W25Q128BV
4. PIN DESCRIPTIONS
4.1 Chip Select (/CS)
The SPI Chip Select (/CS) pin enables and disables device operation. When /CS is high the device is
deselected and the Serial Data Output (DO, or IO0, IO1, IO2, IO3) pins are at high impedance. When
deselected, the devices power consumption will be at standby levels unless an internal erase, program or
write status register cycle is in progress. When /CS is brought low the device will be selected, power
consumption will increase to active levels and instructions can be written to and data read from the device.
After power-up, /CS must transition from high to low before a new instruction will be accepted. The /CS
input must track the VCC supply level at power-up (see “Write Protection” and Figure 38). If needed a pull-
up resister on /CS can be used to accomplish this.
4.2 Serial Data Input, Output and IOs (DI, DO and IO0, IO1, IO2, IO3)
The W25Q128BV supports standard SPI, Dual SPI and Quad SPI operation. Standard SPI instructions
use the unidirectional DI (input) pin to serially write instructions, addresses or data to the device on the
rising edge of the Serial Clock (CLK) input pin. Standard SPI also uses the unidirectional DO (output) to
read data or status from the device on the falling edge of CLK.
Dual and Quad SPI instructions use the bidirectional IO pins to serially write instructions, addresses or
data to the device on the rising edge of CLK and read data or status from the device on the falling edge of
CLK. Quad SPI instructions require the non-volatile Quad Enable bit (QE) in Status Register-2 to be set.
When QE=1, the /WP pin becomes IO2 and /HOLD pin becomes IO3.
4.3 Write Protect (/WP)
The Write Protect (/WP) pin can be used to prevent the Status Register from being written. Used in
conjunction with the Status Register’s Block Protect (CMP, SEC, TB, BP2, BP1 and BP0) bits and Status
Register Protect (SRP) bits, a portion as small as a 4KB sector or the entire memory array can be
hardware protected. The /WP pin is active low. When the QE bit of Status Register-2 is set for Quad I/O,
the /WP pin function is not available since this pin is used for IO2. See Figure 1a-c for the pin
configuration of Quad I/O operation.
4.4 HOLD (/HOLD)
The /HOLD pin allows the device to be paused while it is actively selected. When /HOLD is brought low,
while /CS is low, the DO pin will be at high impedance and signals on the DI and CLK pins will be ignored
(don’t care). When /HOLD is brought high, device operation can resume. The /HOLD function can be
useful when multiple devices are sharing the same SPI signals. The /HOLD pin is active low. When the
QE bit of Status Register-2 is set for Quad I/O, the /HOLD pin function is not available since this pin is
used for IO3. See Figure 1a-c for the pin configuration of Quad I/O operation.
4.5 Serial Clock (CLK)
The SPI Serial Clock Input (CLK) pin provides the timing for serial input and output operations. ("See SPI
Operations")
Publication Release Date: April 01, 2011
- 9 -
Revision E
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