 1,

40, 13

25, 24, 23,

22, 21, 20,
19, 18, 8, 7,
6, 5, 4, 3, 2,

1, 48, 17

A0–A17/

(A18)

Input

Address Inputs: Select a unique, 16-bit word or 8-bit byte.
The Q15/(A-1) input becomes the lowest order address
when BYTE# = LOW (MT28F400B5) to allow for a selection
of an 8-bit byte from the 524,288 available.

31 – 45 DQ15

(A-1)

Input/

Output

Data I/O: MSB of data when BYTE# = HIGH. Address Input:
LSB of address input when BYTE# = LOW during READ or
WRITE operation.

15, 17, 19,
21, 24, 26,

28, 30

25-28, 32-35 29, 31, 33,

35, 38, 40,

42, 44

DQ0–DQ7 Input/

Output

Data I/Os: Data output pins during any READ operation or
data input pins during a WRITE. These pins are used to
input commands to the CEL.

16, 18, 20,
22, 25, 27,

29

– 30, 32, 34,

36, 39, 41,

43

DQ8–
DQ14

Input/

Output

Data I/Os: Data output pins during any READ operation or
data input pins during a WRITE when BYTE# = HIGH. These
pins are High-Z when BYTE# is LOW.

11113V

PP Supply

Write/Erase Supply Voltage: From a WRITE or ERASE
CONFIRM until completion of the WRITE or ERASE, VPP
must be at V

PPH (5V). VPP = “Don’t Care” during all other

operations.

23 30, 31 37 V

CC Supply

Power Supply: +5V ±10%.

13, 32 23, 39 27, 46 V

SS Supply

Ground.

– 29, 37, 38 9, 10, 15, 16 NC –

No Connect: These pins may be driven or left unconnected.

4Mb

SMART 5 BOOT BLOCK FLASH MEMORY

4Mb Smart 5 Boot Block Flash Memory ©2002, Micron Technology Inc.
MT28F004B5_3.fm - Rev. 3, Pub. 8/2002

5

Notes: 1. L = VIL (LOW), H = VIH (HIGH), X = VIL or VIH (“Don’t Care”).

2. V

PPH = 5V.

3. Operation must be preceded by ERASE SETUP command.

4. Operation must be preceded by WRITE SETUP command.

5. The READ ARRAY command must be issued before reading the array after writing or erasing.

6. When WP# = V

IH, RP# may be at VIH or VHH.

7. A1–A8, A10–A17 = V

IL.

8. Value reflects DQ8–DQ15.

TRUTH TABLE (MT28F400B5)

1

FUNCTION RP# CE# OE# WE# WP# BYTE# A0 A9 VPP

DQ0–

DQ7

DQ8–
DQ14

DQ15/

A - 1

Standby

H H X X X X X X X High-Z High-Z High-Z

Reset

L X X X X X X X X High-Z High-Z High-Z

READ

READ (word mode)

H L L H X H X X X Data-Out Data-Out Data-Out

READ (byte mode)

H L L H X L X X X Data-Out High-Z A-1

Output Disable

H L H H X X X X X High-Z High-Z High-Z

WRITE/ERASE (EXCEPT BOOT BLOCK)

2

ERASE SETUP

HLHLX X XXX 20h X X

ERASE CONFIRM

3

HLHLX X XXVPPH D0h X X

WRITE SETUP

H L H L X X X X X 10h/40h X X

WRITE (word mode)

4

HLHLX H XXVPPH Data-In Data-In Data-In

WRITE (byte mode)

4

HLHLX L XXVPPH Data-In X A-1

READ ARRAY

5

HLHLX X XXX FFh X X

WRITE/ERASE (BOOT BLOCK)

2

ERASE SETUP

HLHLX X XXX 20h X X

ERASE CONFIRM

3

VHH LHLXXXXVPPH D0h X X

ERASE CONFIRM

3, 6

HLHLH X XXVPPH D0h X X

WRITE SETUP

H L H L X X X X X 10h/40h X X

WRITE (word mode)

