Table 4. Sector Group Addresses
A20
0
A19
0
A18
0
Sectors
SGA0
SGA1
SGA2
SGA3
SGA4
SGA5
SGA6
SGA7
SA0–SA3
0
0
1
SA4–SA7
0
1
0
SA8–SA11
SA12–SA15
SA16–SA19
SA20–SA23
SA24–SA27
SA28–SA31
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
Write
Device erasure and programming are accomplished
via the command register. The contents of the register
serve as inputs to the internal state machine. The state
machine outputs dictate the function of the device.
It is possible to determine if a sector group is protected
in the system by writing an Autoselect command. Per-
forming a read operation at the address location
XX02H, where the higher order address bits A18, A19,
and A20 is the desired sector group address, will pro-
duce a logical “1” at DQ0 for a protected sector group.
See Table 2 for Autoselect codes.
The command register itself does not occupy any ad-
dressable memory location. The register is a latch used
to store the commands, along with the address and
data information needed to execute the command. The
command register is written to by bringing WE to VIL,
while CE is at VIL and OE is at VIH. Addresses are
latched on the falling edge of WE or CE, whichever
happens later; while data is latched on the rising edge
of WE or CE, whichever happens first. Standard micro-
processor write timings are used.
Temporary Sector Group Unprotect
This feature allows temporary unprotection of previ-
ously protected sector groups of the Am29F016 device
in order to change data in-system. The Sector Group
Unprotect mode is activated by setting the RESET pin
to high voltage (12V). During this mode, formerly pro-
tected sector groups can be programmed or erased by
selecting the sector group addresses. Once the 12 V is
taken away from the RESET pin, all the previously pro-
tected sector groups will be protected again. Refer to
Figures 15 and 16.
Refer to AC Write Characteristics and the Erase/Pro-
gramming Waveforms for specific timing parameters.
Sector Group Protection
The Am29F016 features hardware sector group protec-
tion. This feature will disable both program and erase
operations in any combination of eight sector groups of
memory. Each sector group consists of four adjacent
sectors grouped in the following pattern: sectors 0–3,
4–7, 8–11, 12–15, 16–19, 20–23, 24–27, and 28–31
(see Table 4). The sector group protect feature is en-
abled using programming equipment at the user’s site.
The device is shipped with all sector groups unpro-
tected. Alternatively, AMD may program and protect
sector groups in the factory prior to shipping the device
(AMD’s ExpressFlash™ Service).
Command Definitions
Device operations are selected by writing specific ad-
dress and data sequences into the command register.
Writing incorrect address and data values or writ-
ing them in the improper sequence will reset the
device to the read mode. Table 5 defines the valid
register command sequences. Note that the Erase
Suspend (B0H) and Erase Resume (30H) commands
are valid only while the Sector Erase operation is in
progress. Moreover, both Reset/Read commands are
functionally equivalent, resetting the device to the read
mode.
Am29F016
11
AMD [ AMD ]
