Service manual

CONFIDENTIAL – DO NOT COPY
Page 8-31
File No. SG-0176
BUS OPERATION--2
Notes:
1.Code=00h means unprotected, or code=01h protected.
2.Code=99 means factory locked, or code=19h not factory locked.
WRITE COMMANDS/COMMAND SEQUENCES
To program data to the device or erase sectors of memory , the system must drive WE and
CE to VIL, and OE to VIH.
An erase operation can erase one sector, multiple sectors , or the entire device. A "sector
address" consists of the address bits required to uniquely select a sector. Writing specific
address and data commands or sequences into the command register initiates device
operations. Table A defines the valid register command sequences. Writing incorrect address
and data values or writing them in the improper sequence resets the device to reading array
data. Section has details on erasing a sector or the entire chip, or suspending/resuming the
erase operation.
After the system writes the Automatic Select command sequence, the device enters the
Automatic Select mode. The system can then read Automatic Select codes from the internal
register (which is separate from the memory array) on Q7-Q0. Standard read cycle timings
apply in this mode. Refer to the Automatic Select Mode and Automatic Select Command
Sequence section for more information.
ICC2 in the DC Characteristics table represents the active current specification for the write
mode. The "AC Characteristics" section contains timing specification table and timing
diagrams for write operations.