S-25C256A

9

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Pin Functions

This is an input pin to set a chip in the select status. In the “H” input level, the device is in the non-select status and its

output is high impedance. The device is in standby as long as it is not in Write inside. The device 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 according to 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.

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 the device in the non-select status.

In the hold status, the serial output goes in high impedance, the serial input and the serial clock go in “Don’t care”.

During the hold operation, be sure to set the device in active by setting the chip select ( CS pin) to “L”.

Refer to “ Hold Operation” for details.

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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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S-25C256A Series adds 6 ECC bits for error correction to each 4 bytes with the same address of A14 to A2. The ECC

function can make correction and output correct data even if wrong data of 1 bit is in the 4 bytes when reading.

In addition, the S-25C256A Series rewrites the 4 bytes used as the rewriting minimum unit and 6 ECC bits if only 1 byte

data is input.

Therefore, it is recommended to rewrite data of each 4 bytes with the same address of A14 to A2 in order to get the

maximum endurance in the application in which the data is rewrote frequently.