4

VHH LHLX H XXVPPH Data-In Data-In Data-In

WRITE (word mode)

4, 6

HLHLH H XXVPPH Data-In Data-In Data-In

WRITE (byte mode)

4

VHH LHLX L XXVPPH Data-In X A-1

WRITE (byte mode)

4, 6

HLHLH L XXVPPH Data-In X A-1

READ ARRAY

5

HLHLX X XXX FFh X X

DEVICE IDENTIFICATION

7

Manufacturer
Compatibility (word
mode)

8

HLLHX H LVID X 89hX 00h –

Manufacturer
Compatibility (byte
mode)

HLLHX L LV

ID X 89h High-Z X

Device (word mode, top
boot)

8

HLLHX H HVID X 70h 44h –

Device (byte mode, top
boot)

HLLHX L HV

ID X 70h High-Z X

Device (word mode,
bottom boot)

8

HLLHX H HVID X 71h 44h –

Device (byte mode,
bottom boot)

HLLHX L HV

ID X 71h High-Z X

4Mb

SMART 5 BOOT BLOCK FLASH MEMORY

4Mb Smart 5 Boot Block Flash Memory ©2002, Micron Technology Inc.
MT28F004B5_3.fm - Rev. 3, Pub. 8/2002

6

Notes: 1. L = VIL, H = VIH, X = VIL or VIH.

2. V

PPH = 5V.

3. Operation must be preceded by ERASE SETUP command.

4. Operation must be preceded by WRITE SETUP command.

5. The READ ARRAY command must be issued before reading the array after writing or erasing.

6. When WP# = V

IH, RP# may be at VIH or VHH.

7. A1–A8, A10–A18 = V

IL.

TRUTH TABLE (MT28F004B5)

1

FUNCTION RP# CE# OE# WE# WP# A0 A9 VPP DQ0–DQ7

Standby

HHXXXXXX High-Z

RESET

LXXXXXXX High-Z

READ

READ

HL LHXXXX Data-Out

Output Disable

HLHHXXXX High-Z

WRITE/ERASE (EXCEPT BOOT BLOCK)2

ERASE SETUP

HLHLXXXX 20h

ERASE CONFIRM

3

HLHLXXXVPPH D0h

WRITE SETUP

HLHLXXXX 10h/40h

WRITE

4

HLHLXXXVPPH Data-In

READ ARRAY

5

HLHLXXXX FFh

WRITE/ERASE (BOOT BLOCK)

2

ERASE SETUP

HLHLXXXX 20h

ERASE CONFIRM

3

VHH LHLXXXVPPH D0h

ERASE CONFIRM

3, 6

HLHLHXXVPPH D0h

WRITE SETUP

HLHLXXXX 10h/40h

WRITE

4

VHH LHLXXXVPPH Data-In

WRITE

4, 6

HLHLHXXVPPH Data-In

READ ARRAY

5

HLHLXXXX FFh

DEVICE IDENTIFICATION

7

Manufacturer Compatibility

HLLHXLV

ID X 89h

Device (top boot)

HLLHXHV

ID X 78h

Device (bottom boot)

HLLHXHV

ID X 79h

4Mb

SMART 5 BOOT BLOCK FLASH MEMORY

4Mb Smart 5 Boot Block Flash Memory ©2002, Micron Technology Inc.
MT28F004B5_3.fm - Rev. 3, Pub. 8/2002

7

FUNCTIONAL DESCRIPTION

The MT28F004B5 and MT28F400B5 Flash memo­ries incorporate a number of features ideally suited for
system firmware. The memory array is segmented into
individual erase blocks. Each block may be erased
without affecting data stored in other blocks. These
memory blocks are read, written and erased with com­mands to the command execution logic (CEL). The
CEL controls the operation of the internal state
machine (ISM), which completely controls all WRITE,
BLOCK ERASE, and VERIFY operations. The ISM pro­tects each memory location from over-erasure and
optimizes each memory location for maximum data
retention. In addition, the ISM greatly simplifies the
control necessary for writing the device in-system or in
an external programmer.

