CAT25640 Datasheet, PDF (7/16 Pages) Catalyst Semiconductor – 64-Kb SPI Serial CMOS EEPROM

Byte Write
Once the WEL bit is set, the user may execute a write
sequence, by sending a WRITE instruction, a 16-bit
address and data as shown in Figure 4. Only 13
significant address bits are used by the CAT25640.
The rest are don’t care bits, as shown in Table 5.
Internal programming will start after the low to high C¯¯S
transition. During an internal write cycle, all
commands, except for RDSR (Read Status Register)
will be ignored. The ¯R¯D¯Y¯ bit will indicate if the internal
write cycle is in progress (¯R¯D¯Y¯ high), or the the
device is ready to accept commands (¯R¯D¯Y¯ low).
CAT25640
Page Write
After sending the first data byte to the CAT25640, the
host may continue sending data, up to a total of 64
bytes, according to timing shown in Figure 5. After
each data byte, the lower order address bits are
automatically incremented, while the higher order
address bits (page address) remain unchanged. If
during this process the end of page is exceeded, then
loading will “roll over” to the first byte in the page, thus
possibly overwriting previoualy loaded data. Following
completion of the write cycle, the CAT25640 is
automatically returned to the write disable state.
Table 5. Byte Address
Device
CAT25640
Address Significant Bits
A12 - A0
Address Don't Care Bits
A15 - A13
# Address Clock Pulses
16
Figure 4. Byte WRITE Timing
CS
SCK
012345678
21 22 23 24 25 26 27 28 29 30 31
OPCODE
BYTE ADDRESS*
DATA IN
SI
0 0 0 0 0 0 1 0 ^AN
A0 _{D7 D6 D5 D4 D3 D2 D1 D0}
SO
HIGH IMPEDANCE
* Please check the Byte Address Table (Table 5)
Note: Dashed Line = mode (1, 1) - - - - - -
Figure 5. Page WRITE Timing
CS
SCK
SI
012345678
21 22 23 24-31 32-39 ^{24+(N-1)x8-1..24+(N-1)x8 24+Nx8-1}
OPCODE
00 00 00
BYTE ADDRESS*
DATA IN
1 0 A_N
Data Data Data
A_{0 Byte 1 Byte 2 Byte 3}
Data Byte N
7..1
0
HIGH IMPEDANCE
SO
*Please check the Byte Address Table. (Table 5)
Note: Dashed Line = mode (1, 1) - - - - - -
© Catalyst Semiconductor, Inc.
7
Characteristics subject to change without notice
Doc. No. MD-1128 Rev. B