S-25A010A Datasheet, PDF (20/35 Pages) Seiko Instruments Inc – Write protect function during the low power supply voltage

FOR AUTOMOTIVE 125°C OPERATION SPI SERIAL E²PROM
S-25A010A/020A/040A
Rev.5.2_01
7. Write memory data (WRITE)
Figure 18 and Figure 19 show 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 16 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 20 and Figure 21. 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).
4 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 16 bytes, the higher bits in the address do not change. And 4 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
• WP pin is set to "L"
To cancel the WRITE instruction, input the clock different from a specified value (n = 16 + m × 8 clock) while CS is
in "L".
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