LE25U20AMB
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4
Device Operation
The LE25U20AMB features electrical on-chip erase functions using a single 2.5 V power supply, that have been
added to the EPROM functions of the industry standard that support serial interfaces. Interfacing and control are
facilitated by incorporating the command registers inside the chip. The read, erase, program and other required
functions of the device are executed through the command registers. The command addresses and data input in
accordance with "Table 2 Command Settings" are latched inside the device in order to execute the required
operations. "Figure 3 Serial Input Timing" shows the timing waveforms of the serial data input. First, at the falling
CS
edge the device is selected, and serial input is enabled for the commands, addresses, etc. These inputs are
introduced internally in sequence starting with bit 7 in synchronization with the rising SCK edge. At this time,
output pin SO is in the high-impedance state. The output pin is placed in the low-impedance state when the data is
output in sequence starting with bit 7 synchronized to the falling clock edge during read, status register read and
silicon ID. Refer to "Figure 4 Serial Output Timing" for the serial output timing.
The LE25U20AMB supports both serial interface SPI mode 0 and SPI mode 3. At the falling CS
edge, SPI mode 0
is automatically selected if the logic level of SCK is low, and SPI mode 3 is automatically selected if the logic level
of SCK is high.
Table 2 Command Settings
Command 1st bus cycle 2nd bus cycle 3rd bus cycle 4th bus cycle 5th bus cycle 6th bus cycle Nth bus cycle
Read
03h A23-A16 A15-A8 A7-A0
0Bh A23-A16 A15-A8 A7-A0 X
Small sector erase
D7h/20h A23-A16 A15-A8 A7-A0
Sector erase
D8h A23-A16 A15-A8 A7-A0
Chip erase
C7h
Page program
02h A23-A16 A15-A8 A7-A0 PD * PD * PD *
Write enable
06h
Write disable
04h
Power down
B9h
Status register read
05h
Status register write
01h DATA
Read silicon ID 1
9Fh
Read silicon ID 2
ABh X X X
Exit power down mode
ABh
Explanatory notes for Table 2
"X" signifies "don't care" (that is to say, any value may be input).
The "h" following each code indicates that the number given is in hexadecimal notation.
Addresses A23 to A18 for all commands are "Don't care".
In order for commands other than the read command to be recognized, CS
must rise after all the bus cycle input.
*: "PD" stands for page program data.
