W39L040 Winbond, W39L040 Datasheet - Page 5

• Manufacturer Part Number: W39L040
• Description: 512 K X 8 CMOS FLASH MEMORY
• Manufacturer: Winbond

W39L040
Logical Inhibit
Writing is inhibited by holding any one of #OE = V
, #CE = V
, or #WE = V
. To initiate a write cycle
IL
IH
IH
#CE and #WE must be a logical zero while #OE is a logical one.
Power-up Write and Read Inhibit
Power-up of the device with #WE = #CE = V
and #OE = V
will not accept commands on the rising
IL
IH
edge of #WE except 5mS delay (see the power up timing in AC Characteristics). The internal state
machine is automatically reset to the read mode on power-up.
Command Definitions
Device operations are selected by writing specific address and data sequences into the command
register. Writing incorrect address and data values or writing them in the improper sequence will reset
the device to the read mode. "Command Definitions" defines the valid register command sequences.
Read Command
The device will automatically power-up in the read state. In this case, a command sequence is not
required to read data. Standard microprocessor read cycles will retrieve array data. This default value
ensures that no spurious alteration of the memory content occurs during the power transition.
The device will automatically returns to read state after completing an Embedded Program or
Embedded Erase algorithm.
Refer to the AC Read Characteristics and Waveforms for the specific timing parameters.
Auto-select Command
Flash memories are intended for use in applications where the local CPU can alter memory contents.
As such, manufacture and device codes must be accessible while the device resides in the target
system. PROM programmers typically access the signature codes by raising A9 to a high voltage.
However, multiplexing high voltage onto the address lines is not generally a desirable system design
practice.
The device contains an auto-select command operation to supplement traditional PROM programming
methodology. The operation is initiated by writing the auto-select command sequence into the
command register. Following the command write, a read cycle from address XX00H retrieves the
manufacture code of DAH. A read cycle from address XX01H returns the device code (W39L040 =
B6hex).
To terminate the operation, it is necessary to write the auto-select exit command sequence into the
register.
Byte Program Command
The device is programmed on a byte-by-byte basis. Programming is a four-bus-cycle operation. The
program command 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. Addresses are latched on the falling edge of #CE or #WE, whichever happens
later and the data is latched on the rising edge of #CE or #WE, whichever happens first. The rising
edge of #CE or #WE (whichever happens first) begins programming using the Embedded Program
Publication Release Date: February 10, 2003
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Revision A3