2. Pin Descriptions and Pinouts
Table 2-1. Pin Descriptions
Name and Function
CHIP SELECT: Asserting the CS pin selects the device. When the CS pin is deasserted, the
device will be deselected and normally be placed in standby mode (not Deep Power-Down mode),
and the SO pin will be in a high-impedance state. When the device is deselected, data will not be
accepted on the SI pin.
A high-to-low transition on the CS pin is required to start an operation, and a low-to-high transition
is required to end an operation. When ending an internally self-timed operation such as a program
or erase cycle, the device will not enter the standby mode until the completion of the operation.
SERIAL CLOCK: This pin is used to provide a clock to the device and is used to control the flow of
data to and from the device. Command, address, and input data present on the SI pin is always
latched on the rising edge of SCK, while output data on the SO pin is always clocked out on the
falling edge of SCK.
SERIAL INPUT: The SI pin is used to shift data into the device. The SI pin is used for all data input
including command and address sequences. Data on the SI pin is always latched on the rising
edge of SCK.
SERIAL OUTPUT: The SO pin is used to shift data out from the device. Data on the SO pin is
always clocked out on the falling edge of SCK.
WRITE PROTECT: The WP pin controls the hardware locking feature of the device. Please refer to
“Protection Commands and Features” on page 12 for more details on protection features and the
The WP pin is internally pulled-high and may be left floating if hardware controlled protection will
not be used. However, it is recommended that the WP pin also be externally connected to VCC
HOLD: The HOLD pin is used to temporarily pause serial communication without deselecting or
resetting the device. While the HOLD pin is asserted, transitions on the SCK pin and data on the SI
pin will be ignored, and the SO pin will be in a high-impedance state.
The CS pin must be asserted, and the SCK pin must be in the low state in order for a Hold
condition to start. A Hold condition pauses serial communication only and does not have an effect
on internally self-timed operations such as a program or erase cycle. Please refer to “Hold” on
page 27 for additional details on the Hold operation.
The HOLD pin is internally pulled-high and may be left floating if the Hold function will not be used.
However, it is recommended that the HOLD pin also be externally connected to VCC whenever
DEVICE POWER SUPPLY: The 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.
GROUND: The ground reference for the power supply. GND should be connected to the system