PRELIMINARY
Publication# 21606
Rev: C Amendment/0
Issue Date: April 1998
Am29DL400B
4 Megabit (512 K x 8-Bit/256 K x 16-Bit)
CMOS 3.0 Volt-only, Simultaneous Operation Flash Memory
DISTINCTIVE CHARACTERISTICS
s
Simultaneous Read/Write operations
-- Host system can program or erase in one bank,
then immediately and simultaneously read from
the other bank
-- Zero latency between read and write operations
-- Read-while-erase
-- Read-while-program
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Single power supply operation
-- 2.7 to 3.6 volt read and write operations for
battery-powered applications
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Manufactured on 0.35 m process technology
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High performance
-- Access times as fast as 70 ns
s
Low current consumption (typical values
at 5 MHz)
-- 7 mA active read current
-- 21 mA active read-while-program or read-while-
erase current
-- 17 mA active program-while-erase-suspended
current
-- 200 nA in standby mode
-- 200 nA in automatic sleep mode
-- Standard t
CE
chip enable access time applies to
transition from automatic sleep mode to active
mode
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Flexible sector architecture
-- Two 16 Kword, two 8 Kword, four 4 Kword, and
six 32 Kword sectors in word mode
-- Two 32 Kbyte, two 16 Kbyte, four 8 Kbyte, and
six 64 Kbyte sectors in byte mode
-- Any combination of sectors can be erased
-- Supports full chip erase
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Unlock Bypass Program Command
-- Reduces overall programming time when
issuing multiple program command sequences
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Sector protection
-- Hardware method of locking a sector to prevent
any program or erase operation within that
sector
-- Sectors can be locked in-system or via
programming equipment
-- Temporary Sector Unprotect feature allows code
changes in previously locked sectors
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Top or bottom boot block configurations
available
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Embedded Algorithms
-- Embedded Erase algorithm automatically
pre-programs and erases sectors or entire chip
-- Embedded Program algorithm automatically
programs and verifies data at specified address
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Minimum 1 million program/erase cycles
guaranteed per sector
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Package options
-- 44-pin SO
-- 48-pin TSOP
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Compatible with JEDEC standards
-- Pinout and software compatible with
single-power-supply flash standard
-- Superior inadvertent write protection
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Data# Polling and Toggle Bits
-- Provides a software method of detecting
program or erase cycle completion
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Ready/Busy# output (RY/BY#)
-- Hardware method for detecting program or
erase cycle completion
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Erase Suspend/Erase Resume
-- Suspends or resumes erasing sectors to allow
reading and programming in other sectors
-- No need to suspend if sector is in the other bank
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Hardware reset pin (RESET#)
-- Hardware method of resetting the device to
reading array data
2
Am29DL400B
P R E L I M I N A R Y
GENERAL DESCRIPTION
The Am29DL400B is an 4 Mbit, 3.0 volt-only flash
memory device, organized as 262,144 words or
524,288 bytes. The device is offered in 44-pin SO and
48-pin TSOP packages. The word-wide (x16) data ap-
pears on DQ0DQ15; the byte-wide (x8) data appears
on DQ0DQ7. This device requires only a single 3.0
volt V
CC
supply to perform read, program, and erase
operations. A standard EPROM programmer can also
be used to program and erase the device.
The standard device offers access times of 70, 80, 90,
and 120 ns, allowing high-speed microprocessors to
operate without wait states. Standard control pins--
chip enable (CE#), write enable (WE#), and output en-
able (OE#)--control read and write operations, and
avoid bus contention issues.
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.
Simultaneous Read/Write Operations with
Zero Latency
The Simultaneous Read/Write architecture provides si-
multaneous operation by dividing the memory space
into two banks. Bank 1 contains boot/parameter sec-
tors, and Bank 2 consists of larger, code sectors of uni-
form size. The device can improve overall system
performance by allowing a host system to program or
erase in one bank, then immediately and simultane-
ously read from the other bank, with zero latency. This
releases the system from waiting for the completion of
program or erase operations.
Am29DL400B Features
The device offers complete compatibility with the
JEDEC single-power-supply Flash command set
standard. Commands are written to the command
register using standard microprocessor write timings.
Register contents 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--an 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--an internal algorithm that automatically
preprograms the array (if it is not already programmed)
before 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 automatically returns to
reading array data.
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 within that bank that is
not selected for erasure. True background erase can
thus be achieved. There is no need to suspend the
erase operation if the read data is in the other bank.
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 to reading array data, enabling the sys-
tem microprocessor to read the boot-up firmware from
the Flash memory.
The device offers two power-saving features. When ad-
dresses 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's Flash technology combines years of Flash mem-
ory manufacturing experience to produce the highest
levels of quality, reliability, and cost effectiveness. The
device electrically erases all bits within a sector simulta-
neously via Fowler-Nordheim tunneling. The bytes are
programmed one byte or word at a time using hot elec-
tron injection.
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