The Functional Description provides detailed infor­mation on the operation of the MT28F004B5 and
MT28F400B5 and is organized into these sections:

•Overview

• Memory Architecture

• Output (READ) operations

•Input Operations

• Command Set

•ISM Status Register

• Command Execution

• Error Handling

•WRITE/ERASE Cycle Endurance

•Power Usage

•Power-Up

OVERVIEW
Smart 5 Technology (B5)

Smart 5 technology allows maximum flexibility for
in-system READ, WRITE and ERASE operations. For
5V-only systems, WRITE and ERASE operations may be
executed with a V

PP voltage of 5V. Due to process tech-

nology advances, 5V V

PP is optimal for application and

production programming.

Seven Independently Erasable
Memory Blocks

The MT28F004B5 and MT28F400B5 are organized
into seven independently erasable memory blocks that
allow portions of the memory to be erased without
affecting the rest of the memory data. A special boot
block is hardware-protected against inadvertent era­sure or writing by requiring either a super-voltage on
the RP# pin or driving the WP# pin HIGH. One of these
two conditions must exist, along with the V

PP voltage

(5V) on the V

PP pin, before a WRITE or ERASE will be

performed on the boot block. The remaining blocks
require that only the V

PP voltage be present on the VPP

pin before writing or erasing.

Hardware-Protected Boot

This block of the memory array can be erased or

written only when the RP# pin is taken to V

HH or when

the WP# pin is brought HIGH. This provides additional
security for the core firmware during in-system firm­ware updates should an unintentional power fluctua­tion or system reset occur. The MT28F004B5 and
MT28F400B5 are available with the boot block starting
at the bottom of the address space (“B” suffix) or the
top of the address space (“T” suffix).

Selectable Bus Size (MT28F400B5 only)

The MT28F400B5 allows selection of an 8-bit (512K
x 8) or 16-bit (256K x 16) data bus for reading and writ­ing the memory. The BYTE# pin is used to select the
bus width. In the x16 configuration, control data is
read or written only on the lower eight bits (DQ0–
DQ7).

Data written to the memory array utilizes all active
data pins for the selected configuration. When the x8
configuration is selected, data is written in byte form;
when the x16 configuration is selected, data is written
in word form.

Internal State Machine (ISM)

Block erase and byte/word write timing are simpli­fied with an ISM that controls all erase and write algo­rithms in the memory array. The ISM ensures
protection against overerasure and optimizes write
margin to each cell.

During WRITE operations, the ISM automatically
increments and monitors WRITE attempts, verifies
write margin on each memory cell and updates the
ISM status register. When BLOCK ERASE is performed,
the ISM automatically overwrites the entire addressed
block (eliminates overerasure), increments and moni­tors ERASE attempts, and sets bits in the ISM status
register.

ISM Status Register

The ISM status register enables an external proces­sor to monitor the status of the ISM during WRITE and
ERASE operations. Two bits of the 8-bit status register
are set and cleared entirely by the ISM. These bits indi­cate whether the ISM is busy with a WRITE or ERASE
task and when an ERASE has been suspended. Addi-

4Mb

SMART 5 BOOT BLOCK FLASH MEMORY

4Mb Smart 5 Boot Block Flash Memory ©2002, Micron Technology Inc.
MT28F004B5_3.fm - Rev. 3, Pub. 8/2002

8

tional error information is set in three other bits: V

PP

status, write status, and erase status.

Command Execution Logic (CEL)

The CEL receives and interprets commands to the
device. These commands control the operation of the
ISM and the read path (i.e., memory array, ID register
or status register). Commands may be issued to the
CEL while the ISM is active. However, there are restric­tions on what commands are allowed in this condition.
See the Command Execution section for more detail.

Deep Power-down Mode

To allow for maximum power conservation, the
MT28F004B5 and MT28F400B5 feature a very low cur­rent, deep power-down mode. To enter this mode, the
RP# pin is taken to V

SS ±0.2V. In this mode, the current

draw is a maximum of 20µA at 5V V

CC. Entering deep

power-down also clears the status register and sets the
ISM to the read array mode.

