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COPYRIGHT
INTEL CORPORATION 1995
November 1995
Order Number 290451-005
28F400BX-T B 28F004BX-T B
Intel’s 4-Mbit Flash Memory Family is an extension of the Boot Block Architecture which includes block-selec-
tive erasure automated write and erase operations and standard microprocessor interface The 4-Mbit Flash
Memory Family enhances the Boot Block Architecture by adding more density and blocks x8 x16 input out-
put control very high speed low power an industry standard ROM compatible pinout and surface mount
packaging The 4-Mbit flash family is an easy upgrade from Intel’s 2-Mbit Boot Block Flash Memory Family
The Intel 28F400BX-T B are 16-bit wide flash memory offerings These high density flash memories provide
user selectable bus operation for either 8-bit or 16-bit applications The 28F400BX-T and 28F400BX-B are
4 194 304-bit non-volatile memories organized as either 524 288 bytes or 262 144 words of information They
are offered in 44-Lead plastic SOP and 56-Lead TSOP packages The x8 x16 pinout conforms to the industry
standard ROM EPROM pinout
The Intel 28F004BX-T B are 8-bit wide flash memories with 4 194 304 bits organized as 524 288 bytes of
information They are offered in a 40-Lead TSOP package which is ideal for space-constrained portable
systems
These devices use an integrated Command User Interface (CUI) and Write State Machine (WSM) for simplified
word byte write and block erasure The 28F400BX-T 28F004BX-T provide block locations compatible with
Intel’s MCS-186 family 80286 i386
TM
i486
TM
i860
TM
and 80960CA microprocessors The 28F400BX-B
28F004BX-B provide compatibility with Intel’s 80960KX and 80960SX families as well as other embedded
microprocessors
The boot block includes a data protection feature to protect the boot code in critical applications With a
maximum access time of 60 ns these 4-Mbit flash devices are very high performance memories which
interface at zero-wait-state to a wide range of microprocessors and microcontrollers A deep power-down
mode lowers the total V
CC
power consumption to 1
mW
This is critical in handheld battery powered systems
For very low power applications using a 3 3V supply refer to the Intel 28F400BL-T B 28F004BL-T B 4-Mbit
Boot Block Flash Memory Family datasheet
Manufactured on Intel’s 0 8 micron ETOX III process the 4-Mbit flash memory family provides world class
quality reliability and cost-effectiveness at the 4-Mbit density level
2
28F400BX-T B 28F004BX-T B
Follow these guidelines to ensure compatibility
1 Connect DU (WP on SmartVoltage products) to
a control signal or to V
CC
or GND
2 If adding a switch on V
PP
for write protection
switch to GND for complete write protection
3 Allow for connecting 5V to V
PP
and disconnect
12V from the V
PP
line if desired
10
PRODUCT FAMILY OVERVIEW
Throughout this datasheet the 28F400BX refers to
both the 28F400BX-T and 28F400BX-B devices and
28F004BX refers to both the 28F004BX-T and
28F004BX-B devices The 4-Mbit flash memory fam-
ily refers to both the 28F400BX and 28F004BX prod-
ucts This datasheet comprises the specifications for
four separate products in the 4-Mbit flash memory
family Section 1 provides an overview of the 4-Mbit
flash memory family including applications pinouts
and pin descriptions Sections 2 and 3 describe in
detail the specific memory organizations for the
28F400BX and 28F004BX products respectively
Section 4 combines a description of the family’s
principles of operations Finally Section 5 describes
the family’s operating specifications
Product Family
X8 X16 Products
28F400BX-T
28F400BX-B
X8-Only Products
28F004BX-T
28F004BX-B
1 2 Main Features
The 28F400BX 28F004BX boot block flash memory
family is a very high performance 4-Mbit (4 194 304
bit) memory family organized as either 256 KWords
(262 144 words) of 16 bits each or 512 Kbytes
(524 288 bytes) of 8 bits each
Seven Separately Erasable Blocks
including a
Hardware-Lockable boot block
(16 384 Bytes)
Two parameter blocks
(8 192 Bytes each) and
Four main blocks
(1 block of 98 304 Bytes and 3
blocks of 131 072 Bytes) are included on the 4-Mbit
family An erase operation erases one of the main
blocks in typically 2 4 seconds and the boot or pa-
rameter blocks in typically 1 0 seconds independent
of the remaining blocks Each block can be indepen-
