AM29SL160C datasheet(18/52 Pages) AMD

18 / 52 page

Am29SL160C

November 1, 2004

The primary method requires VID on the RESET# pin

only, and is implemented either in-system or via pro-

gramming equipment. Figure 1, on page 19 shows the

algorithms and Figure 24, on page 45 shows the timing

diagram. This method uses standard microprocessor

bus cycle timing. For sector unprotect, all unprotected

sectors must first be protected prior to the first sector

unprotect write cycle.

The alternate method intended only for programming

equipment requires VID on address pin A9 and OE#.

This method is compatible with programmer routines

written for earlier 3.0 volt-only AMD flash devices. Pub-

lication number 21622 contains further details. Contact

an AMD representative to request the document con-

taining further details.

The device is shipped with all sectors unprotected.

AMD offers the option of programming and protecting

sectors at its factory prior to shipping the device

through AMD’s ExpressFlash™ Service. Contact an

AMD representative for details.

It is possible to determine whether a sector is protected

or unprotected. See “Autoselect Mode” on page 16 for

details.

Write Protect (WP#)

The write protect function provides a hardware method

of protecting certain boot sectors without using VID.

This function is one of two provided by the WP#/ACC

pin.

If the system asserts VIL on the WP#/ACC pin, the

device disables program and erase functions in the two

“outermost” 8 Kbyte boot sectors independently of

whether those sectors were protected or unprotected

using the method described in “Sector/Sector Block

Protection and Unprotection” on page 17. The two out-

ermost 8 Kbyte boot sectors are the two sectors

containing the lowest addresses in a bottom-boot-con-

figured device, or the two sectors containing the

highest addresses in a top-boot-configured device.

If the system asserts VIH on the WP#/ACC pin, the

device reverts to whether the two outermost 8 Kbyte

boot sectors were last set to be protected or unpro-

tected. That is, sector protection or unprotection for

these two sectors depends on whether they were last

protected or unprotected using the method described

in “Sector/Sector Block Protection and Unprotection”

on page 17.

Note that if the system asserts VHH on the WP#/ACC

pin, all sectors, including the two outermost sectors,

are unprotected. VHH is intended for accelerated in-

system programming of the device during system pro-

duction. It is advisable, therefore, not to assert VHH on

this pin after the system has been placed in the field for

use. If faster programming is desired, the system may

use the unlock bypass program command sequence.

Temporary Sector Unprotect

This feature allows temporary unprotection of previ-

ously protected sectors to change data in-system. The

Sector Unprotect mode is activated by setting the

RESET# pin to VID. During this mode, formerly pro-

tected sectors can be programmed or erased by

selecting the sector addresses. Once VID is removed

from the RESET# pin, all the previously protected

sectors are protected again. Figure 2, on page 20

shows the algorithm, and Figure 22, on page 44 shows

the timing diagrams, for this feature.

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