D A T A S H E E T
I
in the “DC Characteristics” section on page 54
ming algorithm. However, the autoselect codes can
also be accessed in-system through the command
register.
CC2
represents the active current specification for the write
mode. The AC Characteristics section contains timing
specification tables and timing diagrams for write oper-
ations.
When using programming equipment, the autoselect
mode requires V on address pin A9. Address pins
ID
must be as shown in Table 3, “Autoselect Codes (High
Voltage Method),” on page 15. In addition, when verify-
ing sector protection, the sector address must appear
on the appropriate highest order address bits (see
Table 4, “Am29BDS128H Boot Sector/Sector Block
Addresses for Protection/Unprotection,” on page 16).
Table 3 shows the remaining address bits that are
don’t care. When all necessary bits have been set as
required, the programming equipment may then read
the corresponding identifier code on DQ15–DQ0.
However, the autoselect codes can also be accessed
in-system through the command register, for instances
when the device is erased or programmed in a system
without access to high voltage on the A9 pin. The com-
mand sequence is illustrated in Table 20, “Memory
Array Command Definitions,” on page 46. Note that if a
Bank Address (BA) is asserted during the third write
cycle of the autoselect command, the host system can
read autoselect data that bank and then immediately
read array data from the other bank, without exiting the
autoselect mode.
Accelerated Program Operation
The device offers accelerated program operations
through the ACC function. ACC is primarily intended to
allow faster manufacturing throughput at the factory.
If the system asserts V on this input, the device auto-
HH
matically enters the aforementioned Unlock Bypass
mode and uses the higher voltage on the input to
reduce the time required for program operations. The
system would use a two-cycle program command
sequence as required by the Unlock Bypass mode.
Removing V from the ACC input returns the device
HH
to normal operation. Note that sectors must be
unlocked prior to raising ACC to V . Note that the
HH
ACC pin must not be at V for operations other than
HH
accelerated programming, or device damage may
result. In addition, the ACC pin must not be left floating
or unconnected; inconsistent behavior of the device
may result.
When at V , ACC locks all sectors. ACC should be at
IL
V
for all other conditions.
IH
To access the autoselect codes in-system, the host
system can issue the autoselect command via the
command register, as shown in Table 20, “Memory
Array Command Definitions,” on page 46. This method
Autoselect Mode
The autoselect mode provides manufacturer and de-
vice identification, and sector protection verification,
through identifier codes output from the internal regis-
ter (which is separate from the memory array) on
DQ15–DQ0. This mode is primarily intended for pro-
gramming equipment to automatically match a device
to be programmed with its corresponding program-
does not require V . Autoselect mode may only be en-
ID
tered and used when in the asynchronous read mode.
Refer to the “Autoselect Command Sequence” section
on page 36 for more information.
14
Am29BDS128H/Am29BDS640H
27024B3 May 10, 2006
SPANSION [ SPANSION ]
