AM29DL320G datasheet(27/58 Pages) AMD

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Am29DL320G

mand sequence may be written to an address within a

bank that is either in the read or erase-suspend-read

mode. The autoselect command may not be written

while the device is actively programming or erasing in

the other bank.

The autoselect command sequence is initiated by first

writing two unlock cycles. This is followed by a third

write cycle that contains the bank address and the au-

toselect command. The bank then enters the autose-

lect mode. The system may read at any address within

the same bank any number of times without initiating

another autoselect command sequence:

■ A read cycle at address (BA)XX00h (where BA is

the bank address) returns the manufacturer code.

■ A read cycle at address (BA)XX01h in word mode

(or (BA)XX02h in byte mode) returns the device

code.

■ A read cycle to an address containing a sector ad-

dress (SA) within the same bank, and the address

02h on A7–A0 in word mode (or the address 04h on

A6–A-1 in byte mode) returns 01h if the sector is

protected, or 00h if it is unprotected. (Refer to Table

2 for valid sector addresses).

The system must write the reset command to return to

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

bank was previously in Erase Suspend).

Enter SecSiTM Sector/Exit SecSi Sector

Command Sequence

The SecSi Sector region provides a secured data area

containing a random, sixteen-byte electronic serial

number (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 is-

sues the four-cycle Exit SecSi Sector command se-

quence. The Exit SecSi Sector command sequence

returns the device to normal operation. The SecSi

Sector is not accessible when the device is executing

an Embedded Program or Embedded Erase algo-

rithm. Table 13 shows the address and data require-

ments for both command sequences. See also

“S ec Si TM

( S e c ur ed

S i lic on)

S e c t o r

Fla s h

Memory Region” for further information. Note that the

ACC function and unlock bypass modes are unavail-

able when the SecSi Sector is enabled.

Byte/Word Program Command Sequence

The system may program the device by word or byte,

depending on the state of the BYTE# pin. Program-

ming is a four-bus-cycle operation. The program com-

mand 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 algorithm. The

system is not required to provide further controls or

timings. The device automatically provides internally

generated program pulses and verifies the pro-

grammed cell margin. Table 13 shows the address and

data requirements for the byte program command se-

quence.

When the Embedded Program algorithm is complete,

that bank 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 that bank 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 that bank to set DQ5 = 1, or cause the DQ7 and

DQ6 status bits to indicate the operation was success-

ful. 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 bytes or words to a bank faster than using the

standard program command sequence. The unlock

bypass command sequence is initiated by first writing

two unlock cycles. This is followed by a third write

cycle containing the unlock bypass command, 20h.

That bank then enters the unlock bypass mode. A

two-cycle unlock bypass program command sequence

is all that is required to program in this mode. The first

cycle in this sequence contains the unlock bypass pro-

gram command, A0h; the second cycle contains the

program address and data. Additional data is pro-

grammed in the same manner. This mode dispenses

with the initial two unlock cycles required in the stan-

dard program command sequence, resulting in faster

total programming time. Table 13 shows the require-

ments 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 bank

address and the data 90h. The second cycle need

only contain the data 00h. The bank then returns to

the read mode.

The device offers accelerated program operations

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

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