dently erased and programmed 100 000 times
The Boot Block
is located at either the top
(28F400BX-T
28F004BX-T) or the bottom
(28F400BX-B 28F004BX-B) of the address map in
order to accommodate different microprocessor pro-
tocols for boot code location The
hardware locka-
ble boot block
provides the most secure code stor-
age The boot block is intended to store the kernel
code required for booting-up a system When the
RP
pin is between 11 4V and 12 6V the boot block
is unlocked and program and erase operations can
be performed When the RP pin is at or below 6 5V
the boot block is locked and program and erase op-
erations to the boot block are ignored
The 28F400BX products are available in the ROM
EPROM compatible pinout and housed in the
44-Lead PSOP (Plastic Small Outline) package and
the 56-Lead TSOP (Thin Small Outline 1 2mm thick)
package as shown in Figures 3 and 4 The
28F004BX products are available in the 40-Lead
TSOP (1 2mm thick) package as shown in Figure 5
The
Command User Interface (CUI)
serves as the
interface between the microprocessor or microcon-
troller and the internal operation of the 28F400BX
and 28F004BX flash memory products
1 1 Designing for Upgrade to
SmartVoltage Products
Today’s high volume boot block products are up-
gradable to Intel’s SmartVoltage boot block prod-
ucts that provide program and erase operation at 5V
or 12V V
PP
and read operation at 3V or 5V V
CC
Intel’s SmartVoltage boot block products provide the
following enhancements to the boot block products
described in this data sheet
1 DU pin is replaced by WP to provide a means
to lock and unlock the boot block with logic sig-
nals
2 5V Program Erase operation uses proven pro-
gram and erase techniques with 5V
g
10% ap-
plied to V
PP
3 Enhanced circuits optimize performance at 3 3V
V
CC
Refer to the 2 4 or 8 Mbit SmartVoltage Boot Block
Flash Memory Data Sheets for complete specifica-
tions
When you design with 12V V
PP
boot block products
you should provide the capability in your board de-
sign to upgrade to SmartVoltage products
3
28F400BX-T B 28F004BX-T B
Program and Erase Automation
allows program
and erase operations to be executed using a two-
write command sequence to the CUI The internal
Write State Machine (WSM) automatically executes
the algorithms and timings necessary for program
and erase operations including verifications there-
by unburdening the microprocessor or microcontrol-
ler Writing of memory data is performed in word or
byte increments for the 28F400BX family and in byte
increments for the 28F004BX family typically within
9
ms
which is a 100% improvement over current
flash memory products
The
Status Register (SR)
indicates the status of the
WSM and whether the WSM successfully completed
the desired program or erase operation
Maximum Access Time of
60 ns (t
ACC
)
is achieved
over the commercial temperature range (0 C to
70 C) 5% V
CC
supply voltage range (4 75V to
5 25V) and 30 pF output load Maximum Access
Time of
70 ns (t
ACC
)
is achieved over the commer-
cial temperature range 10% V
CC
supply range (4 5V
to 5 5V) and 100 pF output load
I
PP
maximum Program current is 40 mA for x16
operation and 30 mA for x8 operation I
PP
Erase
current is 30 mA maximum V
PP
erase and pro-
gramming voltage is 11 4V to 12 6V (V
PP
e
12V
g
5%) under all operating conditions
As an op-
tion V
PP
can also vary between 10 8V to 13 2V (V
PP
e
12V
g
10%) with a guaranteed number of 100
block erase cycles
Typical I
CC
Active Current of 25 mA
is achieved
for the X16 products (28F400BX)
Typical I
CC
Ac-
tive Current of 20 mA
is achieved for the X8 prod-
ucts (28F400BX 28F004BX) Refer to the I
CC
active
current derating curves in this datasheet
The 4-Mbit boot block flash memory family is also
designed with an Automatic Power Savings (APS)
feature to minimize system battery current drain and
allows for very low power designs Once the device
is accessed to read array data APS mode will imme-
diately put the memory in static mode of operation
where I
CC
active current is typically 1 mA until the
next read is initiated
When the CE and RP pins are at V
CC
and the
BYTE pin (28F400BX-only) is at either V
CC
or
GND the
CMOS Standby
mode is enabled where
I
CC
is typically
50
mA
A
Deep Power-Down Mode
is enabled when the
RP pin is at ground minimizing power consumption