MEMORY ARCHITECTURE

The MT28F004B5 and MT28F400B5 memory array
architecture is designed to allow sections to be erased
without disturbing the rest of the array. The array is
divided into seven addressable blocks that vary in size
and are independently erasable. When blocks rather
than the entire array are erased, total device endur­ance is enhanced, as is system flexibility. Only the
ERASE function is block-oriented. All READ and
WRITE operations are done on a random-access basis.

The boot block is protected from unintentional
ERASE or WRITE operations with a hardware protec­tion circuit that requires a super-voltage be applied to
RP# or that the WP# pin be driven HIGH before erasure
is commenced. The boot block is intended for the core
firmware required for basic system functionality. The

remaining six blocks do not require that either of these
two conditions be met before WRITE or ERASE opera­tions.

Boot Block

The hardware-protected boot block provides extra
security for the most sensitive portions of the firm­ware. This 16KB block may only be erased or written
when the RP# pin is at the specified boot block unlock
voltage (V

HH) or when the WP# pin is VIH. During a

WRITE or ERASE of the boot block, the RP# pin must
be held at V

HH or the WP# pin held HIGH until the

ERASE or WRITE is completed. The V

PP pin must be at

V

PPH (5V) when the boot block is written to or erased.

The MT28F004B5 and MT28F400B5 are available in
two configurations and top or bottom boot block. The
top boot block version supports processors of the x86
variety. The bottom boot block version is intended for
680X0 and RISC applications. Figure 1 illustrates the
memory address maps associated with these two ver­sions.

Parameter Blocks

The two 8KB parameter blocks store less sensitive
and more frequently changing system parameters and
also may store configuration or diagnostic coding.
These blocks are enabled for erasure when the V

PP pin

is at V

PPH. No super-voltage unlock or WP# control is

required.

Main Memory Blocks

The four remaining blocks are general-purpose
memory blocks and do not require a super-voltage on
RP# or WP# control to be erased or written. These
blocks are intended for code storage, ROM-resident
applications or operating systems that require in-sys­tem update capability.

4Mb

SMART 5 BOOT BLOCK FLASH MEMORY

4Mb Smart 5 Boot Block Flash Memory ©2002, Micron Technology Inc.
MT28F004B5_3.fm - Rev. 3, Pub. 8/2002

9

Figure 1

Memory Address Maps

Bottom Boot

MT28F004B5/400B5xx-xxB

Top Bo ot

MT28F004B5/400B5xx-xxT

3FFFFh

30000h

2FFFFh

20000h

1FFFFh

10000h

0FFFFh

04000h

03FFFh

03000h

02FFFh

02000h

01FFFh

00000h

128KB Main Block

128KB Main Block

128KB Main Block

96KB Main Block

8KB Parameter Block

8KB Parameter Block

16KB Boot Block

WORD ADDRESS

7FFFFh

60000h

5FFFFh

40000h

3FFFFh

20000h

1FFFFh

08000h

07FFFh

06000h

05FFFh

04000h

03FFFh

00000h

BYTE ADDRESS

3FFFFh

3E000h
3DFFFh

3D000h

3CFFFh

3C000h

3BFFFh

30000h

2FFFFh

20000h

1FFFFh

10000h

0FFFFh

00000h

16KB Boot Block

8KB Parameter Block

8KB Parameter Block

96KB Main Block

128KB Main Block

128KB Main Block

128KB Main Block

WORD ADDRESS

7FFFFh

7C000h

7BFFFh

7A000h

79FFFh

78000h

77FFFh

60000h

5FFFFh

40000h

3FFFFh

20000h

1FFFFh

00000h

BYTE ADDRESS

4Mb

SMART 5 BOOT BLOCK FLASH MEMORY

4Mb Smart 5 Boot Block Flash Memory ©2002, Micron Technology Inc.
MT28F004B5_3.fm - Rev. 3, Pub. 8/2002

10

OUTPUT (READ) OPERATIONS

The MT28F004B5 and MT28F400B5 feature three
different types of READS. Depending on the current
mode of the device, a READ operation produces data
from the memory array, status register or device iden­tification register. In each of these three cases, the
WE#, CE# and OE# inputs are controlled in a similar
manner. Moving between modes to perform a specific
read is described in the Command Execution section.

