W25Q256FVBIF-TR Datasheet, PDF (34/108 Pages) Winbond – 3V 256M-BIT SERIAL FLASH MEMORY WITH DUAL/QUAD SPI & QPI

W25Q256FV
/CS
CLK
IO₀
Mode 3
Mode 0
012345
Instruction
05h/35h/15h
40404
IO₁
51515
IO₂
62626
IO₃
73737
SR-1/2/3
out
SR-1/2/3
out
Figure 8b. Read Status Register Instruction (QPI Mode)
8.2.5 Write Status Register-1 (01h), Status Register-2 (31h) & Status Register-3 (11h)
The Write Status Register instruction allows the Status Registers to be written. The writable Status
Register bits include: SRP0, TB, BP[3:0] in Status Register-1; CMP, LB[3:1], QE, SRP1 in Status
Register-2; HOLD/RST, DRV1, DRV0, WPS & ADP in Status Register-3. All other Status Register bit
locations are read-only and will not be affected by the Write Status Register instruction. LB[3:1] are non-
volatile OTP bits, once it is set to 1, it cannot be cleared to 0.
To write non-volatile Status Register bits, a standard Write Enable (06h) instruction must previously have
been executed for the device to accept the Write Status Register instruction (Status Register bit WEL
must equal 1). Once write enabled, the instruction is entered by driving /CS low, sending the instruction
code “01h/31h/11h”, and then writing the status register data byte as illustrated in Figure 9a & 9b.
To write volatile Status Register bits, a Write Enable for Volatile Status Register (50h) instruction must
have been executed prior to the Write Status Register instruction (Status Register bit WEL remains 0).
However, SRP1 and LB[3:1] cannot be changed from “1” to “0” because of the OTP protection for these
bits. Upon power off or the execution of a Software/Hardware Reset, the volatile Status Register bit
values will be lost, and the non-volatile Status Register bit values will be restored.
During non-volatile Status Register write operation (06h combined with 01h/31h/11h), after /CS is driven
high, the self-timed Write Status Register cycle will commence for a time duration of tW (See AC
Characteristics). While the Write Status Register cycle is in progress, the Read Status Register
instruction may still be accessed to check the status of the BUSY bit. The BUSY bit is a 1 during the Write
Status Register cycle and a 0 when the cycle is finished and ready to accept other instructions again.
After the Write Status Register cycle has finished, the Write Enable Latch (WEL) bit in the Status Register
will be cleared to 0.
During volatile Status Register write operation (50h combined with 01h/31h/11h), after /CS is driven high,
the Status Register bits will be refreshed to the new values within the time period of tSHSL2 (See AC
Characteristics). BUSY bit will remain 0 during the Status Register bit refresh period.
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