S29AL004D Ver la hoja de datos (PDF) - Spansion Inc.

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S29AL004D

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

Spansion Inc. 

Advance Information

The system must issue the reset command to re-enable the device for reading

array data if DQ5 goes high, or while in the autoselect mode. See the Reset Com-

mand‚ on page 19 section, next.

See also Requirements for Reading Array Data‚ on page 11 for more information.

The table provides the read parameters, and Figure 13, on page 37 shows the

timing diagram.

Reset Command

Writing the reset command to the device resets the device to reading array data.

Address bits are don’t care for this command.

The reset command may be written between the sequence cycles in an erase

command sequence before erasing begins. This resets the device to reading array

data. Once erasure begins, however, the device ignores reset commands until the

operation is complete.

The reset command may be written between the sequence cycles in a program

command sequence before programming begins. This resets the device to read-

ing array data (also applies to programming in Erase Suspend mode). Once

programming begins, however, the device ignores reset commands until the op-

eration is complete.

The reset command may be written between the sequence cycles in an autoselect

command sequence. Once in the autoselect mode, the reset command must be

written to return to reading array data (also applies to autoselect during Erase

Suspend).

If DQ5 goes high during a program or erase operation, writing the reset command

returns the device to reading array data (also applies during Erase Suspend).

Autoselect Command Sequence

The autoselect command sequence allows the host system to access the manu-

facturer and devices codes, and determine whether or not a sector is protected.

Table on page 24 shows the address and data requirements. This method is an

alternative to that shown in Table on page 15, which is intended for PROM pro-

grammers and requires VID on address bit A9.

The autoselect command sequence is initiated by writing two unlock cycles, fol-

lowed by the autoselect command. The device then enters the autoselect mode,

and the system may read at any address any number of times, without initiating

another command sequence.

A read cycle at address XX00h retrieves the manufacturer code. A read cycle at

address XX01h in word mode (or 02h in byte mode) returns the device code. A

read cycle containing a sector address (SA) and the address 02h in word mode

(or 04h in byte mode) returns 01h if that sector is protected, or 00h if it is un-

protected. Refer to Table 2 on page 13 and Table on page 14 for valid sector

addresses.

The system must write the reset command to exit the autoselect mode and return

to reading array data.

Word/Byte Program Command Sequence

The system may program the device by word or byte, depending on the state of

the BYTE# pin. Programming is a four-bus-cycle operation. The program com-

mand sequence is initiated by writing two unlock write cycles, followed by the

February 18, 2005 S29AL004D_00_A1

S29AL004D

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