Memory Array

To read the memory array, WE# must be HIGH, and
OE# and CE# must be LOW. Valid data is output on the
DQ pins when these conditions have been met and a
valid address is given. Valid data remains on the DQ
pins until the address changes, or until OE# or CE#
goes HIGH, whichever occurs first. The DQ pins con­tinue to output new data after each address transition
as long as OE# and CE# remain LOW.

The MT28F400B5 features selectable bus widths.
When the memory array is accessed as a 256K x 16,
BYTE# is HIGH, and data will be output on DQ0–
DQ15. To access the memory array as a 512K x 8,
BYTE# must be LOW, DQ8–DQ14 are High-Z, and all
data is output on DQ0–DQ7. The DQ15/(A - 1) pin
becomes the lowest order address input so that
524,288 locations can be read.

After power-up or RESET, the device is automati­cally in the array read mode. All commands and their
operations are described in the Command Set and
Command Execution sections.

Status Register

Performing a READ of the status register requires
the same input sequencing as a READ of the array
except that the address inputs are “Don’t Care.” The
status register contents are always output on DQ0–
DQ7, regardless of the condition of BYTE# on the
MT28F400B5. DQ8–DQ15 are LOW when BYTE# is
HIGH, and DQ8–DQ14 are High-Z when BYTE# is
LOW. Data from the status register is latched on the
falling edge of OE# or CE#, whichever occurs last. If the
contents of the status register change during a READ of
the status register, either OE# or CE# may be toggled
while the other is held LOW to update the output.

Following a WRITE or ERASE, the device automati­cally enters the status register read mode. In addition,
a READ during a WRITE or ERASE produces the status
register contents on DQ0–DQ7. When the device is in
the erase suspend mode, a READ operation produces
the status register contents until another command is
issued, while in certain other modes, READ STATUS

REGISTER may be given to return to the status register
read mode. All commands and their operations are
described in the Command Set and Command Execu­tion sections.

Identification Registers

A READ of the two 8-bit device identification regis­ters requires the same input sequencing as a READ of
the array. WE# must be HIGH, and OE# and CE# must
be LOW. However, ID register data is output only on
DQ0–DQ7, regardless of the condition of BYTE# on the
MT28F400B5. A0 is used to decode between the two
bytes of the device ID register; all other address inputs
are “Don’t Care.” When A0 is LOW, the manufacturer
compatibility ID is output, and when A0 is HIGH, the
device ID is output. DQ8–DQ15 are High-Z when
BYTE# is LOW. When BYTE# is HIGH, DQ8–DQ15 are
00h when the manufacturer compatibility ID is read
and 44h when the device ID is read.

To get to the identification register read mode,
READ IDENTIFICATION may be issued while the
device is in certain other modes. In addition, the iden­tification register read mode can be reached by apply­ing a super-voltage (V

ID) to the A9 pin. Using this

method, the ID register can be read while the device is
in any mode. When A9 is returned to V

IL or VIH, the

device returns to the previous mode.

INPUT OPERATIONS

The DQ pins are used either to input data to the
array or to input a command to the CEL. A command
input issues an 8-bit command to the CEL to control
the mode of operation of the device. A WRITE is used
to input data to the memory array. The following sec­tion describes both types of inputs. More information
describing how to use the two types of inputs to write
or erase the device is provided in the Command Execu­tion section.

Commands

To perform a command input, OE# must be HIGH,
and CE# and WE# must be LOW. Addresses are “Don’t
Care” but must be held stable, except during an ERASE
CONFIRM (described in a later section). The 8-bit
command is input on DQ0–DQ7, while DQ8–DQ15 are
“Don’t Care” on the MT28F400B5. The command is
latched on the rising edge of CE# (CE#-controlled) or
WE# (WE#-controlled), whichever occurs first. The
condition of BYTE# on the MT28F400B5 has no effect
on a command input.