tn28f010-90 Intel Corporation, tn28f010-90 Datasheet - Page 9

• Manufacturer Part Number: tn28f010-90
• Description: 1024k 128k X 8 Cmos Flash Memory
• Manufacturer: Intel Corporation

Read Command
While V
memory contents can be accessed via the read
command The read operation is initiated by writing
00H into the command register Microprocessor
read cycles retrieve array data The device remains
enabled for reads until the command register con-
tents are altered
The default contents of the register upon V
er-up is 00H This default value ensures that no spu-
rious alteration of memory contents occurs during
the V
hard-wired to the 28F010 the device powers-up and
remains enabled for reads until the command-regis-
ter contents are changed Refer to the AC Read
Characteristics and Waveforms for specific timing
parameters
Intelligent Identifier Command
Flash memories are intended for use in applications
where the local CPU alters memory contents As
such manufacturer- and device-codes must be ac-
cessible while the device resides in the target sys-
tem PROM programmers typically access signature
codes by raising A9 to a high voltage However mul-
tiplexing high voltage onto address lines is not a de-
sired system-design practice
The 28F010 contains an Intelligent Identifier opera-
tion to supplement traditional PROM-programming
methodology The operation is initiated by writing
90H into the command register Following the com-
mand write a read cycle from address 0000H re-
trieves the manufacturer code of 89H A read cycle
from address 0001H returns the device code of
B4H To terminate the operation it is necessary to
write another valid command into the register
Set-up Erase Erase Commands
Set-up Erase is a command-only operation that
stages the device for electrical erasure of all bytes in
the array The set-up erase operation is performed
by writing 20H to the command register
To commence chip-erasure the erase command
(20H) must again be written to the register The
erase operation begins with the rising edge of the
WE
the next WE
This two-step sequence of set-up followed by execu-
tion ensures that memory contents are not acciden-
tally erased Also chip-erasure can only occur when
high voltage is applied to the V
PP
pulse and terminates with the rising edge of
PP
power transition Where the V
is high for erasure and programming
pulse (i e Erase-Verify Command)
PP
pin In the absence
PP
supply is
PP
pow-
of this high voltage memory contents are protected
against erasure Refer to AC Erase Characteristics
and Waveforms for specific timing parameters
Erase-Verify Command
The erase command erases all bytes of the array in
parallel After each erase operation all bytes must
be verified The erase verify operation is initiated by
writing A0H into the command register The address
for the byte to be verified must be supplied as it is
latched on the falling edge of the WE
register write terminates the erase operation with the
rising edge of its WE
The 28F010 applies an internally-generated margin
voltage to the addressed byte Reading FFH from
the addressed byte indicates that all bits in the byte
are erased
The erase-verify command must be written to the
command register prior to each byte verification to
latch its address The process continues for each
byte in the array until a byte does not return FFH
data or the last address is accessed
In the case where the data read is not FFH another
erase operation is performed (Refer to Set-up
Erase Erase) Verification then resumes from the
address of the last-verified byte Once all bytes in
the array have been verified the erase step is com-
plete The device can be programmed At this point
the verify operation is terminated by writing a valid
command (e g Program Set-up) to the command
register Figure 6 the Quick Erase algorithm illus-
trates how commands and bus operations are com-
bined to perform electrical erasure of the 28F010
Refer to AC Erase Characteristics and Waveforms
for specific timing parameters
Set-up Program Program Commands
Set-up program is a command-only operation that
stages the device for byte programming Writing 40H
into the command register performs the set-up
operation
Once the program set-up operation is performed
the next WE
programming operation Addresses are internally
latched on the falling edge of the WE
is internally latched on the rising edge of the WE
pulse The rising edge of WE
gramming operation The programming operation
terminates with the next rising edge of WE
to write the program-verify command Refer to AC
Programming Characteristics and Waveforms for
specific timing parameters
pulse causes a transition to an active
pulse
also begins the pro-
pulse Data
pulse The
28F010
used
9