ADVANCE INFORMATION
GENERAL DESCRIPTION
The Am29LV400B is a 4 Mbit, 3.0 volt-only Flash
memory organized as 524,288 bytes or 262,144 words.
The device is offered in 48-ball FBGA, 44-pin SO, and
48-pin TSOP packages. The word-wide data (x16)
appears on DQ15鈥揇Q0; the byte-wide (x8) data
appears on DQ7鈥揇Q0. This device is designed to be
programmed in-system using only a single 3.0 volt V
CC
supply. No V
PP
is required for write or erase opera-
tions. The device can also be programmed in standard
EPROM programmers.
This device is manufactured using AMD鈥檚 0.35
碌m
process technology, and offers all the features and
benefits of the Am29LV400, which was manufactured
using 0.5
碌m
process technology. In addition, the
Am29LV400B features unlock bypass programming
and in-system sector protection/unprotection.
The standard device offers access times of 70, 80, 90
and 120 ns, allowing high speed microprocessors to
operate without wait states. To eliminate bus conten-
tion the device has separate chip enable (CE#), write
enable (WE#) and output enable (OE#) controls.
The device requires only a
single 3.0 volt power sup-
ply
for both read and write functions. Internally gener-
ated and regulated voltages are provided for the
program and erase operations.
The device is entirely command set compatible with the
JEDEC single-power-supply Flash standard.
Com-
mands are written to the command register using
standard microprocessor write timings. Register con-
tents serve as input to an internal state-machine that
controls the erase and programming circuitry. Write
cycles also internally latch addresses and data needed
for the programming and erase operations. Reading
data out of the device is similar to reading from other
Flash or EPROM devices.
Device programming occurs by executing the program
command sequence. This initiates the
Embedded
Program
algorithm鈥攁n internal algorithm that auto-
matically times the program pulse widths and verifies
proper cell margin. The
Unlock Bypass
mode facili-
tates faster programming times by requiring only two
write cycles to program data instead of four.
Device erasure occurs by executing the erase com-
mand sequence. This initiates the
Embedded Erase
algorithm鈥攁n internal algorithm that automatically pre-
programs the array (if it is not already programmed) be-
fore executing the erase operation. During erase, the
device automatically times the erase pulse widths and
verifies proper cell margin.
The host system can detect whether a program or
erase operation is complete by observing the RY/BY#
pin, or by reading the DQ7 (Data# Polling) and DQ6
(toggle)
status bits.
After a program or erase cycle
has been completed, the device is ready to read array
data or accept another command.
The
sector erase architecture
allows memory sectors
to be erased and reprogrammed without affecting the
data contents of other sectors. The device is fully
erased when shipped from the factory.
Hardware data protection
measures include a low
V
CC
detector that automatically inhibits write opera-
tions during power transitions. The
hardware sector
protection
feature disables both program and erase
operations in any combination of the sectors of mem-
ory. This can be achieved in-system or via program-
ming equipment.
The
Erase Suspend
feature enables the user to put
erase on hold for any period of time to read data from,
or program data to, any sector that is not selected for
erasure. True background erase can thus be achieved.
The
hardware RESET# pin
terminates any operation
in progress and resets the internal state machine to
reading array data. The RESET# pin may be tied to the
system reset circuitry. A system reset would thus also
reset the device, enabling the system microprocessor
to read the boot-up firmware from the Flash memory.
The device offers two power-saving features. When
addresses have been stable for a specified amount of
time, the device enters the
automatic sleep mode.
The system can also place the device into the
standby
mode.
Power consumption is greatly reduced in both
these modes.
AMD鈥檚 Flash technology combines years of Flash
memory manufacturing experience to produce the
highest levels of quality, reliability and cost effective-
ness. The device electrically erases all bits within
a sector simultaneously via Fowler-Nordheim tun-
neling. The data is programmed using hot electron
injection.
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