AT25128B/AT25256B
Pin Description
2.5
2.6
Serial Data Input (SI)
The Serial Data Input (SI) pin is used to transfer data into the device. It receives instructions, addresses
and data. Data is latched on the rising edge of the Serial Data Clock (SCK).
Serial Data Clock (SCK)
The Serial Data Clock (SCK) pin is used to synchronize the communication between a master and the
AT25128B/AT25256B. Instructions, addresses or data present on the Serial Data Input (SI) pin is latched
in on the rising edge of SCK, while output on the Serial Data Output (SO) pin is clocked out on the falling
edge of SCK.
2.7
Suspend Serial Input (HOLD)
The Suspend Serial Input (HOLD) pin is used in conjunction with the Chip Select (CS) pin to pause the
AT25128B/AT25256B. When the device is selected and a serial sequence is underway, HOLD can be
used to pause the serial communication with the master device without resetting the serial sequence. To
pause, the HOLD pin must be brought low while the Serial Data Clock (SCK) pin is low. To resume serial
communication, the HOLD pin is brought high while the SCK pin is low (SCK may still toggle during
HOLD). Inputs to the Serial Data Input (SI) pin will be ignored while the Serial Data Output (SO) pin will
be in the high‑impedance state.
2.8
Device Power Supply (VCC)
The Device Power Supply (VCC) pin is used to supply the source voltage to the device. Operations at
invalid VCC voltages may produce spurious results and should not be attempted.
DS20006193A-page 6
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