AM29LV400BB55RSE データシートの表示（PDF） - Advanced Micro Devices

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AM29LV400BB55RSE

4 Megabit (512 K x 8-Bit/256 K x 16-Bit) CMOS 3.0 Volt-only Boot Sector Flash Memory

Advanced Micro Devices 

DATA SHEET

tions and to Figure 13 for the timing diagram. ICC1 in

the DC Characteristics table represents the active cur-

rent specification for reading array data.

Writing Commands/Command Sequences

To write a command or command sequence (which in-

cludes programming data to the device and erasing

sectors of memory), the system must drive WE# and

CE# to VIL, and OE# to VIH.

For program operations, the BYTE# pin determines

whether the device accepts program data in bytes or

words. Refer to “Word/Byte Configuration” for more in-

formation.

The device features an Unlock Bypass mode to facili-

tate faster programming. Once the device enters the

Unlock Bypass mode, only two write cycles are re-

quired to program a word or byte, instead of four. The

“Word/Byte Program Command Sequence” section

has details on programming data to the device using

both standard and Unlock Bypass command se-

quences.

An erase operation can erase one sector, multiple sec-

tors, or the entire device. Tables 2 and 3 indicate the

address space that each sector occupies. A “sector

address” consists of the address bits required to

uniquely select a sector. The “Command Definitions”

section has details on erasing a sector or the entire

chip, or suspending/resuming the erase operation.

After the system writes the autoselect command se-

quence, the device enters the autoselect mode. The

system can then read autoselect codes from the inter-

nal register (which is separate from the memory array)

on DQ7–DQ0. Standard read cycle timings apply in

this mode. Refer to the Autoselect Mode and Autose-

lect Command Sequence sections for more informa-

tion.

ICC2 in the DC Characteristics table represents the ac-

tive current specification for the write mode. The “AC

Characteristics” section contains timing specification

tables and timing diagrams for write operations.

Program and Erase Operation Status

During an erase or program operation, the system

may check the status of the operation by reading the

status bits on DQ7–DQ0. Standard read cycle timings

and ICC read specifications apply. Refer to “Write Op-

eration Status” for more information, and to “AC Char-

acteristics” for timing diagrams.

Standby Mode

When the system is not reading or writing to the de-

vice, it can place the device in the standby mode. In

this mode, current consumption is greatly reduced,

and the outputs are placed in the high impedance

state, independent of the OE# input.

The device enters the CMOS standby mode when the

CE# and RESET# pins are both held at VCC ± 0.3 V.

(Note that this is a more restricted voltage range than

VIH.) If CE# and RESET# are held at VIH, but not within

VCC ± 0.3 V, the device will be in the standby mode, but

the standby current will be greater. The device re-

quires standard access time (tCE) for read access

when the device is in either of these standby modes,

before it is ready to read data.

If the device is deselected during erasure or program-

ming, the device draws active current until the

operation is completed.

ICC3 in the DC Characteristics table represents the

standby current specification.

Automatic Sleep Mode

The automatic sleep mode minimizes Flash device en-

ergy consumption. The device automatically enables

this mode when addresses remain stable for tACC + 30

ns. The automatic sleep mode is independent of the

CE#, WE#, and OE# control signals. Standard ad-

dress access timings provide new data when ad-

dresses are changed. While in sleep mode, output

data is latched and always available to the system.

ICC4 in the DC Characteristics table represents the au-

tomatic sleep mode current specification.

RESET#: Hardware Reset Pin

The RESET# pin provides a hardware method of re-

setting the device to reading array data. When the RE-

SET# pin is driven low for at least a period of tRP, the

device immediately terminates any operation in

progress, tristates all output pins, and ignores all

read/write commands for the duration of the RESET#

pulse. The device also resets the internal state ma-

chine to reading array data. The operation that was in-

terrupted should be reinitiated once the device is

ready to accept another command sequence, to en-

sure data integrity.

Current is reduced for the duration of the RESET#

pulse. When RESET# is held at VSS±0.3 V, the device

draws CMOS standby current (ICC4). If RESET# is held

at VIL but not within VSS±0.3 V, the standby current will

be greater.

If RESET# is asserted during a program or erase op-

eration, the RY/BY# pin remains a “0” (busy) until the

internal reset operation is complete, which requires a

time of tREADY (during Embedded Algorithms). The sys-

tem can thus monitor RY/BY# to determine whether

the reset operation is complete. If RESET# is asserted

when a program or erase operation is not executing

(RY/BY# pin is “1”), the reset operation is completed

within a time of tREADY (not during Embedded Algo-

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Am29LV400B

21523D4 December 4, 2006

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