and providing write protection during power-up con-
ditions
I
CC
current
during deep power-down mode
is
0 20
mA
typical
An initial maximum access time
or Reset Time of 300 ns is required from RP
switching until outputs are valid Equivalently the
device has a maximum wake-up time of 215 ns until
writes to the Command User Interface are recog-
nized When RP is at ground the WSM is reset the
Status Register is cleared and the entire device is
protected from being written to This feature pre-
vents data corruption and protects the code stored
in the device during system reset The system Reset
pin can be tied to RP to reset the memory to nor-
mal read mode upon activation of the Reset pin
With on-chip program erase automation in the
4-Mbit family and the RP functionality for data pro-
tection when the CPU is reset and even if a program
or erase command is issued the device will not rec-
ognize any operation until RP returns to its normal
state
For the 28F400BX Byte-wide or Word-wide In-
put Output Control
is possible by controlling the
BYTE pin When the BYTE pin is at a logic low
the device is in the byte-wide mode (x8) and data is
read and written through DQ 0 7 During the byte-
wide mode DQ 8 14 are tri-stated and DQ15 A-1
becomes the lowest order address pin When the
BYTE pin is at a logic high the device is in the
word-wide mode (x16) and data is read and written
through DQ 0 15
4
28F400BX-T B 28F004BX-T B
This increase in software sophistication augments
the probability that a code update will be required
after the PC is shipped The 4-Mbit flash memory
products provide an inexpensive update solution for
the notebook and handheld personal computers
while extending their product lifetime Furthermore
the 4-Mbit flash memory products’ power-down
mode provides added flexibility for these battery-
operated portable designs which require operation
at very low power levels
The 4-Mbit flash memory products also provide ex-
cellent design solutions for Digital Cellular Phone
and Telecommunication switching applications re-
quiring high performance high density storage capa-
bility coupled with modular software designs and a
small form factor package (X8-only bus) The
4-Mbit’s blocking scheme allows for an easy seg-
mentation of the embedded code with 16 Kbytes of
Hardware-Protected Boot code 4 Main Blocks of
program code and 2 Parameter Blocks of 8 Kbytes
each for frequently updatable data storage and diag-
nostic messages (e g phone numbers authoriza-
tion codes) Figure 2 is an example of such an appli-
cation with the 28F004BX-T
These are a few actual examples of the wide range
of applications for the 4-Mbit Boot Block flash mem-
ory family which enable system designers achieve
the best possible product design Only your imagina-
tion limits the applicability of such a versatile product
family
1 3 Applications
The 4-Mbit boot block flash memory family com-
bines high density high performance cost-effective
flash memories with blocking and hardware protec-
tion capabilities Its flexibility and versatility will re-
duce costs throughout the product life cycle Flash
memory is ideal for Just-In-Time production flow re-
ducing system inventory and costs and eliminating
component handling during the production phase
During the product life cycle when code updates or
feature enhancements become necessary flash
memory will reduce the update costs by allowing ei-
ther a user-performed code change via floppy disk
or a remote code change via a serial link The 4-Mbit
boot block flash memory family provides full func-
tion blocked flash memories suitable for a wide
range of applications These applications include
Extended PC BIOS and ROM-able
applications
storage Digital Cellular Phone program and data
storage
Telecommunication
boot firmware
Print-
er
firmware font storage and various other embed-
ded applications where both program and data stor-
age are required
Reprogrammable systems such as personal com-
puters are ideal applications for the 4-Mbit flash
memory products Portable and handheld personal
computer applications are becoming more complex
with the addition of power management software to
take advantage of the latest microprocessor tech-
nology the availability of ROM-based application
software pen tablet code for electronic hand writing
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