S-25A640A Datasheet, PDF (12/32 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
 Pin Functions
1. CS (chip select input) pin
This is an input pin to set a chip in the select status. In the "H" input level, this IC is in the non-select status and its
output is "High-Z". This IC is in standby as long as it is not in write inside. This IC goes in active by setting the chip
select to "L". Input any instruction code after power-on and a falling of chip select.
2. SI (serial data input) pin
This pin is to input serial data. This pin receives an instruction code, an address and write data. This pin latches data
at rising edge of serial clock.
3. SO (serial data output) pin
This pin is to output serial data. The data output changes at falling edge of serial clock.
4. SCK (serial clock input) pin
This is a clock input pin to set the timing of serial data. An instruction code, an address and write data are received at
a rising edge of clock. Data is output during falling edge of clock.
5. WP (write protect input) pin
Write protect is purposed to protect the area size against the write instruction (BP1, BP0 in the status register). Fix
this pin "H" or "L" not to set it in the floating state.
Refer to " Protect Operation" for details.
6. HOLD (hold input) pin
This pin is used to pause serial communications without setting this IC in the non-select status.
In the hold status, the serial output goes in "High-Z", the serial input and the serial clock go in "Don't care". During the
hold operation, be sure to set this IC in active by setting the chip select ( CS pin) to "L".
Refer to " Hold Operation" for details.
 Initial Delivery State
Initial delivery state of all addresses is "FFh".
Moreover, initial delivery state of the status register nonvolatile memory is as follows.
• SRWD = 0
• BP1 = 0
• BP0 = 0
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