AM29F160D datasheet(21/47 Pages) SPANSION

21 / 47 page

November 2, 2006 Am29F160D_00_D6

Am29F160D

D A TA SH EE T

Autoselect Command Sequence

The autoselect command sequence allows the host

system to access the manufacturer and devices codes,

and determine whether or not a sector is protected.

The Command Definitions table shows the address

and data requirements. This method is an alternative to

that shown in the Autoselect Codes (High Voltage

Method) table, which is intended for PROM program-

mers and requires VID on address bit A9.

The autoselect command sequence is initiated by

writing two unlock cycles, followed 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 manufac-

turer 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) re-

turns 01h if that sector is protected, or 00h if it is un-

protected. Refer to the Sector Address tables for valid

sector addresses. When a read occurs at an address

within the 16 Kbyte boot sector (SA34 for top boot de-

vices and SA0 for bottom boot devices), the input on

WP# may determine what code is returned.

1 Sector is protected from erasure. Programing opera-

tions within sector is still permitted.

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 byte or word,

on 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 tim-

ings. The device automatically provides internally gen-

erated program pulses and verify the programmed cell

margin. The Command Definitions take shows the ad-

dress and data requirements for the byte program com-

mand sequence.

When the Embedded Program algorithm is complete,

the device then returns to reading array data 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#. See “Write Operation Status” for in-

formation 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-

ming operation. The program command sequence

should be reinitiated once the device resets to reading

array data, to ensure data integrity.

Programming is allowed in any sequence and across

sector boundaries. A bit cannot be programmed

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

the operation and set DQ5 to “1”, or cause the Data#

Polling algorithm to indicate the operation was suc-

cessful. However, a succeeding read shows 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 9 on page 22 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 data

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

device then returns to the read mode.

16Kb Sector

Protection

WP#

input

Autoselect

Code

protected

VIH

01 (protected)

protected

VIL

01 (protected)

unprotected

VIH

00 (unprotected)

unprotected

VIL

01 (protected)1

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