AM29PDS322D datasheet(24/51 Pages) SPANSION

24 / 51 page

Am29PDS322D

23569A5 December 4, 2006

D A TA

SH EE T

and the system may read any number of autoselect

codes without reinitiating the command sequence.

Table 10 shows the address and data requirements for

the command sequence. To determine sector protec-

tion information, the system must write to the appropri-

ate sector group address (SGA). Tables 3 and 5 show

the address range associated with each sector.

The system must write the reset command to return to

the read mode (or erase-suspend-read mode if the de-

vice was previously in Erase Suspend).

Enter SecSi Sector/Exit SecSi Sector

Command Sequence

The SecSi Sector region provides a secured data area

containing an 16-byte random Electronic Serial Num-

ber (ESN). The system can access the SecSi Sector

region by issuing the three-cycle Enter SecSi Sector

command sequence. The device continues to access

the SecSi Sector region until the system issues the

four-cycle Exit SecSi Sector command sequence. The

Exit SecSi Sector command sequence returns the de-

vice to normal operation. Table 10 shows the address

and data requirements for both command sequences.

See also “SecSi (Secured Silicon) Sector Flash Mem-

ory Region” for further information. Note that a hard-

ware reset (RESET#=V

IL) will reset the device to

reading array data.

Word Program Command Sequence

Programming is a four-bus-cycle operation. The pro-

gram command sequence is initiated by writing two

unlock write cycles, followed by the program set-up

command. The program address and data are written

next, which in turn initiate the Embedded Program al-

gorithm. The system is not required to provide further

controls or timings. The device automatically provides

internally generated program pulses and verifies the

programmed cell margin. Table 10 shows the address

and data requirements for the program command se-

quence.

When the Embedded Program algorithm is complete,

the device then returns to the read mode and ad-

dresses are no longer latched. The system can deter-

mine the status of the program operation by using

DQ7, DQ6, or RY/BY#. Refer to the Write Operation

Status section for information on these status bits.

Any commands written to the device during the Em-

bedded Program Algorithm are ignored. Note that a

hardware reset immediately terminates the program

operation. The program command sequence should

be reinitiated once the device has returned to the read

mode, to ensure data integrity.

Programming is allowed in any sequence and across

sector boundaries. A bit cannot be programmed

from “0” back to a “1.” Attempting to do so may

cause the device to set DQ5 = 1, or cause the DQ7

and DQ6 status bits to indicate the operation was suc-

cessful. However, a succeeding read will show that the

data is still “0.” Only erase operations can convert a “0”

to a “1.”

Unlock Bypass Command Sequence

The unlock bypass feature allows the system to pro-

gram words to the device faster than using the stan-

dard program command sequence. The unlock bypass

command sequence is initiated by first writing two un-

lock cycles. This is followed by a third write cycle con-

taining the unlock bypass command, 20h. The device

then enters the unlock bypass mode. A two-cycle un-

lock bypass program command sequence is all that is

required to program in this mode. The first cycle in this

sequence contains the unlock bypass program com-

mand, A0h; the second cycle contains the program

address and data. Additional data is programmed in

the same manner. This mode dispenses with the initial

two unlock cycles required in the standard program

command sequence, resulting in faster total program-

ming time. Table 10 shows the requirements for the

command sequence.

During the unlock bypass mode, only the Unlock By-

pass Program and Unlock Bypass Reset commands

are valid. To exit the unlock bypass mode, the system

must issue the two-cycle unlock bypass reset com-

mand sequence. The first cycle must contain the data

90h. The second cycle must contain the data 00h. The

device then returns to reading array data. See Figure

4 for the unlock bypass algorithm.

The device offers accelerated program operations

through the WP#/ACC pin. When the system asserts

HH on the WP#/ACC pin, the device automatically en-

ters the Unlock Bypass mode. The system may then

write the two-cycle Unlock Bypass program command

sequence. The device uses the higher voltage on the

WP#/ACC pin to accelerate the operation. Note that

the WP#/ACC pin must not be at V

HH any operation

other than accelerated programming, or device dam-

age may result. In addition, the WP#/ACC pin must not

be left floating or unconnected; inconsistent behavior

of the device may result.

Figure 5 illustrates the algorithm for the program oper-

ation. Refer to the Erase and Program Operations

table in the AC Characteristics section for parameters,

and Figure 18 for timing diagrams.

Chip Erase Command Sequence

Chip erase is a six bus cycle operation. The chip erase

command sequence is initiated by writing two unlock

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