LE28FV4001T-25 查看數據表（PDF） - SANYO -> Panasonic
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LE28FV4001T-25 Datasheet PDF : 14 Pages
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LE28FV4001M, T, R-20/25
Product Overview
The LE28FV4001M, LE28FV4001T, and LE28FV4001R are 524288-word × 8-bit flash memory products that provide
sector erase and byte programming functions. These flash memories can be erased and programmed using a 3.3-volt
single-voltage power supply, they conform to the JEDEC standards for byte-wide memory pin assignments, and are pin
compatible with industry standard EPROM, flash EPROM, and EEPROM memories.
The maximum byte programming time for the LE28FV4001M, LE28FV4001T, and LE28FV4001R is 35 µs, and the
maximum sector erase time is 4 ms. Optimization is possible using the toggle bit and Data polling functions, which
indicate the completion of the write cycle for both programming and erase operations. These products provide both
hardware and software protection functions to protect data from being overwritten unintentionally. These products
guarantee 10,000 rewrite cycles in sector units. Data is retained for at least 10 years.
The block diagram for these products as well as the pin assignments for the 40-pin TSOP and 32-pin SOP packages are
shown on page 2. The pin functions and command settings are listed on page 3.
Device Operation
Commands are provided to access the device memory operation functions. The commands are written to a command
register with standard microprocessor write timing. Commands are written by setting WE to the low level while CE is
held low. The address is latched on the falling edge of WE or CE, whichever falls last. Data is latched on the rising edge
of WE or CE, whichever rises first. However, during the software write protect sequence, the address is latched on the
rising edge of OE or CE, whichever rises first.
Command Definition
The Command Settings section on page 3 presents a list of the commands and an overview of their functions. This
section describes those functions in detail.
To execute the LE28FV4001M, LE28FV4001T, and LE28FV4001R byte program or erase function, the software protect
function must be executed first.
1. Sector erase operation
The sector erase operation consists of a setup command and an execute command. The setup command sets the
device to a state where all the bytes within the sector can be erased electrically. A sector has 256 bytes. Since almost
all applications use erase operations that are not whole chip erase operations but rather are single sector erase
operations, this sector erase operation significantly increases the flexibility and ease-of-use of the LE28F4001 Series.
The setup command is executed by writing 20H to the command register.
An execute command (DDH) must be written to the command register to execute the sector erase operation. The
sector erase operation starts on the rising edge of WE pulse and is automatically completed by an internal timer.
Figure 6 shows the timing and waveforms for this operation.
This two-stage sequence in which a setup command and a following execute command are required guarantees that
the memory at the sector specified by the address data will not be erased accidentally.
2. Sector erase flowchart
The quick and reliable erasure of up to 256 bytes of memory can be achieved by following the sector erase flowchart
shown in Figure 1. The whole operation consists of executing two commands. A sector erase operation completes in
a maximum of 4 ms. Although the erase operation can be terminated by executing a reset operation, the sector may
not be completely erased if that reset is executed before the 4 ms time-out period elapses. The erase command can be
re-executed as many times as required before the erase completes. Excessive erasure cannot cause problems with the
LE28FV4001 Series products.
No. 5468-4/14
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