S-25A640A Datasheet, PDF (18/32 Pages) Seiko Instruments Inc – Function to prevent malfunction by monitoring clock pulse

FOR AUTOMOTIVE 125°C OPERATION SPI SERIAL E²PROM
S-25A640A, S-25A640B
Rev.3.2_01
7. Write memory data (WRITE)
Figure 17 shows the timing chart when inputting 1-byte data. Input the instruction code, the address and data from
serial data input (SI) after inputting "L" to the chip select ( CS ). To start WRITE (tPR), set the chip select ( CS ) to "H"
after inputting data or before inputting a rising of the next serial clock. Bit WIP and WEL are reset to "0" when write
has completed.
This IC can Page write of 32 bytes. Its function to transmit data is as same as Byte write basically, but it operates
Page write by receiving sequential 8-bit write data as much data as page size has. Input the instruction code, the
address and data from serial data input (SI) after inputting “L” in CS , as the WRITE operation (page) shown in
Figure 18. Input the next data while keeping CS in “L”. After that, repeat inputting data of 8-bit sequentially. At the
end, by setting CS to “H”, the WRITE operation starts (tPR).
5 of the lower bits in the address are automatically incremented every time when receiving write data of 8-bit. Thus,
even if write data exceeds 32 bytes, the higher bits in the address do not change. And 5 of lower bits in the address
roll over so that write data which is previously input is overwritten.
These are cases when the WRITE instruction is not accepted or operated.
• Bit WEL is not set to "1" (not set to "1" beforehand immediately before the WRITE instruction)
• During WRITE operation
• The address to be written is in the protect area by BP1 and BP0
To cancel the WRITE instruction, input the clock different from a specified value (n = 24 + m × 8 clock) while CS is
in "L".
CS
WP
High / Low
SCK
SI
1 2 3 4 5 6 7 8 9 10 11 21 22 23 24 25 26 27 28 29 30 31 32
Instruction
16-bit Address
Data Byte 1
A15 A14 A13 A3 A2 A1 A0 D7 D6 D5 D4 D3 D2 D1 D0
High-Z
SO
Remark The higher addresses A15 to A13 = Don't care.
Figure 17 WRITE Operation (1 Byte)
18