AM29LV200 AMD [Advanced Micro Devices], AM29LV200 Datasheet - Page 12

• Manufacturer Part Number: AM29LV200
• Description: 2 Megabit (256 K x 8-Bit/128 K x 16-Bit) CMOS 3.0 Volt-only Boot Sector Flash Memory
• Manufacturer: AMD [Advanced Micro Devices]

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.
Table 5 shows the address and data requirements.
This method is an alternative to that shown in Table 4,
which is intended for PROM programmers and requires
V
The autoselect command sequence is initiated by writ-
ing two unlock cycles, followed by the autoselect com-
mand. 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 unpro-
tected. Refer to Tables 2 and 3 for valid sector
addresses.
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 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 tim-
ings. The device automatically provides internally gen-
erated program pulses and verifies the programmed
cell margin. Table 5 shows the address and data re-
quirements for the byte program command 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 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-
ming operation. The program command sequence
should be reinitiated once the device has reset to read-
ing 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-
ID
on address bit A9.
P R E L I M I N A R Y
Am29LV200
cessful. However, a succeeding read will show that the
data is still “0”. Only erase operations can convert a “0”
to a “1”.
Figure 2 illustrates the algorithm for the program oper-
ation. See the Erase/Program Operations table in “AC
Characteristics” for parameters, and to Figure 16 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
cycles, followed by a set-up command. Two additional
unlock write cycles are then followed by the chip erase
command, which in turn invokes the Embedded Erase
algorithm. The device does not require the system to
preprogram prior to erase. The Embedded Erase algo-
rithm automatically preprograms and verifies the entire
memory for an all zero data pattern prior to electrical
erase. The system is not required to provide any con-
trols or timings during these operations. Table 5 shows
the address and data requirements for the chip erase
command sequence.
Note: See Table 5 for program command sequence.
Increment Address
Figure 2. Program Operation
in progress
Embedded
algorithm
Program
No
Command Sequence
Write Program
Last Address?
Programming
from System
Verify Data?
Completed
Data Poll
START
Yes
Yes
20513D-5
No
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