AM29LV800BB70 Просмотр технического описания (PDF) - Advanced Micro Devices

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AM29LV800BB70

8 Megabit (1 M x 8-Bit/512 K x 16-Bit) CMOS 3.0 Volt-only Boot Sector Flash Memory

Advanced Micro Devices 

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

information.

The device features an Unlock Bypass mode to facili-

tate faster programming. Once the device enters the Un-

lock Bypass mode, only two write cycles are required 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 sequences.

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 ad-

dress” 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 “Autoselect

Command Sequence” sections for more information.

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 Operation

Status” for more information, and to “AC Characteris-

tics” for timing diagrams.

Standby Mode

When the system is not reading or writing to the device,

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, inde-

pendent 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 requires

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.

In the DC Characteristics table, ICC3 and ICC4 repre-

sents the standby current specification.

Automatic Sleep Mode

The automatic sleep mode minimizes Flash device

energy 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 address

access timings provide new data when addresses are

changed. While in sleep mode, output data is latched

and always available to the system. ICC4 in the DC

Characteristics table represents the automatic sleep

mode current specification.

RESET#: Hardware Reset Pin

The RESET# pin provides a hardware method of reset-

ting 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 ensure 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.

The RESET# pin may be tied to the system reset cir-

cuitry. A system reset would thus also reset the Flash

memory, enabling the system to read the boot-up firm-

ware from the Flash memory.

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

system 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 ex-

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

completed within a time of tREADY (not during Embed-

ded Algorithms). The system can read data tRH after

the RESET# pin returns to VIH.

Refer to the AC Characteristics tables for RESET# pa-

rameters and to Figure 14 for the timing diagram.

Am29LV800B

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